HETEROCYCLIC DERIVATIVES

Abstract: The invention concerns a thiazole of the formula I, wherein Q¹ is an optionally substituted 6-membered monocyclic or 10-membered bicyclic heterocyclic moiety containing one or two nitrogen atoms; X is oxy, thio, sulphinyl, sulphonyl or imino; Ar is phenylene which may optionally bear one or two substituents, or Ar is an optionally substituted 6-membered heterocyclene moiety contining up to three nitrogen atoms; R¹ is hydrogen, (1-6C)alkyl, (2-6C)alkenyl, (2-6C)alkynyl or substituted (1-4C)alkyl; R² is hydrogen, (1-6C)alkyl, (3-6C)alkenyl, (3-6C)alkynyl or substituted (1-4C)alkyl or R² is optionally substituted benzoyl; and Q² is optionally substituted thiazolyl; or a pharmaceutically-acceptable salt thereof. The invention also concerns processes for the manufacture of a thiazole of the formula I and pharmaceutical compositions containing said thiazole.

Description: This invention concerns novel heterocyclic derivatives and more particularly novel thiazoles which are inhibitors of the enzyme 5-lipoxygenase (hereinafter referred to as 5-LO). The invention also concerns processes for the manufacture of said thiazoles and novel pharmaceutical compositions containing said thiazoles. Also included in the invention is the use of said thiazoles in the treatment of various inflammatory and/or allergic diseases in which the direct or indirect products of 5-LO catalysed oxidation of arachidonic acid are involved, and the production of new medicaments for such use. As stated above the thiazoles described hereinafter are inhibitors of 5-LO, which enzyme is known to be involved in catalysing the oxidation of arachidonic acid to give rise via a cascade process to the physiologically active leukotrienes such as leukotriene B₄ (LTB₄) and the peptido-lipid leukotrienes such as leukotriene C₄ (LTC₄) and leukotriene D₄ (LTD₄) and various metabolites. The biosynthetic relationship and physiological properties of the leukotrienes are summarised by G.W. Taylor and S.R. Clarke in Trends in Pharmacological Sciences , 1986, 7 , 100-103. The leukotrienes and their metabolites have been implicated in the production and development of various inflammatory and allergic diseases such as arthritic diseases, asthma, allergic rhinitis, atopic dermatitis, psoriasis, cardiovascular and cerebrovascular disorders and inflammatory bowel disease. In addition the leukotrienes are mediators of inflammatory diseases by virtue of their ability to modulate lymphocyte and leukocyte function. Other physiologically active metabolites of arachidonic acid, such as the prostaglandins and thromboxanes, arise via the action of the enzyme cyclooxygenase on arachidonic acid. We have now discovered that certain thiazoles are effective as inhibitors of the enzyme 5-LO and thus of leukotriene biosyntheses. Thus, such compounds are of value as therapeutic agents in the treatment of, for example, allergic conditions, psoriasis, asthma, cardiovascular and cerebrovascular disorders, and/or inflammatory and arthritic conditions, mediated alone or in part by one or more leukotrienes. According to the invention there is provided a thiazole of the formula I (set out hereinafter) wherein Q¹ is a 6-membered monocyclic or 10-membered bicyclic heterocyclic moiety containing one or two nitrogen atoms which may optionally bear one, two or three substituents selected from halogeno, hydroxy, oxo, cyano, (1-4C)alkyl, (1-4C)alkoxy, fluoro-(1-4C)alkyl, (1-4C)alkylamino-(1-4C)alkyl and di-[(1-4C)alkyl]amino-(1-4C)alkyl; wherein A is (1-6C)alkylene, (3-6C)alkenylene, (3-6C)alkynylene or cyclo(3-6C)alkylene; wherein X is oxy, thio, sulphinyl, sulphonyl or imino; wherein Ar is phenylene which may optionally bear one or two substituents selected from halogeno, hydroxy, amino, nitro, carboxy, cyano, carbamoyl, (1-4C)alkyl, (1-4C)alkoxy, (1-4C)alkylthio, (1-4C)alkylsulphinyl, (1-4C)alkylsulphonyl, (1-4C)alkylamino, di-[(1-4C)alkyl]amino, (1-4C)alkoxycarbonyl, N-[(1-4C)alkyl]carbamoyl, N,N-di-[(1-4C)alkyl]carbamoyl, (2-4C)alkanoylamino, hydroxy-(2-4C)alkoxy, (1-4C)alkoxy-(2-4C)alkoxy, amino-(2-4C)alkoxy, cyano-(1-4C)alkoxy, carbamoyl-(1-4C)alkoxy, N-[(1-4C)alkyl]carbamoyl-(1-4C)alkoxy, N,N-di-[(1-4C)alkyl]carbamoyl-(1-4C)alkoxy, (1-4C)alkylamino(2-4C)alkoxy, di-[(1-4C)alkyl]amino-(2-4C)alkoxy, (1-4C)alkoxycarbonyl-(1-4C)alkoxy, fluoro-(1-4C)alkyl, hydroxy-(1-4C)alkyl, amino-(1-4C)alkyl, cyano-(1-4C)alkyl, (1-4C)alkoxy-(1-4C)alkyl, (1-4C)alkylamino-(1-4C)alkyl, di-[(1-4C)alkyl]amino-(1-4C)alkyl and (2-4C)alkanoylamino-(1-4C)alkyl, or Ar is a 6-membered heterocyclene moiety containing up to three nitrogen atoms which may optionally bear one or two substituents selected from halogeno, hydroxy, amino, cyano, (1-4C)alkyl, (1-4C)alkoxy, (1-4C)alkylamino and di-[(1-4C)alkyl]amino; wherein R¹ is hydrogen, (1-6C)alkyl, (2-6C)alkenyl, (2-6C)alkynyl, fluoro-(1-4C)alkyl, cyano-(1-4C)alkyl, hydroxy-(1-4C)alkyl, (1-4C)alkoxy-(1-4C)alkyl and (2-4C)alkanoyloxy-(1-4C)alkyl; wherein R² is hydrogen, (1-6C)alkyl, (3-6C)alkenyl, (3-6C)alkynyl, (1-4C)alkoxycarbonyl-(1-4C)alkyl, carboxy-(1-4C)alkyl, carbamoyl-(1-4C)alkyl, cyano(1-4C)alkyl or (2-4C)alkanoyl or R² is benzoyl which may optionally bear a substituent selected from halogeno, (1-4C)alkyl and (1-4C)alkoxy; and wherein Q² is thiazolyl which may optionally bear one or two substituents selected from halogeno, amino, nitro, cyano, carbamoyl, (1-4C)alkyl, (1-4C)alkoxy, (1-4C)alkylamino, di-[(1-4C)alkyl]amino, (1-4C)alkoxycarbonyl, N-[(1-4C)alkyl]carbamoyl, N,N-di-[(1-4C)alkyl]carbamoyl, (2-4C)alkanoylamino, fluoro-(1-4C)alkyl and hydroxy(14C)alkyl; or a pharmaceutically-acceptable salt thereof. The chemical formulae referred to herein by Roman numerals are set out for convenience on a separate sheet hereinafter. In this specification the generic term "alkyl" includes both straight-chain and branched-chain alkyl groups. However references to individual alkyl groups such as "propyl" are specific for the straight-chain version only and references to individual branched-chain alkyl groups such as "isopropyl" are specific for the branched-chain version only. An analogous convention applies to other generic terms. It is to be understood that, insofar as certain of the compounds of formula I defined above may exist in optically active or racemic forms by virtue of one or more substituents containing an asymmetric carbon atom, the invention includes in its definition of active ingredient any such optically active or racemic form which possesses the property of inhibiting 5-LO. The synthesis of optically active forms may be carried out by standard techniques of organic chemistry well known in the art, for example by synthesis from optically active starting materials or by resolution of a racemic form. Similarly, inhibitory properties against 5-LO may be evaluated using the standard laboratory techniques referred to hereinafter. It is also to be understood that, insofar as certain of the compounds of the formula I as defined above may exhibit the phenomenon of tautomerism, for example a compound of the formula I wherein Q¹ bears an oxo or hydroxy substituent, and as any formula drawing presented herein may represent only one of the possible tautomeric forms the invention includes in its definition any tautomeric form of a compound of the formula I which possesses the property of inhibiting 5-LO and is not to be limited merely to any one tautomeric form utilised within the formulae drawings. Suitable values for the generic terms referred to above include those set out below. A suitable value for Q¹ when it is a 6-membered monocyclic or 10-membered bicyclic heterocyclic moiety containing one or two nitrogen atoms is, for example, pyridyl, pyridazinyl, pyrimidinyl, pyrazinyl, quinolyl, isoquinolyl, cinnolinyl, quinazolinyl, quinoxalinyl, phthalazinyl or naphthyridinyl, or a hydrogenated derivative thereof such as, for example, 1,2-dihydropyridyl or 1,2-dihydroquinolyl. The heterocyclic moiety may be attached through any available position including through any available nitrogen atom and it may bear a substituent on any available position including on any available nitrogen atom. When Q¹ is a 10-membered bicyclic heterocyclic moiety containing one or two nitrogen atoms it will be appreciated that Q¹ may be attached to A from either of the two rings of the bicyclic heterocyclic moiety. Conveniently Q¹ is, for example, 2-pyridyl, 3-pyridyl, 4-pyridyl, 3-pyridazinyl, 4-pyridazinyl, 2-pyrimidinyl, 4-pyrimidinyl, 5-pyrimidinyl, 2-pyrazinyl, 2-quinolyl, 3-quinolyl, 6-quinolyl, 7-quinolyl, 1-isoquinolyl, 3-isoquinolyl, 6-isoquinolyl, 7-isoquinolyl, 3-cinnolyl, 6-cinnolyl, 7-cinnolyl, 2-quinazolinyl, 4-quinazolinyl, 6-quinazolinyl, 7-quinazolinyl, 2-quinoxalinyl, 5-quinoxalinyl, 6-quinoxalinyl, 1-phthalazinyl, 6-phthalazinyl, 1,5-naphthyridin-2-yl, 1,5-naphthyridin-3-yl, 1,6-naphthyridin-3-yl, 1,6-naphthyridin-7-yl, 1,7-naphthyridin-3-yl, 1,7-naphthyridin-6-yl, 1,8-naphthyridin-3-yl, 2,6-naphthyridin-6-yl or 2,7-naphthyridin-3-yl. A suitable value for a halogeno substituent which may be present on Q¹, Ar, R² or Q² is, for example, fluoro, chloro, bromo or iodo. A suitable value for a (1-4C)alkyl substituent which may be present on Q¹, Ar, R² or Q² is, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl or sec -butyl. A suitable value for a (1-4C)alkoxy substituent which may be present on Q¹, Ar, R² or Q² is, for example, methoxy, ethoxy, propoxy, isopropoxy or butoxy. A suitable value for a fluoro-(1-4C)alkyl substituent which may be present on Q¹, Ar or Q², or for R¹ when it is fluoro-(1-4C)alkyl, is, for example, fluoromethyl, difluoromethyl, trifluoromethyl, 2-fluoroethyl, 2,2,2-trifluoroethyl and pentafluoroethyl. A suitable value for (1-4C)alkylamino-(1-4C)alkyl substituent which may be present on Q¹ is, for example, methylaminomethyl, 2-methylaminoethyl, 3-methylaminopropyl, ethylaminomethyl or 2-ethylaminoethyl; and for a di-[(1-4C)alkyl]amino-(1-4C)alkyl substituent is, for example, dimethylaminomethyl, 2-dimethylaminoethyl, 3-dimethylaminopropyl, diethylaminomethyl or 2-diethylaminoethyl. A suitable value for A when it is (1-6C)alkylene is, for example, methylene, ethylene, ethylidene, trimethylene, propylidene, tetramethylene or pentamethylene; when it is (3-6C)alkenylene is, for example, 1-propenylene, 2-methylprop-1-enylene, 3-methylprop-1-enylene, 1-butenylene or 2-butenylene; and when it is (3-6C)alkynylene is, for example, 1-propynylene, 3-methylprop-1-ynylene, 1-butynylene or 2-butynylene. A suitable value for A when it is cyclo(3-6C)alkylene is, for example, cyclopropylidene, 1,2-cyclopropylene, cyclopentylidene, 1,2-cyclopentylene, cyclohexylidene or 1,4-cyclohexylene. A suitable value for Ar when it is phenylene is, for example, 1,3-phenylene or 1,4-phenylene. A suitable value for Ar when it is a 6-membered heterocyclene moiety containing up to three nitrogen atoms is, for example, pyridylene, pyrimidinylene, pyridazinylene, pyrazinylene or 1,3,5-triazinylene. Conveniently Ar when it is a 6-membered heterocyclene moiety containing up to three nitrogen atoms is, for example, 2,4-, 2,5-, 3,5- or 2,6-pyridylene, 2,4-, 2,5- or 4,6-pyrimidinylene, 3,5- or 3,6-pyridazinylene or 2,5- or 2,6-pyrazinylene. Suitable values for substituents which may be present on Ar include, for example:- A suitable value for R¹ when it is (1-6C)alkyl is, for example, methyl, ethyl, propyl, butyl, pentyl or hexyl; when it is (2-6C)alkenyl is, for example, vinyl, allyl, 2-butenyl or 3-butenyl; when it is (2-6C)alkynyl is, for example, ethynyl, 1-propynyl, 2-propynyl, 1-butynyl or 2-butynyl; when it is cyano-(1-4C)alkyl is, for example, cyanomethyl, 2-cyanoethyl or 3-cyanopropyl; when it is hydroxy-(1-4C)alkyl is, for example, hydroxymethyl, 2-hydroxyethyl or 3-hydroxypropyl; when it is (1-4C)alkoxy-(1-4C)alkyl is, for example, methoxymethyl, 2-methoxyethyl, 3-methoxypropyl, ethoxymethyl, 2-ethoxyethyl or 3-ethoxypropyl; and when it is (2-4C)alkanoyloxy-(1-4C)alkyl is, for example, acetoxymethyl, 2-acetoxyethyl, 3-acetoxypropyl, propionyloxymethyl, 2-propionyloxyethyl or 3-propionyloxypropyl. A suitable value for R² when it is (1-6C)alkyl is, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec -butyl, pentyl or hexyl; when it is (3-6C)alkenyl is, for example allyl, 2-butenyl or 3-butenyl; when it is (3-6C)alkynyl is, for example 2-propynyl or 2-butynyl; and when it is (2-4C)alkanoyl is, for example, acetyl, propionyl or butyryl. A suitable value for R² when it is (1-4C)alkoxycarbonyl-(1-4C)alkyl is, for example, methoxycarbonylmethyl, 2-methoxycarbonylethyl, ethoxycarbonylmethyl or 2-ethoxycarbonylethyl; when it is carboxy-(1-4C)alkyl is, for example, carboxymethyl, 2-carboxyethyl or 3-carboxypropyl; when it is carbamoyl-(1-4C)alkyl is, for example, carbamoylmethyl, 2-carbamoylethyl or 3-carbamoylpropyl; and when it is cyano-(1-4C)alkyl is, for example, cyanomethyl, 2-cyanoethyl or 3-cyanopropyl. A suitable value for Q² when it is thiazolyl is 2-, 4- or 5- thiazolyl. Suitable values for substituents which may be present on Q² include, for example:- A suitable pharmaceutically-acceptable salt of a thiazole of the invention which is sufficiently basic is an acid-addition salt with, for example, an inorganic or organic acid, for example hydrochloric, hydrobromic, sulphuric, phosphoric, trifluoroacetic, citric or maleic acid. In addition a suitable pharmaceutically-acceptable salt of a thiazole of the invention which is sufficiently acidic (for example a thiazole of the invention which contains a carboxy