Alcohol and ether derivatives

Abstract: The invention concerns a compound of the formula I, wherein Ar¹ is optionally substituted phenyl or naphthyl; A¹ is (1-6C)alkylene, (3-6C)alkenylene, (3-6C)alkynylene or cyclo(3-6C)alkylene; Ar² is optionally substituted phenylene, or a 6 membered heterocyclene moiety containing up to three nitrogen atoms; R¹ is hydrogen, (1-6C)alkyl, (3-6C)alkenyl, (3-6C)alkynyl, cyano-(1-­ 4C)alkyl or (2-4C)alkanoyl, or optionally substituted benzoyl; wherein R² is hydrogen, (1-6C)alkyl, (2-6C)alkenyl, (2-6C)alkynyl or substituted (1-4C)alkyl; and wherein R³ is hydroxy-(1-4C)alkyl, mercapto-(1-4C)alkyl, (1-4C)alkoxy-­ (1-4C)alkyl, (3-4C)alkenyloxy-(1-4C)alkyl, (3-4C)alkynyloxy-(1-­ 4C)alkyl, (1-4C)alkoxy(2-4C)alkoxy-(1-4C)alkyl, (1-4C)alkylthio-(1-­ 4C)alkyl, (1-4C)alkylsulphinyl-(1-4C)alkyl, (1-4C)alkylsulphonyl-(1-­ 4C)alkyl, (1-4C)alkoxycarbonyl-(1-4C)alkyl, (2-4C)alkanoyl-(1-­ 4C)alkyl, (2-4C)alkanoyloxy-(1-4C)alkyl or cyano-(1-4C)alkyl; or R³ is oxiranyl, oxetanyl, tetrahydrofuranyl or tetrahydropyranyl; or a pharmaceutically-acceptable salt thereof. The compounds of the invention are inhibitors of the enzyme 5-lipoxygenase.

Description: This invention concerns novel alcohol and ether derivatives and more particularly novel alcohol and ether derivatives which are inhibitors of the enzyme 5-lipoxygenase (hereinafter referred to as 5-LO). The invention also concerns processes for the manufacture of said derivatives and novel pharmaceutical compositions containing said derivatives. Also included in the invention is the use of said derivatives 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 alcohol and ether derivatives 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 alcohol and ether derivatives 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. It is disclosed by J.R. Crowley et al . in Biomedical Mass Spectrometry , 1982, 9 , 146-152 that 1-(3-phenylmethoxyphenyl)ethane-1,2-diol and 1-(4-phenylmethoxyphenyl)ethane-1,2-diol may be used as chemical intermediates in the synthesis of 1-(3-hydroxyphenyl)ethane-1,2-diol and 1-(4-hydroxyphenyl)ethane-1,2-diol respectively. It is further disclosed in Chemical Abstracts , 1975, 83 , 178502s that 1-[2-methoxy-5-(phenylmethoxy)phenyl]ethane-1,2-diol and 1-[5-methoxy-2-(phenylmethoxy)phenyl]ethane-1,2-diol may be used as chemical intermediates in the synthesis of potential metabolites of 2-amino- N -(beta-hydroxy-2,5-dimethoxyphenethyl)acetamide (Midodrine). It is further disclosed in European Patent Application No. 0 181 568 that certain phenyl, pyridyl or quinolyl derivatives which bear, for example, a phenoxymethyl substituent are inhibitors of the enzyme lipoxygenase. A typical example of the compounds disclosed is 2-(3-(1-hydroxyhexyl)phenoxymethyl)quinoline (first compound in Table I on page 46). According to the invention there is provided a compound of the formula I (set out hereinafter) wherein Ar¹ is phenyl or naphthyl which may optionally bear one or more substituents selected from halogeno, hydroxy, carboxy, cyano, (1-4C)alkyl, (2-4C)alkenyl, (2-4C)alkynyl, (1-4C)alkoxy, (1-4C)alkylthio, (1-4C)alkysulphinyl, (1-4C)alkylsulphonyl, (1-4C)alkylamino, di-[(1-4C)alkyl]amino, (1-4C)alkoxycarbonyl, (2-4C)alkanoyl, hydroxy-(1-4C)alkyl and fluoro-(1-4C)alkyl; wherein A¹ is (1-6C)alkylene, (3-6C)alkenylene, (3-6C)alkynylene or cyclo(3-6C)alkylene; wherein Ar² is phenylene which may optionally bear one or two substituents selected from halogeno, hydroxy, amino, nitro, cyano, carbamoyl, (1-4C)alkyl, (3-4C)alkenyloxy, (1-4C)alkoxy, (1-4C)alkylthio, (1-4C)alkylsulphinyl, (1-4C)alkysulphonyl, (1-4C)alkylamino, di-[(1-4C)alkyl]amino, fluoro-(1-4C)alkyl, (1-4C)alkoxycarbonyl, N-[(1-4C)alkyl]carbamoyl, N,N-di-[(1-4C)alkyl]carbamoyl, (2-4C)alkanoylamino, cyano-(1-4C)alkoxy, carbamoyl-(1-4C)alkoxy and (1-4C)alkoxycarbonyl-(1-4C)alkoxy; or Ar² is a 6-membered heterocyclene moiety containing up to three nitrogen atoms; wherein R¹ is (1-6C)alkyl, (3-6C)alkenyl, (3-6C)alkynyl, cyano-(1-4C)alkyl or (2-4C)alkanoyl, or R¹ is benzoyl which may optionally bear a substituent selected from halogeno, (1-4C)alkyl and (1-4C)alkoxy; and wherein R² is (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 or (2-4C)alkanoyloxy-(1-4C)alkyl; wherein R³ is hydroxy-(1-4C)alkyl, mercapto-(1-4C)alkyl, (1-4C)alkoxy-(1-4C)alkyl, (3-4C)alkenyloxy-(1-4C)alkyl, (3-4C)alkynyloxy-(1-4C)alkyl, (1-4C)alkoxy-(2-4C)alkoxy-(1-4C)alkyl, (1-4C)alkylthio-(1-4C)alkyl, (1-4C)alkylsulphinyl-(1-4C)alkyl, (1-4C)alkylsulphonyl-(1-4C)alkyl, (1-4C)alkoxycarbonyl-(1-4C)alkyl, (2-4C)alkanoyl-(1-4C)alkyl, (2-4C)alkanoyloxy-(1-4C)alkyl or cyano-(1-4C)alkyl; or R³ is oxiranyl, oxetanyl, tetrahydrofuranyl or tetrahydropyranyl; 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. Suitable values for the generic terms referred to above include those set out below. A suitable value for a halogeno substituent which may be present on Ar¹, Ar² or R¹ is, for example, fluoro, chloro, bromo or iodo. A suitable value for a (1-4C)alkyl substituent which may be present on Ar¹, Ar² or R¹ is, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec -butyl or tert -butyl. A suitable value for a (2-4C)alkenyl substituent on Ar¹ is, for example, vinyl, allyl, 2-butenyl or 3-butenyl. A suitable value for a (2-4C)alkynyl substituent on Ar¹ is, for example, ethynyl, 1-propynyl, 2-propynyl, 1-butynyl or 2-butynyl. A suitable value for a (1-4C)alkoxy substituent which may be present on Ar¹, Ar² or R¹ is, for example, methoxy, ethoxy, propoxy, isopropoxy or butoxy. A suitable value for a (2-4C)alkanoyl substituent which may be present on Ar¹ or for R¹ when it is (2-4C)alkanoyl is, for example, acetyl, propionyl or butyryl. Suitable values for substituents which may be present on Ar¹ or Ar² include, for example:- for (1-4C)alkythio: methylthio, ethylthio, propylthio, isopropylthio and butylthio; for (1-4C)alkylsulphinyl: methylsulphinyl, ethylsulphinyl, propylsulphinyl, isopropylsulphinyl and butylsulphinyl; for (1-4C)alkylsulphonyl: methylsulphonyl, ethylsulphonyl, propylsulphonyl, isopropylsulphonyl and butylsulphonyl; for (1-4C)alkylamino: methylamino, ethylamino propylamino and butylamino; for di-[(1-4C)alkyl]amino: dimethylamino, diethylamino and dipropylamino; for (1-4C)alkoxycarbonyl: methoxycarbonyl, ethoxycarbonyl and tert -butoxycarbonyl; for fluoro-(1-4C)alkyl: fluoromethyl, difluoromethyl, trifluoromethyl, 2-fluoroethyl, 2,2,2-trifluoroethyl and pentafluoroethyl. A suitable value for a hydroxy-(1-4C)alkyl substituent which may be present on Ar¹ is, for example, hydroxymethyl, 1-hydroxyethyl, 2-hydroxyethyl, 1-hydroxypropyl, 2-hydroxypropyl or 3-hydroxypropyl. A suitable value for the number of substituents which may be present on Ar¹ is, for example, one, two or three. A suitable value for A¹ 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 A¹ 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 Ar² when it is phenylene is, for example, 1,3-phenylene or 1,4-phenylene. A suitable value for Ar² 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 Ar² 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 Ar² include, for example:- for (3-4C)alkenyloxy: allyloxy, methylallyoxy, but-2-enyloxy and but-3-enyloxy; for N-[(1-4C)alkyl]carbamoyl: N-methylcarbamoyl, N-ethylcarbamoyl and N-propylcarbamoyl; for N,N-di-[(1-4C)alkyl]-carbamoyl: N,N-dimethylcarbamoyl and N,N-diethylcarbamoyl; for (2-4C)alkanoylamino: acetamido, propionamido and butyramido; for cyano-(1-4C)alkoxy: cyanomethoxy, 2-cyanoethoxy and 3-cyanopropoxy; for carbamoyl-(1-4C)alkoxy; carbamoylmethoxy, 2-carbamoylethoxy and 3-carbamoylpropoxy; for (1-4C)alkoxycarbonyl-(1-4C)-alkoxy: methoxycarbonylmethoxy, 2-methoxycarbonylethoxy, ethoxycarbonylmethoxy and 2-ethoxycarbonylethoxy. A suitable value for R¹ or R² when it is (1-6C)alkyl is, for example, methyl, ethyl, propyl, butyl, pentyl or hexyl. A suitable value for R¹ when it is (3-6C)alkenyl is, for example, allyl, 2-butenyl or 3-butenyl; and when it is (3-6C)alkynyl is, for example, 2-propynyl or 2-butynyl. A suitable value for R² when it is (2-6C)alkenyl is, for example, vinyl, allyl, 2-butenyl or 3-butenyl; and when it is (2-6C)alkynyl is, for example, ethynyl, 1-propynyl, 2-propynyl, 1-butynyl or 2-butynyl. A suitable value for R¹, R² or R³ when it is cyano-(1-4C)alkyl is, for example, cyanomethyl, 2-cyanoethyl or 3-cyanopropyl. A suitable value for R² when it is fluoro-(1-4C)alkyl is, for example, fluoromethyl, difluoromethyl, trifluoromethyl, 2-fluoroethyl, 2,2,2-trifluoroethyl or pentafluoroethyl. A suitable value for R² or R³ when it is hydroxy-(1-4C)alkyl is, for example, hydroxymethyl, 1-hydroxyethyl, 2-hydroxyethyl, 1-hydroxypropyl, 2-hydroxypropyl or 3-hydroxypropyl; when it is (1-4C)alkoxy-(1-4C)alkyl is, for example, methoxymethyl, 1-methoxyethyl, 2-methoxyethyl, 1-methoxypropyl, 2-methoxypropyl, 3-methoxypropyl, ethyoxymethyl, 1-ethoxyethyl, 2-ethoxyethyl, 1-ethoxypropyl, 2-ethoxypropyl 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 R³ when it is mercapto-(1-4C)alkyl is, for example, mercaptomethyl, 1-mercaptoethyl, 2-mercaptoethyl, 1-mercaptopropyl, 2-mercaptopropyl or 3-mercaptopropyl; when it is (3-4C)alkenyloxy-(1-4C)alkyl is, for example, allyloxymethyl, 1-(allyloxy)ethyl or 2-(allyloxy)ethyl; when it is (3-4C)alkynyloxy-(1-4)alkyl is, for example, 2-propynyloxymethyl, 1-(2-propynyloxy)ethyl or 2-(2-propynyloxy)ethyl; when it is (1-4C)alkoxy-(2-4C)alkoxy-(1-4C)alkyl is, for example, 2-methoxyethoxymethyl or 2-ethoxyethoxymethyl; when it is (1-4C)alkylthio-(1-4C)alkyl is, for example, methylthiomethyl, 1-methylthioethyl, 2-methylthioethyl, 1-methylthiopropyl, 2-methylthiopropyl, 3-methylthiopropyl, ethylthiomethyl, 1-ethylthioethyl, 2-ethylthioethyl, 1-ethylthiopropyl, 2-ethylthiopropyl or 3-ethylthiopropyl; when it is (1-4C)alkylsulphinyl-(1-4C)alkyl is, for example, methylsulphinylmethyl, 1-methylsulphinylethyl, 2-methylsulphinylethyl, 1-methylsulphinylpropyl, 2-methylsulphinylpropyl or 3-methylsulphinylpropyl; when it is (1-4C)alkylsulphonyl-(1-4C)alkyl is, for example, methylsulphonylmethyl, 1-methylsulphonylethyl, 2-methylsulphonylethyl, 1-methylsulphonylpropyl, 2-methylsulphonylpropyl or 3-methylsulphonylpropyl; when it is (1-4C)alkoxycarbonyl-(1-4C)alkyl is, for example, methoxycarbonylmethyl, 2-methoxycarbonylethyl, ethoxycarbonylmethyl or 2-ethoxycarbonylethyl; and when it