SUBSTITUTED TRIAZOLO PYRIDAZINE DERIVATIVES AS INVERSE AGONISTS OF THE GABAA alpha 5 RECEPTOR SUBTYPE

Abstract: The present invention provides a compound of formula (I), wherein L is O, S or NH; X is amino, phenyl or a five- or six-membered heterocycle, each of which is optionally substituted; Y is C1-4alkylidene; Z is an optionally substituted five- or six-membered heterocycle; and n is 1 or 2; or a pharmaceutically acceptable salt thereof or a prodrug thereof; processes for their preparation, their use in enhancing cognition and methods of treatment comprising their administration.

Description: SUBSTITUTED TRIAZOLO PYRIDAZINE DERIVATIVES AS INVERSE AGONISTS OF THE GABAACX5 RECEPTOR SUBTYPE The present invention relates to a class of substituted tπazolo- pyridazme derivatives and to their use in therapy. More particularly, this invention is concerned with substituted l,2,4-tπazolo[4,3-b]pyridazιne derivatives which are hgands for GABAA 0.5 receptors and are therefore useful in the therapy where cognition enhancement is required. Receptors for the major inhibitory neurotransmitter, gamma- o aminobutvric acid (GABA), are divided into two mam classes: (1) GABAA receptors, which are members of the hgand-gated ion channel superfamily and (2) GABAB receptors, which may be members of the G-protem linked receptor superfamily. Since the first cDNAs encoding individual GABAΛ receptor subumts were cloned the number of known members of the mammalian family has grown to thirteen (six α subumts, three β subumts, three γ subunits and one δ subumt). It may be that further subumts remain to be discovered; however, none has been reported since 1993. Although knowledge of the diversity of the GABAA receptor gene family represents a huge step forward in our understanding of this iigand- gated ion channel, insight into the extent of subtype diversity is still at an early stage. It has been indicated that an α subumt. a β subumt and a γ subumt constitute the minimum requirement for forming a fully functional GABAA receptor expressed by transiently transfecting cDNAs into cells. As indicated above, a δ subumt also exists, but is apparently uncommon in the native receptor. Studies of receptor size and visualisation by electron microscopy conclude that, like other members of the hgand-gated ion channel family, the native GABAA receptor exists in pentameric form. The selection of at least one α. one β and one γ subumt from a repertoire of thirteen allows for the possible existence of more than 10.000 pentameric subumt combinations. Moreover, this calculation overlooks the additional permutations that would be possible if the arrangement of subumts around the ion channel had no constraints (i.e. there could be 120 possible variants for a receptor composed of five different subumts). Receptor subtype assemblies which do exist include αlβ2γ2, α2β2/3γ2, α3βγ2/3, α2βγl, α5β3γ2/3, α6βγ2, α6βδ and α4βδ. Subtype assemblies containing an αl subumt are present in most areas of the brain and account for over 40% of GABAA receptors in the rat. Subtype assemblies containing α2 and α3 subumts respectively account for about 25% and 17% of GABAA receptors in the rat. Subtype assemblies containing an α5 subumt are primarily hippocampal and represent about 4% of receptors in the rat A characteristic property of some GABAA receptors is the presence of a number of modulatory sites, of which the most explored is the benzodiazepme (BZ) binding site through which anxiolytic drugs such as diazepam and temazepam exert their effect. Before the cloning of the GABAA receptor gene family, the benzodiazepme binding site was historically subdivided into two subtypes, BZ1 and BZ2, on the basis of radioligand binding studies. The BZl subtype has been shown to be pharmacologically equivalent to a GABAA receptor comprising the αl subumt in combination with β2 and γ2 This is the most abundant GABA A receptor subtype, representing almost half of all GABAΛ receptors in the brain. A number of dementing illnesses such as Alzheimer's disease are characterised by a progressive deterioration in cognition in the sufferer. It would clearly be desirable to enhance cognition m subjects desirous of such treatment, for example for subjects suffering from a dementing illness. It has been reported by McNamara and Skelton m Psychobiology, 21:101-108, that the benzodiazepme receptor inverse agonist β-CCM enhanced spatial learning m the Morris watermaze. However, β-CCM and other conventional benzodiazepme receptor inverse agonists are proconvulsant which makes it clear that they cannot be used as cognition enhancing agents in humans. However, we have now discovered that it is possible to obtain medicaments which have cognition enhancing effects, but which do not possess proconvulsant effects previously described with benzodiazepme receptor partial or full inverse agonists. It has now been discovered that use of an α5 subtype receptor partial or full inverse agonist which is relatively free of activity at αi and/or α 2 and/or as subtype receptor binding sites can be used to provide a medicament which is useful for enhancing cognition but which is not proconvulsant. Inverse agonists at