group) is an alkali metal salt, for example a sodium or potassium salt, an alkaline earth metal salt, for example a calcium or magnesium salt, an ammonium salt or a salt with an organic base which affords a physiologically-acceptable cation, for example a salt with methylamine, dimethylamine, trimethylamine, piperidine, morpholine or tris-(2-hydroxyethyl)amine. Particular novel compounds of the invention are, for example, thiazoles of the formula I wherein:- (a) Q¹ is 2-pyridyl, 3-pyridyl, 3-pyridazinyl, 2-pyrimidinyl or 2-pyrazinyl which may optionally bear one substituent selected from chloro, hydroxy, cyano, methyl, methoxy and trifluoromethyl; and A, X, Ar, R¹, R² and Q² and have any of the meanings defined hereinbefore; (b) Q¹ is 2-pyridyl, 3-pyridyl, 4-pyridyl, 2-pyrimidinyl or 2-pyrazinyl; A is 1-propenylene or 1-propynylene; and X is oxy; and Ar, R¹, R² and Q² have any of the meanings defined hereinbefore; (c) Q¹ is 2-quinolyl, 3-quinolyl, 6-quinolyl, 7-quinolyl, 3-isoquinolyl, 6-isoquinolyl, 7-isoquinolyl, 3-cinnolyl, 2-quinazolinyl 6-quinazolinyl, 2-quinoxalinyl, 6-quinoxalinyl, 6-phthalazinyl, 1,7-naphthyridin-3-yl, 1-7-naphthyridin-6-yl, 1,8-naphthyridin-3-yl or 2,7-naphthyridin-3-yl which may optionally bear one or two substituents selected from chloro, hydroxy, oxo, cyano, methyl, methoxy and trifluoromethyl; and A, X, Ar, R¹, R² and Q² have any of the meanings defined hereinbefore; (d) Q¹ is 1,2-dihydro-2-oxoquinolin-3-yl, 1,2-dihydro-2-oxoquinolin-6-yl, 1,2-dihydro-2-oxoquinolin-7-yl, 3,4-dihydro-4-oxoquinazolin-6-yl, 1,2-dihydro-2-oxo-1,7-naphthyridin-3-yl or 1,2-dihydro-2-oxo-1,8-naphthyridin-3-yl which may optionally bear one or two substituents selected from chloro, cyano, methyl, methoxy and trifluoromethyl; and A, X, Ar, R¹, R² and Q² and have any of the meanings defined hereinbefore; (e) Q¹ is 1,2-dihydro-2-oxoquinolin-3-yl or 1,2-dihydro-2-oxoquinolin-6-yl which may optionally bear one or two substituents selected from fluoro, chloro, methyl, ethyl, methoxy, trifluoromethyl, 2-fluoroethyl and 2-dimethylaminoethyl; A is methylene; and X is oxy; and Ar, R¹, R² and Q² have any of the meanings defined hereinbefore; (f) A is methylene, ethylene, trimethylene, 1-propenylene, 2-methylprop-1-enylene or 1-propynylene and Q¹, X, Ar, R¹, R² and Q² have any of the meanings defined hereinbefore; (g) X is oxy and Q¹, A, Ar, R¹, R² and Q² have any of the meanings defined hereinbefore; (h) Ar is 1,3-phenylene or 1,4-phenylene which may optionally bear one substituent selected from chloro, bromo, hydroxy, amino, nitro, methyl, methoxy, methylthio, methylsulphinyl, methylsulphonyl, methylamino, dimethylamino, trifluoromethyl, acetamido, cyanomethoxy and carbamoylmethoxy; and Q¹, A, X, R¹, R² and Q² have any of the meanings defined hereinbefore; (i) Ar is 1,3-phenylene or 1,4-phenylene which may optionally bear one substituent selected from fluoro, chloro, hydroxy, amino, methoxy and trifluoromethyl; and Q¹, A, X, R¹, R² and Q² have any of the meanings defined hereinbefore; (j) Ar is 2,4-, 2,5-, 3,5- or 2,6-pyridylene or 4,6-pyrimidinylene which may optionally bear one substituent selected from chloro, methyl and methoxy; and Q¹, A, X, R¹, R² and Q² have any of the meanings defined hereinbefore; (k) Ar is 3,5-pyridylene; and Q¹, A, X, R¹, R² and Q² have any of the meanings defined hereinbefore; (l) R¹ is hydrogen, methyl, ethyl, propyl, vinyl, ethynyl, 1-propynyl, trifluoromethyl, hydroxymethyl, methoxymethyl or acetoxymethyl; and Q¹, A, X, Ar, R² and Q² have any of the meanings defined hereinbefore; (m) R¹ is methyl or ethyl; and Q¹, A, X, Ar, R² and Q² have any of the meanings defined hereinbefore; (n) R² is hydrogen, methyl, ethyl, allyl, 2-propynyl or cyanomethyl; and Q¹, A, X, Ar, R¹ and Q² have any of the meanings defined hereinbefore; or (o) R² is methyl, ethyl or allyl; and Q¹, A, X, Ar, R¹ and Q² have any of the meanings defined hereinbefore; (p) Q² is 2- or 4-thiazolyl; and Q¹, A, X, Ar, R¹ and R² have any of the meanings defined hereinbefore; (g) Q² is 2-thiazolyl; and Q¹, A, X, Ar, R¹ and R² have any of the meanings defined hereinbefore; or a pharmaceutically-acceptable salt thereof. A particular compound of the invention comprises a thiazole of the formula I wherein Q¹ is pyridyl, pyrimidinyl, pyrazinyl, quinolyl, isoquinolyl, quinazolinyl or quinoxalinyl which may optionally bear one, two or three substituents selected from fluoro, chloro, hydroxy, oxo, methyl, ethyl, methoxy, trifluoromethyl, 2-fluoroethyl and 2-dimethylaminoethyl; wherein A is methylene, 1-propenylene or 1-propynylene; wherein X is oxy; wherein Ar is 1,3-phenylene or 1,4-phenylene which may optionally bear one substituent selected from fluoro, chloro, hydroxy, amino, nitro, methyl, methoxy and trifluoromethyl, or Ar is 3,5-pyridylene; wherein R¹ is methyl or ethyl; wherein R² is hydrogen, methyl, ethyl or allyl; and Q² is 2-thiazolyl; or a pharmaceutically acceptable salt thereof. A further particular compound of the invention comprises a thiazole of the formula I wherein Q¹ is 2-pyridyl, 3-pyridyl, 3-pyridazinyl, 2-pyrimidinyl or 2-pyrazinyl which may optionally bear one substituent selected from chloro, hydroxy, cyano, methyl, methoxy and trifluoromethyl; or Q¹ is 2-quinolyl, 3-quinolyl, 6-quinolyl, 7-quinolyl, 3-isoquinolyl, 6-isoquinolyl, 7-isoquinolyl, 3-cinnolyl, 2-quinazolinyl, 6-quinazolinyl, 2-quinoxalinyl, 6-quinoxalinyl, 6-phthalazinyl, 1,7-naphthyridin-3-yl, 1,7-naphthyridin-6-yl, 1,8-naphthyridin-3-yl or 2,7-naphthyridin-3-yl which may optionally bear one or two substituents selected from chloro, hydroxy, oxo, cyano, methyl, methoxy and trifluoromethyl; or Q¹ is 1,2-dihydro-2-oxoquinolin-3-yl, 1,2-dihydro-2-oxoquinolin-6-yl, 1,2-dihydro-2-oxoquinolin-7-yl, 3,4-dihydro-4-oxoquinazolin-6-yl, 1,2-dihydro-2-oxo-1,7-naphthyridin-3-yl or 1,2-dihydro-2-oxo-1,8-naphthyridin-3-yl which may optionally bear one or two substituents selected from chloro, cyano, methyl, methoxy and trifluoromethyl; wherein A is methylene, ethylene, trimethylene, 1-propenylene, 2-methylprop-1-enylene or 1-propynylene; wherein X is oxy; wherein Ar is 1,3-phenylene or 1,4-phenylene which may optionally bear one substituent selected from chloro, bromo, hydroxy, amino, nitro, methyl, methoxy, methylthio, methylsulphinyl, methylsulphonyl, methylamino, dimethylamino, trifluoromethyl, acetamido, cyanomethoxy and carbamoylmethoxy; wherein Ar is 2,4-, 2,5-, 3,5- or 2,6-pyridylene or 4,6-pyrimidinylene which may optionally bear one substituent selected from chloro, methyl and methoxy; wherein R¹ is hydrogen, methyl, ethyl, propyl, vinyl, ethynyl, 1-propynyl, trifluoromethyl, hydroxymethyl, methoxymethyl or acetoxymethyl; wherein R² is hydrogen, methyl, ethyl, allyl, 2-propynyl or cyanomethyl; and wherein Q² is 2-thiazolyl; or a pharmaceutically-acceptable salt thereof. A further preferred compound of the invention comprises a thiazole of the formula I wherein Q¹ is 2-quinolyl, 3-quinolyl, 6-quinolyl, 3-isoquinolyl, 2-quinazolinyl, 6-quinazolinyl, 6-quinoxalinyl, 1,2-dihydro-2-oxoquinolin-3-yl or 1,2-dihydro-2-oxoquinolin-6-yl which may optionally bear one or two substituents selected from fluoro, chloro, hydroxy, methyl and 2-dimethylaminoethyl; wherein A is methylene; wherein X is oxy; wherein Ar is 1,3-phenylene or 1,4-phenylene which may optionally bear one substituent selected from fluoro and methoxy, or Ar is 3,5-pyridylene; wherein R¹ is methyl or ethyl; wherein R² is methyl; and wherein Q² is 2-thiazolyl; or a pharmaceutically-acceptable salt thereof. A preferred compound of the invention comprises a thiazole of the formula I wherein Q¹ is 2-pyridyl, 3-pyridyl, 4-pyridyl, 2-pyrimidinyl, 2-pyrazinyl or 1-isoquinolyl, wherein A is 1-propenylene or 1-propynylene; wherein X is oxy; wherein Ar is 1,3-phenylene or 1,4-phenylene which may optionally bear one substituent selected from fluoro and methoxy, or Ar is 3,5-pyridylene; wherein R¹ is methyl or ethyl; wherein R² is methyl; and wherein Q² is 2-thiazolyl; or a pharmaceutically-acceptable salt thereof. Specific especially preferred compounds of the invention include, for example, the following thiazoles of the formula I, or a pharmaceutically-acceptable salt thereof :- 2-[1-[3-(3-isoquinolylmethoxy)phenyl]-1-methoxypropyl]thiazole, 2-[1-[3-(3-(2-pyridyl)prop-2-yn-1-yloxy)phenyl]-1-methoxypropyl]thiazole, 2-[1-[3-(3-(3-pyridyl)prop-2-yn-1-yloxy)phenyl]-1-methoxypropyl]thiazole, 2-[1-[3-(3-(3-pyridyl)prop-2-yn-1-yloxy)phenyl]-1-methoxyethyl]thiazole, 2-[1-methoxy-1-[3-methoxy-4-(quinol-2-ylmethoxy)phenyl]propyl] thiazole, 2-[1-methoxy-1-[3-(1,2-dihydro-1-methyl-2-oxoquinolin-6-ylmethoxy)phenyl]propyl]thiazole, and 2-[1-[5-fluoro-3-(3-(2-pyridyl)prop-2-yn-1-yloxy)phenyl]-1-methoxypropyl]thiazole. A compound of the invention comprising a thiazole of the formula I, or a pharmaceutically-acceptable salt thereof, may be prepared by any process known to be applicable to the preparation of structurally-related compounds. Such procedures are provided as a further feature of the invention and are illustrated by the following representative examples in which, unless otherwise stated, Q¹, A, X, Ar, R¹, R² and Q² have any of the meanings defined hereinbefore. (a) The alkylation, in the presence of a suitable reagent, of a compound of the formula II with a compound of the formula Q¹-A-Z wherein Z is a displaceable group; provided that, when there is an amino, alkylamino, hydroxy or carboxy group in Q¹, Ar, R¹, R² or Q¹ any amino, alkylamino or carboxy group is protected by a conventional protecting group and any hydroxy group may be protected by a conventional protecting group or alternatively any hydroxy group need not be protected; whereafter any undesired protecting group in Q¹, Ar, R¹, R² or Q² is removed by conventional means. A suitable displaceable group Z is, for example, a halogeno, sulphonyloxy or hydroxy group, for example a chloro, bromo, iodo, methanesulphonyloxy or toluene- p -sulphonyloxy group. A suitable reagent for the alkylation reaction when Z is a halogeno or sulphonyloxy group is, for example, a suitable base, for example, an alkali or alkaline earth metal carbonate, hydroxide or hydride, for example sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, sodium hydride or potassium hydride. The alkylation reaction is preferably performed in a suitable inert solvent or diluent, for example N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulphoxide, acetone, 1,2-dimethoxyethane or tetrahydrofuran, and at a temperature in the range, for example, -10 to 150°C, conveniently at or near ambient temperature. A suitable reagent for the alkylation reaction when Z is a hydroxy group is, for example, the reagent obtained when a compound of the formula Q¹-A-OH is reacted with a di-(1-4C)alkyl azodicarboxylate in the presence of a triarylphosphine, for example with diethyl azodicarboxylate in the presence of triphenylphosphine. The alkylation reaction is preferably performed in a suitable inert solvent or diluent, for example acetone, 1,2-dimethoxyethane or tetrahydrofuran, and at a temperature in the range, for example, 10 to 80°C, conveniently at or near ambient temperature. A suitable protecting group for an amino or alkylamino group is, for example, an acyl group, for example a (1-4C)alkanoyl group, (especially acetyl), a (1-4C)alkoxycarbonyl group (especially methoxycarbonyl, ethoxycarbonyl or t -butoxycarbonyl), an arylmethoxycarbonyl group (especially benzyloxycarbonyl) or an aroyl group (especially benzoyl). The deprotection conditions for the above protecting groups necessarily vary with the choice of protecting group. Thus, for example, an acyl group such as an alkanoyl, alkoxycarbonyl or an aroyl group may be removed for example, by hydrolysis with a suitable base such as an alkali metal hydroxide, for example lithium or sodium hydroxide. Alternatively an acyl group such as a t -butoxycarbonyl group may be removed, for example, by treatment with a suitable acid such as hydrochloric, sulphuric or phosphoric acid or trifluoroacetic acid, and an arylmethoxycarbonyl group such as a benzyloxycarbonyl group may be removed, for example, by hydrogenation over a catalyst such as palladium-on-charcoal. A suitable protecting group for a carboxy group is, for example, an esterifying group, for example a (1-4C)alkyl group (especially methyl or ethyl) or an arylmethyl group (especially benzyl). The deprotection conditions for the above protecting groups necessarily vary with the choice of protecting group. Thus, for example, an esterifying group such as an alkyl or arylmethyl group may be removed, for example, by hydrolysis with a suitable base such as an alkali metal hydroxide, for example lithium or sodium hydroxide. Alternatively an esterifying group such as an arylmethyl group may be removed, for example, by hydrogenation over a catalyst such as palladium-on-charcoal. A suitable protecting group for a hydroxy group is, for example, an acyl group, for example a (1-4C)alkanoyl group (especially acetyl), an aroyl group (especially benzoyl) or an arylmethyl group (especially benzyl). The deprotection conditions for the above protecting groups will necessarily vary with the choice of protecting group. Thus, for example, an acyl group such as an alkanoyl or an aroyl group may be removed, for example, by hydrolysis with a suitable base such as an alkali metal hydroxide, for example lithium or sodium hydroxide. Alternatively an arylmethyl group such as a benzyl group may be removed, for example, by hydrogenation over a catalyst such as palladium-on-charcoal. The