is (2-4C)alkanoyl-(1-4C)alkyl is, for example, acetonyl, 2-oxobutyl, 3-oxobutyl, 3-oxopentyl or 4-oxopentyl. A suitable value for R³ when it is oxetanyl, tetrahydrofuranyl or tetrahydropyranyl is, for example, 2-oxetanyl, 3-oxetanyl, 2-tetrahydrofuranyl, 3-tetrahydrofuranyl, 2-tetrahydropyranyl, 3-tetrahydropyranyl or 4-tetrahydropyranyl. A suitable pharmaceutically-acceptable salt of a compound 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 compound of the invention which is sufficiently acidic (for example acompound 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 compounds of the formula I wherein:- (a) Ar¹ is phenyl, naphth-1-yl or naphth-2-yl which may optionally bear one, two or three substituents selected from fluoro, chloro, bromo, iodo, cyano, methyl, methoxy, methylthio, methylsulphinyl, methylsulphonyl, methoxycarbonyl, difluoromethyl and trifluoromethyl; and A¹, Ar², R¹, R² and R³ have any of the meanings defined hereinbefore; (b) Ar¹ is phenyl or naphth-2-yl which may optionally bear one or two substituents selected from fluoro, chloro, bromo, methyl, tert -butyl and trifluoromethyl; and A¹, Ar², R¹, R² and R³ have any of the meanings defined hereinbefore; (c) A¹ is methylene, ethylene, trimethylene, 1-propenylene, 2-methylprop-1-enylene or 1-propynylene and Ar¹, Ar², R¹, R² and R³ have any of the meanings defined hereinbefore; (d) A¹ is methylene, 1-propenylene or 1-propynylene; and Ar¹, Ar², R¹, R² and R³ have any of the meanings defined hereinbefore; (e) Ar² is 1,3-phenylene or 1,4-phenylene which may optionally bear one substituent selected from chloro, bromo, hydroxy, amino, nitro, methyl, methoxy, allyloxy, methylthio, methylsulphinyl, methylsulphonyl, methylamino, dimethylamino, trifluoromethyl, acetamido, cyanomethoxy and carbamoylmethoxy and Ar¹, A¹, X, R¹, R² and R³ have any of the meanings defined hereinbefore; (f) Ar² is 1,3-phenylene or 1,4-phenylene which may optionally bear one substituent selected from fluoro, chloro, methoxy and trifluoromethyl; and Ar¹, A¹, R¹, R² and R³ have any of the meanings defined hereinbefore; (g) Ar² is 2,4-, 2,5-, 3,5- or 2,6-pyridylene or 4,6-pyrimidylene; and Ar¹, A¹, R¹, R² and R³ have any of the meanings defined hereinbefore; (h) Ar² is 3,5-pyridylene; and Ar¹, A¹, R¹, R² and R³ have any of the meanings defined hereinbefore; (i) R¹ is methyl, ethyl, allyl, 2-propynyl or cyanomethyl; and Ar¹, A¹, Ar², R² and R³ have any of the meanings defined hereinbefore; (j) R¹ is methyl, ethyl or allyl; and Ar¹, A¹, Ar², R² and R³ have any of the meanings defined hereinbefore; (k) R² is methyl, ethyl, propyl, vinyl, ethynyl, 1-propynyl, trifluoromethyl, hydroxymethyl, methoxymethyl or acetoxymethyl; and Ar¹, A¹, Ar², R¹ and R³ have any of the meanings defined hereinbefore; (l) R² is methyl, ethyl, hydroxymethyl or methoxymethyl; and Ar¹, A¹, Ar², R¹ and R³ have any of the meanings defined hereinbefore; (m) R³ is hydroxymethyl, 1-hydroxyethyl, 2-hydroxyethyl, mercaptomethyl, 1-mercaptoethyl, 2-mercaptoethyl, methoxymethyl, 1-methoxyethyl, 2-methoxyethyl, ethoxymethyl, methylthiomethyl, 1-methylthioethyl, 2-methylthioethyl, methylsulphonylmethyl, methoxycarbonylmethyl, ethoxycarbonylmethyl, acetoxymethyl or cyanomethyl; and Ar¹, A¹, Ar², R¹ and R² have any of the meanings defined hereinbefore; (n) R³ is hydroxymethyl, 1-hydroxyethyl, 2-hydroxyethyl, mercaptomethyl, methoxymethyl, 1-methoxyethyl, 2-methoxyethyl, ethoxymethyl, allyloxymethyl, 2-propynyloxymethyl, 1-(2-propynyloxy)ethyl, 2-methoxyethoxymethyl, methylthiomethyl, 1-methylthioethyl, 2-methylthioethyl, methoxycarbonylmethyl, ethoxycarbonylmethyl, 2-acetylethyl, acetoxymethyl or cyanomethyl; and Ar¹, A¹, Ar², R¹ and R² have any of the meanings defined hereinbefore; (o) R³ is oxiranyl, 2-oxetanyl, 2-tetrahydrofuranyl or 2-tetrahydropyranyl; and Ar¹, A¹, Ar², R¹ and R² have any of the meanings defined hereinbefore; or a pharmaceutically-acceptable salt thereof. A preferred compound of the invention comprises a compound of the formula I wherein Ar¹ is phenyl or naphth-2-yl which may optionally bear one substituent selected from fluoro, methyl and trifluoromethyl; A¹ is methylene, 1-propenylene or 1-propynylene; Ar² is 1,3-phenylene or 1,4-phenylene which may optionally bear one substituent selected from fluoro, methoxy and trifluoromethyl; or Ar² is 3,5-pyridylene; R¹ is methyl or ethyl; R² is methyl, ethyl, hydroxymethyl or methoxymethyl; and R³ is 1-hydroxyethyl, 2-hydroxyethyl, mercaptomethyl, methoxymethyl, 1-methoxyethyl, 2-methoxyethyl, ethoxymethyl, 2-propynyloxymethyl, 1-(2-propynyloxy)ethyl, methylthiomethyl, 1-methylthioethyl, 2-methylthioethyl, acetoxymethyl or cyanomethyl; or a pharmaceutically-acceptable salt thereof. A further preferred compound of the invention comprises a compound of the formula I wherein Ar¹ is naphth-2-yl or 7-fluoronaphth-2-yl; A¹ is methylene; Ar² is 1,3-phenylene or 5-fluoro-1,3-phenylene; R¹ is methyl; R² is methyl, ethyl or methoxymethyl; and R³ is mercaptomethyl, methoxymethyl, 1-methoxyethyl or 2-propynyloxymethyl; or a pharmaceutically-acceptable salt thereof. A further preferred compound of the invention comprises a compound of the formula I wherein Ar¹ is phenyl; A¹ is 1-propynylene; Ar² is 1,3-phenylene or 5-fluoro-1,3-phenylene; R¹ is methyl; R² is methyl or ethyl; and R³ is methoxymethyl; or pharmaceutically-acceptable salts thereof. Specific especially preferred compounds of the invention include, for example, the following compounds of the formula I, or pharmaceutically-acceptable salts thereof:- 2-methoxy-2-[3-(naphth-2-ylmethoxy)phenyl]but-1-yl methyl ether, 2-methoxy-2-[3-(naphth-2-ylmethoxy)phenyl]prop-1-yl methyl ether, 2-methoxy-2-[3-(naphth-2-ylmethoxy)phenyl]but-3-yl methyl sulphide, 2-methoxy-2-[3-(naphth-2-ylmethoxy)phenyl]but-1-yl 2-propynyl ether, 2-[5-fluoro-3-(7-fluoronaphth-2-ylmethoxy)phenyl]-2-methoxybut-1-yl methyl ether and 2-methoxy-2-[5-fluoro-3-(3-phenylprop-2-ynyloxy)phenyl]but-1-yl methyl ether. A compound of the invention comprising an alcohol or ether derivative 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, Ar¹, A¹, Ar², R¹, R² and R³ have any of the meanings defined hereinbefore. (a) The alkylation, in the presence of a suitable base, of a compound of the formula II with a compound of the formula Ar¹-A¹-Z wherein Z is a displaceable group; provided that, when there is an amino, alkylamino, hydroxy or carboxy group in Ar¹, Ar², R¹, R² or R³, 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 Ar¹, Ar², R¹, R² or R³ is removed by conventional means. A suitable displaceable group Z is, for example, a halogeno or sulphonyloxy group, for example a chloro, bromo, iodo, methane-sulphonyloxy or toluene- p -sulphonyloxy group. 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, 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 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 material of the formula II may be obtained by standard procedures of organic chemistry. The preparation of examples of such starting materials is described within the accompanying non-limiting Examples which are provided for the purposes of illustration only. Thus the starting material of the formual II may be obtained, for example, by deprotecting a protected ether derivative of the formula III wherein R⁴ is a protecting group and Ar², R¹, R² and R³ have the meanings defined hereinbefore. A suitable protecting group R⁴ 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 or, for example, by treatment with an alkali metal diarylphosphide such as lithium diphenylphosphide. Alternatively a (1-4C)alkoxymethyl group or a tetrahydropyranyl group may be removed, for example, by treatment with a suitable acid such as hydrochloric or trifluoroacetic acid. The protecting group R⁴ may be, for example, a tri-(1-4C)alkylsilyl group which can be removed while the protecting group for any amino, imino, alkylamino, carboxy or hydroxy group in Ar², R¹, R² or R³ is retained. The protected starting material of the formula III may be obtained by standard procedures of organic chemistry. Thus, for example, an alcohol of the formula R⁴-O-Ar²-CH(OH)-R³, wherein R⁴ is a protecting group as defined hereinbefore, may be obtained by the reaction of an aldehyde of the formula R⁴-O-Ar²-CHO with an organometallic compound of the formula R³-M or R³-M-Z, wherein R³ has the meaning defined hereinbefore, M is a metallic group, for example lithium, magnesium or zinc, and Z is a halogeno group, for example chloro, bromo or iodo, and provided that any amino, alkylamino, or hydroxy group in Ar² or R³ 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 -butylmethylether or diethyl ether) at a temperature in the range, for example, -100 to 50°C (especially -80 to 30°C). The secondary alcohol of the formula R⁴-O-Ar²-CH(OH)-R³ may be oxidised to give a ketone of the formula R⁴-O-Ar²-CO-R³. 