α , which are not free of activity at a- and/or α 2 and/or α 3 but which are selective for 0.5 can also be used. Inverse agonists which are both selective for αr. and are relatively free of activity at α j , α 2 and 3 receptor binding sites are preferred. EP-A-0085840 and EP-A-0134946 describe related series of 1,2,4- tnazolo[3,4-a]phthalazιne derivatives which are stated to possess antianxiety activity. However, there is no disclosure nor any suggestion in either of these publications of replacing the benzo moiety of the tπazolo- phthalazine ring system with any other functionality nor is there any suggestion that the compounds have any cognition enhancing properties. The present invention provides a compound of the formula (I). wherein: L is 0. S or NH: X is: NR 2 R 3 ; phenyl optionally substituted by one or two groups independently chosen from R G , halogen, CN and OR G , where R G is Ci-oalkyl, C2-6alkenyl, C 2 -6alkynyl or CF3, or by a methylenedioxy or ethylenedioxy group; or a 5-membered heteroaromatic ring containing 1, 2, 3 or 4 heteroatoms independently chosen from oxygen, nitrogen and sulphur, at most one of the heteroatoms being oxygen or sulphur, or a 6-membered heteroaromatic ring containing 1, 2, 3, or 4 nitrogen atoms, the ring being optionally fused to a benzene ring and optionally substituted by one or more groups independently chosen from R 7 , OR 7 , OCOR 7 , NR 8 R 9 , NR 8 COR 9 , CN and CF where R 7 is independently as defined for R G , R 8 is independently as defined for R 2 and R 9 is independently as defined for R\ when the 6-membered heteroaromatic ring is pyridine it is optionally in the form of the N- oxide; Y is optionally branched Cι- alkylidene optionally substituted by an oxo group; Z is pyrazine, pyrimidine or a 5-membered heteroaromatic ring containing at least one nitrogen or an oxygen and optionally 1, 2 or 3 other heteroatoms independently selected from oxygen, nitrogen and sulphur, at most one of the other heteroatoms being oxygen or sulphur, the ring being optionally substituted by a group R 1 , NR R\ NR 2 COR ! . CN. CF , phenyl. benzyl or pyridyl or a 5-membered heteroaromatic ring containing at least one nitrogen or an oxygen and optionally 1, 2 or 3 other heteroatoms independently selected from oxygen, nitrogen and sulphur, at most one of the other heteroatoms being oxygen or sulphur; R 1 is Ci-calkyl, C 2 -6alkenyl, C2-Galkynyl or CF3; R 2 and R 3 are each independently hydrogen, Ci calkyl, Ci-r.alkenyl. C2-f»alkynyl or CF3 or R 2 and R 3 , together with the nitrogen atom to which they are attached, form a 4-7 membered ring: and n is 1 or 2; or a pharmaceutically acceptable salt thereof or a prodrug thereof. In one embodiment there is provided a compound of formula I ' : wherein L ' , X ' , Y ' and Z ' are as defined for L, X, Y and Z, or a pharmaceutically acceptable salt thereof or a prodrug thereof. As used herein, the expression "Ci-r.alkyl" includes methyl and ethyl groups, and straight-chained, branched or cyclic propyl, butyl, pentyl and hexyl groups. Particular alkyl groups are methyl, ethyl, n-propyl, isopropyl and t-butyl and cyclohexyl. Derived expressions such as "C2-6alkenyl" and "C2-6alkynyl" are to be construed in an analogous manner. Suitable 5- and 6-membered heteroaromatic rings include pyridinyl, pyridazinyl, pyrimidinyl, pyrazinyl, furyl, thienyl, pyrrolyl, pyrazolyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, imidazolyl. oxadiazolyl and thiadiazolyl groups. The term "halogen" as used herein includes fluorine, chlorine. bromine and iodine, especially fluorine, chlorine and bromine. It will be understood that the fused ring containing the (CH 2 )n moiety is, when n=2 a [2.2.2]bicyclo-octenyl ring and when n=l a [2.2.1]bicycloheptenyl ring. Preferably L is an oxygen atom. Preferably X is pyridinyl optionally fused to a benzene ring and optionally in the form of the N-oxide, or X is phenyl. imidazolyl or thiazolyl and X is optionally substituted by one or two groups chosen from Ci- G alkyl, cyano and halogen, preferably chosen from methyl, cyano and bromine, or X is a group NR 2 R 3 in which R 2 and R :! independently represent Ci-nalkyl or form a 4-7 membered ring, preferably a five membered ring, together with the nitrogen atom to which they are attached. Apt values for Y include CH 2 , CH(CH 3 ), CH2CH2 and CH 2 CH2CH 2 optionally substituted by an oxo group. Preferably Y is CH 2 or CH 2 CO and most preferably CH2. Suitable groups Z include pyπmidinyl, pyrazmyl, pyrrolyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, oxadiazolyl and thiadiazolyl which groups are optionally substituted by Ci-r-alkyl, pyridyl or amino. Favoured values for Z include furans, pyrimidmes, pyrazmes, isoxazoles, oxazoles, thiazoles, oxadiazoles and thiadiazoles each of which is optionally substituted by Cι.r,alkyl, pyridyl or amino. More preferably Z is an oxadiazole, furan, pyrimidine, pyrazine, oxazole or isoxazole optionally substituted by d-Galkyl or pyridyl. More preferably still Z is optionally substituted by methyl, ethyl, isopropyl or pyridyl. In one embodiment, as mentioned above, the present invention provides compounds of formula I 1 which are preferably substituted as indicated above. In a further embodiment there is provided a compound of formula I • d " ) wherein L ' , X " , Y ' and Z ' are as defined for L. X. Y and Z above. In a particularly preferably embodiment of the compound of formula I " , L is O. Y ' is CHi. X " is pyridyl which is unsubstituted or substituted by Cϊ.