starting materials of the formula II may be obtained by standard procedures or organic chemistry. The preparation of examples of such starting materials is described within the accompanying non-limiting Examples which are provided for the purpose of illustration only. Other necessary starting materials are obtainable by analogous procedures to those described or by modification thereto which are within the ordinary skill of an organic chemist. Thus the starting material of the formula II may be obtained, for example, by deprotecting a protected thiazole of the formula III wherein R³ is a protecting group and X, Ar, R¹, R² and Q² have the meanings defined hereinbefore. A suitable protecting group R³ is, for example, an arylmethyl group (especially benzyl), a tri-(1-4C)alkylsilyl group (especially trimethylsilyl or t -butyldimethylsilyl), an aryldi-(1-4C)- alkylsilyl group (especially dimethylphenylsilyl), a (1-4C)alkyl group (especially methyl), a (1-4C)alkoxymethyl group (especially methoxymethyl) or a tetrahydropyranyl group (especially tetrahydropyran-2-yl). The deprotection conditions for the above protecting groups will necessarily vary with the choice of protecting group. Thus, for example, an arylmethyl group such as a benzyl group may be removed, for example, by hydrogenation over a catalyst such as palladium-on-charcoal. Alternatively a trialkylsilyl or an aryl dialkylsilyl group such as a t -butyldimethylsilyl or a dimethylphenylsilyl group may be removed, for example, by treatment with a suitable acid such as hydrochloric, sulphuric, phosphoric or trifluoroacetic acid or with an alkali metal or ammonium fluoride such as sodium fluoride or, preferably, tetrabutylammonium fluoride. Alternatively an alkyl group may be removed, for example, by treatment with an alkali metal (1-4C)alkylsulphide such as sodium thioethoxide, for example, by treatment with an alkali metal diarylphosphide such as lithium diphenylphosphide or, for example, by treatment with a boron or aluminium trihalide such as boron tribromide. Alternatively a (1-4C)alkoxymethyl group or tetrahydropyranyl group may be removed, for example, by treatment with a suitable acid such as hydrochloric or trifluoroacetic acid. The protecting group R³ may be, for example, a tri-(1-4C)-alkylsilyl group which can be removed while the protecting group for any amino, alkylamino, carboxy or hydroxy group in Ar, R¹, or R² or Q² is retained. The protected starting material of the formula III may be obtained by standard procedures of organic chemistry as illustrated in the accompanying non-limiting Examples. Thus, for example, an alcohol of the formula R³-X-Ar-CH(OH)-Q², wherein R³ is a protecting group as defined hereinbefore, may be obtained by the reaction of an aldehyde of the formula R³-X-Ar-CHO with an organometallic compound of the formula Q²-M, wherein Q² has the meaning defined hereinbefore and M is a metallic group, for example lithium, and provided that any amino, alkylamino, carboxy or hydroxy group in Ar or Q² is protected by a conventional protecting group. The reaction may be carried out in, for example, a suitable solvent or diluent such as an ether (for example tetrahydrofuran, t -butyl methyl ether or diethyl ether) at a temperature in the range, for example, -100 to 25°C (especially -80 to -50°C). The secondary alcohol of the formula R³-X-Ar-CH(OH)-Q² may be oxidised to give a ketone of the formula R³-X-Ar-CO-Q². A particular suitable oxidising agent is, for example, any agent known in the art for the oxidation of a secondary alcohol to a ketone, for example, manganese dioxide, chromium trioxide pyridine complex, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (hereinafter DDQ), a mixture of dimethylsulphoxide, oxalyl chloride and triethylamine, a mixture of acetic anhydride and dimethylsulphoxide or a mixture of dimethylsulphoxide and a dialkylcarbodiimide, for example N,N′-dicyclohexylcarbodiimide or N-ethyl-N′-(3-dimethylaminopropyl)carbodiimide. A tertiary alcohol of the formula IV, wherein R³ has the meaning defined hereinbefore, may be obtained by the reaction of the ketone R³-X-Ar-CO-Q² with an organometallic compound of the formula R¹-M-Z, wherein M is a metallic group, for example magnesium, and Z is a halogeno group, for example chloro, bromo or iodo, and provided that any amino, alkylamino, carboxy or hydroxy group in Ar, R¹ or Q² is protected by a conventional protecting group. The reaction may be carried out in a suitable solvent or diluent such as an ether (for example tetrahydrofuran, t -butyl methyl ether or diethyl ether) at a temperature in the range, for example, -30 to 100°C (especially ambient temperature to 80°C). It will be appreciated that the tertiary alcohol of the formula IV may be obtained from the aldehyde of the formula R³-X-Ar-CHO by reversing the order of introduction of the groups Q² and R¹. Thus the aldehyde of the formula R³-X-Ar-CHO may be treated initially with the organometallic compound of the formula R¹-M-Z, the product so obtained may be oxidised using a suitable oxidising agent as described above and the resultant ketone may be treated with the organometallic compound Q²-M to give the compound of the formula IV, and provided that any amino, alkylamino, carboxy or hydroxy group in Ar, R¹ or Q² is protected by a conventional protecting group. The protected thiazole of the formula III, wherein R³ has the meaning defined hereinbefore, may be obtained by the alkylation of the tertiary alcohol of the formula IV with an alkylating agent of the formula R²-Z, wherein Z is a displaceable group as defined hereinbefore other than hydroxy, in the presence of a suitable base as defined hereinbefore, and provided that any amino, alkylamino, carboxy or hydroxy group in Ar, R¹, R² or Q² is protected by a conventional protecting group, Alternatively the tertiary alcohol of the formula IV may be obtained by the reaction of a compound of the formula R³-X-Ar-Z, wherein R³, X and Ar have the meanings defined hereinbefore and Z is a halogeno group as defined hereinbefore, and provided that any amino, alkylamino, hydroxy or carboxy group in Ar is protected with a conventional protecting group as defined hereinbefore, with either an organometallic compound of the formula R⁵-M, wherein R⁵ is a (1-6C)alkyl group such as butyl and M is a metallic group, for example lithium, to give an organometallic compound of the formula R³-X-Ar-M, or with a metal such as magnesium to give an organometallic compound of the formula R³-X-Ar-M-Z, whereafter either of these organometallic compounds may be reacted with a ketone of the formula R¹-CO-Q², wherein R¹ and Q² have the meanings defined herein before, and provided that any amino, alkylamino or hydroxy group in R¹ or Q² is protected by a conventional protecting group. (b) The alkylation, in the presence of a suitable base as defined hereinbefore, of a compound of the formula V with a compound of the formula R²-Z, wherein R² has the meaning defined hereinbefore and Z is a displaceable group as defined hereinbefore, provided that, when there is an amino, imino, alkylamino, hydroxy or carboxy group in Q¹, X Ar, R¹, R² or Q², or any amino, imino, alkylamino, hydroxy or carboxy group is protected by a conventional protecting group; whereafter any undesired protecting group in Q¹, X, Ar, R¹, R² or Q² is removed by conventional means. A suitable protecting group for an imino group is, for example, any one of the protecting group defined hereinbefore as a suitable protecting group for an amino or alkylamino group. The starting materials of the formula V may be obtained by standard procedures or organic chemistry. The preparation of examples of such starting materials is described within the accompanying non-limiting Examples which are provided for the purpose of illustration only. Other necessary starting materials are obtainable by analogous procedures to those described or by modification thereto which are within the ordinary skill of an organic chemist. Thus the tertiary alcohol starting material of the formula V may be obtained, for example, by the reaction of an aldehyde of the formula Q¹-A-X-Ar-CHO with an organometallic compound of the formula Q²-M, having the meaning defined hereinbefore and using the conditions defined hereinbefore, to give a secondary alcohol of the formula Q¹-A-X-Ar-CH(OH)-Q² and provided that any amino, imino, alkylamino, carboxy or hydroxy group in Q¹, X, Ar or Q² is protected by a conventional protecting group. The product so obtained may be oxidised using a suitable oxidising agent, as defined hereinbefore, to give a ketone of the formula Q¹-A-X-Ar-CO-Q², which in turn may be treated with an organometallic compound of the formula R¹-M-Z, having the meaning defined hereinbefore, provided that any hydroxy group in R¹ is protected by a conventional protecting group, and using the conditions defined hereinbefore, to give the required tertiary alcohol starting material of the formula V. It will be appreciated that the tertiary alcohol of the formula V may be obtained from the aldehyde of the formula Q¹-A-X-Ar-CHO by reversing the order of the introduction of the groups Q² and R¹, i.e. by reaction of the aldehyde of the formula Q¹-A-X-Ar-CHO with the organometallic compound of the formula R¹-M-Z, oxidation of the secondary alcohol to a ketone of the formula Q¹-A-X-Ar-CO-R¹ and reaction of said ketone with the organometallic compound of the formula Q²-M, and provided that any amino, imino, alkylamino, carboxy or hydroxy group in Q¹, X, Ar, R¹ or Q² is protected by a conventional protecting group. Alternatively the ketone intermediate of the formula Q¹-A-X-Ar-CO-R¹ may be obtained, for example, by the alkylation, in the presence of a suitable base as defined hereinbefore, of a ketone of the formula H-X-Ar-CO-R¹ with a compound of the formula Q¹-A-Z, wherein Z is a displaceable group as defined hereinbefore, and provided that any amino, alkylamino, carboxy or hydroxy group in Q¹, or R¹ is protected by a conventional protecting group. The aldehyde starting material of the formula Q¹-A-X-Ar-CHO may be obtained, for example, by the alkylation, in the presence of a suitable base as defined hereinbefore, of an aldehyde of the formula H-X-Ar-CHO with a compound of the formula Q¹-A-Z, wherein Z is a displaceable group as defined hereinbefore other than hydroxy, and provided that any amino, alkylamino, carboxy or hydroxy group in Q¹ or Ar is protected by a conventional protecting group. Alternatively the tertiary alcohol starting material of the formula V may be obtained, for example, by the reaction of an ester of the formula Q¹-A-X-Ar-CO₂R⁴, wherein R⁴ is a (1-4C)alkyl group such as methyl or ethyl, with an organometallic compound of the formula Q²-M, having the meaning defined hereinbefore and using the conditions defined hereinbefore for the corresponding reaction of the aldehyde of the formula R³-X-Ar-CHO, and provided that any amino, imino, alkylamino, carboxy or hydroxy group in Q¹, X, Ar or Q² is protected by a conventional protecting group, to give a ketone of the formula Q¹-A-X-Ar-CO-Q². The product so obtained may be treated with an organometallic compound of the formula R¹-M-Z, having the meaning defined hereinbefore and using the conditions defined hereinbefore, to give the required tertiary alcohol starting material of the formula V. It will be appreciated that the tertiary alcohol of the formula V may be obtained from the ester of the formula Q¹-A-X-Ar-CO₂R⁴ by reversing the order of the introduction of the groups Q² and R¹, i.e. by reaction of the ester of the formula Q¹-A-X-Ar-CO₂R⁴ with the organometallic compound of the formula R¹-M-Z, to give a ketone of the formula Q¹-A-X-Ar-CO-R¹ and reaction of said ketone with the organometallic compound of the formula Q²-M, and provided that any amino, imino, alkylamino, carboxy or hydroxy group in Q¹, X, Ar, R¹ or Q² is protected by a conventional protecting group. The ester starting material of the formula Q¹-A-X-Ar-CO₂R⁴ may be obtained, for example, by the alkylation, in the presence of a suitable base as defined hereinbefore, of an ester of the formula H-X-Ar-CO₂R⁴, wherein R⁴ has the meaning defined hereinbefore, with a compound of the formula Q¹-A-Z, wherein Z is a displaceable group as defined hereinbefore other than hydroxy, and provided that any amino, alkylamino, carboxy or hydroxy group in Q¹ or Ar is protected by a conventional protecting group. Alternatively the tertiary alcohol starting material of the formula V may be obtained, for example, by the alkylation, in the presence of a suitable base, of a compound of the formula Q¹-A-X-H, wherein Q¹, A and X have the meanings defined hereinbefore, with a compound of the formula Z-Ar-Z, wherein Z is a displaceable group as defined hereinbefore other than hydroxy, and provided that any amino, alkylamino, carboxy or hydroxy group in Q¹ or Ar is protected by a conventional protecting group, to give a compound of the formula Q¹-A-X-Ar-Z. The product so obtained may be treated with an organometallic compound of the formula R⁵-M, wherein R⁵ is a (1- 6C)alkyl group such as butyl and M is a metallic group, for example lithium, to give an organometallic compound of the formula Q¹-A-X-Ar-M which may be reacted with a ketone of the formula Q².CO.R¹, provided that any amino, alkylamino or hydroxy group in Q² or R¹ is protected by a conventional protecting group, to give the required tertiary alcohol starting material of the formula V. (c) For the production of those compounds of the formula I wherein A is a (3-6C)alkynylene