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 R⁴ has the meaning defined hereinbefore, may be obtained by the reaction of the ketone R⁴-O-Ar²-CO-R³ with an organometallic compound of the formula R²-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 or hydroxy group in Ar², R² or R³ 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 R⁴-O-Ar²-CHO by reversing the order of introduction of the groups R³ and R². Thus the aldehyde of the formula R⁴-O-Ar²-CHO may be treated initially with the organometallic compound of the formula R²-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 R³-M or R³-M-Z to give the compound of the formula IV, and provided that any amino, alkylamino or hydroxy group in Ar², R² or R³ is protected by a conventional protecting group. The protected ether derivative of the formula III, wherein R⁴ 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 R¹-Z, wherein Z is a displaceable group as defined hereinbefore, in the presence of a suitable base as defined hereinbefore, and provided that any amino, alkylamino or hydroxy group in Ar², R² or R³ is protected by a conventional protecting group; Alternatively the tertiary alcohol starting material of the formula IV may be obtained by the reaction of a compound of the formula R⁴-O-Ar²-Z, wherein R⁴ and Ar² have the meanings defined hereinbefore and Z is a halogeno group as defined hereinbefore and provided that any amino, alkylamino or hydroxy group in Ar² is protected with a conventional protecting group, with either an organometallic compound of the formula R⁶-M, wherein R⁶ 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 R⁴-O-Ar²-M, or with a metal such as magnesium to given an organometallic compound of the formula R⁴-O-Ar²-M-Z; whereafter either of these organometallic compounds may be reacted with a ketone of the formula R²-CO-R³, wherein R² and R³ have the meanings defined hereinbefore, and provided that any hydroxy group in R² and R³ 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 R¹-Z, wherein R¹ and Z have the meanings defined hereinbefore, provided that, when there is an amino, alkylamino, hydroxy or carboxy group in Ar¹, Ar², R² or R³, any amino, alkylamino, hydroxy or carboxy group is protected by a conventional protecting group; whereafter any undesired protecting group in Ar¹, Ar², R² or R³ is removed by conventional means. The tertiary alcohol starting material of the formula V may be obtained, for example, by the reaction of an aldehyde of the formula Ar¹-A¹-O-Ar²-CHO with an organometallic compound of the formula R³-M or R³-M-Z, having the meaning defined hereinbefore and using the conditions defined hereinbefore, to give a secondary alcohol of the formula Ar¹-A¹-O-Ar²-CH(OH)-R³ and provided that any amino, alkylamino, carboxy or hydroxy group in Ar¹, Ar² or R³ 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 Ar¹-A¹-O-Ar²-CO-R³, which in turn may be treated with an organometallic compound of the formula R²-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 aldehyde of the formula Ar¹-A¹-O-Ar²-CHO by reversing the order of the introduction of the groups R³ and R², i.e. by reaction of the aldehyde of the formula Ar¹-A¹-O-Ar²-CHO with the organometallic compound of the formula R²-M-Z, oxidation of the secondary alcohol to a ketone of the formula Ar¹-A¹-O-Ar²-CO-R² and reaction of said ketone with the organometallic compound of the formula R³-M or R³-M-Z, and provided that any amino, alkylamino, carboxy or hydroxy group in Ar¹, Ar², R² or R³ is protected by a conventional protecting group. Alternatively the ketone intermediate of the formula Ar¹-A¹-O-Ar²-CO-R² 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-O-Ar²-CO-R² with a compound of the formula Ar¹-A¹-Z, wherein Z is a displaceable group as defined hereinbefore, and provided that any amino, alkylamino, carboxy or hydroxy group in Ar¹ or Ar² is protected by a conventional protecting group. The aldehyde starting material of the formula Ar¹-A¹-O-Ar²-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-O-Ar²-CHO with a compound of the formula Ar¹-A¹-Z, wherein Z is a displaceable group, as defined hereinbefore, and provided that any amino, alkylamino, carboxy or hydroxy group in Ar¹ or Ar² 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 Ar¹-A¹-O-Ar²-CO₂R⁵, wherein R⁵ is a (1-4C)alkyl group such as methyl or ethyl, with an organometallic compound of the formula R³-M or R³-M-Z, having the meaning defined hereinbefore and using the conditions defined hereinbefore for the corresponding reaction of the aldehyde of the formula R⁴-O-Ar²-CHO, and provided that any amino, alkylamino, carboxy or hydroxy group in Ar¹, Ar² or R³ is protected by a conventional protecting group, to give a ketone of the formula Ar¹-A¹-O-Ar²-CO-R³. The product so obtained may be treated with an organometallic compound of the formula R²-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 Ar¹-A¹-O-Ar²-CO₂R⁵ by reversing the order of the introduction of the groups R³ and R², i.e. by reaction of the ester of the formula Ar¹-A¹-O-Ar²-CO₂R⁵ with the organometallic compound of the formula R²-M-Z, to give a ketone of the formula Ar¹-A¹-O-Ar²-CO-R² and reaction of said ketone with the organometallic compound of the formula R³-M or R³-M-Z and provided that any amino, alkylamino, carboxy or hydroxy group in Ar¹, Ar², R² or R³ is protected by a conventional protecting group. The ester starting material of the formula Ar¹-A¹-O-Ar²-CO₂R⁵ 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-O-Ar²-CO₂R⁵, wherein R⁵ has the meaning defined hereinbefore, with a compound of the formula Ar¹-A¹-Z, wherein Z is a displaceable group as defined hereinbefore, and provided that any amino, alkylamino, carboxy or hydroxy group in Ar¹ or Ar² is protected by a conventional protecting group. Alternatively the ketone of the formula Ar¹-A¹-O-Ar²-CO-R³ may be obtained by the reaction of a nitrile of the formula Ar¹-A¹-O-Ar²-CN with an organometallic compound of the formula R³-M or R³-M-Z using the conditions defined hereinbefore for the corresponding reaction of the aldehyde of the formula R⁴-O-Ar²-CHO. 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 HO-Ar²-Z, wherein Ar² has the meaning defined hereinbefore and Z is a halogeno group as defined hereinbefore, with a compound of the formula Ar¹-A¹-Z, wherein Ar¹, A¹ and Z have the meanings defined hereinbefore, and provided that any amino, alkylamino, carboxy or hydroxy group in Ar¹ or Ar² is protected by a conventional protecting group, to give a compound of the formula Ar¹-A¹-O-Ar²-Z. The product so obtained may be treated either with an organometallic compound of the formula R⁶-M, wherein R⁶ 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 Ar¹-A¹-O-Ar²-M, or with a metal such as magnesium to give an organometallic compound of the formula Ar¹-A¹-O-Ar²-M-Z. Either of these organometallic compounds may be reacted with a ketone of the formula R²-CO-R³, provided that any hydroxy group in R² or R³ 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 Ar¹ or Ar² bears an alkylsulphinyl or alkylsulphonyl substituent, or R³ is an alkylsulphinylalkyl or alkylsulphonylalkyl group, the oxidation of a compound of the formula I wherein Ar¹ or Ar² bears an alkylthio substituent or wherein R³ is an alkylthioalkyl 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 carrying a sulphinyl group is required 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. (d) For the production of those compounds of the formula I wherein Ar² bears an alkanoylamino substituent, the acylation of a compound of the formula I wherein Ar² bears an amino substituent. A suitable acylating agent is, for example, any agent known in the art for the acylation of amino to acylamino, 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. (e) For the production of those compounds of the formula I wherein R¹ is alkanoyl or benzoyl optionally bearing a substituent as defined hereinbefore, the acylation of a compound of the formula I wherein R¹ is hydrogen. For the production of those compounds of the formula I wherein R¹ 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 R¹ 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. (f) For the production of those compounds of the formula I wherein Ar¹ bears an alkenyl substituent, A¹ is alkenylene, or R¹ or R² is alkenyl, the reduction of the corresponding compound wherein Ar¹ bears an alkynyl substituent, A¹ is alkynylene, R¹ is alkynyl or R² 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). (g) For the production of those compounds of the formula I wherein Ar² or R³ bears an alkoxy or substituted alkoxy substituent, an alkenyloxy substituent or an alkynyloxy substituent, the alkylation of a compound of the formula I wherein Ar² or R³ 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, or alkenyloxy or alkynyloxy, 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, or for example an alkenyl or alkynyl halide, for example a (3-4C)alkenyl chloride or bromide or a (3-4C)alkynyl chloride or bromide, 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, 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. 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 and V. As stated previously, the alcohol and ether derivatives 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 µM; Test b): IC₅₀ (LTB₄) in the range, for example, 0.1-40 µM IC₅₀ (TxB₂) in the range, for example, 40-200 µM; Test c): oral ED₅₀ (LTB₄) in the range, for example, 5-200 mg/kg; Test d): IC₅₀ (LTC₄) in the range, for example, 0.001-1 µM, IC₅₀ (PGE₂) in the range, for example, 20-1000 µM; Test e): inhibition of inflammation in the range, for example, 0.3-100 µg intradermally; Test f): ED₅₀ in the range, for example, 0.5-10 mg/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-methoxy-2-[3-(naphth-2-ylmethoxy)phenyl]but-1-yl methyl ether has an IC₅₀ of 0.5 µM against LTB₄ and of >40 µM against TxB₂ in test b), and an oral ED₅₀ of 30 mg/kg versus LTB₄ in test c). In general those compounds of the formula I which are particularly preferred have an IC₅₀ of <1 µM against LTB₄ and of >40 µM against TxB₂ in test b), and an oral ED₅₀ of <100 mg/kg against LTB₄ in test c). These compounds are examples of compounds 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 an alcohol or an ether derivative 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 an alcohol or ether derivative 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 2 g 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 an alcohol or an ether derivative 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 an alcohol or ether derivative 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, compounds 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 cerebrovascular 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, 0.5 mg to 75 mg 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, 0.5 mg 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 compound 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 compounds of the formula I may also be used in combination with leukotriene antagonists such as those disclosed in European Patent Specifications Nos. 179619, 199543, 220066, 227241, 242167, 290145, 337765, 337766 and 337767, which are incorporated herein by way of reference. 