βalkyl and Z is a furan, isoxazole or pyrazine which is unsubstituted or substituted by Ci calkyl Preferably X ' is isoxazolyl, furyl or pyrazmyl which is unsubstituted or substituted by methyl, more particularly X" is methyhsoxazolyl, furyl or pyrazmyl Preferably Z" is isoxazolyl or furyl which is unsubstituted or substituted by methyl, more particularly Z is methyhsoxazolyl or furyl In one embodiment of the invention Z is not furyl For use in medicine, the salts of the compounds of formula I will be pharmaceutically acceptable salts. Hence in a favoured aspect this invention provides the compounds of the formula I and pharmaceutically acceptable salts thereof Other salts may, however, be useful in the preparation of the compounds according to the invention or of their pharmaceutically acceptable salts. Suitable pharmaceutically acceptable salts of the compounds of this invention include acid addition salts which may, for example, be formed by mixing a solution of the compound according to the invention with a solution of a pharmaceutically acceptable acid such as hydrochloric acid, sulphuric acid, methanesulphomc acid, fumaπc acid, maleic acid, succinic acid, acetic acid, benzoic acid, oxalic acid citric acid, tartanc acid or phosphoric acid. Furthermore, where the compounds of the invention carry an acidic moiety, suitable pharmaceutically acceptable salts thereof may include alkali metal salts, e g. sodium or potassium salts: alkaline earth metal salts, e.g. calcium or magnesium salts, and salts formed with suitable organic gands, e.g quaternary ammonium salts The present invention includes within its scope prodrugs of the compounds of formula I above In general, such prodrugs will be functional derivatives of the compounds of formula I which are readily convertible m υwo into the required compound of formula I Conventional procedures for the selection and preparation of suitable prodrug derivatives are described, for example, in Design of Prodrugs, ed. H. Bundgaard, Elsevier, 1985. Where the compounds according to the invention have at least one asymmetric centre, they may accordingly exist as enantiomers. Where the compounds according to the invention possess two or more asymmetric centres, they may additionally exist as diastereoisomers. It is to be understood that all such isomers and mixtures thereof m any proportion are encompassed within the scope of the present invention. One apt group of compounds of this invention are of the formula (II)- (ID and pharmaceutically acceptable salts thereof wherein Z is as defined in relation to formula (I); X 1 is: a 6-membered heteroaromatic ring containing one or two nitrogen atoms optionally substituted by one or two Ci G alkyl groups which ring is optionally fused to a benzene ring and when the 6-membered heterocycle is pyndine it is optionally in the form of the N-oxide: a 5-membered heteroaromatic ring containing one or two nitrogen atoms and optionally one additional heteroatom selected from nitrogen. oxygen or sulphur and optionally substituted by C i-r.alkyl; an amme of the formula NR 10 R n where R 10 and R n are independently hydrogen or Ci. calkyl or are joined to form together with the nitrogen atom to which they are attached to form a 4-7 membered ring; or a phenyl ring optionally substituted by Br or CN: and Y 1 is CH 2 or CHCO Particular values of X 1 include cyanophenyl, bromophenyl, thiazolyl. pyridinyl, methylpyridinyl, dimethylpyridinyl, N-oxopyridinyl fused benzene pyridinyl, imidazolyl and N-methylimidazolyl. Specific compounds within the scope of the present invention include: 3-(5-methylisoxazol-3-yl)-6-(6-methylpyridin-2-yl)methyloxy-7,8,9,10- tetrahydro-(7,10-ethano)-l,2,4-triazolo[3,4-a]phthalazine; 3-(3-furyl)-6-(6-methylpyridin-2-yl)methyloxy-7,8,9,10-tetrahydro-(7,10- ethano)-l,2,4-triazolo[3,4-a]phthalazine: 3-(2-furyl)-6-(2-pyridyl)methyloxy-7,8,9,10-tetrahydro-(7,10-ethano)-l,2,4- tnazolo[3,4-a]phthalazine; 6-(6-methylpyridin-2-yl)methyloxy-3-(2-pyrazinyl)-7,8,9,10-tetrahydro- (7, 10-ethano)- l,2,4-triazolo[3,4-aJphthalazine; 3-(3-methyl-l,2,4-oxadiazol-5-yl)-6-(6-methylpyridin-2-yl)methyloxy- 7,8,9,10-tetrahydro-(7, 10-ethano)-l,2,4-triazolo[3,4-a]phthalazine; 3-(3-methyl-l,2,4-oxadiazol-5-yl)-6-(2-pyridyl)methyloxy-7 > 8,9,10- tetrahydro-(7,10-ethano)-l,2,4-triazolo[3,4-a]phthalazine; 3-(3-methyl-l,2,4-oxadiazol-5-yl)-6-(3-pyridyl)methyloxy-7,8,9,10- tetrahydro-(7.10-ethano ) -l,2,4-tnazolo[3,4-a]phthalazine; 6-(5.6-dimethylpyridin-2-yl)methyloxy-3-(3-methyl-1.2.4-oxadiazol-5-yl)- 7,8,9, 10-tetrahydro-(7.10-ethano)-l,2,4-trιazolo[3,4-a]phthalazine; 6-(4,6-dimethylpyridin-2-yl)methyloxy-3-(3-methyl-l,2.4-oxadiazol-5-yl)- 7,8,9,10-tetrahydro-(7, 10-ethano)-l,2,4-triazolo[3,4-a]phthalazine; 3-(3-methyl-1.2,4-oxadιazol-5-yl)-6-(2-quinolino)methyloxy-7.8,9.10- tetrahydro-(7,10-ethano)-l,2,4-triazolo[3,4-a]phthalazine; 