group, the coupling, in the presence of a suitable organometallic catalyst, of a heterocyclic compound of the formula Q¹-Z, wherein Q¹ has the meaning defined hereinbefore and Z is a halogeno group such as iodo, with an ethynyl compound of the formula VI, wherein A¹ is (1-4C)alkylene and X, Ar, R¹, R² and Q² have the meanings defined hereinbefore. A suitable organometallic catalyst is, for example, any agent known in the art for such a coupling reaction. Thus, for example, a suitable reagent is formed when, for example, bis(triphenylphosphine)palladium chloride or tetrakis(triphenylphosphine)palladium, and a copper halide, for example cuprous iodide, are mixed. The coupling is generally carried out in a suitable inert solvent or diluent, for example acetonitrile, 1,2-dimethoxyethane, toluene or tetrahydrofuran, at a temperature in the range, for example, 10 to 80°C, conveniently at or near 70°C, and in the presence of a suitable base such as, for example, a tri-(1-4C)alkylamine such as triethylamine, or a cyclic amine such as piperidine. The ethynyl compound of the formula VI, used as a starting material, may be obtained, for example, by the alkylation, in the presence of a suitable base, of a compound of the formula II, wherein X, Ar, R¹, R² and Q² have the meanings defined hereinbefore, with an alkylating agent of the formula H-C≡C-A¹-Z, wherein A¹ has the meaning defined hereinbefore and Z is a halogeno group, and provided that any amino, alkylamino, carboxy or hydroxy group in Ar, R¹, R² or Q² is protected by a conventional protecting group. (d) For the production of those compounds of the formula I wherein Ar bears an alkylsulphinyl or alkylsulphonyl substituent or X is a sulphinyl or sulphonyl group, the oxidation of a compound of the formula I wherein Ar bears an alkylthio substituent or wherein X is a thio group. A suitable oxidising agent is, for example, any agent known in the art for the oxidation of thio to sulphinyl and/or sulphonyl, for example, hydrogen peroxide, a peracid (such as 3-chloroperoxybenzoic or peroxyacetic acid), an alkali metal peroxysulphate (such as potassium peroxymonosulphate), chromium trioxide or gaseous oxygen in the presence of platinum. The oxidation is generally carried out under as mild conditions as possible and with the required stoichiometric amount of oxidising agent in order to reduce the risk of over oxidation and damage to other functional groups. In general the reaction is carried out in a suitable solvent or diluent such as methylene chloride, chloroform, acetone, tetrahydrofuran or t -butyl methyl ether and at a temperature, for example, at or near ambient temperature, that is in the range 15 to 35°C. When a compound wherein X is sulphinyl and/or Ar bears an alkylsulphinyl substituent a milder oxidising agent may also be used, for example sodium or potassium metaperiodate, conveniently in a polar solvent such as acetic acid or ethanol. It will be appreciated that when a compound of the formula I containing a sulphonyl group is required, it may be obtained by oxidation of the corresponding sulphinyl compound as well as of the corresponding thio compound. (e) For the production of those compounds of the formula I wherein Q¹, Ar or Q² bears an alkanoylamino or alkanoylaminoalkyl substituent, the acylation of a compound of the formula I wherein Q¹, Ar or Q² bears an amino or aminoalkyl substituent. A suitable acylating agent is, for example, any agent known in the art for the acylation of amino to acylamino or of aminoalkyl to acylaminoalkyl, for example an acyl halide, for example a (2-6C)alkanoyl chloride or bromide, in the presence of a suitable base, an alkanoic acid anhydride, for example a (2-6C)alkanoic acid anhydride, or an alkanoic acid mixed anhydride, for example the mixed anhydride formed by the reaction of an alkanoic acid and a (1-4C)alkoxycarbonyl halide, for example a (1-4C)alkoxycarbonyl chloride, in the presence of a suitable base. In general the reaction is carried out in a suitable solvent or diluent such as methylene chloride, acetone, tetrahydrofuran or t -butyl methyl ether and at a temperature, for example, at or near ambient temperature, that is in the range 15 to 35°C. A suitable base when it is required is, for example, pyridine, 4-dimethylaminopyridine, triethylamine, ethyldiisopropylamine, N-methylmorpholine, an alkali metal carbonate, for example potassium carbonate, or an alkali metal carboxylate, for example sodium acetate. (f) For the production of those compounds of the formula I wherein R² is alkanoyl or benzoyl optionally bearing a substituent as defined hereinbefore, the acylation of a compound of the formula I wherein R² is hydrogen. For the production of those compounds of the formula I wherein R² is alkanoyl the acylation reaction may be carried out using, for example, a suitable acylating agent as defined hereinbefore. For the production of those compounds of the formula I wherein R² is benzoyl optionally bearing a substituent the acylation may be carried out using, for example, a benzoyl halide, for example a benzoyl chloride or bromide, in the presence of a suitable base as defined hereinbefore. (g) For the production of those compounds of the formula I wherein A is alkenylene or R¹ is alkenyl, the reduction of the corresponding compound wherein A is alkynylene or R¹ is alkynyl. In general conditions which are standard in the art for the reduction of an alkynyl or alkynylene group are used. Thus, for example, the reduction may be carried out by the hydrogenation of a solution of the alkynyl or alkynylene compound in an inert solvent or diluent in the presence of a suitable metal catalyst. A suitable inert solvent is, for example, an alcohol, for example methanol or ethanol, or an ether, for example tetrahydrofuran or t -butyl methyl ether. A suitable metal catalyst is, for example, palladium or platinum on an inert support, for example charcoal or barium sulphate. Preferably a palladium-on-barium sulphate catalyst is used to substantially prevent over-reduction of the alkynyl or alkynylene group to an alkyl or alkylene group respectively. The reaction is generally carried out at a temperature at or near ambient temperature, that is in the range 15 to 35°C. Alternatively the reduction may be carried out by treating a solution of the alkynyl or alkynylene compound in an inert solvent or diluent with a suitable mixture such as a 1:1 mixture of an organometallic hydride, for example a di-(1-6C)alkylaluminium hydride such as diisobutylaluminium hydride, and an alkyl metal, for example a (1-6C)alkyl lithium such as methyl lithium. A suitable inert solvent or diluent is, for example, tetrahydrofuran, diethyl ether or t -butyl methyl ether and, in general, the reaction is carried out at a temperature, for example, in the range -25°C to ambient temperature (especially -10 to 10°C). (h) For the production of those compounds of the formula I wherein Ar bears an alkoxy or substituted alkoxy substituent, the alkylation of a compound of the formula I wherein Ar bears a hydroxy substituent. A suitable alkylating agent is, for example any agent known in the art for the alkylation of hydroxy to alkoxy or substituted alkoxy, for example an alkyl or substituted alkyl halide, for example a (1-6C)alkyl chloride, bromide or iodide or a substituted (1-4C)alkyl chloride, bromide or iodide, in the presence of a suitable base. A suitable base for the alkylation reaction is, for example, an alkali or alkaline earth metal carbonate, hydroxide or hydride, for example sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, sodium hydride or potassium hydride. The alkylation reaction is preferably performed in a suitable inert solvent or diluent, for example N,N-dimethylformamide, dimethylsulphoxide, acetone, 1,2-dimethoxyethane or tetrahydrofuran, and at a temperature in the range, for example, 10 to 150°C, conveniently at or near ambient temperature. When a pharmaceutically-acceptable salt of a novel compound of the formula I is required, it may be obtained, for example, by reaction of said compound with a suitable acid or base using a conventional procedure. When an optically active form of a compound of the formula I is required, it may be obtained by carrying out one of the aforesaid procedures using an optically active starting material, or by resolution of a racemic form of said compound using a conventional procedure. Many of the intermediates defined herein are novel, for example those of the formulae II, III, IV, V and VI and these are provided as a further feature of the invention. As stated previously, the thiazoles of the formula I are inhibitors of the enzyme 5-LO. The effects of this inhibition may be demonstrated using one or more of the standard procedures set out below:- a) An in vitro spectrophotometric enzyme assay system, which assesses the inhibitory properties of a test compound in a cell free system using 5-LO isolated from guinea pig neutrophils and as described by D.Aharony and R.L. Stein ( J . Biol . Chem ., 1986, 261 (25), 11512-11519). This test provides a measure of the intrinsic inhibitory properties against soluble 5-LO in an extracellular environment. b) An in vitro assay system involving incubating a test compound with heparinised human blood, prior to challenge with the calcium ionophore A23187 and then indirectly measuring the inhibitory effects on 5-LO by assaying the amount of LTB₄ using the specific radioimmunoassay described by Carey and Forder (F. Carey and R.A. Forder, Brit . J . Pharmacol . 1985, 84, 34P) which involves the use of a protein-LTB₄ conjugate produced using the procedure of Young et alia ( Prostaglandins , 1983, 26 (4),605-613). The effects of a test compound on the enzyme cyclooxygenase (which is involved in the alternative metabolic pathway for arachidonic acid and gives rise to prostaglandins, thromboxanes and related metabolites) may be measured at the same time using the specific radioimmunoassay for thromboxane B₂(TxB₂) described by Carey and Forder (see above). This test provides an indication of the effects of a test compound against 5-LO and also cyclooxygenase in the presence of blood cells and proteins. It permits the selectivity of the inhibitory effect on 5-LO or cyclooxygenase to be assessed. c) An ex vivo assay system, which is a variation of test b) above, involving administration of a test compound (usually orally as the suspension produced when a solution of the test compound in dimethylsulphoxide is added to carboxymethylcellulose), blood collection, heparinisation, challenge with A23187 and radioimmunoassay of LTB₄ and TxB₂. This test provides an indication of the bioavailability of a test compound as an inhibitor of 5-LO or cyclooxygenase. d) An in vitro assay system involving the measurement of the inhibitory properties of a test compound against the liberation of LTC₄ and PGE₂ induced by zymosan on mouse resident peritoneal macrophages, using the procedure of Humes (J.L. Humes et alia , Biochem . Pharmacol ., 1983, 32 , 2319-2322) and conventional radioimmunoassay systems to measure LTC₄ and PGE₂. This test provides an indication of inhibitory effects against 5-LO and cyclooxygenase in a non-proteinaceous system. e) An in vivo system involving the measurement of the effects of a test compound in inhibiting the inflammatory response to arachidonic acid in the rabbit skin model developed by D. Aked et alia ( Brit . J . Pharmacol ., 1986, 89 , 431-438). This test provides an in vivo model for 5-LO inhibitors administered topically or orally. f) An in vivo system involving measuring the effects of a test compound administered orally or intravenously on a leukotriene dependent bronchoconstriction induced by an antigen challenge in guinea pigs pre-dosed with an antihistamine (mepyramine), a β-adrenergic blocking agent (propranolol) and a cyclooxygenase inhibitor (indomethacin), using the procedure of W.H. Anderson et alia ( British J Pharmacology , 1983, 78 (1), 67-574). This test provides a further in vivo test for detecting 5-LO inhibitors. Although the pharmacological properties of the compounds of the formula I vary with structural changes as expected, in general compounds of the formula I possess 5-LO inhibitory effects at the following concentrations or doses in one or more of the above tests a)-f):- Test a): IC₅₀ in the range, for example, 0.1-30 micromolar; Test b): IC₅₀ (LTB₄) in the range, for example, 0.1-40 micromolar, IC₅₀ (TxB₂) in the range, for example, 40-200 micromolar; Test c): oral ED₅₀(LTB₄) in the range, for example, 10-200 mg/kg; Test d): IC₅₀ (LTC₄) in the range, for example, 0.001-1 micromolar, IC₅₀ (PGE₂) in the range, for example, 20-1000 micromolar; Test e): inhibition of inflammation in the range, for example, 0.3-100 micrograms intradermally; Test f): ED₅₀ in the range, for example, 0.5-10mg/kg i.v. No overt toxicity or other untoward effects are present in tests c), e) and/or f) when compounds of the formula I are administered at several multiples of their minimum inhibitory dose or concentration. Thus, by way of example, the compound 2-[1-[3-(3-(2-pyridyl)prop-2-yn-1-yloxy)phenyl]-1-methoxypropyl]thiazole has, an IC₅₀ of 0.7 micromolar against LTB₄ and of >40 micromolar against TxB₂ in test b), and an oral ED₅₀ of 50mg/kg versus LTB₄ in test c). In general those compounds of the formula I which are particularly preferred have an IC₅₀ of <5 micromolar against LTB₄ and of >100 micromolar TxB₂ in test b), and an oral ED₅₀ of <100 mg/kg against LTB₄ in test c). These compounds are examples of thiazoles