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; (vii) melting points are uncorrected and were determined using a Mettler SP62 automatic melting point block 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; and (viii) the specific rotation, [α] t , of plane polarised light was determined using the sodium D line (5890 Angstroms), at 20°C, and generally using sample concentrations of approximately 1 g/100 ml of solvent. EXAMPLE 1 A mixture of 2-[3-(naphth-2-ylmethoxy)phenyl]butane-1,2-diol (0.6 g), sodium hydride (0.22 g of a 50% w/w dispersion in mineral oil) and dimethylformamide (10 ml) was stirred at ambient temperature for 5 minutes. Methyl iodide (0.29 ml) and 1,4,7,10,13-pentaoxacyclopentadecane (hereinafter 15-crown-5, 0.06 g) were added and the mixture was stirred at ambient temperature for 15 hours. The mixture was evaporated and the residue was partitioned between methylene chloride and water. The organic layer was separated, washed with water, dried (MgSO₄) and evaporated. The residue was purified by column chromatography using initially methylene chloride and then increasingly polar mixtures of methylene chloride and diethyl ether, up to a 19:1 v/v mixture, as eluent. There was thus obtained 2-methoxy-2-[3-(naphth-2-ylmethoxy)phenyl]but-1-yl methyl ether as an oil which crystallised on standing (0.51 g, 87%), m.p. 47-48°C. The butane-1,2-diol starting material was obtained as follows:- Alkylation of a solution of 3-cyanophenol in dimethylformamide with 2-bromomethylnaphthalene in the presence of potassium carbonate gave 3-(naphth-2-ylmethoxy)benzonitrile, m.p. 91-93°C. This material was treated with ethylmagnesium bromide using the procedure described in Organic Synthesis , Collect . Vol . III, p.26, to give 3-(naphth-2-ylmethoxy)propiophenone, m.p. 56-57°C. A solution of this product (6 g) in tetrahydrofuran (12 ml) was added dropwise to a solution of isopropoxydimethylsilylmethyl magnesium chloride [prepared as described in J. Org. Chem ., 1983, 48 , 2120 from chloromethylisopropoxydimethylsilane (8.2 ml) and magnesium powder (1.09 g) in tetrahydrofuran (2 ml)]. The mixture was stirred at ambient temperature for 1 hour, washed with saturated aqueous solution of ammonium chloride and then with a saturated aqueous solution of sodium chloride. The organic layer was separated, dried (MgSO₄) and evaporated to give 1-isopropoxydimethylsilyl-2-[3-(naphth-2-ylmethoxy)phenyl]butan-2-ol as a yellow oil. A mixture of the product so obtained, sodium bicarbonate (1.73 g), hydrogen peroxide (18 ml, 30% w/v in water), methanol (60 ml) and tetrahydrofuran (60 ml) was heated to reflux for 15 hours. The mixture was evaporated to remove the organic solvents and the residue was extracted with diethyl ether. The organic layer was separated, washed with a saturated aqueous solution of sodium chloride, dried (MgSO₄) and evaporated. The residue was purified by column chromatography using initially methylene chloride and then increasingly polar mixtures of methylene chloride and acetone, up to a 9:1 v/v mixture, as eluent. There was thus obtained 2-[3-(naphth-2-ylmethoxy)phenyl]butane-1,2-diol (5.4 g, 81%), m.p. 100-101°C. EXAMPLE 2 A mixture of 3-(naphth-2-ylmethoxy)propiophenone (8.7 g), ethyl bromoacetate (5 ml), powdered zinc (2 g), a crystal of iodine and tetrahydrofuran (30 ml) was heated to 60°C for 30 minutes. The mixture was poured into water (50 ml), neutralised by adding 2N aqueous hydrochloric acid, and extracted with diethyl ether. The organic extract was dried (MgSO₄) and evaporated. The residue was purified by column chromatography using methylene chloride as eluent. There was thus obtained ethyl 3-hydroxy-3-[3-(naphth-2-ylmethoxy)phenyl]pentanoate (11.4 g, 100%), m.p. 61-62°C. EXAMPLE 3 The procedure described in Example 2 was repeated except that 3-(naphth-2-ylmethoxy)acetophenone was used in place of 3-(naphth-2-ylmethoxy)propiophenone and bromoacetonitrile was used in place of ethyl bromoacetate. There was thus obtained 3-hydroxy-3-[3-(naphth-2-ylmethoxy)phenyl]butyronitrile, m.p. 80-81°C, which was methylated using the procedure described in Example 1 except that tetrahydrofuran was used in place of dimethylformamide. There was thus obtained 3-methoxy-3-[3-(naphth-2-ylmethoxy)phenyl]butyronitrile, m.p. 98-99°C (18% yield from the acetophenone). 3-(Naphth-2-ylmethoxy)acetophenone, m.p. 88-89°C, used as a starting material was obtained by the alkylation of a solution of 3-hydroxyacetophenone in dimethylformamide with 2-bromomethylnaphthalene in the presence of potassium carbonate. EXAMPLE 4 The methylation described in Example 1 was repeated except that the appropriate alcohol was used in place of 2-[3-naphth-2-ylmethoxy)phenyl]butane-1,2-diol. There were thus obtained the compounds described in the following table:- EXAMPLE 5 A mixture of 2-[3-(naphth-2-ylmethoxy)phenyl]butane-1,2-diol (1 g), sodium hydride (0.13 g of a 50% w/w dispersion in mineral oil) and tetrahydrofuran (100 ml) was stirred at ambient temperature for 5 minutes. Methyl iodide (0.38 ml) was added and the mixture was stirred at ambient temperature for 15 hours. The mixture was evaporated and the residue was partitioned between methylene chloride and water. The organic layer was separated, washed with water, dried (MgSO₄) and evaporated. The residue was purified by column chromatography using initially methylene chloride and then increasingly polar mixtures of methylene chloride and diethyl ether, up to a 94:6 v/v mixture, as eluent. There was thus obtained 1-methoxy-2-[3-(naphth-2-ylmethoxy)phenyl]butan-2-ol (0.62 g, 57%), m.p. 47-48°C. EXAMPLE 6 A mixture of 2-[3-(naphth-2-ylmethoxy)phenyl]butane-1,2-diol (1.05 g), tert -butyldimethylsilyl chloride (0.585 g), imidazole (0.55 g) and dimethylformamide (10 ml) was stirred at ambient temperature for 15 hours. The mixture was evaporated and the residue was purified by column chromatography using methylene chloride as eluent. There was thus obtained 1- tert -butyldimethylsilyloxy-2-[3-(naphth-2-ylmethoxy)phenyl]butan-2-ol as a colourless oil (1.15 g, 81%). This product was methylated using the procedure described in Example 1 except that tetrahydrofuran was used in place of dimethylformamide as the reaction solvent. There was thus obtained 2-methoxy-2-[3-naphth-2-ylmethoxy)phenyl]but-1-yl tert -butyldimethylsilyl ether (0.825 g, 70%), m.p. 74-76°C. A mixture of a portion (0.62 g) of the product so obtained and tetrabutylammonium fluoride (4.27 ml of a 1M solution in tetrahydrofuran) was stirred at ambient temperature for 1 hour. The mixture was evaporated and the residue was partitioned between methylene chloride and water. The organic layer was separated, washed with water, dried (MgSO₄) and evaporated. The residue was purified by column chromatography using initially methylene chloride and then increasingly polar mixtures of methylene chloride and diethyl ether, up to a 9:1 v/v mixture, as eluent. There was thus obtained 2-methoxy-2-[3-(naphth-2-ylmethoxy)phenyl]butan-1-ol (0.41 g, 86%), m.p. 80-81°C. EXAMPLE 7 The procedure described in Example 6 was repeated except that the appropriate diol was used in place of 2-[3-naphth-2-ylmethoxy)phenyl]butane-1,2-diol. There were thus obtained the compounds described in the following table:- EXAMPLE 8 A mixture of 2-methoxy-2-[3-(naphth-2-ylmethoxy)phenyl]butan-1-ol (0.52 g), sodium hydride (0.1 g of a 50% w/w dispersion in mineral oil) and dimethylformamide (10 ml) was stirred at ambient temperature for 5 minutes. Ethyl iodide (0.25 ml) was added and the mixture was heated to 40°C for 4 hours. The mixture was partitioned between methylene chloride and water. The organic layer was separated, washed with water, dried (MgSO₄) and evaporated. The residue was purified by column chromatography using initially methylene chloride and then increasingly polar mixtures of methylene chloride and diethyl ether, up to a 19:1 v/v mixture, as eluent. There was thus obtained as an oil which crystallised on standing 2-methoxy-2-[3-naphth-2-ylmethoxy)phenyl]but-1-yl ethyl ether (0.47 g, 83%), m.p. 64-65°C. EXAMPLE 9 The procedure described in Example 8 was repeated except that the appropriate alkylating or acylating agent was used in place of ethyl iodide. There were thus obtained the compounds described in the following table:- EXAMPLE 10 A mixture of 2-methoxy-2-[3-(naphth-2-ylmethoxy)phenyl]prop-1-yl methyl sulphide (0.43 g), m -chloroperbenzoic acid (0.63 g) and methylene chloride (5 ml) was stirred at ambient temperature for 15 hours. The mixture was evaporated and the residue was purified by column chromatography using a 19:1 v/v mixture of methylene chloride and diethyl ether as eluent. There was thus obtained 2-methoxy-2-[3-(naphth-2-ylmethoxy)phenyl]prop-1-yl methyl sulphone (0.165 g, 35% m.p. 149-150°C. EXAMPLE 11 A mixture of 3-[3-(naphth-2-ylmethoxy)phenyl]pent-1-en-3-yl methyl ether (4.3 g) m -chloroperbenzoic acid (3.1 g) sodium bicarbonate (1.5 g) and methylene chloride (20 ml) was stirred at ambient temperature for 15 hours. The mixture was partitioned between diethyl ether and water and the organic layer was separated, dried (MgSO₄) and evaporated. The residue was purified by column chromatography using a 4:1 v/v mixture of methylene chloride and petroleum ether (b.p. 60-80°C) as eluent. There were thus obtained:-a less polar isomer as a colourless oil (0.41 g, 9%) and a more polar isomer (0.13 g, 3%), m.p. 45-47°C, of 1-[3-(naphth-2-ylmethoxy)phenyl]-1-oxiranylprop-1-yl methyl ether. The less polar isomer displayed the following characteristic NMR signals (CDCl₃); δ values):- 0.82(t, 3H), 1.5-2.1(m, 2H), 2.69(d, 2H), 3.1(t, 1H), 3.25(s, 3H), 5.22(s, 2H), 6.8-7.88(m, 11H). The 3-[3-(naphth-2-ylmethoxy)phenyl]pent-1-en-3-yl methyl ether starting material was obtained as follows:- Vinylmagnesium bromide (76 ml of a 1M solution in tetrahydrofuran) was added dropwise to a solution of 3-(naphth-2-ylmethoxy)propiophenone (17.4 g) in tetrahydrofuran (150 ml) and the mixture was stirred at ambient temperature for 30 minutes. The mixture was poured into a mixture of water and ice (total volume 1 litre) containing ammonium chloride (20 g). The mixture was extracted with diethyl ether, dried (MgSO₄) and evaporated. There was thus obtained 3-[3-(naphth-2-ylmethoxy)phenyl]pent-1-en-3-ol as a yellow oil (19.4 g) which was used without further purification. A portion (1.6 g) of this alcohol was methylated using the procedure described in Example 1 except that tetrahydrofuran was used in place of dimethylformamide as the reaction solvent. There was thus obtained 3-[3-(naphth-2-ylmethoxy)phenyl]pent-1-en-3-yl methyl ether (0.75 g, 45%), m.p. 39-40°C. EXAMPLE 12 A mixture of 2-(3-hydroxyphenyl)-2-methoxybut-1-yl methyl ether (0.5 g), 3-phenylprop-2-ynyl bromide (0.75 g), potassium carbonate (0.37 g) and dimethylformamide (6 ml) was stirred at ambient temperature for 15 hours. The mixture was partitioned between methylene chloride and water. The organic layer was washed with a saturated aqueous sodium chloride