3-(3-methyl-1.2,4-oxadiazol-5-yl)-6-(2-pyridyl-N-oxide)methyloxy-7.8,9,10- tetrahydro-(7.10-ethano)-l,2,4-triazolo[3,4-a]phthalazine; 6-(2-imidazolyl)methyloxy-3-(3-methyl-l,2,4-oxadiazol-δ-yl)-7,8,9.10- tetrahydro-(7.10-ethano)-l,2,4-trιazolo[3.4-a]phthalazine; 6-[2-(l-methyl)imidazolyl]methyloxy-3-(3-methyl-l,2,4-oxadiazol-5-yl)- 7.8.9.10-tetrahydro-(7.10-ethano)- 1.2.4-tπazolof3,4-a]phthalazιne: 6-[2-(cyano)phenyl]methyloxy-3-(3-methyl-l,2,4-oxadιazol-5-yl)-7,8,9,10- tetrahydro-(7,10-ethano)-l,2,4-triazolo[3,4-a]phthalazine; 6-(2-bromophenyl)methyloxy-3-(3-methyl-l,2,4-oxadiazol-δ-yl)-7,8,9,10- tetrahydro-(7,10-ethano)-l,2,4-triazolo[3,4-a]phthalazme; 3-(3-methyl-l,2,4-oxadiazol-5-yl)-6-(4-thiazolo)methyloxy-7,8,9,10- tetrahydro-(7,10-ethano)-l,2,4-triazolo[3,4-a]phthalazine; 3-(3-methyl-l,2,4-oxadiazol-5-yl)-6-(N-pyrrolidinylcarbonyl)methyloxy- 7,8,9, 10-tetrahydro-(7,10-ethano)-l,2,4-triazolo[3,4-a]phthalazine; 3-(3-ethyl-l,2,4-oxadiazol-5-yl)-6-(6-methylpyridin-2-yl)methyloxy- 7,8,9, 10-tetrahydro-(7,10-ethano)-l,2,4-trιazolo[3,4-a]phthalazine; 3-(3-isopropyl-l,2,4-oxadiazol-δ-yl)-6-(6-methylpyridιn-2-yl)methyloxy- 7,8,9.10-tetrahydro-(7,10-ethano)-l,2,4-tnazolo[3,4-a]phthalazine; 6-(6-methylpyridin-2-yl)methyloxy-3-[3-(pyridin-3-yl)-l,2,4-oxadiazol-5-yl]- 7,8,9,10-tetrahydro-(7,10-ethano)-l,2,4-triazolo[3,4-a]phthalazine; 6-(6-methylpyridin-2-yl)methyloxy-3-[3-(pyridin-4-yl)-l,2,4-oxadiazol-δ-yl]- 7,8,9, 10-tetrahydro-(7,10-ethano)-l,2,4-triazolo[3,4-a]phthalazine; 6-(5,6-dimethylpyridin-2-yl)methyloxy-3-[3-(pyridin-3-yl)-l,2,4-oxadiazol- 5-yl]-7,8,9,10-tetrahydro-(7,10-ethano)-l,2,4-tπazolo[3,4-a]phthalazme; 3-(2-methyloxazol-4-yl)-6-(2-pyridyl)methyloxy-7,8,9,10-tetrahydro-(7,10- ethano)-l,2,4-trιazolo[3,4-a]phthalazme; 3-(2-methyloxazol-4-yl)-6-(6-methylpyridιn-2-yl)methyloxy-7,8,9,10- tetrahydro-(7, 10-ethano)- l,2,4-trιazolo[3,4-a]phthalazme; and pharmaceutically acceptable salts and prodrugs thereof. Further specific compounds are: 3-(δ-methylisoxazol-3-yl)-6-(2-pyridyl)methyloxy-7.8.9.10-tetrahydro-(7, 10- ethano)-l,2,4-triazolo[3,4-a]phthalazine; 3-(5-methylisoxazol-3-yl)-6-(2-cyanophenyl)methyloxy-7,8,9, 10-tetrahydro- (7, 10-ethano)-l,2,4-trιazolo[3,4-a]phthalazine: 6-(3-methylp3'rιdin-2-yl)methyloxy-3-(2-pyrazmyl)-7.8,9,10-tetrahydro- (7.10-ethano)-l,2,4-tnazolo[3,4-a]phthalazιne: 3-(2-pyrazιnyl)-6-(2-pyπdyl)methyloxy-7,8,9,10-tetrahydro-(7,10-ethano)- l,2,4-trιazolo[3,4-a]ρhthalazme; 3-(δ-methyhsoxazol-3-yl)-6-(2-pyndyl)methyloxy-7,8,9,10-tetrahydro-(7,10- methano)-l,2,4-tπazolo[3,4-a]phthalazme; 3-(5-methylιsoxazol-3-yl)-6-(6-methylpyrιdm-2-yl)methyloxy-7,8,9,10- tetrahydro-(7,10-methano)-l,2,4-tπazolo[3,4-a]phthalazιne; 3-(3-furyl)-6-(2-pyπdyl)methyloxy-7,8,9,10-tetrahydro-(7,10-methano)- l,2,4-tπazolo[3,4-a]phthalazme; and pharmaceutically acceptable salts and prodrugs thereof The compounds of the present invention have a binding affinity (K,) for the of-, subumt of lOOnM or less, typically 50nM or less and preferably of lOnM or less. In a preferred embodiment the compounds of the invention possess at least a 2-fold, suitably at least a 5-fold and advantageously at least a 10-fold, most preferably at least a 50-fold binding selectivity for the as subumt relative to the α 1 ( α 2 and α 3 subumts The invention also provides pharmaceutical compositions comprising one or more compounds of this invention and a pharmaceutically acceptable carrier Preferably these compositions are in unit dosage forms such as tablets, pills, capsules, powders, granules sterile parenteral solutions or suspensions, metered aerosol or liquid sprays, drops, ampoules, auto- jector devices or suppositories; for oral parenteral, intranasal, sublingual or rectal administration, or for administration by inhalation or insufflation. For preparing solid compositions such as tablets, the principal active ingredient is mixed with a pharmaceutical carrier, e.g. conventional tabletmg ingredients such as corn starch, lactose, sucrose, sorbitol, talc, steaπc acid, magnesium stearate, dicalcium phosphate or gums, and other pharmaceutical diluents, e.g. water, to form a solid preformulation composition containing a homogeneous mixture of a compound of the present invention or a pharmaceutically acceptable salt thereof When referring to these preformulation compositions as homogeneous, it is meant that the active mgredient is dispersed evenly throughout the composition so that the composition may be readily subdivided into equally effective unit dosage forms such as tablets, pills and capsules. This solid preformulation composition is then subdivided into unit dosage forms of the type described above containing from 0.1 to about 500 mg of the active ingredient of the present invention. Typical unit dosage forms contain from 1 to 100 mg, for example 1, 2, δ, 10, 2δ, δO or 100 mg, of the active ingredient. The tablets or pills of the novel composition can be coated or otherwise compounded to provide a dosage form affording the advantage of prolonged action. For example, the tablet or pill can comprise an inner dosage and an outer dosage component, the latter being in the form of an envelope over the former. The