of the invention which show selective inhibitory properties for 5-LO as opposed to cyclooxygenase, which selective properties are expected to impart improved therapeutic properties, for example, a reduction in or freedom from the gastrointestinal side-effects frequently associated with cyclooxygenase inhibitors such as indomethacin. According to a further feature of the invention there is provided a pharmaceutical composition which comprises a thiazole of the formula I, or a pharmaceutically-acceptable salt thereof, in association with a pharmaceutically-acceptable diluent or carrier. The composition may be in a form suitable for oral use, for example a tablet, capsule, aqueous or oily solution, suspension or emulsion; for topical use, for example a cream, ointment, gel or aqueous or oily solution or suspension; for nasal use, for example a snuff, nasal spray or nasal drops; for vaginal or rectal use, for example a suppository; for administration by inhalation, for example as a finely divided powder or a liquid aerosol; for sub-lingual or buccal use, for example a tablet or capsule; or for parenteral use (including intravenous, subcutaneous, intramuscular, intravascular or infusion), for example a sterile aqueous or oily solution or suspension. In general the above compositions may be prepared in a conventional manner using conventional excipients. The amount of active ingredient (that is a thiazole of the formula I or a pharmaceutically-acceptable salt thereof) that is combined with one or more excipients to produce a single dosage form will necessarily vary depending upon the host treated and the particular route of administration. For example, a formulation intended for oral administration to humans will generally contain, for example, from 0.5 mg to 2g of active agent compounded with an appropriate and convenient amount of excipients which may vary from about 5 to about 98 percent by weight of the total composition. Dosage unit forms will generally contain about 1 mg to about 500 mg of an active ingredient. According to a further feature of the invention there is provided a thiazole of the formula I, or a pharmaceutically-acceptable salt thereof, for use in a method of treatment of the human or animal body by therapy. The invention also includes a method of treating a disease or medical condition mediated alone or in part by one or more leukotrienes which comprises administering to a warm-blooded animal requiring such treatment an effective amount of an active ingredient as defined above. The invention also provides the use of such an active ingredient in the production of a new medicament for use in a leukotriene mediated disease or medical condition. The size of the dose for therapeutic or prophylactic purposes of a thiazole of the formula I will naturally vary according to the nature and severity of the conditions, the age and sex of the animal or patient and the route of administration, according to well known principles of medicine. As mentioned above, thiazoles of the formula I are useful in treating those allergic and inflammatory conditions which are due alone or in part to the effects of the metabolites of arachidonic acid arising by the linear (5-LO catalysed) pathway and in particular the leukotrienes, the production of which is mediated by 5-LO. As previously mentioned, such conditions include, for example, asthmatic conditions, allergic reactions, allergic rhinitis, allergic shock, psoriasis, atopic dermatitis, cardiovascular and cerebrovasular disorders of an inflammatory nature, arthritic and inflammatory joint disease, and inflammatory bowel diseases. In using a compound of the formula I for therapeutic or prophylactic purposes it will generally be administered so that a daily dose in the range, for example, 0.5mg to 75mg per kg body weight is received, given if required in divided doses. In general lower doses will be administered when a parenteral route is employed. Thus, for example, for intravenous administration, a dose in the range, for example, 0.5mg to 30 mg per kg body weight will generally be used Similarly, for administration by inhalation, a dose in the range, for example, 0.5 mg to 25 mg per kg body weight will be used. Although the compounds of the formula I are primarily of value as therapeutic agents for use in warm-blooded animals (including man), they are also useful whenever, it is required to inhibit the enzyme 5-LO. Thus, they are useful as pharmacological standards for use in the development of new biological tests and in the search for new pharmacological agents. By virtue of their effects on leukotriene production, the compounds of the formula I have certain cytoprotective effects, for example they are useful in reducing or suppressing certain of the adverse gastrointestinal effects of the cyclooxygenase inhibitory non-steroidal anti-inflammatory agents (NSAIA), such as indomethacin, acetylsalicylic acid, ibuprofen, sulindac, tolmetin and piroxicam Furthermore, co-administration of a 5-LO inhibitor of the formula I with a NSAIA can result in a reduction in the quantity of the latter agent needed to produce a therapeutic effect, thereby reducing the likelihood of adverse side-effects. According to a further feature of the invention there is provided a pharmaceutical composition which comprises a thiazole of the formula I, or a pharmaceutically-acceptable salt thereof as defined hereinbefore, in conjunction or admixture with a cyclooxygenase inhibitory non-steroidal anti-inflammatory agent (such as mentioned above), and a pharmaceutically-acceptable diluent or carrier. The cytoprotective effects of the compounds of the formula I may be demonstrated, for example in a standard laboratory model which assesses protection against indomethacin-induced or ethanol-induced ulceration in the gastrointestinal tract of rats. The compositions of the invention may in addition contain one or more therapeutic or prophylactic agents known to be of value for the disease under treatment. Thus, for example a known platelet aggregation inhibitor, hypolipidemic agent, anti-hypertensive agent, beta-adrenergic blocker or a vasodilator may usefully also be present in a pharmaceutical composition of the invention for use in treating a heart or vascular disease or condition. Similarly, by way of example, an anti-histamine, steroid (such as beclomethasone dipropionate), sodium cromoglycate, phosphodiesterase inhibitor or a beta-adrenergic stimulant may usefully also be present in a pharmaceutical composition of the invention for use in treating a pulmonary disease or condition. The invention will now be illustrated in the following non-limiting Examples in which, unless otherwise stated:- (i) evaporations were carried out by rotary evaporations in vacuo and work-up procedures were carried out after removal of residual solids by filtration; (ii) operations were carried out at room temperature, that is in the range 18-20°C and under an atmosphere of an inert gas such as argon; (iii) column chromatography (by the flash procedure) and medium pressure liquid chromatography (MPLC) were performed on Merck Kieselgel silica (Art. 9385) obtained from E. Meck, Darmstadt, W. Germany; (iv) yields are given for illustration only and are not necessarily the maximum attainable; (v) the end-products of the formula I have satisfactory microanalyses and their structures were confirmed by NMR and mass spectral techniques; (vi) intermediates were not generally fully characterised and purity was assessed by thin layer chromatographic, infra-red (IR) or NMR analysis; and (vii) melting points are uncorrected and were determined using a Mettler SP62 automatic melting point apparatus or an oil-bath apparatus; melting points for the end-products of the formula I were determined after recrystallisation from a conventional organic solvent such as ethanol, methanol, acetone, ether or hexane, alone or in admixture. Example 1 A mixture of 2-[1-(3-hydroxyphenyl)-1-methoxypropyl]thiazole (0.5 g, 2 mmol), 3-bromomethyl-1,2-dihydro-1-methylquinolin-2-one (0.5 g, 2 mmol), potassium carbonate (0.35 g, 2.5 mmol) and dimethylformamide (3 ml) was stirred at ambient temperature for 48 hours. The mixture was filtered, the filtrate was added to water (30 ml) and the mixture was extracted with ethyl acetate (3 x 15 ml). The organic extracts were combined, washed with a dilute aqueous sodium hydroxide solution and with a saturated sodium chloride solution, dried (Na₂SO₄) and evaporated. The residue was purified by column chromatography eluting with toluene/ethyl acetate (7/3 v/v) to give 2-[1-methoxy-1-[3-(1,2-dihydro-1-methyl-2-oxoquinolin-3-ylmethoxy)-phenyl]propyl]thiazole (0.84 g, 100%), m.p. 123-125°C. The thiazole starting material was obtained as follows:- A solution of 3-methoxyphenylmagnesium bromide in tetrahydrofuran (500 ml) was prepared from 3-methoxybromobenzene (187 g) and magnesium turnings (24 g) and was added over 1.5 hours to a mixture of propionic anhydride (260 g) and diethyl ether (500 ml) which had been cooled to -70°C. A saturated aqueous solution of ammonium chloride (500 ml) was added and the mixture was allowed to warm to ambient temperature. The organic layer was separated and washed in turn with a dilute aqueous sodium hydroxide solution and with a saturated aqueous sodium chloride solution. The organic layer was dried (Na₂SO₄) and evaporated to give 3-methoxypropiophenone as a yellow oil (160 g). The product so obtained was added to hot pyridine hydrochloride [prepared by adding concentrated hydrochloric acid (272 ml) to pyridine (242 ml) and heating the mixture to distil off all of the water, which position was indicated when the boiling point of the distillate reached a temperature of 210°C] and the temperature was maintained at 210°C for 30 minutes. The mixture was poured onto ice. The yellow solid which was precipitated was filtered off, washed with water and dried. There was thus obtained 3-hydroxypropiophenone (125 g) which was used without further purification. Tert -butyldimethylsilyl chloride (150 g) was added to a mixture of 3-hydroxypropiophenone (125 g), imidazole (142 g) and dimethylformamide (330 ml) and the mixture was stirred at ambient temperature for 16 hours. The mixture was poured into water (600 ml) and extracted with diethyl ether (600 ml). The organic layer was separated, washed with water (4 x 30 ml), dried (Na₂SO₄) and evaporated to give 3-( tert -butyldimethylsilyloxy)propiophenone as an oil (186 g, b.p. 114-118°C at 0.01 mm Hg). A solution of the product so obtained (186 g) in diethyl ether (350 ml) was added over 45 minutes to a cooled (-70°C) solution of thiazol-2-yl-lithium [prepared by adding over 45 minutes a solution of 2-bromothiazole (66 ml) in diethyl ether (150 ml) to a mixture of n-butyl-lithium (1.6 M in hexane, 460 ml) and diethyl ether (625 ml) which had been cooled to -70°C]. The mixture was stirred and allowed to warm to ambient temperature and then a saturated aqueous ammonium chloride solution (500 ml) was added. The organic solution was separated, washed with a saturated aqueous sodium chloride solution, dried (Na₂SO₄) and evaporated. The was thus obtained 2-[1-(3- tert -butyldimethylsilyloxyphenyl)-1-hydroxypropyl]thiazole, as an oil (245 g), which was used without further purification. A solution of the product so obtained (245 g) in tetrahydrofuran (500 ml) was added to a slurry of sodium hydride (55% w/w dispersion in oil, 30.6 g) in tetrahydrofuran (500 ml) and the mixture was stirred at ambient temperature for 16 hours. Methyl iodide (87 ml) was added and the mixture was stirred at ambient temperature for 2 hours. The mixture was poured into a saturated aqueous ammonium chloride solution (500 ml) and extracted with diethyl ether (3 x 400 ml). The combined extracts were washed with a saturated aqueous sodium chloride solution, dried (Na₂SO₄) and evaporated. There was thus obtained 2-[1-(3- tert -butyldimethylsilyloxyphenyl)-1-methoxypropyl]thiazole as a pale yellow oil (250 g). A mixture of the product so obtained (245 g), tetra-n-butylammonium fluoride (1M in tetrahydrofuran, 756 ml) and tetrahydrofuran (400 ml) was stirred at ambient temperature for 1 hour. The mixture was poured into a saturated aqueous ammonium chloride solution. The organic layer was separated, evaporated and redissolved in ethyl acetate (500 ml). The aqueous layer was extracted with ethyl acetate (2 x 250 ml). The organic solutions were combined, washed with a saturated aqueous ammonium chloride solution (250 ml) and with a saturated aqueous sodium chloride solution, dried (Na₂SO₄) and evaporated. The residue was recrystallisd from a mixture of petrol (b.p. 60-80°C) and ethanol to give 2-[1-(3-hydroxyphenyl)-1-methoxypropyl]thiazole (129 g), m.p. 111-113°C. The 3-bromomethyl-1,2-dihydro-methylquinolin-2-one starting material was obtained as follows:- Sodium hydride (555 w/w suspension in oil; 0.268 g) was added portionwise to a stirred suspension of 1,2-dihydro-2-oxoquinoline-3-carbaldehyde (1 g) in dimethylformamide (10 ml) which had been cooled in an ice bath. The mixture was allowed to warm to ambient temperature and was then heated to 60°C for 1 hour. The mixture was recooled in an ice bath and methyl iodide (0.41 ml) was added. Dimethylformamide (50 ml) was added and the mixture was stirred at ambient temperature for 16 hours. The mixture was poured into water (50 ml) and extracted with methylene chloride (3 x 50 ml). The combined extracts were washed with water (50 ml) and evaporated. The residue was triturated under diethyl ether to give 1,2-dihydro-1-methyl-2-oxoquinoline-3-carbaldehyde as a pale yellow solid (0.81 g, 74%). The product so obtained was converted to 3-bromomethyl-1,2-dihydro-1-methylquinolin-2-one using the known procedure ( Chem. Pharm. Bull. , 1985, 33 , 3775) for the conversion of 1,2-dihydro-2-oxoquinoline-3-carbaldehyde to 3-bromomethyl-1,2-dihydroquinolin-2-one. Example 2 Using a similar procedure to that described in Example 1, except that the appropriate alkylating agent was used in place of 3-bromomethyl-1,2-dihydro-1-methylquinolin-2-one and the appropriate thiazole was used, there were obtained the compounds described in the following table:- Example 3 Diethyl azodicarboxylate (0.38 ml) was added dropwise to a mixture of 2-[1-(3-hydroxyphenyl)-1-methoxypropyl]thiazole (0.37 g), triphenylphosphine (0.57 g), 3-(3-pyridyl)prop-2-en-1-ol (0.27 g) and tetrahydrofuran (7 ml) which had been cooled to 0-5°C in an ice-bath. The mixture was stirred at this temperature range for 2 hours and then at ambient temperature for 4 hours. Further portions of diethyl azodicarboxylate (0.1 ml), triphenylphosphine (0.14 g) and the propenol (0.045 g) were added and the mixture was stirred at ambient temperature for 18 hours. The mixture was partitioned between ethyl acetate (40 ml) and dilute aqueous hydrochloric acid (40 ml). The aqueous layer was separated and basified by adding potassium carbonate portionwise. The resulting solution was extracted with ethyl acetate (3 x 20 ml). The combined extracts were dried (Na₂SO₄) and evaporated. The residue was purified by column chromatography eluting with toluene/ethyl acetate (2/3 v/v) to give 2-[1-[3-(3-(3-pyridyl)-prop-2-en-1-yloxy)phenyl]-1-methoxypropyl]thiazole as a colourless oil (0.162 g). 