solution, dried (MgSO₄) and evaporated. The residue was purified by column chromatography using a 49:1 v/v mixture of methylene chloride and diethyl ether as eluent. There was thus obtained 2-methoxy-2-[3-(3-phenylprop-2-ynyloxy)phenyl]but-1-yl methyl ether as a colourless oil (0.68 g, 85%). NMR Spectrum (CDCl₃; δ values) 0.79(t, 3H), 1.7-2.1(m, 2H), 3.15(s, 3H), 3.31(s, 3H), 3.65(m, 2H), 4.92(s, 2H), 6.8-7.5(m, 9H). The 2-(3-hydroxyphenyl)-2-methoxybut-1-yl methyl ether starting material was obtained as follows:- 3-Methoxymethoxybenzaldehyde was prepared from 3-hydroxybenzaldehyde and dimethoxymethane using the method described in Synthesis , 1976, 244. Ethylmagnesium bromide (161 ml of a 3M solution in diethyl ether) was added to a solution of 3-methoxymethoxybenzaldehyde (73 g) in diethyl ether (150 ml) which had been cooled to 0°C. The mixture was allowed to warm to ambient temperature and was stirred for 1 hour. The mixture was poured into a mixture of diethyl ether (2 litres) and 1N aqueous hydrochloric acid (500 ml). The organic layer was washed with water and with a saturated aqueous sodium chloride solution, dried (MgSO₄) and evaporated to give, as an oil (83.8 g, 97%), α-ethyl-3-methoxymethoxybenzyl alcohol. A mixture of the product so obtained, manganese dioxide (300 g) and methylene chloride (1.1 litre) was stirred at ambient temperature for 15 hours, filtered through silica gel and evaporated. There was thus obtained, as an oil (50 g, 60%), 3-methoxymethoxypropiophenone. A portion (19.4 g) of this product was reacted with isopropoxydimethylsilylmethylmagnesium chloride using the procedure described in the portion of Example 1 which is concerned with the preparation of starting materials. The product so obtained was treated with hydrogen peroxide using the method described therein to give, as a colourless oil (26.6 g, 74%), 2-(3-methoxymethoxyphenyl)butane-1,2-diol. A portion (16.3 g) of this diol was methylated using the procedure described in Example 1 to give 2-methoxy-2-(3-methoxymethoxyphenyl)but-1-yl methyl ether (16.3 g) and a mixture of this material, concentrated hydrochloric acid (10 ml), isopropanol (40 ml) and tetrahydrofuran (160 ml) was stirred at ambient temperature for 15 hours. The mixture was evaporated and the residue was partitioned between ethyl acetate and water. The organic layer was washed with a saturated aqueous sodium chloride solution, dried (MgSO₄) and evaporated. The residue was purified by column chromatography using initally methylene chloride and then increasingly polar mixture of methylene chloride and diethyl ether, up to a 17:3 v/v mixture, as eluent. There was thus obtained 2-(3-hydroxyphenyl)-2-methoxybut-1-yl methyl ether (6.9 g, 51%), m.p. 74-75°C. EXAMPLE 13 The procedure described in Example 12 was repeated except that the appropriate phenol was used in place of 2-(3-hydroxyphenyl)-2-methoxybut-1-yl methyl ether. There were thus obtained the compounds described in the following table:- EXAMPLE 14 Using the procedure described in Example 12, 3-(3-hydroxyphenyl)-3,4-dimethoxybutan-1-ol was reacted with 2-bromomethylnaphthalene to give 3,4-dimethoxy-3-[3-(naphth-2-ylmethoxy)phenyl]butan-1-ol in 87% yield, m.p. 64-65°C. The 3-(3-hydroxyphenyl)-3,4-dimethoxybutan-1-ol, used as a starting material, was obtained as follows:- A mixture of 3-(3-benzyloxyphenyl)-3-oxopropan-1-ol (2.07 g), dihydropyran (1.1 g), an acidic ion-exchange resin (0.2 g, 'Amberlyst 15') and methylene chloride (5 ml) was stirred at ambient temperature for 4 hours. The mixture was filtered and filtrate was evaporated. The residue was purified by column chromatography using a 50:1 v/v mixture of methylene chloride and acetone as eluent. There was thus obtained 3-benzyloxyphenyl 2-tetrahydropyran-2-yloxymethyl ketone (1.85 g, 67%), as an oil. Using the procedure described in the second and third paragraphs of the portion of Example 1 which is concerned with the preparation of starting materials, the ketone so obtained was reacted with isopropoxydimethylsilylmethylmagnesium chloride and the product was oxidised with hydrogen peroxide. There was thus obtained 2-(3-benzyloxyphenyl)-4-tetrahydropyran-2-yloxybutane-1,2-diol (1.65 g, 83%), as an oil. Using the procedure described in Example 1, the diol so obtained was reacted with methyl iodide to give 2-(3-benzyloxyphenyl)-2-methoxy-4-tetrahydropyran-2-yloxybut-1-yl methyl ether (1.61 g, 91%), as an oil. A mixture of the product so obtained, acidic ion-exchange resin (0.2 g, 'Amberlyst 15') and methanol (15 ml) was heated to 45°C for 2 hours. The mixture was filtered and the filtrate was evaporated. There was thus obtained 3-(3-benzyloxyphenyl)-3,4-dimethoxybutan-1-ol (1.3 g, 99%), which was used without further purification. A mixture of the product so obtained, 10% palladium-on-charcoal catalyst (0.3 g) and ethanol (15 ml) was stirred under an atmosphere of hydrogen for 6 hours. The mixture was filtered and the filtrate was evaporated. The residue was purified by column chromatography using a 4:1 v/v mixture of methylene chloride and acetone as eluent. There was thus obtained 3-(3-hydroxyphenyl)-3,4-dimethoxybutan-1-ol (0.73 g, 78%), as an oil. NMR Spectrum (CDCl₃, delta values) 1.8-2.1(m, 2H), 3.08(s, 3H), 3.25(s, 3H), 3.1-3.5(m, 2H), 3.79(s, 2H), 4.21(t, 1H), 6.5-7.25(m, 4H). EXAMPLE 15 Using the procedure described in Example 12, (2RS,3SR)-2-(5-fluoro-3-hydroxyphenyl)-2-methoxybutan-3-ol was reacted with 2-bromomethylnaphthalene to give (2RS,3SR)-2-[5-fluoro-3-(naphth-2-ylmethoxy)phenyl]-2-methoxybutan-3-ol in 94% yield, m.p. 62-63°C. The (2RS,3RS)-2-(5-fluoro-3-hydroxyphenyl)-2-methoxybutan-3-ol, used as a starting material, was obtained as follows:- Using the procedure described in the last two paragraphs of Example 6, erythro - or (2RS,3SR)-2-(3-benzyloxy-5-fluorophenyl)-3-( tert -butyldimethylsilyloxy)butan-2-ol (5 g) was reacted with methyl iodide and the tert -butyldimethylsilyl group was removed from the product obtained. There was thus obtained (2RS,3SR)-2-(3-benzyloxy-5-fluorophenyl)-2-methoxybutan-3-ol (3.9 g, 99%), as an oil. Using the procedure described in the second last paragraph of Note a. below Table IV in Example 13, the product so obtained was hydrogenolysed. There was thus obtained the required starting material (0.07 g, 76%), m.p. 84-85°C. EXAMPLE 16 Using the procedure described in Example 8, (2RS,3SR)-2-(5-fluoro-3-(naphth-2-ylmethoxy)phenyl]-2-methoxybutan-3-ol was reacted with methyl iodide to give (2RS,3SR)-2-(5-fluoro-3-(naphth-2-ylmethoxy)phenyl]-2-methoxybut-3-yl methyl ether in 60% yield, m.p. 75-76°C. The reaction described immediately above was repeated except that prop-2-ynyl bromide was used in place of methyl iodide. There was thus obtained (2RS,3SR)-2-(5-fluoro-3-(naphth-2-ylmethoxy)phenyl]-2-methoxybut-3-yl prop-2-ynyl ether in 76% yield, m.p. 58-59°C. EXAMPLE 17 Using the procedure described in Example 8, 2-methoxy-2-[3-(naphth-2-ylmethoxy)phenyl]butan-1-ol (Example 6) was reacted with prop-2-ynyl bromide to give 2-methoxy-2-[3-(naphth-2-ylmethoxy)phenyl]but-1-yl prop-2-ynyl ether in 92% yield, m.p. 54°C. EXAMPLE 18 The procedure described in Example 12 was repeated except that ( E )-cinnamyl bromide was used in place of 3-phenylprop-2-ynyl bromide. There was thus obtained 2-(3-( E )-cinnamyloxyphenyl)-2-methoxybut-1-yl methyl ether in 70% yield, as an oil. NMR Spectrum (CDCl₃, delta values) 0.8(t, 3H), 1.8-2.1(m, 2H), 3.15(s, 3H), 3.3(s, 3H), 3.64(d of d's, 2H), 4.7(d, 2H), 6.2-7.5(m, 11H). EXAMPLE 19 Using the procedure described in Note c. below Table III in Example 9, 2-[3-(3-phenylprop-2-ynyloxy)phenyl]-2,3-dimethoxypropan-1-ol (Example 13, Compound No. 3) was reacted with thioacetic acid. The mercaptan so obtained was reacted with methyl iodide using the conditions described in Example 1. There was thus obtained 2-methoxy-3-methylthio-2-[3-(3-phenylprop-2-ynyloxy)phenyl]prop-1-yl methyl ether in 27% overall yield, as an oil. NMR Spectrum (CDCl₃, delta values) 1.91(s, 3H), 3.0(m, 2H), 3.14(s, 3H), 3.37(s, 3H), 3.85(s, 2H), 4.92(s, 2H), 6.85-7.5(m, 9H). EXAMPLE 20 Using the procedure described in Example 12, 2-(3-hydroxyphenyl)-2-methoxy-4-(2,5,5-trimethyl-1,3-dioxan-2-yl)but-1-yl methyl ether was reacted with 3-phenylprop-2-ynyl bromide to give 2-methoxy-2-[3-(3-phenylprop-2-ynyloxy)phenyl]-4-(2,5,5-trimethyl-1,3- dioxan-2-yl)but-1-yl methyl ether in 85% yield, as an oil. A mixture of a portion (0.54 g) of the product so obtained, acetone (15 ml) and 6N hydrochloric acid solution (1 ml) was stirred at ambient temperature for 15 hours. The mixture was evaporated and the residue was partitioned between diethyl ether and water. The organic phase was washed with water, dried (MgSO₄) and evaporated. The residue was purified by column chromatography using a 25:1 v/v mixture of methylene chloride and acetone as eluent. There was thus obtained 3,4-dimethoxy-3-[3-(3-phenylprop-2-ynyloxy)phenyl]butyl methyl ketone (0.42 g, 96%), as an oil. NMR Spectrum (CDCl₃, delta values) 2.04(s, 3H), 1.97-2.27(m, 4H), 3.17(s, 3H), 3.29(s, 3H), 3.62(s, 2H), 4.92(s, 2H), 6.85-7.25(m, 9H). The 2-(3-hydroxyphenyl)-2-methoxy-4-(2,5,5-trimethyl-1,3-dioxan-2-yl)but-1-yl methyl ether, used as a starting material, was obtained as follows:- A solution of 3-benzyloxyphenyl methoxymethyl ketone (3.2 g) in tetrahydrofuran (2 ml) was added to a solution of 2-(2,5,5-trimethyl-1,3-dioxan-2-yl)ethylmagnesium bromide [prepared by heating a mixture of 2-(2,5,5-trimethyl-1,3-dioxan-2-yl)ethyl bromide (3.55 g), magnesium powder (1.08 g) and tetrahydrofuran (25 ml) to 40°C for 30 minutes] in tetrahydrofuran (25 ml) which had been cooled to ambient temperature. The mixture was stirred at ambient temperature for 15 hours and evaporated. The residue was partitioned between methylene chloride and water. The organic phase was washed with water, dried (MgSO₄) and evaporated. The residue was purified by column chromatography using a 10:1 v/v mixture of methylene chloride and diethyl ether as eluent. There was thus obtained 2-(3-benzyloxyphenyl)-1-methoxy-4-(2,5,5-trimethyl-1,3-dioxan-2-yl)butan-2-ol (2.85 g, 55%), as an oil. Using the procedure described in Example 1, the product so obtained was reacted with methyl iodide. There was thus obtained 2-(3-benzyloxyphenyl)-2-methoxy-4-(2,5,5-trimethyl-1,3-dioxan-2-yl)but-1-yl methyl ether (2.9 g, 98%), as an oil. Using the procedure