two components can be separated by an enteric layer which serves to resist disintegration in the stomach and permits the inner component to pass intact into the duodenum or to be delayed in release. A variety of materials can be used for such enteric layers or coatings, such materials including a number of polymeric acids and mixtures of polymeric acids with such materials as shellac, cetyl alcohol and cellulose acetate. The present invention also provides a compound of the invention for use m a method of treatment of the human or animal body. Preferably the treatment is for a condition associated with GABA \ receptors comprising the as subumt and/or for the enhancement of cognition. The present invention further provides the use of a compound of the present invention in the manufacture of a medicament for the enhancement of cognition. Also disclosed is a method of treatment of a subject suffering from a cognition deficit which comprises administering to that subject an effective amount of a compound according to the present invention. The liquid forms in which the novel compositions of the present invention may be incorporated for administration orally or by injection include aqueous solutions, suitably flavoured syrups, aqueous or oil suspensions, and flavoured emulsions with edible oils such as cottonseed oil, sesame oil, coconut oil or peanut oil, as well as elixirs and similar pharmaceutical vehicles. Suitable dispersing or suspending agents for aqueous suspensions include synthetic and natural gums such as tragacanth, acacia, alginate, dextran, sodium carboxymethylcellulose, 5 methylcellulose, polyvinyl-pyrrolidone or gelatin. For the enhancement of cognition, a suitable dosage level is about 0.01 to 250 mg/kg per day, preferably about 0.05 to 100 mg/kg per day, and especially about 0.05 to 5 mg/kg per day. The compounds may be administered on a regimen of 1 to 4 times per day. 0 The compounds in accordance with the present invention may be prepared by a process which comprises reacting a compound of formula III with a compound of formula IV: lδ (III) flV) wherein n, L, X, Y and Z are as defined above and G is a leaving group such as chlorine. Compounds of formula III represent a further feature of the present invention. The groups Z which are preferred for compounds of formula I 20 are preferred for these compounds likewise. The reaction between compounds III and IV is conveniently effected by stirring the reactants in a suitable solvent, typically N,N-dιmethyl- formamide. in the presence of a strong base such as sodium hydride or lithium hexamethyldisilylazide, typically without heating. The intermediates of formula III above may be prepared by reacting a compound of formula V, which constitutes a further feature of the present invention, with a compound of formula VI: (V) (VI) wherein G, n and Z are as defined above, and W represents a suitable leaving group such as a carboxylic acid ester, chlorine or hydroxy. The reaction is advantageously conducted in an inert organic solvent and generally in the presence of an organic nitrogen base. Suitable solvents include xylene, dioxane, tetrahydrofuran and lower aliphatic halogenated and aromatic hydrocarbons. Suitable organic nitrogen bases that may be employed include trialkylamines and pvridine. The reaction is generally conducted at a temperature range of from room temperature to the reflux temperature of the reaction mixture, for a period of time that depends on the reactants employed and the temperature at which the reaction is carried out. The compound of formula VI may be activated before reaction by reacting with a compound such as l.l ' -dicarbonyldiimide to form the ketohydrazine. The compound of formula (V) is prepared by reaction of a compound of formula (VII): (VII) where G and n are as defined above, with hydrazine, usually in the form of its monohydrate, generally in a solvent such as ethanol and generally by refluxing for a suitable period such as 14-24 hours Where they are not commercially available, the starting materials of formula IV, VI and VII may be prepared by methods analogous to those described in the accompanying Examples, or bv standard methods known from the art. It will be understood that any compound of formula I initially obtained from the above process may, where appropriate, subsequently be elaborated into a further compound of formula I by techniques known from the art. It will also be appreciated that where more than one isomer can be obtained from a reaction then the resulting mixture of isomers can be separated by conventional means Where the above-described process for the preparation of the compounds according to the invention gives rise to mixtures of stereoisomers, these isomers may be separated by conventional techniques such as preparative chromatography. The novel compounds may be prepared racemic form, or individual enantiomers may be prepared either by enantiospecific synthesis or by resolution The novel compounds may, for example, be resolved into their component enantiomers by standard techniques such as preparative HPLC, or the formation of diastereomeπc pairs by salt formation with an optically active