3-(3-Pyridyl)prop-2-en-1-ol, used as a starting material, was obtained as follows:- Triethylamine (1.4 ml) and ethyl chloroformate (0.94 ml) were added in succession to a stirred suspension of 3-(3-pyridyl)propenoic acid [1.49 g; prepared from pyridine-3-carbaldehyde and malonic acid using the general method described in Organic Synthesis , Coll, Vol. 4, 1963, 730] in tetrahydrofuran (40 ml) which had been cooled to -15°C. The mixture was stirred at this temperature for 30 minutes and then filtered. The filtrate was added over 15 minutes to a stirred solution of sodium borohydride (0.94 g) in water (8 ml) which had been cooled in an ice-bath. The mixture was stirred at ambient temperature for 3 hours then partitioned between diethyl ether and a dilute aqueous sodium hydroxide solution. The aqueous layer was extracted with diethyl ether and ethyl acetate. The combined organic extracts were washed with a saturated aqueous sodium chloride solution, dried (Na₂SO₄) and evaporated. The residue was purified by column chromatography eluting with toluene/ethyl acetate (1/1 v/v) to give 3-(3-pyridyl)prop-2-en-1-ol as an oil (0.84 g). Example 4 The procedure described in Example 3 was repeated except that 3-(2-pyridyl)prop-2-en-1-ol was used in place of 3-(3-pyridyl)prop-2-en-1-ol. There was thus obtained 2-[1-[3-(3-(2-pyridyl)prop-2-en-1-yloxy)phenyl]-1-methoxypropyl]thiazole as an oil. 3-(2-Pyridyl)prop-2-en-1-ol used as a starting material was obtained using the procedure described in the portion of Example 3 which is concerned with the preparation of starting materials and replacing pyridine-3-carbaldehyde with pyridine-2-carbaldehyde. Example 5 A solution of 2-[1-(3-(2-propynyloxy)phenyl)-1-methoxypropyl]thiazole (8.6 g) in acetonitrile (40 ml) was added to a stirred mixture of 2-iodopyridine (6.2 g), triethylamine (4.02 ml), bis(triphenylphosphine)palladium chloride (0.416 g), cuprous iodide (0.416 g) and acetonitrile (160 ml), the mixture was stirred at ambient temperature for 15 minutes, and then heated to 60°C for 2.5 hours. The mixture was cooled to ambient temperature and partitioned between diethyl ether and water. The organic layer was washed with a saturated aqueous sodium chloride solution, dried (MgSO₄) and evaporated. The residue was partitioned between diethyl ether and 2N aqueous hydrochloric acid. The aqueous layer was cooled to 10°C in an ice-bath, basified by adding 4N aqeuous sodium hydroxide solution and extracted with diethyl ether (2 x 150 ml). The combined extracts were washed with water, dried (MgSO₄) and evaporated. There was thus obtained, as an oil which crystallised on standing and was recrystallised from diethyl ether, 2-[1-[3-(3-(2-pyridyl)prop-2-yn-1-yloxy)phenyl]-1-methoxypropyl]thiazole (5 g, 46%), m.p. 61-63°C. The 2-[1-(3-(2-propynyloxy)phenyl)-1-methoxypropyl]thiazole, used as a starting material, was obtained as follows:- A mixture of 2-[1-(3-hydroxyphenyl)-1-methoxypropyl]thiazole (31 g), 2-propynyl bromide (80% solution in toluene, 48.1 ml), potassium carbonate (48 g) and acetone (375 ml) was stirred and heated to reflux for 17 hours. The mixture was filtered and the filtrate was evaporated. The residue was partitioned between diethyl ether and water and the organic layer was washed with water, dried (MgSO₄) and evaporated. The residue was purified by chromatography eluting with hexane/ethyl acetate (1:1 v/v) to give 2-[1-(3-(2-propynyloxy)phenyl)-1-methoxypropyl]thiazole as an oil (34 g, 94%). Example 6 Using a similar procedure to that described in Example 5, except that the appropriate iodo-heterocycle was used in place of 2-iodopyridine and the appropriate thiazole was used, there were obtained the compounds described in the following table:- Example 7 A mixture of 2-[1-(3-hydroxyphenyl)-1-methoxypropyl]thiazole (0.25 g), potassium carbonate (0.28 g), 3-(3-pyridyl)prop-2-yn-1-yl bromide hydrobromide (0.28 g) and acetone (5 ml) was stirred and heated to reflux for 17 hours. The mixture was cooled to ambient temperature, filtered and the filtrate was evaporated. The residue was purified by column chromatography eluting with hexane/ethyl acetate (1:1 v/v) to give 2-[1-[3-(3-(3-pyridyl)prop-2-yn-1-yloxy)phenyl]-1-methoxypropyl]thiazole as an oil (0.217 g, 59%). The 3-(3-pyridyl)prop-2-yn-1-yl bromide hydrobromide used as a starting material was obtained as follow:- 2-Propynyl alcohol (2.1 g) was added dropwise to a stirred mixture of 3-iodopyridine (2.2 g), bis(triphenylphosphine)palladium chloride (0.1 g), triethylamine (1.4 ml), cuprous iodide (0.1 g) and acetonitrile (10 ml) and the mixture was stirred at ambient temperature for 30 minutes and the heated to 60°C for 2 hours. The mixture was cooled to ambient temperature, poured into water (100 ml) and neutralised by adding dilute aqueous hydrochloric acid. The mixture was extracted with diethyl ether (2 x 100 ml) and the combined extracts were washed with water (100 ml), dried (MgSO₄) and evaporated. The residue was purified by column chromatography eluting with methylene chloride to give 3-(3-pyridyl)prop-2-yn-1-yl alcohol (0.8 g), m.p. 99-100°C. A solution of bromine (0.8 g) in methylene chloride (3 ml) was added to a mixture of triphenylphosphine (1.73 g) and methylene chloride (18 ml) which had been cooled to 5°C in an ice-bath. A solution of the alcohol (0.8 g) obtained immediately above in methylene chloride (20 ml) was added and the mixture was stirred for 10 minutes and cooled to approximately 8°C. The mixture was filtered to give 3-(3-pyridyl)prop-2-yn-1-yl bromide hydrobromide (1.05 g, 63%), m.p. 158-160°C, which was used without further purification. Example 8 A mixture of 2-[1-hydroxy-1-(3-hydroxyphenyl)-2,2,2-trifluoroethyl]thiazole (0.33 g), 2-chloromethylquinoline hydrochloride (0.22 g), potassium carbonate (0.5 g) and dimethylformamide (5 ml) was stirred at ambient temperature for 24 hours. The mixture was partitioned between ethyl acetate and water and the organic layer was separated, washed with a saturated aqueous sodium chloride solution, dried (MgSO₄) and evaporated. The residue was purified by column chromatography eluting with chloroform/ethyl acetate (9/1 v/v) to give 2-[1-hydroxy-1-[3-(quinol-2-ylmethoxy)phenyl]-2,2,2-trifluoroethyl]thiazole (0.15 g, 30%), m.p. 177°C. The 2-[1-hydroxy-1-(3-hydroxyphenyl)-2,2,2-trifluoroethyl]thiazole used as a starting material was obtained as follows:- A solution of 3-methoxy-α,α,α-trifluoroacetophenone (1.86 g) in tetrahydrofuran (10 ml) was added dropwise to a cooled (-60°C) soltuion of thiazol-2-yl-lithium [prepared by adding a solution of n-butyl-lithium (1.46 M in hexane, 6.8 ml) to a mixture of thiazole (1 ml) and tetrahydrofuran (10 ml) which had been cooled to -60°C]. The mixture was allowed to warm to ambient temperature and was stirred for 18 hours. The mixture was partitioned between ethyl acetate and a saturated aqueous ammonium chloride solution. The organic layer was washed with water and with a saturated aqueous sodium chloride solution, dried (MgSO₄) and evaporated. The solid residue was recrystallised from a mixture of hexane and ethyl acetate to give 2-[1-hydroxy-1-(3-methoxyphenyl)-2,2,2-trifluoroethyl]thiazole as a pale brown solid (1.56 g), m.p. 88-92°C. Boron tribromide (1.5 ml) was added dropwise to a mixture of the product so obtained (1.56 g) and methylene chloride (20 ml) which had been cooled to -70°C. The mixture was allowed to warm to ambient temperature and was stirred for 2 hours. A saturated aqueous sodium bicarbonate solution was added carefully until there was no further effervescence and the mixture was extracted with methylene chloride (3 x 30 ml). The combined extracts were washed with water and with a saturated sodium chloride solution, dried (MgSO₄) and evaporated to give 2-[1-hydroxy-1-(3-hydroxyphenyl)-2,2,2-trifluoroethyl]thiazole as a yellow solid (0.74 g), m.p. 133-135°C. Example 9 Using a similar procedure to that described in Example 1, except that the appropriate alkylating agent was used in place of 3-bromomethyl-1,2-dihydro-1-methylquinolin-2-one and the appropriate thiazole was used, there were thus obtained the compounds described in the following table:- Example 10 The reaction described in Example 5 was repeated except that 4-iodopyridine ( J. Chem. Soc. , 1953, 3232) was used in place of 2-iodopyridine. There was thus obtained 2-[1-[3-(3-(4-pyridyl)prop-2-yn-1-yloxy)phenyl]-1-methoxypropyl]thiazole in 78% yield, as an oil. NMR Spectrum (CDCl₃, delta values) 0.8(t, 3H), 2.55(m, 2H), 3.2(s, 3H), 4.9(s, 2H), 6.9-7.7(m, 10H). Example 11 The reaction described in Example 5 was repeated except that 1-iodoisoquinoline ( Chem. Pharm. Bull. Jap. , 1982, 30 , 1731) was used in place of 2-iodopyridine. There was thus obtained 2-[1-[3-(3-(1-isoquinolyl)prop-2-yn-1-yloxy)phenyl]-1-methoxypropyl]thiazole in 48% yield, m.p. 73-75 °C. Example 12 The reaction described in Example 5 was repeated except that 2-[1-[3-methoxy-4-(2-propynyloxy)phenyl]-1-methoxypropyl]thiazole was used in place of 2-[1-(3-(2-propynyloxy)phenyl)-1-methoxypropyl]thiazole and that the reaction mixture was stirred at ambient temperature for 16 hours. There was thus obtained 2-[1-[3-methoxy-4-(3-(2-pyridyl)prop-2-yn-1-yloxy)phenyl]-1-methoxypropyl]thiazole in 41% yield, as an oil. NMR Spectrum (CDCl₃, delta values) 0.8(t, 3H), 2.4(m, 1H), 2.7(m, 1H), 3.2(s, 3H), 3.85(s, 3H), 5.0(s, 2H), 7.0(m, 3H), 7.25(m, 2H), 7.4(d, 1H), 7.65(d, 1H), 7.7(d, 1H), 8.6(d, 1H). The 2-[1-[3-methoxy-4-(2-propynyloxy)phenyl]-1-methoxypropyl]thiazole, used as a starting material, was obtained as follows:- Tert -butyldimethylsilyl chloride (14 g) was added to a mixture of ethyl vanillate (15 g), imidazole (13 g) and tetrahydrofuran (100 ml) and the mixture was stirred at ambient temperature for 48 hours. The mixture was filtered and evaporated to give ethyl 4-( tert -butyldimethylsilyloxy)-3-methoxybenzoate (25.1 g). A solution of the product so obtained in tetrahydrofuran (50 ml) was cooled to -70°C and to this was added a cooled (-70°C) solution of thiazol-2-yl- lithium [prepared by adding 2-bromothiazole (14.1 g) to a mixture of n-butyl-lithium (1.5 M in hexane, 57.3 ml) and diethyl ether (30 ml) which had been cooled to -70°C]. The mixture was stirred for 16 hours and allowed to warm to ambient temperature. The mixture was poured into a saturated aqueous ammonium chloride solution and extracted with ethyl acetate (3 x 100 ml). The combined extracts were washed with water and with a saturated aqueous sodium chloride solution, dried (MgSO₄) and evaporated. The residue was purified by column chromatography using increasingly polar mixtures of methylene chloride and ethyl acetate as eluent. There was thus obtained 4-hydroxy-3-methoxyphenyl 2-thiazolyl ketone (4.5 g) in 24% yield, m.p. 103°C. The product so obtained (4.0 g) was reacted with tert -butyldimethylsilyl chloride using the procedure described immediately above to give 4- tert -butyldimethylsilyloxy-3-methoxyphenyl 2-thiazolyl ketone (6.5 g). A solution of a portion of the ketone so obtained (5.9 g) in tetrahydrofuran (5 ml) was added to a diethyl ether solution of ethylmagnesium iodide [prepared from iodoethane (2.8 ml) and magnesium (0.816 g) under diethyl ether (10 ml)] and the mixture was heated to reflux for 15 minutes. The mixture was poured into a saturated aqueous ammonium chloride solution and extracted with ethyl acetate (3 x 25 ml). The combined extracts were washed with water (2 x 50 ml), with a saturated aqueous sodium chloride solution, dried (MgSO₄) and evaporated. There was thus obtained 2-[1-(4- tert -butyldimethylsilyloxy-3-methoxyphenyl)-1-hydroxypropyl] thiazole (5.8 g). The product so obtained was reacted with methyl iodide using the procedure described in Example 1 except that the product was purified by column chromatography using increasingly