described in the second last paragraph of Note a. below Table IV in Example 13, the product so obtained was hydrogenolysed. There was thus obtained the required starting material (1.84 g, 80%), as an oil. EXAMPLE 21 Using the procedure described in Example 12, 2-(5-fluoro-3-hydroxyphenyl)-2-methoxybut-1-yl methyl ether was reacted with 2-bromomethyl-7-fluoronaphthalene to give 2-[5-fluoro-3-(7-fluoronaphth-2-ylmethoxy)phenyl]-2-methoxybut-1-yl methyl ether in 76% yield, as an oil. NMR Spectrum (CDCl₃, delta values) 0.79(t, 3H), 1.7-2.0(m, 2H), 3.14(s, 3H), 3.32(s, 3H), 3.57(d, 1H), 3.64(d, 1H), 5.2(s, 2H), 6.64(m, 1H), 6.73(m, 1H), 6.86(t, 1H), 7.2-7.9(m, 6H). The 2-bromomethyl-7-fluoronaphthalene used as a starting material was obtained as follows:- 3-Fluorobenzyl chloride was reacted with acetylacetaldehyde dimethyl acetal using the procedure described for the corresponding reaction of 3-methylbenzyl chloride ( Synthesis , 1974, 566). There was thus obtained 4-(3-fluorophenyl)-3-hydroxy-3-methylbutanal dimethyl acetal (b.p. 125-135°C at 0.25 mm Hg). A mixture of the material so obtained (15 g), glacial acetic acid (60 ml) and hydrobromic acid (48% w/v. 48 ml) was heated on a steam bath for 1 hour. The mixture was evaporated and the residue was purified by column chromatography using petroleum ether (b.p. 60-80°C) as eluent. There was thus obtained 7-fluoro-2-methylnaphthalene (4 g). A mixture of 7-fluoro-2-methylnaphthalene (3 g), N-bromosuccinimide (3.3 g), 2,2'-azobisisobutyronitrile (0.2 g) and carbon tetrachloride (100 ml) was heated to reflux and irradiated with the light from a 275 watt bulb for 1 hour. The mixture was cooled to ambient temperature and filtered. The filtrate was evaporated and the residue was purified by column chromatography using a 19:1 v/v mixture of petroleum ether (b.p. 60-80°C) and toluene as eluent. There was thus obtained 2-bromomethyl-7-fluoronaphthalene (2.8 g), m.p. 62°C. EXAMPLE 22 Using the procedure described in Example 12, 2-(5-hydroxypyrid-3-yl)-2-methoxybut-1-yl methyl ether (0.21 g) was reacted with 2-bromomethylnaphthalene (0.25 g) to give 2-methoxy-2-[5-(naphth-2-ylmethoxy)pyrid-3-yl]but-1-yl methyl ether (0.13 g, 37%), as an oil. NMR Spectrum (CD₃SOCD₃, delta values) 0.65(t, 3H), 1.7-2.0(m, 2H), 3.1(s, 3H), 3.2(s, 3H), 3.6(s, 2H), 5.4(s, 2H), 7.4(m, 1H), 7.5-7.65(m, 3H), 7.9-8.0(m, 4H), 8.15(d, 1H), 8.3(d, 1H). EXAMPLE 23 The reaction described in Example 21 was repeated except that (+)-2-(5-fluoro-3-hydroxyphenyl)-2-methoxybut-1-yl methyl ether was used as the phenol. There was thus obtained (+)-2-[5-fluoro-3-(7-fluoronaphth-2-ylmethoxy)phenyl]-2-methoxybut-1-yl methyl ether in 89% yield, as an oil, [α]²⁰ +17.0° (chloroform, c = 1 g/100 ml). The (+)- and (-)-2-(5-fluoro-3-hydroxyphenyl)-2-methoxybut-1-ylmethyl ethers used as the starting materials for Examples 23 and 24 respectively, were obtained as follows:- A mixture of 2-oxobutyric acid (21 g), sec -butanol (32 ml) and p -toluenesulphonic acid (5.25 g) was stirred at ambient temperature for 75 hours. The mixture was partitioned between diethyl ether and water. The organic phase was dried (MgSO₄) and evaporated. There was thus obtained sec -butyl 2-oxobutyrate (16.1 g, 50%). The product so obtained (15 g) was added dropwise to a solution of 3-benzyloxy-5-fluorophenylmagnesium bromide [prepared by heating a mixture of benzyl 3-bromo-5-fluorophenyl ether (31 g), magnesium powder (2.46 g) and diethyl ether (150 ml) to reflux for 1 hour] in diethyl ether and the mixture was stirred at ambient temperature for 15 hours. The mixture was partitioned between diethyl ether and a saturated aqueous ammonium chloride solution. The organic layer was washed with water, dried (MgSO₄) and evaporated. The residue was purified by column chromatography using a 3:1 v/v mixture of methylene chloride and petroleum ether as eluent. There was thus obtained sec -butyl 2-(3-benzyloxy-5-fluorophenyl)-2-hydroxybutyrate (16.3 g, 42%), as an oil. A mixture of a portion (10 g) of the product so obtained, potassium carbonate (5.4 g), water (5 ml) and methanol (42 ml) was heated to 80°C for 4 hours. The mixture was evaporated and the residue was partitioned between diethyl ether and water. The aqueous phase was acidified by the addition of concentrated hydrochloric acid and extracted with ethyl acetate. The organic layer was dried (MgSO₄) and evaporated. There was thus obtained 2-(3-benzyloxy-5-fluorophenyl)-2-hydroxybutyric acid (7.1 g, 84%), m.p. 105-106°C. A mixture of a portion (8.5 g) of the acid so obtained, quinine (9.07 g) and ethanol (100 ml) was stirred at ambient temperature for 30 minutes. The mixture was evaporated to leave the salt as a white solid. This material was dissolved in hot ethanol (28 ml), diisopropyl ether (230 ml) was added and the solution was allowed to stand at ambient temperature for 75 hours. The precipitated solid (7.13 g) was filtered off, dissolved in hot ethanol (35 ml) and then diisopropyl ether (300 ml) was added. The solution was allowed to stand at ambient temperature for 15 hours. The precipitate (4.93 g) was filtered off. The salt so obtained was dissolved in 2N aqueous hydrochloric acid solution and the solution was extracted with diethyl ether. The organic phase was washed with a saturated aqueous sodium chloride solution, dried (MgSO₄) and evaporated. There was thus obtained (-)-2-(3-benzyloxy-5-fluorophenyl)-2-hydroxybutyric acid (2.24 g). The mother liquors from the crystallisation steps described immediately above were combined and evaporated to give the crude quinine salt (13.5 g). This salt was dissolved in 2N aqueous hydrochloric acid solution and extracted with diethyl ether. The organic phase was dried (MgSO₄) and evaporated. There was thus obtained crude (-)-2-(3-benzyloxy-5-fluorophenyl)-2-hydroxybutyric acid (5.34 g). This acid was dissolved in diisopropyl ether (320 ml) and (-)-phenethylamine (2.13 g) was added. The solution was stored at ambient temperature for 75 hours. The precipitate (5.8 g) was filtered off. This salt was recrystallised from a mixture of ethanol (20 ml) and diisopropyl ether (500 ml). The precipitate (2.71 g) was filtered off, dissolved in 2N aqueous hydrochloric acid solution and extracted with diethyl ether. The organic phase was washed with a saturated aqueous sodium chloride solution, dried (MgSO₄) and evaporated to give (+)-2-(3-benzyloxy-5-fluorophenyl)-2-hydroxybutyric acid (1.86 g). A solution of diazomethane in diethyl ether was added to a solution of (-)-2-(3-benzyloxy-5-fluorophenyl)-2-hydroxybutyric acid (2.24 g) in diethyl ether (35 ml) until the reaction mixture retained a yellow colouration. The mixture was evaporated to give methyl (-)-2-(3-benzyloxy-5-fluorophenyl)-2-hydroxybutyrate (2.27 g). Lithium aluminium hydride (0.345 g) was added to a solution of the ester so obtained in diethyl ether (70 ml) and the mixture was stirred at ambient temperature for 1 hour. Water (10 ml) was added dropwise and the mixture was filtered. The organic layer was dried (MgSO₄) and evaporated to give (-)-2-(3-benzyloxy-5-fluorophenyl)butane-1,2-diol (2.2 g), as an oil. Using the procedure described in Example 1, a portion (0.29 g) of the diol so obtained was reacted with methyl iodide to give (-)-2-(3-benzyloxy-5-fluorophenyl)-2-methoxybut-1-yl methyl ether in 99% yield, as an oil. Using the procedure described in the last paragraph of Note a. below Table IV in Example 13, the product so obtained was hydrogenolysed to give (-)-2-(5-fluoro-3-hydroxyphenyl)-2-methoxybut-1-yl methyl ether (0.22 g, 96%), as an oil. Using the procedure described in the four paragraphs immediately above, (+)-2-(3-benzyloxy-5-fluorophenyl)-2-hydroxybutyric acid was converted into (+)-2-(5-fluoro-3-hydroxyphenyl)-2-methoxybut-1-yl methyl ether in 90% yield, as an oil. EXAMPLE 24 The reaction described in Example 21 was repeated except that (-)-2-(5-fluoro-3-hydroxyphenyl)-2-methoxybut-1-yl methyl ether was used as the phenol. There was thus obtained (-)-2-[5-fluoro-3-(7-fluoronaphth-2-ylmethoxy)phenyl]-2-methoxybut-1-yl methyl ether in 44% yield, as an oil, [α]²⁰ -14.1° (chloroform, c = 1 g/100 ml). EXAMPLE 25 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:- (a) Tablet I mg/tablet Compound X 100 Lactose Ph.Eur 182.75 Croscarmellose sodium 12.0 Maize starch paste (5% w/v paste) 2.25 Magnesium stearate 3.0 (b) Tablet II mg/tablet Compound X 50 Lactose Ph.Eur 223.75 Croscarmellose sodium 6.0 Maize starch 15.0 Polyvinylpyrrolidone (5% w/v paste) 2.25 Magnesium stearate 3.0 (c) Tablet III mg/tablet Compound X 1.0 Lactose Ph.Eur 93.25 Croscarmellose sodium 4.0 Maize starch paste (5% w/v paste) 0.75 Magnesium stearate 1.0 (d) Capsule mg/capsule Compound X 10 mg Lactose Ph.Eur 488.5 Magnesium stearate 1.5 (e) Injection I (50 mg/ml) Compound X 5.0% w/v 1M Sodium hydroxide solution 0.1M Hydrochloric acid (to adjust pH to 7.6) 15.0% v/v Polyethylene glycol 400 4.5% w/v Water for injection to 100% (f) Injection II (10 mg/ml) Compound X 1.0% w/v Sodium phosphate BP 3.6% w/v 0.1M Sodium hydroxide solution 15.0% v/v Water for injection to 100% (g) Injection III (1mg/ml, buffered to pH6) Compound X 0.1% w/v Sodium phosphate BP 2.26% w/v Citric acid 0.38% w/v Polyethylene glycol 400 3.5% w/v Water for injection to 100% (h) Aerosol I mg/ml Compound X 10.0 Sorbitan trioleate 13.5 Trichlorofluoromethane 910.0 Dichlorodifluoromethane 490.0 (i) Aerosol II mg/ml Compound X 0.2 Sorbitan trioleate 0.27 Trichlorofluoromethane 70.0 Dichlorodifluoromethane 280.0 Dichlorotetrafluoroethane 1094.0 (j) Aerosol III mg/ml Compound X 2.5 Sorbitan trioleate 3.38 Trichlorofluoromethane 67.5 Dichlorodifluoromethane 1086.0 Dichlorotetrafluoroethane 191.6 (k) Aerosol IV mg/ml Compound X 2.5 Soya lecithin 2.7 Trichlorofluoromethane 67.5 Dichlorodifluoromethane 1086.0 Dichlorotetrafluoroethane 191.6 Note The above formulations may be obtained by conventional procedures well known in the pharmaceutical art. The tablets (a)-(c) may be enteric coated by conventional means, for example to provide a coating of cellulose acetate phthalate. The aerosol formulations (h)-(k) may be used in conjunction with standard, metered dose aerosol dispensers, and the suspending agents sorbitan trioleate and soya lecithin may be replaced by an alternative suspending agent such as sorbitan monooleate, sorbitan sesquioleate, polysorbate 80, polyglycerol oleate or oleic acid.