acid, such as (-)-dι-p-toluoyl-d-tartanc acid and/or (+)-dι-p-toluoyl-l-tartaπc acid followed by fractional crystallization and regeneration of the free base The novel compounds mav also be resolved bv formation of diastereome c esters or amides, followed by chromatographic separation and removal of the chiral auxiliary. During any of the above synthetic sequences it may be necessary and/or desirable to protect sensitive or reactive groups on any of the molecules concerned. This may be achieved by means of conventional protecting groups, such as those described in Protective Groups in Organic Chemistry, ed. J.F.W. McOmie, Plenum Press, 1973; and T.W. Greene & P.G.M. Wuts, Protective Groups in Organic Synthesis, John Wiley & Sons, 1991. The protecting groups may be removed at a convenient subsequent stage using methods known from the art. The following Examples illustrate the preparation of compounds according to the invention. The compounds in accordance with this invention potently inhibit the binding of [ 3 H]-flumazenil to the benzodiazepine binding site of human GABAA receptors containing the αδ subunit stably expressed in Ltk- cells. Reagents • Phosphate buffered saline (PBS). • Assay buffer: 10 mM KH2PO4, 100 mM KC1, pH 7.4 at room temperature. • [ H]-Flumazenil (18 nM for αlβ3γ2 cells; 18 nM for α2β3γ2 cells: 10 nM for α3β3γ2 cells; 10 nM for αδβ3γ2 cells) in assay buffer. • Flunitrazepam 100 μM in assay buffer. • Cells resuspended in assay buffer (1 tray to 10 ml). Harvesting Cells Supernatant is removed from cells. PBS (approximately 20 ml) is added. The cells are scraped and placed in a δO ml centrifuge tube. The procedure is repeated with a further 10 ml of PBS to ensure that most of the cells are removed. The cells are pelleted by centrifuging for 20 mm at 3000 rpm in a benchtop centrifuge, and then frozen if desired. The pellets are resuspended in 10 ml of buffer per tray (25 cm x 2δ cm) of cells. Assay Can be carried out in deep 96-well plates or in tubes. Each tube contains: • 300 μl of assay buffer. • δO μl of [ 3 H]-flumazenil (final concentration for αlβ3γ2: 1.8 nM; for α2β3γ2: 1.8 nM; for α3β3γ2: 1.0 nM; for αδβ3γ2: 1.0 nM). • 50 μl of buffer or solvent carrier (e.g. 10% DMSO) if compounds are dissolved in 10% DMSO (total); test compound or flunitrazepam (to determine non-specific binding), 10 μM final concentration. • 100 μl of cells. Assays are incubated for 1 hour at 40°C, then filtered using either a Tomtec or Brandel cell harvester onto GF/B filters followed by 3 x 3 ml washes with ice cold assay buffer. Filters are dried and counted by liquid scintillation counting. Expected values for total binding are 3000-4000 dpm for total counts and less than 200 dpm for non-specific binding if using liquid scintillation counting, or 1500-2000 dpm for total counts and less than 200 dpm for non-specific binding if counting with meltilex solid scintillant. Binding parameters are determined by non-linear least squares regression analysis, from which the inhibition constant K, can be calculated for each test compound. The compounds of the accompanying Examples were tested in the above assay, and all were found to possess a K, value for displacement of [ 3 H]Ro 15-1788 from the αδ subunit of the human GABAA receptor of 25 nM or less. REFERENCE EXAMPLE 1 3-Chloro-6-hvdrazino-4,δ-diazatricyclof6.2.2,71dodeca-2(7).3.δ-triene a) 4,5-Diazatricvclof6.2.2. .7] dodec-2(7)-ene-3.6-dione. Bicyclo[2.2.2]oct-2-ene-2,3-dicarboxylic acid anhydride (prepared as described in J. Org. Chem., 1993, 6740-6744) (60.8g, 0.342mol) was dissolved in 50% aqueous acetic acid (1600ml) with sodium acetate trihydrate (δδ.δg, 1.2mol eq) and hydrazine hydrate (19.82ml, 1.2mol eq). The reaction mixture was heated under reflux for 16 h then allowed to cool. The solid produced was collected by filtration and washed with water and diethyl ether before drying in a vacuum oven at 80°C to give the required product (δ9.3g, m.p. = 214°C). Η NMR (2δ0 MHz, DMSO) δ 1.16 (4H, d, J=7.1 Hz), 1.69 (4H, d, =7.1 Hz), 3.18 (2H. s), 11.31 (2H, br, s, NH); MS (ES + ) m/e 193 [MH] + . b) 3.6-Dichloro-4.δ-diazatricvclor6.2.2.-?.71dodeca-2(7).3.δ-triene The product from Example 1 Step a) (δ9.2g) was dissolved in phosphorus oxychloride (300ml) and heated under reflux for 14h. The solvent was removed under vacuum and azeotroped 2x toluene. The residue was dissolved in dichloromethane (200ml) and stirred rapidly and the solution was neutralised by the addition of solid and aqueous sodium hydrogen carbonate (cautiously). When effervescence had ceased, the organic layer was separated and the aqueous layer was extracted with δ dichloromethane (2x200ml). The combined organic layers were dried (MgSO 4 ), filtered and evaporated to give the required product (δ9.δg, m.p. > 370°C). Η NMR (2δ0 MHz. CDC1. 3 ) δ 1.39 (4 H. d. .7=8.1 Hz), 1.92 (4 H, d, =8.1 Hz), 3.47 (2 H, s); MS (ES + ) m/e 229 [MU] c) 3-Chloro-6-hvdrazino-4.