polar mixtures of methylene chloride and ethyl acetate as eluent. There was thus obtained 2-[1-(4- tert -butyldimethylsilyloxy3-methoxyphenyl)-1-methoxypropyl]thiazole (3 g). Tetra- n -butylammonium fluoride (1 M in tetrahydrofuran; 16 ml) was added over 5 minutes to a solution of the product so obtained in tetrahydrofuran (50 ml). The mixture was poured into a saturated aqueous ammonium chloride solution and extracted with ethyl acetate (3 x 70 ml). The combined extracts were washed with water, with a saturated aqueous sodium chloride solution, dried (MgSO₄) and evaporated. There was thus obtained 2-[1-(4-hydroxy-3-methoxyphenyl)-1-methoxypropyl]thiazole (1.3 g), m.p. 127-129°C (recrystallised from a mixture of petroleum ether (b.p 60-80°C) and methylene chloride). After repetition of the above reactions, a mixture of the product so obtained (1.8 g), 2-propynyl bromide (80% w/v solution in toluene, 1 ml), potassium carbonate (1.2 g) and dimethylformamide (10 ml) was stirred at ambient temperature for 16 hours. The mixture was partitioned between ethyl acetate and water. The organic layer was washed with water and with a saturated aqueous sodium chloride solution, dried (MgSO₄) and evaporated. The residue was purified by column chromatography using a 9:1 v/v mixture of methylene chloride and ethyl acetate as eluent. There was thus obtained the required starting material (0.65 g), as a gum. NMR Spectrum (CDCl₃, delta values) 0.8(t, 3H), 2.3-2.5(m, 2H), 2.5(t, 1H), 2.6-2.8(m, 2H), 3.2(s, 3H), 3.8(s, 3H), 4.7(d, 2H), 7.0(m, 3H), 7.25(d, 1H), 7.7(d, 1H). Example 13 Using a similar procedure to that described in Example 8, 3-(2-pyridyl)prop-2-yn-1-yl bromide hydrobromide was reacted with 2-[1-(5-fluoro-3-hydroxyphenyl)-1-methoxypropyl]thiazole to give 2-[1-[5-fluoro-3-(3-(2-pyridyl)prop-2-yn-1-yloxy)phenyl]-1-methoxypropyl]thiazole in 54% yield, as an oil. NMR Spectrum (CDCl₃, delta values) 0.8(t, 3H), 2.5(m, 2H), 3.2(s, 3H), 4.9(s, 2H), 6.4-7.7(m, 8H), 8.6(d, 1H). The 3-(2-pyridyl)prop-2-yn-1-yl bromide hydrobromide, used as a starting material, was obtained by repetition of the procedure described in the portion of Example 7 which is concerned with the preparation of starting materials, except that 2-iodopyridine was used in place of 3-iodopyridine. There was thus obtained the required starting material in 7% yield, as a solid salt. NMR Spectrum (CD₃SOCD₃) 4.55 (s, 2H), 7.55 (m, 1H), 7.7 (m, 1H), 8.0 (m, 1H), 8.68 (m, 1H). Example 14 Sodium hydride (50% w/w dispersion in mineral oil, 0.29 g) was added portionwise to a solution of 2-[1-(5-hydroxypyrid-3-yl)-1-methoxypropyl]thiazole (0.75 g) in dimethylformamide (20 ml) and the mixture was stirred at ambient temperature for 30 minutes. The mixture was cooled to -10°C and 3-(2-pyridyl)prop-2-yn-1-yl bromide hydrobromide (0.83 g) was added. The mixture was stirred at -5°C for 1 hour. The mixture was partitioned between ethyl acetate and water. The organic phase was washed with water, dried (MgSO₄) and evaporated. The residue was purified by column chromatography using ethyl acetate as eluent. There was thus obtained 2-[1-[5-(3-(2-pyridyl)prop-2-yn-1-yloxy)pyrid-3-yl]-1-methoxypropyl]thiazole in 28% yield, as an oil. NMR Spectrum (CDCl₃, delta values) 0.8(t, 3H), 2.4-2.7(m, 2H), 3.25(s, 3H), 5.0(s, 2H), 7.2-7.7(m, 7H), 8.32(m, 1H), 8.58(m, 1H). Example 15 Using a similar procedure to that described in Example 1, 2-bromomethylquinoline was reacted with 2-[1-(4-hydroxy-3-methoxyphenyl)-1-methoxypropyl]thiazole to give 2-[1-methoxy-1-[3-methoxy-4-(quinol-2-ylmethoxy)phenyl]propyl]thiazole in 52% yield, m.p. 100-102°C (recrystallised from a mixture of petroleum ether (b.p. 60-80°C) and methylene chloride). Example 16 Using a similar procedure to that described in Example 1, 3-bromomethyl-1,2-dihydroquinolin-2-one was reacted with 2-[1-(4-hydroxy-3-methoxyphenyl)-1-methoxypropyl]thiazole to give 2-[1-methoxy-1-[3-methoxy-4-(1,2-dihydro-2-oxoquinolin-3-ylmethoxy)phenyl]propyl]thiazole in 28% yield, m.p. 170-171°C (recrystallised from a mixture of hexane and ethyl acetate). Example 17 Sodium hydride (0.032 g of a 55% w/w dispersion in mineral oil) was added portionwise to a stirred solution of 2-[1-hydroxy-1-[3-(quinol-2-ylmethoxy)phenyl]-2,2,2-trifluoroethyl]thiazole in tetrahydrofuran (1 ml) and the mixture was stirred at ambient temperature for 10 minutes. A solution of methyl iodide (0.07 ml) in tetrahydrofuran (0.7 ml) was added and the mixture was stirred at ambient temperature for 3 days. The mixture was evaporated and the residue was purified by column chromatography using a 6:1 v/v mixture of toluene and ethyl acetate as eluent. There was thus obtained 2-[1-methoxy-1-[3-(quinol-2-ylmethoxy)phenyl]-2,2,2-trifluoroethyl]thiazole (0.2 g, 74%), as an oil. NMR Spectrum (CD₃SOCD₃, delta values) 3.3 (s, 3H), 5.4 (s, 2H), 7.1 (m, 1H), 7.2 (m, 1H), 7.4-7.8 (m, 5H), 7.9 (d of d′s, 2H), 8.0 (m, 2H), 8.4 (d, 1H). NMR Spectral Data For those compounds of the invention within Examples 2 to 7 hereinbefore which were obtained as oils, the following NMR spectral data were obtained: Example 2, Compound No. 2: (CDCl₃, delta values) 0.6-0.7(t, 3H), 2.3-2.7(m, 2H), 3.1(s, 3H), 5.1(s, 2H), 6.9-7.05(m, 3H), 7.2-7.4(m, 2H), 7.5(d, 1H), 7.6-7.7(m, 2H), 7.8(t, 1H), 8.6(m, 1H). Example 2, Compound No. 6: (CDCl₃, delta values) 0.75(t, 3H), 2.32-2.78(m, 2H), 3.2(s, 3H), 5.3(s, 2H), 6.85-8.15(m, 9H), 8.9(s, 2H). Example 2, Compound No. 12: (CD₃SOCD₃, delta values) 3.2 (s, 3H), 3.3 (s, 3H), 5.3 (s, 2H), 6.9-8.9 (m, 12H). Example 3: (CDCl₃, delta values) 0.8(t, 3H), 2.35-2.8(m, 2H), 3.2(s, 3H), 4.7(d, 2H), 6.4-6.55(m, 1H), 6.7-6.8(d, 1H), 6.8-6.9(m, 1H), 7.05-7.35(m, 5H), 7.6-7.8(m, 2H), 8.5(d, 1H), 8.6(d, 1H). Example 4: (CD₃SOCD₃, delta values) 0.7 (t, 3H), 2.3-2.7 (m, 2H), 3.2 (s, 3H), 4.8 (d, 2H), 6.75-7.05 (m, 5H), 7.1-7.4 (m, 2H), 7.45 (m, 3H), 7.6-7.7 (m, 2H), 7.7-7.8 (m, 1H), 8.5 (m, 1H). Example 6, Compound No. 1: (CDCl₃, delta values) 0.8(t, 3H), 2.4-2.7(m, 2H), 3.2(s, 3H), 4.9(s, 2H), 6.9-7.4(m, 5H), 7.7(d, 1H), 8.5-8.7(m, 3H). Example 6, Compound No. 3: (CD₃SOCD₃, delta values) 1.95 (s, 3H), 3.2 (s, 3H), 5.1 (s, 2H), 6.9-7.4 (m, 5H), 7.6-7.7 (m, 2H), 8.6-8.85 (m, 3H). Example 7: (CDCl₃, delta values) 0.75(t, 3H), 2.4-2.8(m, 2H), 3.2(s, 3H), 4.9(s, 2H), 6.9-7.8(m, 8H), 8.5-8.7(m, 2H). Example 18 The following illustrate representative pharmaceutical dosage forms containing the compound of formula I, or a pharmaceutically-acceptable salt salt thereof (hereafter compound X), for therapeutic or prophylactic use in humans:

Claims: Claims for the following Contracting States : AT, BE, CH, DE, DK, FR, GB, IT, LI, LU, NL, SE A thiazole of the formula I wherein Q¹ is a 6-membered monocyclic or 10-membered bicyclic heterocyclic moiety containing one or two nitrogen atoms which may optionally bear one, two or three substituents selected from halogeno, hydroxy, oxo, cyano, (1-4C)alkyl, (1-4C)alkoxy, fluoro-(1-4C)alkyl, (1-4C)alkylamino-(1-4C)alkyl and di-[(1-4C)alkyl]amino-(1-4C)alkyl; wherein A is (1-6C)alkylene, (3-6C)alkenylene, (3-6C)alkynylene or cyclo(3-6C)alkylene; wherein X is oxy, thio, sulphinyl, sulphonyl or imino; wherein Ar is phenylene which may optionally bear one or two substituents selected from halogeno, hydroxy, amino, nitro, carboxy, cyano, carbamoyl, (1-4C)alkyl, (1-4C)alkoxy, (1-4C)alkylthio, (1-4C)alkylsulphinyl, (1-4C)alkylsulphonyl, (1-4C)alkylamino, di-[(1-4C)alkyl]amino, (1-4C)alkoxycarbonyl, N-[(1-4C)alkyl]carbamoyl, N,N-di-[(1-4C)alkyl]carbamoyl, (2-4C)alkanoylamino, hydroxy-(2-4C)alkoxy, (1-4C)alkoxy-(2-4C)alkoxy, amino-(2-4C)alkoxy, cyano-(1-4C)alkoxy, carbamoyl-(1-4C)alkoxy, N-[(1-4C)alkyl]carbamoyl-(1-4C)alkoxy, N,N-di-[(1-4C)alkyl]carbamoyl-(1-4C)alkoxy, (1-4C)alkylamino-(2-4C)alkoxy, di-[(1-4C)alkyl]amino-(2-4C)alkoxy, (1-4C)alkoxycarbonyl-(1-4C)alkoxy, fluoro-(1-4C)alkyl, hydroxy-(1-4C)alkyl, amino-(1-4C)alkyl, cyano-(1-4C)alkyl, (1-4C)alkoxy-(1-4C)alkyl, (1-4C)alkylamino-(1-4C)alkyl, di-[(1-4C)alkyl]amino-(1-4C)alkyl and (2-4C)alkanoylamino-(1-4C)alkyl, or Ar is a 6-membered heterocyclene moiety containing up to three nitrogen atoms which may optonally bear one or two substituents selected from halogeno, hydroxy, amino, cyano, (1-4C)alkyl, (1-4C)alkoxy, (1-4C)alkylamino and di-[(1-4C)alkyl]amino; wherein R¹ is hydrogen, (1-6C)alkyl, (2-6C)alkenyl, (2-6C)alkynyl, fluoro-(1-4C)alkyl, cyano(1-4C)alkyl, hydroxy-(1-4C)alkyl, (1-4C)alkoxy-(1-4C)alkyl and (2-4C)alkanoyloxy-(1-4C)alkyl; wherein R² is hydrogen, (1-6C)alkyl, (3-6C)alkenyl, (3-6C)alkynyl, (1-4C)alkoxycarbonyl-(1-4C)alkyl, carboxy-(1-4C)alkyl, carbamoyl-(1-4C)alkyl, cyano(1-4C)alkyl or (2-4C)alkanoyl or R² is benzoyl which may optionally bear a substituent selected from halogeno, (1-4C)alkyl and (1-4C)alkoxy; and wherein Q² is thiazolyl which may optionally bear one or two substituents selected from halogeno, amino, nitro, cyano, carbamoyl, (1-4C)alkyl, (1-4C)alkoxy, (1-4C)alkylamino, di-[(1-4C)alkyl]amino, (1-4C)alkoxycarbonyl, N-[(1-4C)alkyl]carbamoyl, N,N-di-[(1-4C)alkyl]carbamoyl, (2-4C)alkanoylamino, fluoro-(1-4C)alkyl and hydroxy-(1-4C)alkyl; or a pharmaceutically-acceptable salt thereof. A thiazole of the formula I as claimed in claim 1 wherein Q¹ is pyridyl, pyrimidinyl, pyrazinyl, quinolyl, isoquinolyl, quinazolinyl or quinoxalinyl which may optionally bear one, two or three substituents selected from fluoro, chloro, hydroxy, oxo, methyl, ethyl, methoxy, trifluoromethyl, 2-fluoroethyl and 2-dimethylaminoethyl; wherein A is methylene, 1-propenylene or 1-propynylene; wherein X is oxy; wherein Ar is 1,3-phenylene or 1,4-phenylene which may optionally bear one substituent selected from fluoro, chloro, hydroxy, amino, nitro, methyl, methoxy and trifluoromethyl, or Ar is 3,5-pyridylene; wherein R¹ is methyl or ethyl; wherein R² is hydrogen, methyl, ethyl or allyl; and Q² is 2-thiazolyl; or a pharmaceutically acceptable salt thereof. A thiazole of the formula I as claimed in claim 1 wherein Q¹ is 2-pyridyl, 3-pyridyl, 3-pyridazinyl, 2-pyrimidinyl or 2-pyrazinyl which may optionally bear one substituent selected from chloro, hydroxy, cyano, methyl, methoxy and trifluoromethyl; or Q¹ is 2-quinolyl, 3-quinolyl, 6-quinolyl, 7-quinolyl, 3-isoquinolyl, 6-isoquinolyl, 7-isoquinolyl, 3-cinnolyl, 2-quinazolinyl, 6-quinazolinyl, 2-quinoxalinyl, 6-quinoxalinyl, 6-phthalazinyl, 1,7-naphthyridin-3-yl, 1,7-naphthyridin-6-yl, 1,8-naphthyridin-3-yl or 2,7-naphthyridin-3-yl which may optionally bear one or two substituents selected from chloro, hydroxy, oxo, cyano, methyl, methoxy and trifluoromethyl; or Q¹ is 1,2-dihydro-2-oxoquinolin-3-yl, 1,2-dihydro-2-oxoquinolin-6-yl, 1,2-dihydro-2-oxoquinolin-7-yl, 3,4-dihydro-4-oxoquinazolin-6-yl, 1,2-dihydro-2-oxo-1,7-naphthyridin-3-yl or 1,2-dihydro-2-oxo-1,8-naphthyridin-3-yl which may optionally bear one or two substitutents selected from chloro, cyano, methyl, methoxy and trifluoromethyl; wherein A is methylene, ethylene, trimethylene, 1-propenylene, 2-methylprop-1-enylene or 1-propynylene; wherein X is oxy; wherein Ar is 1,3-phenylene or 1,4-phenylene which may optionally bear one substituent selected from chloro, bromo, hydroxy, amino, nitro, methyl, methoxy, methylthio, methylsulphinyl, methylsulphonyl, methylamino, dimethylamino, trifluoromethyl, acetamido, cyanomethoxy and carbamoylmethoxy; wherein Ar is 2,4-, 2,5-, 3,5- or 2,6-pyridylene or 4,6-pyrimidinylene which may optionally bear one substituent selected from chloro, methyl and methoxy; wherein R¹ is hydrogen, methyl, ethyl, propyl, vinyl, ethynyl, 1-propynyl, trifluoromethyl, hydroxymethyl, methoxymethyl or acetoxymethyl; wherein R² is hydrogen, methyl, ethyl, allyl, 2-propynyl or cyanomethyl; and wherein Q² is 2-thiazolyl; or a pharmaceutically-acceptable salt thereof. A thiazole of the formula I as claimed in claim 1 wherein Q¹ is 2-quinolyl, 3-quinolyl, 6-quinolyl, 3-isoquinolyl, 2-quinazolinyl, 6-quinazolinyl, 6-quinoxalinyl, 1,2-dihydro-2-oxoquinolin-3-yl or 1,2-dihydro-2-oxoquinolin-6-yl which may optionally bear one or two substituents selected from fluoro, chloro, hydroxy, methyl and 2-dimethylaminoethyl; wherein A is methylene; wherein X is oxy; wherein Ar is 1,3-phenylene or 1,4-phenylene which may optionally bear one substituent selected from fluoro and methoxy, or Ar is 3,5-pyridylene; wherein R¹ is methyl or ethyl; wherein R² is methyl; and wherein Q² is 2-thiazolyl; or a pharmaceutically-acceptable salt thereof. A thiazole of the formula I as claimed in claim 1 wherein Q¹ is 2-pyridyl, 3-pyridyl, 4-pyridyl, 2-pyrimidinyl, 2-pyrazinyl or 1-isoquinolyl, wherein A is 1-propenylene or 1-propynylene; wherein X is oxy; wherein Ar is 1,3-phenylene or 1,4-phenylene which may optionally bear one substituent selected from fluoro and methoxy, or Ar is 3,5-pyridylene; wherein R¹ is methyl or ethyl; wherein R² is methyl; and wherein Q² is 2-thiazolyl; or a pharmaceutically-acceptable salt thereof. A thiazole of the formula I as claimed in claim 1, or a pharmaceutically-acceptable salt thereof, selected from the group consisting of, 2-[1-[3- (3-isoquinolylmethoxy)phenyl]-1-methoxypropyl]thiazole, 2-[1-[3-(3-(2-pyridyl)prop-2-yn-1-yloxy)phenyl]-1-methoxypropyl]thiazole, 2-[1-[3-(3-(3-pyridyl)prop-2-yn-1-yloxy)phenyl]-1-methoxypropyl]thiazole, 2-[1-[3-(3-(3-pyridyl)prop-2-yn-1-yloxy)phenyl]-1-methoxyethyl]thiazole, 2-[1-methoxy-1-[3-methoxy-4-(quinol-2-ylmethoxy)phenyl]propyl]thiazole, 2- [1-methoxy-1-[3(1,2-dihydro-1-methyl-2-oxoquinolin-6-ylmethoxy)phenyl]propyl]thiazole, and 2-[1-[5-fluoro-3-(3-(2-pyridyl)prop-2-yn-1-yloxy)phenyl]-1-methoxypropyl]thiazole. A