Claims: Claims for the following Contracting States : AT, BE, CH, DE, FR, GB, IT, LI, LU, NL, SE A compound of the formula I wherein Ar¹ is phenyl or naphthyl which may optionally bear one or more substituents selected from halogeno, hydroxy, carboxy, cyano, (1-4C)alkyl, (2-4C)alkenyl, (2-4C)alkynyl, (1-4C)alkoxy, (1-4C)alkylthio, (1-4C)alkysulphinyl, (1-4C)alkylsulphonyl, (1-4C)alkylamino, di-[(1-4C)alkyl]amino, (1-4C)alkoxycarbonyl, (2-4C)alkanoyl, hydroxy-(1-4C)alkyl and fluoro-(1-4C)alkyl; wherein A¹ is (1-6C)alkylene, (3-6C)alkenylene, (3-6C)alkynylene or cyclo(3-6C)alkylene; wherein Ar² is phenylene which may optionally bear one or two substituents selected from halogeno, hydroxy, amino, nitro, cyano, carbamoyl, (1-4C)alkyl, (3-4C)alkenyloxy, (1-4C)alkoxy, (1-4C)alkylthio, (1-4C)alkylsulphinyl, (1-4C)alkysulphonyl, (1-4C)alkylamino, di-[(1-4C)alkyl]amino, fluoro-(1-4C)alkyl, (1-4C)alkoxycarbonyl, N-[(1-4C)alkyl]carbamoyl, N,N-di-[(1-4C)alkyl]carbamoyl, (2-4C)alkanoylamino, cyano-(1-4C)alkoxy, carbamoyl-(1-4C)alkoxy and (1-4C)alkoxycarbonyl-(1-4C)alkoxy; or Ar² is a 6-membered heterocyclene moiety containing up to three nitrogen atoms; wherein R¹ is (1-6C)alkyl, (3-6C)alkenyl, (3-6C)alkynyl, cyano-(1-4C)alkyl or (2-4C)alkanoyl, or R¹ is benzoyl which may optionally bear a substituent selected from halogeno, (1-4C)alkyl and (1-4C)alkoxy; and wherein R² is (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 or (2-4C)alkanoyloxy-(1-4C)alkyl; wherein R³ is hydroxy-(1-4C)alkyl, mercapto-(1-4C)alkyl, (1-4C)alkoxy-(1-4C)alkyl, (3-4C)alkenyloxy-(1-4C)alkyl, (3-4C)alkynyloxy-(1-4C)alkyl, (1-4C)alkoxy-(2-4C)alkoxy-(1-4C)alkyl, (1-4C)alkylthio-(1-4C)alkyl, (1-4C)alkylsulphinyl-(1-4C)alkyl, (1-4C)alkylsulphonyl-(1-4C)alkyl, (1-4C)alkoxycarbonyl-(1-4C)alkyl, (2-4C)alkanoyl-(1-4C)alkyl, (2-4C)alkanoyloxy-(1-4C)alkyl or cyano-(1-4C)alkyl; or R³ is oxiranyl, oxetanyl, tetrahydrofuranyl or tetrahydropyranyl; or a pharmaceutically-acceptable salt thereof. A compound of the formula I as claimed in claim 1 wherein Ar¹ is phenyl, naphth-1-yl or naphth-2-yl which may optionally bear one, two or three substituents selected from fluoro, chloro, bromo, iodo, cyano, methyl, methoxy, methylthio, methylsulphinyl, methylsulphonyl, methoxycarbonyl, difluoromethyl and trifluoromethyl; A¹ is methylene, ethylene, trimethylene, 1-propenylene, 2-methylprop-1-enylene or 1-propynylene; Ar² is 1,3-phenylene or 1,4-phenylene which may optionally bear one substituent selected from chloro, bromo, hydroxy, amino, nitro, methyl, methoxy, allyloxy, methylthio, methylsulphinyl, methylsulphonyl, methylamino, dimethylamino, trifluoromethyl, acetamido, cyanomethoxy and carbamoylmethoxy; or Ar² is 2,4-, 2,5-, 3,5- or 2,6-pyridylene or 4,6-pyrimidylene; R¹ is methyl, ethyl, allyl, 2-propynyl or cyanomethyl; R² is methyl, ethyl, propyl, vinyl, ethynyl, 1-propynyl, trifluoromethyl, hydroxymethyl, methoxymethyl or acetoxymethyl; and R³ is hydroxymethyl, 1-hydroxyethyl, 2-hydroxyethyl, mercaptomethyl, 1-mercaptoethyl, 2-mercaptoethyl, methoxymethyl, 1-methoxyethyl, 2-methoxyethyl, ethoxymethyl, methylthiomethyl, 1-methylthioethyl, 2-methylthioethyl, methylsulphonylmethyl, methoxycarbonylmethyl, ethoxycarbonylmethyl, acetoxymethyl or cyanomethyl; or a pharmaceutically-acceptable salt thereof. A compound of the formula I as claimed in claim 1 wherein Ar¹ is phenyl or naphth-2-yl which may optionally bear one or two substituents selected from fluoro, chloro, bromo, methyl, tert -butyl and trifluoromethyl; A¹ is methylene, 1-propenylene or 1-propynylene; Ar² is 1,3-phenylene or 1,4-phenylene which may optionally bear one substituent selected from fluoro, chloro, methoxy and trifluoromethyl; or Ar² is 3,5-pyridylene; R¹ is methyl, ethyl or allyl; R² is methyl, ethyl, hydroxymethyl or methoxymethyl; and R³ is hydroxymethyl, 1-hydroxyethyl, 2-hydroxyethyl, mercaptomethyl, methoxymethyl, 1-methoxyethyl, 2-methoxyethyl, ethoxymethyl, allyloxymethyl, 2-propynyloxymethyl, 1-(2-propynyloxy)ethyl, 2-methoxyethoxymethyl, methylthiomethyl, 1-methylthioethyl, 2-methylthioethyl, methoxycarbonylmethyl, ethoxycarbonylmethyl, 2-acetylethyl, acetoxymethyl or cyanomethyl; or a pharmaceutically-acceptable salt thereof. A compound of the formula I as claimed in claim 1 wherein Ar¹ is phenyl or naphth-2-yl which may optionally bear one substituent selected from fluoro, methyl and trifluoromethyl; A¹ is methylene, 1-propenylene or 1-propynylene; Ar² is 1,3-phenylene or 1,4-phenylene which may optionally bear one substituent selected from fluoro, methoxy and trifluoromethyl; or Ar² is 3,5-pyridylene; R¹ is methyl or ethyl; R² is methyl, ethyl, hydroxymethyl or methoxymethyl; and R³ is 1-hydroxyethyl, 2-hydroxyethyl, mercaptomethyl, methoxymethyl, 1-methoxyethyl, 2-methoxyethyl, ethoxymethyl, 2-propynyloxymethyl, 1-(2-propynyloxy)ethyl, methylthiomethyl, 1-methylthioethyl, 2-methylthioethyl, acetoxymethyl or cyanomethyl; or a pharmaceutically-acceptable salt thereof. A compound of the formula I as claimed in claim 1 wherein Ar¹ is naphth-2-yl or 7-fluoronaphth-2-yl; A¹ is methylene; Ar² is 1,3-phenylene or 5-fluoro-1,3-phenylene; R¹ is methyl; R² is methyl, ethyl or methoxymethyl; and R³ is mercaptomethyl, methoxymethyl, 1-methoxyethyl or 2-propynyloxymethyl; or a pharmaceutically-acceptable salt thereof. A compound of the formula I as claimed in claim 1 wherein Ar¹ is phenyl; A¹ is 1-propynylene; Ar² is 1,3-phenylene or 5-fluoro-1,3-phenylene; R¹ is methyl; R² is methyl or ethyl; and R³ is methoxymethyl; or pharmaceutically-acceptable salts thereof. A compound of the formula I, or a pharmaceutically-acceptable salt thereof, as claimed in claim 1 selected from the group consisting of 2-methoxy-2-[3-(naphth-2-ylmethoxy)phenyl]but-1-yl methyl ether, 2-methoxy-2-[3-(naphth-2-ylmethoxy)phenyl]prop-1-yl methyl ether, 2-methoxy-2-[3-(naphth-2-ylmethoxy)phenyl]but-3-yl methyl sulphide, 2-methoxy-2-[3-(naphth-2-ylmethoxy)phenyl]but-1-yl 2-propynyl ether, 2-[5-fluoro-3-(7-fluoronaphth-2-ylmethoxy)phenyl]-2-methoxybut-1-yl methyl ether and 2-methoxy-2-[5-fluoro-3-(3-phenylprop-2-ynyloxy)phenyl]but-1-yl methyl ether. A process for the manufacture of a compound of the formula I, or a pharmaceutically-acceptable salt thereof, as claimed in any one of claims 1 to 7 which comprises:- (a) the alkylation, in the presence of a suitable base, of a compound of the formula II with a compound of the formula Ar¹-A¹-Z wherein Z is a displaceable group; provided that, when there is an amino, alkylamino, hydroxy or carboxy group in Ar¹, Ar², R¹, R² or R³, 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 Ar¹, Ar², R¹, R² or R³ 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 R¹-Z, wherein R¹ and Z have the meanings defined hereinbefore, provided that, when there is an amino, alkylamino, hydroxy or carboxy group in Ar¹, Ar², R² or R³, any amino, alkylamino, hydroxy or carboxy group is protected by a conventional protecting group; whereafter any undesired protecting group in Ar¹, Ar², R² or R³ is removed by conventional means; (c) for the production of those compounds of the formula I wherein Ar¹ or Ar² bears an alkylsulphinyl or alkylsulphonyl substituent, or R³ is an alkylsulphinylalkyl or alkylsulphonylalkyl group, the oxidation of a compound of the formula I wherein Ar¹ or Ar² bears an alkylthio substituent or wherein R³ is an alkylthioalkyl group; (d) for the production of those compounds of the formula I wherein Ar² bears an alkanoylamino substituent, the acylation of a compound of the formula I wherein Ar² bears an amino substituent; (e) for the production of those compounds of the formula I wherein R¹ is alkanoyl or benzoyl optionally bearing a substituent as defined hereinbefore, the acylation of a compound of the formula I wherein R¹ is hydrogen; (f) for the production of those compounds of the formula I wherein Ar¹ bears an alkenyl substituent, A¹ is alkenylene, or R¹ or R² is alkenyl, the reduction of the corresponding compound wherein Ar¹ bears an alkynyl substituent, A¹ is alkynylene, R¹ is alkynyl or R² is alkynyl; or (g) for the production of those compounds of the formula I wherein Ar² or R³ bears an alkoxy or substituted alkoxy substituent, an alkenyloxy substituent or an alkynyloxy substituent, the alkylation of a compound of the formula I wherein Ar² or R³ bears a hydroxy substituent. A pharmaceutical composition which comprises an alcohol or an ether derivative of the formula I, or a pharmaceutically-acceptable salt thereof, as claimed in any one of claims 1 to 7 in association