δ-dιazatrιcvcIo[6.2.2.71dodeca-2(7).3.5-tπene The preceding product (40. Og, 0.17δmol) was added to a stirred solution of hydrazine monohydrate (δ6.8g, 1.13mol) in ethanol (600ml) and the solution refluxed for 18h. The mixture was cooled to room δ temperature and the solvent removed in vacuo. Water (lδOml) was added to the residue and the mixture acidified to pH 1-2 with δN hydrochloric acid. The aqueous was extracted with dichloromethane (x3) and then basified with powdered K2CO3 and extracted with dichloromethane (x3). The combined dichloromethane was dried (MgSO ) and evaporated to give 0 a pale yellow solid (29.0g, 78%), mp 136-140°C, Η NMR (2δOMHz, CDCI3) δ 1.27-1.45 (4H, m, 2, of CH2), 1.79-1.91 (4H, m, 2, of CH2), 3.05 (1H, s, CH), 3.40 (1H, s, CH), 3.94 (2H, br s, NH 2 NH), 6.18 (1H, br s. NHNH2); MS (ES + ) m/e 225 [MH] + . 5 EXAMPLE 1 3-(5-Methylisoxazol-3-yl)-6-(6-methylpyridin-2-yl)methyloxy-7.8.9.10- tetrahvdro-(7,10-ethano)-1.2,4-triazolof3,4-a]phthalazine. 0 a) 6-Chloro-3-(δ-methylιsoxazol-3-yl)-7.8.9.10-tetrahvdro-(7.10-ethano)- 1.2.4-trιazoIof3.4-a]phthalazιne 1,1 -Carbonyldiιmidazole (2.0g, 12.6mmol) was added to a stirred solution of δ-methylιsoxazole-3-carboxylic acid DMF (δOml). The solution was stirred for O.δh before adding the preceding hydrazine (2.63g, 5 11.7mmol). After lh at room temperature, the solution was poured into water and the resultant precipitate was filtered, washed with water (30ml) and hexane (100ml), and dried in vacuo to give the ketohydrazine (3.1g, 79%); MS (ES + ) m/e 334 [MH] + . A solution of the ketohydrazine (l.Og, 3.0mmol) and triethylamme hydrochloπde (0.2g, 1.45mmol). in xylene 0 (30ml), was heated at reflux for 4h. The solution was cooled to room temperature and the solvent removed m vacuo. The residue was chromatographed through silica gel, eluting with ethyl acetate, to give the tiύe-phthalazine (0.60g, 63%), mp 186-188 °C; Η NMR (2δ0MHz, CDC ) δ 1.22-1.54 (4H, m, 2 of CH2), 1.94-2.06 (4H, m, 2 of CH2), 2.58 (3H, s, Me), 3.60 (1H, s, CH), 4.08 (1H, s, CH), 6.90 (1H, s, Ar-H); MS (ES + ) m/e 316 [MH] + . b) 3-(5-Methylisoxazol-3-yl)-6-(6-methylpyridin-2-yl)methyloxy-7.8.9.10- tetrahvdro-(7,10-ethano)-l,2,4-triazolo 3,4-a]phthalazine To a solution of 6-methyl-2-pyridylcarbinol (0.47g, 3.8mmol), in DMF (δOml), was added sodium hydride (O.lδg of a 60% dispersion in oil, 3.8mmol) and the mixture was stirred at room temperature for 0.2δh. After this time, the preceding product (l.Og, 3.2mmol) was added and the reaction mixture stirred at 55°C for 16h. The solvent was removed under vacuum and the residue partitioned between ethyl acetate and water. The aqueous was separated and extracted further with ethylacetate (x3). The combined extracts were dried (Na 2 SO /MgSO ) and evaporated, and the residue chromatographed on silica gel eluting with ethyl acetate to give the required product (0.35g, 28%), mp 223-225 °C; Η NMR (250MHz CDCI3) δ 1.38-1.54 (4H, m, 2 of CH 2 ), 1.84-1.98 (4H, m, 2 of CH 2 ), 2.58 (3H. s. Me), 2.60 (3H, s, Me), 3.58 (1H. s CH), 3.98 (1H, s. CH), 5.59 (2H. s. CH 2 ), 6.85 (1H, s, Ar-H), 7.14 (1H, d, J=7.7 Hz), 7.44 (1H, d, J=7.6Hz. Ar- H), 7.64 (1H, dd, J=7.7 and 7.6 Hz, Ar-H); MS (ES + ) m/e 403 [MH] ÷ . Anal. Found C, 64.91; H, 5.38; N, 20.28. C22H22N6O2.O.3H2O requires C, 64.79: H, 5.δ8; N. 20.60 %. EXAMPLE 2 3-(3-Furyl)-6-(6-methylpyrid n-2-yl)methyloxy-7.8.9.10-tetrahvdro-(7.10- ethano)-1.2.4-triazolof3.4-alphthalazine. a) 6-Chloro-3- ( 3-furyl ) -7.8.9.10-tetrahvdro-(7.10-ethano)- 1.2,4- triazolof3,4-a]phthaIazine To a solution of 3-chloro-6-hydrazino-4,5- diazatricyclo[6.2.2.2,7]dodeca-2(7),3,δ-triene (l.Og, 4.45mmol), in xylene (20ml), was added triethylamine (0.67g, 6.7mmol) and 3-furoyl chloride (0.58g, 4.4mmol). The mixture was stirred at room temperature for lh and then heated at reflux for 16h. The solution was cooled to room temperature, the solvent evaporated under reduced pressure, and the residue partitioned between dichloromethane (150ml) and water (30ml). The aqueous was separated and extracted further with dichloromethane (x2). The combined extracts were dried (Na2S0 4 ), evaporated, and the residue chromatographed on silica gel eluting with ethyl acetate to afford the title-product (0.75g, δ6%); Η NMR (2δ0 MHz. CDCls) δ 1.41-1.55 (4H, m, 2 of CH 2 ), 1.90-2.05 (4H, m, 2 of CH 2 ), 3.57 (IH, s, CH), 4.04 (IH, s, CH), 7.30-7.31 (IH, m, Ar-H), 7.59-7.60 (IH, m. Ar-H), 8.61 (IH, s, Ar-H); MS (ES + ) m/e 301 [MH] + . b) 3-(3-Furyl)-6-(6-methylpyridin-2-yl)methyloxy-7.8.9.10-tetrahvdro- (7.10-ethano)-l,2,4-triazolof3.4-alphthalazine The title-compound was prepared from the preceding product and 6- methyl-2-pyridylcarbinol using the procedure given for Example 1 part b, mp 205-206 °C; ] H NMR (250 MHz, CDC1 3 ) δ 1.38-1.56 (4H, m, 2 of CH2), 1.84-2.02 (4H, m, 2 of CH 2 ), 2.63 (3H. s, Me), 3.58 (IH, s, CH), 3.96 (IH, s, CH), δ.58 (2H, s, CH 2 ), 7.14 (IH, d, J=7.6Hz, Ar-H). 7.26 (IH, s. Ar-H), 7.31 (IH, d, J=7.7Hz, Ar-H), 7.55-7.56 (IH, m. Ar-H). 