process for the manufacture of a thiazole of the formula I as claimed in claim 1, or a pharmaceutically-acceptable salt thereof, which comprises:- (a) the alkylation, in the presence of a suitable reagent, of a compound of the formula II with a compound of the formula Q¹-A-Z wherein Z is a displaceable group; provided that, when there is an amino, alkylamino, hydroxy or carboxy group in Q¹, Ar, R¹, R² or Q², any amino, alkylamino or carboxy group is protected by a conventional protecting group and any hydroxy group may be protected by a conventional protecting group or alternatively any hydroxy group need not be protected; whereafter any undesired protecting group in Q¹, Ar, R¹, R² or Q² is removed by conventional means; (b) the alkylation, in the presence of a suitable base as defined hereinbefore, of a compound of the formula V with a compound of the formula R²-Z, wherein R² has the meaning defined hereinbefore and Z is a displaceable group, provided that, when there is an amino, imino, alkylamino, hydroxy or carboxy group in Q¹, X, Ar, R¹, R² or Q², any amino, imino, alkylamino, hydroxy or carboxy group is protected by a conventional protecting group; whereafter any undesired protecting group in Q¹, X, Ar, R¹, R² or Q² is removed by conventional means; (c) for the production of those compounds of the formula I wherein A is a (3-6C)alkynylene group, the coupling, in the presence of a suitable organometallic catalyst, of a heterocyclic compound of the formula Q¹-Z, wherein Q¹ has the meaning defined hereinbefore and Z is a halogeno group such as iodo, with an ethynyl compound of the formula VI wherein A¹ is (1-4C)alkylene and X, Ar, R¹, R² and Q² have the meanings defined hereinbefore; (d) for the production of those compound of the formula I wherein Ar bears an alkylsulphinyl or alkylsulphonyl substituent or X is a sulphinyl or sulphonyl group, the oxidation of a compound of the formula I wherein Ar bears an alkylthio substituent or wherein X is a thio group; (e) for the production of those compounds of the formula I wherein Q¹, Ar or Q² bears an alkanoylamino or alkanoylaminoalkyl substituent, the acylation of a compound of the formula I wherein Q¹, Ar or Q² bears an amino or aminoalkyl substituent; (f) for the production of those compounds of the formula I wherein R² is alkanoyl or benzoyl optionally bearing a substituent as defined hereinbefore, the acylation of a compound of the formula I wherein R² is hydrogen; (g) for the production of those compounds of the formula I wherein A is alkenylene or R¹ is alkenyl, the reduction of the corresponding compound wherein A is alkynylene or R¹ is alkynyl: or (h) for the production of those compounds of the formula I wherein Ar bears an alkoxy or substituted alkoxy substituent, the alkylation of a compound of the formula I wherein Ar bears a hydroxy substituent; and when a pharmaceutically-acceptable salt of a novel compound of the formula I is required, it may be obtained by reaction of said compound with a suitable acid or base using a conventional procedure. A pharmaceutical composition which comprises a thiazole of the formula I, or a pharmaceutically-acceptable salt thereof, as claimed in any one of claims 1 to 6 in association with a pharmaceutically-acceptable diluent or carrier. A thiazole of the formula I, or a pharmaceutically-acceptable salt thereof, as claimed in any one of claims 1 to 6 for use in a method of treatment of the human or animal body by therapy. The use of a thiazole of the formula I, or a pharmaceutically-acceptable salt thereof, as claimed in any one of claims 1 to 6 in the production of a new medicament for use in a leukotriene mediated disease or medical condition. Claims for the following Contracting States: ES, GR A process for the manufacture of a thiazole of the formula I wherein Q¹ is a 6-membered monocyclic or 10-membered bicyclic heterocyclic moiety containing one or two nitrogen atoms which may optionally bear one, two or three substituents selected from halogeno, hydroxy, oxo, cyano, (1-4C)alkyl, (1-4C)alkoxy, fluoro-(1-4C)alkyl, (1-4C)alkylamino-(1-4C)alkyl and di-[(1-4C)alkyl]amino-(1-4C)alkyl; wherein A is (1-6C)alkylene, (3-6C)alkenylene, (3-6C)alkynylene or cyclo(3-6C)alkylene; wherein X is oxy, thio, sulphinyl, sulphonyl or imino; wherein Ar is phenylene which may optionally bear one or two substituents selected from halogeno, hydroxy, amino, nitro, carboxy, cyano, carbamoyl, (1-4C)alkyl, (1-4C)alkoxy, (1-4C)alkylthio, (1-4C)alkylsulphinyl, (1-4C)alkylsulphonyl, (1-4C)alkylamino, di-[(1-4C)alkyl]amino, (1-4C)alkoxycarbonyl, N-[(1-4C)alkyl]carbamoyl, N,N-di-[(1-4C)alkyl]carbamoyl, (2-4C)alkanoylamino, hydroxy-(2-4C)alkoxy, (1-4C)alkoxy-(2-4C)alkoxy, amino-(2-4C)alkoxy, cyano-(1-4C)alkoxy, carbamoyl-(1-4C)alkoxy, N-[(1-4C)alkyl]carbamoyl-(1-4C)alkoxy, N,N-di-[(1-4C)alkyl]carbamoyl-(1-4C)alkoxy, (1-4C)alkylamino-(2-4C)alkoxy, di-[(1-4C)alkyl]amino-(2-4C)alkoxy, (1-4C)alkoxycarbonyl-(1-4C)alkoxy, fluoro-(1-4C)alkyl, hydroxy-(1-4C)alkyl, amino-(1-4C)alkyl, cyano-(1-4C)alkyl, (1-4C)alkoxy-(1-4C)alkyl, (1-4C)alkylamino-(1-4C)alkyl, di-[(1-4C)alkyl]amino-(1-4C)alkyl and (2-4C)alkanoylamino-(1-4C)alkyl, or Ar is a 6-membered heterocyclene moiety containing up to three nitrogen atoms which may optonally bear one or two substituents selected from halogeno, hydroxy, amino, cyano, (1-4C)alkyl, (1-4C)alkoxy, (1-4C)alkylamino and di-[(1-4C)alkyl]amino; wherein R¹ is hydrogen, (1-6C)alkyl, (2-6C)alkenyl, (2-6C)alkynyl, fluoro-(1-4C)alkyl, cyano(1-4C)alkyl, hydroxy-(1-4C)alkyl, (1-4C)alkoxy-(1-4C)alkyl and (2-4C)alkanoyloxy-(1-4C)alkyl; wherein R² is hydrogen, (1-6C)alkyl, (3-6C)alkenyl, (3-6C)alkynyl, (1-4C)alkoxycarbonyl-(1-4C)alkyl, carboxy-(1-4C)alkyl, carbamoyl-(1-4C)alkyl, cyano(1-4C)alkyl or (2-4C)alkanoyl or R² is benzoyl which may optionally bear a substituent selected from halogeno, (1-4C)alkyl and (1-4C)alkoxy; and wherein Q² is thiazolyl which may optionally bear one or two substituents selected from halogeno, amino, nitro, cyano, carbamoyl, (1-4C)alkyl, (1-4C)alkoxy, (1-4C)alkylamino, di-[(1-4C)alkyl]amino, (1-4C)alkoxycarbonyl, N-[(1-4C)alkyl]carbamoyl, N,N-di-[(1-4C)alkyl]carbamoyl, (2-4C)alkanoylamino, fluoro-(1-4C)alkyl and hydroxy-(1-4C)alkyl; or a pharmaceutically-acceptable salt thereof, characterised by (a) the alkylation, in the presence of a suitable reagent, of a compound of the formula II with a compound of the formula Q¹-A-Z wherein Z is a displaceable group; provided that, when there is an amino, alkylamino, hydroxy or carboxy group in Q¹, Ar, R¹, R² or Q², any amino, alkylamino or carboxy group is protected by a conventional protecting group and any hydroxy group may be protected by a conventional protecting group or alternatively any hydroxy group need not be protected; whereafter any undesired protecting group in Q¹, Ar, R¹, R² or Q² is removed by conventional means; (b) the alkylation, in the presence of a suitable base, of a compound of the formula V with a compound of the formula R²-Z, wherein R² has the meaning defined hereinbefore and Z is a displaceable group, provided that, when there is an amino, imino, alkylamino, hydroxy or carboxy group in Q¹, X, Ar, R¹, R² or Q², any amino, imino, alkylamino, hydroxy or carboxy group is protected by a conventional protecting group; whereafter any undesired protecting group in Q¹, X, Ar, R¹, R² or Q² is removed by conventional means; (c) for the production of those compounds of the formula I wherein A is a (3-6C)alkynylene group, the coupling, in the presence of a suitable organometallic catalyst, of a heterocyclic compound of the formula Q¹-Z, wherein Q¹ has the meaning defined hereinbefore and Z is a halogeno group such as iodo, with an ethynyl compound of the formula VI wherein A¹ is (1-4C)alkylene and X, Ar, R¹, R² and Q² have the meanings defined hereinbefore; (d) for the production of those compound of the formula I wherein Ar bears an alkylsulphinyl or alkylsulphonyl substituent or X is a sulphinyl or sulphonyl group, the oxidation of a compound of the formula I wherein Ar bears an alkylthio substituent or wherein X is a thio group; (e) for the production of those compounds of the formula I wherein Q¹, Ar or Q² bears an alkanoylamino or alkanoylaminoalkyl substituent, the acylation of a compound of the formula I wherein Q¹, Ar or Q² bears an amino or aminoalkyl substituent; (f) for the production of those compounds of the formula I wherein R² is alkanoyl or benzoyl optionally bearing a substituent as defined hereinbefore, the acylation of a compound of the formula I wherein R² is hydrogen; (g) for the production of those compounds of the formula I wherein A is alkenylene or R¹ is alkenyl, the reduction of the corresponding compound wherein A is alkynylene or R¹ is alkynyl: or (h) for the production of those compounds of the formula I wherein Ar bears an alkoxy or substituted alkoxy substituent, the alkylation of a compound of the formula I wherein Ar bears a hydroxy substituent; and when a pharmaceutically-acceptable salt of a novel compound of the formula I is required, it may be obtained by reaction of said compound with a suitable acid or base using a conventional procedure. A process as claimed in claim 1 for the manufacture of a thiazole of the formula I wherein Q¹ is pyridyl, pyrimidinyl, pyrazinyl, quinolyl, isoquinolyl, quinazolinyl or quinoxalinyl which may optionally bear one, two or three substituents selected from fluoro, chloro, hydroxy, oxo, methyl, ethyl, methoxy, trifluoromethyl, 2-fluoroethyl and 2-dimethylaminoethyl; wherein A is methylene, 1-propenylene or 1-propynylene; wherein X is oxy; wherein Ar is 1,3-phenylene or 1,4-phenylene which may optionally bear one substituent selected from fluoro, chloro, hydroxy, amino, nitro, methyl, methoxy and trifluoromethyl, or Ar is 3,5-pyridylene; wherein R¹ is methyl or ethyl; wherein R² is hydrogen, methyl, ethyl or allyl; and Q² is 2-thiazolyl; or a pharmaceutically acceptable salt thereof. A process as claimed in claim 1 for the manufacture of a thiazole of the formula I wherein Q¹ is 2-pyridyl, 3-pyridyl, 3-pyridazinyl, 2-pyrimidinyl or 2-pyrazinyl which may optionally bear one substituent selected from chloro, hydroxy, cyano, methyl, methoxy and trifluoromethyl; or Q¹ is 2-quinolyl, 3-quinolyl, 6-quinolyl, 7-quinolyl, 3-isoquinolyl, 6-isoquinolyl, 7-isoquinolyl, 3-cinnolyl, 2-quinazolinyl, 6-quinazolinyl, 2-quinoxalinyl, 6-quinoxalinyl, 6-phthalazinyl, 1,7-naphthyridin-3-yl, 1,7-naphthyridin-6-yl, 1,8-naphthyridin-3-yl or 2,7-naphthyridin-3-yl which may optionally bear one or two substituents selected from chloro, hydroxy, oxo, cyano, methyl, methoxy and trifluoromethyl; or Q¹ is 1,2-dihydro-2-oxoquinolin-3-yl, 1,2-dihydro-2-oxoquinolin-6-yl, 1,2-dihydro-2-oxoquinolin-7-yl, 3,4-dihydro-4-oxoquinazolin-6-yl, 1,2-dihydro-2-oxo-1,7-naphthyridin-3-yl or 1,2-dihydro-2-oxo-1,8-naphthyridin-3-yl which may optionally bear one or two substitutents selected from chloro, cyano, methyl, methoxy and trifluoromethyl; wherein A is methylene, ethylene, trimethylene, 1-propenylene, 2-methylprop-1-enylene or 1-propynylene; wherein X is oxy; wherein Ar is 1,3-phenylene or 1,4-phenylene which may optionally bear one substituent selected from chloro, bromo, hydroxy, amino, nitro, methyl, methoxy, methylthio, methylsulphinyl, methylsulphonyl, methylamino, dimethylamino, trifluoromethyl, acetamido, cyanomethoxy and carbamoylmethoxy; wherein Ar is 2,4-, 2,5-, 3,5- or 2,6-pyridylene or 4,6-pyrimidinylene which may optionally bear one substituent selected from chloro, methyl and methoxy; wherein R¹ is hydrogen, methyl, ethyl, propyl, vinyl, ethynyl, 1-propynyl, trifluoromethyl, hydroxymethyl, methoxymethyl or acetoxymethyl; wherein R² is hydrogen, methyl, ethyl, allyl, 2-propynyl or cyanomethyl; and wherein Q² is 2-thiazolyl; or a pharmaceutically-acceptable salt thereof. A process as claimed in claim 1 for the manufacture of a thiazole of the formula I wherein Q¹ is 2-quinolyl, 3-quinolyl, 6-quinolyl, 3-isoquinolyl, 2-quinazolinyl, 6-quinazolinyl, 6-quinoxalinyl, 1,2-dihydro-2-oxoquinolin-3-yl or 1,2-dihydro-2-oxoquinolin-6-yl which may optionally bear one or two substituents selected from fluoro, chloro, hydroxy, methyl and 2-dimethylaminoethyl; wherein A is methylene; wherein X is oxy; wherein Ar is 1,3-phenylene or 1,4-phenylene which may optionally bear one substituent selected from fluoro and methoxy, or Ar is 3,5-pyridylene; wherein R¹ is methyl or ethyl; wherein R² is methyl; and wherein Q² is 2-thiazolyl; or a pharmaceutically-acceptable salt thereof. A process as claimed in claim 1 for the manufacture of a thiazole of the formula I wherein Q¹ is 2-pyridyl, 3-pyridyl, 4-pyridyl, 2-pyrimidinyl, 2-pyrazinyl or 1-isoquinolyl, wherein A is 1-propenylene or 1-propynylene; wherein X is oxy; wherein Ar is 1,3-phenylene or 1,4-phenylene which may optionally bear one substituent selected from fluoro and methoxy, or Ar is 3,5-pyridylene; wherein R¹ is methyl or ethyl; wherein R² is methyl; and wherein Q² is 2-thiazolyl; or a pharmaceutically-acceptable salt thereof. A process for the manufacture of a pharmaceutical composition characterised by bringing into association a thiazole of the formula I, or a pharmaceutically-acceptable salt thereof, as defined in any one of claims 1 to 5 and a pharmaceutically-acceptable diluent or carrier.

Inventors: CRAWLEY, GRAHAM CHARLES, EDWARDS, MARTIN PAUL
Applicants: ICI PHARMA, IMPERIAL CHEMICAL INDUSTRIES PLC
Application year: 1990
Main classification: C07D417
IPC codes: A61K31, C07D471, A61P37, A61P43, A61P29, C12N9, C07D277, C07D417