with a pharmaceutically-acceptable diluent or carrier. Claims for the following Contracting States : ES, GR A process for the manufacture of a compound of the formula I wherein Ar¹ is phenyl or naphthyl which may optionally bear one or more substituents selected from halogeno, hydroxy, carboxy, cyano, (1-4C)alkyl, (2-4C)alkenyl, (2-4C)alkynyl, (1-4C)alkoxy, (1-4C)alkylthio, (1-4C)alkysulphinyl, (1-4C)alkylsulphonyl, (1-4C)alkylamino, di-[(1-4C)alkyl]amino, (1-4C)alkoxycarbonyl, (2-4C)alkanoyl, hydroxy-(1-4C)alkyl and fluoro-(1-4C)alkyl; wherein A¹ is (1-6C)alkylene, (3-6C)alkenylene, (3-6C)alkynylene or cyclo(3-6C)alkylene; wherein Ar² is phenylene which may optionally bear one or two substituents selected from halogeno, hydroxy, amino, nitro, cyano, carbamoyl, (1-4C)alkyl, (3-4C)alkenyloxy, (1-4C)alkoxy, (1-4C)alkylthio, (1-4C)alkylsulphinyl, (1-4C)alkysulphonyl, (1-4C)alkylamino, di-[(1-4C)alkyl]amino, fluoro-(1-4C)alkyl, (1-4C)alkoxycarbonyl, N-[(1-4C)alkyl]carbamoyl, N,N-di-[(1-4C)alkyl]carbamoyl, (2-4C)alkanoylamino, cyano-(1-4C)alkoxy, carbamoyl-(1-4C)alkoxy and (1-4C)alkoxycarbonyl-(1-4C)alkoxy; or Ar² is a 6-membered heterocyclene moiety containing up to three nitrogen atoms; wherein R¹ is (1-6C)alkyl, (3-6C)alkenyl, (3-6C)alkynyl, cyano-(1-4C)alkyl or (2-4C)alkanoyl, or R¹ is benzoyl which may optionally bear a substituent selected from halogeno, (1-4C)alkyl and (1-4C)alkoxy; and wherein R² is (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 or (2-4C)alkanoyloxy-(1-4C)alkyl; wherein R³ is hydroxy-(1-4C)alkyl, mercapto-(1-4C)alkyl, (1-4C)alkoxy-(1-4C)alkyl, (3-4C)alkenyloxy-(1-4C)alkyl, (3-4C)alkynyloxy-(1-4C)alkyl, (1-4C)alkoxy-(2-4C)alkoxy-(1-4C)alkyl, (1-4C)alkylthio-(1-4C)alkyl, (1-4C)alkylsulphinyl-(1-4C)alkyl, (1-4C)alkylsulphonyl-(1-4C)alkyl, (1-4C)alkoxycarbonyl-(1-4C)alkyl, (2-4C)alkanoyl-(1-4C)alkyl, (2-4C)alkanoyloxy-(1-4C)alkyl or cyano-(1-4C)alkyl; or R³ is oxiranyl, oxetanyl, tetrahydrofuranyl or tetrahydropyranyl; or a pharmaceutically-acceptable salt thereof; characterised by (a) the alkylation, in the presence of a suitable base, of a compound of the formula II with a compound of the formula Ar¹-A¹-Z wherein Z is a displaceable group; provided that, when there is an amino, alkylamino, hydroxy or carboxy group in Ar¹, Ar², R¹, R² or R³, 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 Ar¹, Ar², R¹, R² or R³ 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 R¹-Z, wherein R¹ and Z have the meanings defined hereinbefore, provided that, when there is an amino, alkylamino, hydroxy or carboxy group in Ar¹, Ar², R² or R³, any amino, alkylamino, hydroxy or carboxy group is protected by a conventional protecting group; whereafter any undesired protecting group in Ar¹, Ar², R² or R³ is removed by conventional means; (c) for the production of those compounds of the formula I wherein Ar¹ or Ar² bears an alkylsulphinyl or alkylsulphonyl substituent, or R³ is an alkylsulphinylalkyl or alkylsulphonylalkyl group, the oxidation of a compound of the formula I wherein Ar¹ or Ar² bears an alkylthio substituent or wherein R³ is an alkylthioalkyl group; (d) for the production of those compounds of the formula I wherein Ar² bears an alkanoylamino substituent, the acylation of a compound of the formula I wherein Ar² bears an amino substituent; (e) for the production of those compounds of the formula I wherein R¹ is alkanoyl or benzoyl optionally bearing a substituent as defined hereinbefore, the acylation of a compound of the formula I wherein R¹ is hydrogen; (f) for the production of those compounds of the formula I wherein Ar¹ bears an alkenyl substituent, A¹ is alkenylene, or R¹ or R² is alkenyl, the reduction of the corresponding compound wherein Ar¹ bears an alkynyl substituent, A¹ is alkynylene, R¹ is alkynyl or R² is alkynyl; or (g) for the production of those compounds of the formula I wherein Ar² or R³ bears an alkoxy or substituted alkoxy substituent, an alkenyloxy substituent or an alkynyloxy substituent, the alkylation of a compound of the formula I wherein Ar² or R³ bears a hydroxy substituent. A process as claimed in claim 1 for the manufacture of a compound of the formula I wherein Ar¹ is phenyl, naphth-1-yl or naphth-2-yl which may optionally bear one, two or three substituents selected from fluoro, chloro, bromo, iodo, cyano, methyl, methoxy, methylthio, methylsulphinyl, methylsulphonyl, methoxycarbonyl, difluoromethyl and trifluoromethyl; A¹ is methylene, ethylene, trimethylene, 1-propenylene, 2-methylprop-1-enylene or 1-propynylene; Ar² is 1,3-phenylene or 1,4-phenylene which may optionally bear one substituent selected from chloro, bromo, hydroxy, amino, nitro, methyl, methoxy, allyloxy, methylthio, methylsulphinyl, methylsulphonyl, methylamino, dimethylamino, trifluoromethyl, acetamido, cyanomethoxy and carbamoylmethoxy; or Ar² is 2,4-, 2,5-, 3,5- or 2,6-pyridylene or 4,6-pyrimidylene; R¹ is methyl, ethyl, allyl, 2-propynyl or cyanomethyl; R² is methyl, ethyl, propyl, vinyl, ethynyl, 1-propynyl, trifluoromethyl, hydroxymethyl, methoxymethyl or acetoxymethyl; and R³ is hydroxymethyl, 1-hydroxyethyl, 2-hydroxyethyl, mercaptomethyl, 1-mercaptoethyl, 2-mercaptoethyl, methoxymethyl, 1-methoxyethyl, 2-methoxyethyl, ethoxymethyl, methylthiomethyl, 1-methylthioethyl, 2-methylthioethyl, methylsulphonylmethyl, methoxycarbonylmethyl, ethoxycarbonylmethyl, acetoxymethyl or cyanomethyl; or a pharmaceutically-acceptable salt thereof. A process as claimed in claim 1 for the manufacture of a compound of the formula I wherein Ar¹ is phenyl or naphth-2-yl which may optionally bear one or two substituents selected from fluoro, chloro, bromo, methyl, tert -butyl and trifluoromethyl; A¹ is methylene, 1-propenylene or 1-propynylene; Ar² is 1,3-phenylene or 1,4-phenylene which may optionally bear one substituent selected from fluoro, chloro, methoxy and trifluoromethyl; or Ar² is 3,5-pyridylene; R¹ is methyl, ethyl or allyl; R² is methyl, ethyl, hydroxymethyl or methoxymethyl; and R³ is hydroxymethyl, 1-hydroxyethyl, 2-hydroxyethyl, mercaptomethyl, methoxymethyl, 1-methoxyethyl, 2-methoxyethyl, ethoxymethyl, allyloxymethyl, 2-propynyloxymethyl, 1-(2-propynyloxy)ethyl, 2-methoxyethoxymethyl, methylthiomethyl, 1-methylthioethyl, 2-methylthioethyl, methoxycarbonylmethyl, ethoxycarbonylmethyl, 2-acetylethyl, acetoxymethyl or cyanomethyl; or a pharmaceutically-acceptable salt thereof. A process as claimed in claim 1 for the manufacture of a compound of the formula I wherein Ar¹ is phenyl or naphth-2-yl which may optionally bear one substituent selected from fluoro, methyl and trifluoromethyl; A¹ is methylene, 1-propenylene or 1-propynylene; Ar² is 1,3-phenylene or 1,4-phenylene which may optionally bear one substituent selected from fluoro, methoxy and trifluoromethyl; or Ar² is 3,5-pyridylene; R¹ is methyl or ethyl; R² is methyl, ethyl, hydroxymethyl or methoxymethyl; and R³ is 1-hydroxyethyl, 2-hydroxyethyl, mercaptomethyl, methoxymethyl, 1-methoxyethyl, 2-methoxyethyl, ethoxymethyl, 2-propynyloxymethyl, 1-(2-propynyloxy)ethyl, methylthiomethyl, 1-methylthioethyl, 2-methylthioethyl, acetoxymethyl or cyanomethyl; or a pharmaceutically-acceptable salt thereof. A process as claimed in claim 1 for the manufacture of a compound of the formula I wherein Ar¹ is naphth-2-yl or 7-fluoronaphth-2-yl; A¹ is methylene; Ar² is 1,3-phenylene or 5-fluoro-1,3-phenylene; R¹ is methyl; R² is methyl, ethyl or methoxymethyl; and R³ is mercaptomethyl, methoxymethyl, 1-methoxyethyl or 2-propynyloxymethyl; or a pharmaceutically-acceptable salt thereof. A process as claimed in claim 1 for the manufacture of a compound of the formula I wherein Ar¹ is phenyl; A¹ is 1-propynylene; Ar² is 1,3-phenylene or 5-fluoro-1,3-phenylene; R¹ is methyl; R² is methyl or ethyl; and R³ is methoxymethyl; or pharmaceutically-acceptable salts thereof. A process for the manufacture of a pharmaceutical composition characterised by bringing into association an alcohol or an ether derivative of the formula I, or a pharmaceutically-acceptable salt thereof, as claimed in any one of claims 1 to 6 and a pharmaceutically-acceptable diluent or carrier.

Inventors: GIRODEAU JEAN-MARC MARIE MAURI, GIRODEAU, JEAN-MARC MARIE MAURICE
Applicants: ZENECA LTD, ZENECA PHARMA SA, ZENECA LIMITED, ZENECA PHARMA S.A.
Application year: 1989
Main classification: C07C43
IPC codes: C07C45, A61K31, C07C317, C07C43, C07D319, C07C49, C07C235, C07D307, C07C217, C07F7, C07D309, C07D213, A61P37, C07C65, C07D303, A61P43, C07C255, C07C41, C07C59, C07C47, C07C69, C07C323, A61P29