7.64 (IH, dd, J=7.7 and 7.6Hz, Ar-H), 8.50 (IH, s, Ar-H): MS (ES T ) m/e 388 [MH] + ; Anal. Found C, 67,23; H, δ.41; N, 17.51. C22H21N5O2.O.20 H 2 O requires C. 67.41: H, 5.53; N, 17.87%). EXAMPLE 3 3-(2-Furyl ) -6- ( 2- p yridyl ) methyloxy-7.8.9.10-tetrahvdro-(7.10-ethano)- 1.2.4- triazolo f 3 , 4- a]phthalazine δ The title-compound was prepared from 3-chloro-6-hydrazino-4,δ- diazatricyclo[6.2.2.2,7]dodeca-2(7),3,δ-triene and 2-furoyl chloride using the procedure described for Example 2 part a. The resultant triazolopyridazine was reacted with 2-pyridylcarbinol using the procedure described for Example 1 part b to afford the desired product, mp 24δ°C; Η 0 NMR (360 MHz, CDC1 3 ) δ 1.40-1.56 (4H, m, 2 of CH 2 ), 1.86-1.98 (4H, m, 2 of CH 2 ), 3.58 (IH, s, CH), 3.99 (IH, s, CH), 5.6δ (2H. s, CH 2 ), 6.61-6.62 (IH, m, Ar-H), 7.28-7.31 (IH, m, Ar-H), 7.39 (IH, d. J=3.δHz, Ar-H), 7.δ4 (IH, d, J=7.7 Hz, Ar-H), 7.6δ (IH, s, Ar-H), 7.75-7.79 (IH, m, Ar-H), 8.64- 8.66 (IH, m, Ar-H); MS (ES + ) m/e 374 [MH] + ; Anal. Found C, 67,37; H, 5 5.03; N, 18.80. C 2 iH 19 N 5 O2 requires C, 67.δδ; H, 5.13; N, 18.76%. EXAMPLE 4 6-(6-Methylpyridin-2-vI)methyloxy-3-(2-pyrazinyl)-7.8,9.10-tetrahvdiO- 0 (7.10-ethano)-1.2.4-triazolof3.4-a hthalazine. a) 6-Chloro-3-(2-Pyrazinyl)-7.8.9.10-tetrahvdro-(7.10-ethano)-1.2.4- triazoIor3.4-a1phthalazine The title-compound was prepared from 3-chloro-6-hydrazino-4,5- 5 diazatricyclo[6.2.2.2,7]dodeca-2(7),3,5-triene and pyrazme-2-carboxylic acid using the procedure described for Example 1 part a; Η NMR (2δOMHz, CDCI3) 1.40-1.56 (4H, m, 2 of CH 2 ), 1.90-2.08 (4H, m. 2 of CH 2 ), 3.61 (IH, s, CH), 4.12 (IH, s, CH), 8.74 (IH, d, J=1.5Hz. Ar-H). 8.86 (IH, dd, J=1.3 and l.δHz. Ar-H), 9.72 (IH, d. J=1.3Hz, Ar-H), MS (ES + ) m/e 313 30 [MH] + . b) 6- ( 6-Methylρyrιdιn-2-yl)methyloxy-3-(2-pyrazmyl)-7.8.9.10- tetrahydro-(7,10-ethano)-l,2,4-trιazolof3,4-alphthalazιne To a solution of 6-methyl-2-pyridylcarbmol hydrochloπde (0.275g, 1.72mmol), in DMF (10ml), was added NaH (0.138g of 60% dispersion in δ oil, 3.4δmmol) and the mixture was stirred at room temperature for 0.25h. The product from Example 4 step a (0.225g, 0.72mmol) was added and the mixture stirred at room temperature for 2h and then at 60° C for Iδh. The solvent was removed under vacuum and the residue partitioned between water (20ml) and ethyl acetate (100ml). The aqueous was extracted 10 further with ethyl acetate (x2) and the combined organic was dried (MgS0 ) and evaporated. The residue was triturated with ethyl acetate to give the title -compound (0.16g, 56%), mp 204-206 °C; Η NMR (360MHz, CDC1 3 ) δ 1.40-1.56 (4H, m, 2 of CH2), 1.87-2.02 (4H. m, 2 of CH 2 ), 2.61 (3H, s, Me), 3.60 (IH, s, CH), 4.03 (IH, s, CH), 5.δ7 (2H, s, CH 2 ), 7.14 (IH, d, Iδ J=7.7Hz, Ar-H), 7.35 (IH, d, J=7.7Hz, Ar-H), 7.64 (IH, dd, J=7.7 and 7.7Hz, Ar-H), 8.68 (IH, d, J=1.5Hz, Ar-H), 8.82 (IH, dd, J=1.3 and 1.5Hz, Ar-H), 9.65 (IH, d, J=1.3Hz, Ar-H); MS (ES + ) m/e 400 [MH] + . EXAMPLE 5 20 3-(3-Methyl-1.2,4-oxadιazoI-5-yl)-6-(6-methylpyrιdιn-2-vI)methyloxy- 7.8,9, 10-tetrahvdro-(7,10-ethano)-1.2.4-trιazolo.3.4-alphthalazme INTERMEDIATE 1 25 6-Chloro-3-(3-methyl-1.2.4-oxadιazol-δ-yl)-7.8.9.10-tetrahvdro-(7.10- ethano)-1.2.4-trιazolef3,4-a]phthalazιne a) Ethyl-[3-(methyl)-1.2.4-oxadιazol-5-yl)lcarboxylate 30 Pyndine (32.7ml, 0.404mol) was added dropwise to a stirred suspension of acetamide oxime (10. Og. 0.13δmol). in 1.2-dιchloroethane, a t room temperature, under nitrogen. The mixture was cooled to 0°C , and ethyl oxalyl chloride (22.6ml, 0.202mol) was added dropwise over 0.2h. After stirring at 0°C for O.lh the mixture was warmed to room temperature for 0.3h and then to 80°C and stirred for 2.1h. The mixture was diluted with CH2CI2 (200ml) and washed with 2N HCl (100ml), H 2 O (2x100ml) and brine (100ml). The solution was dried (MgSO 4 ) and evaporated in vacuo to give the title oxadiazole (20.0δg, 9δ%); Η NMR (250MHz, CDCI3) δ 1.46 (3H, t, J=7.2Hz, Me), 2.52 (3H, s, Me), 4.55 (2H, q, J=7.2Hz, CH 2 ). b) 6-Chloro-3-(3-methyl-1.2.4-oxadiazol-5-vn-7.8.9.10-tetrahvdro-(7.10- ethano)-l,2.4-trιazolof3.4-alphthalazine Ethyl-[3-(methyl)-l,2,4-oxadiazol-5-yl]carboxylate (0.987g, 6.32mmol) was added to a solution of 3-chloro-6-hydrazino-4,δ- diazatricyclo[6.2.2.2,7]dodeca-2(7),3,5-triene (1.18g, 5.3mmol) in anhydrous dioxane (28ml) and the reaction mixture stirred at reflux for 3 days. The solvent was removed under vacuum and the residue was partitioned between dichloromethane (120ml) and water (30ml). The dichloromethane was separated, dried (MgSO- and evaporated in vacuo and the residue chromatographed on silica gel eluting with 15% ethyl acetate/dichloromethane to give the title -product (0.32g, 19%); Η NMR (360MHz, CDCI3) δ 1.42-1.57 (4H, m, 2 of CH 2 ), 1.95-2.08 (4H, m, 2 of CH 2 ), 2.62 (3H, s, Me), 3.64 (IH, s, CH), 4.13 (IH, s. CH); MS (ES + ) m/e 317 [MH] + . 3-(3-Methyl-1.2.4-oxadiazol-5-ylV6-(6-methvIpyridin-2-yl)methyloxy- 7.8,9.10-tetrahvdro-(7.10-ethano)-1.2.4-trιazolof3.4-alphthalazine The title-compound was prepared from the preceding product and 6- methyl-2-pyridinylcarbinol hydrochloride using the procedure given for Example 4 part b, mp 191-193 °C: Η NMR (360MHz, CDCI3) δ 1.38-1.56 (4H. m, 2 of CH 2 ). 1.86-2.03 (4H. m. 2 of CH 2 ). 2.60 (3H. s. Me). 2.60 (3H, s, Me), 3.62 (IH, s, CH), 4.02 (IH, s, CH), δ.62 (2H, s, CH), 7 14 (IH, d, J=7.7Hz, Ar-H), 7.49 (IH, d, J=7.7Hz, Ar-H), 7 6δ (IH, dd, J=7.7 and 7.7Hz, Ar-H); MS (ES + ) m/e 404 [MH] + ; Anal. Found C, 61.90; H, 5.10; N, 23.50. C ιH2iN 7 O 2 . 0.1(ethyl acetate). 0.2H 2 O requires C, 61.81; H, δ.38; δ N, 23.58%. EXAMPLE 6 3-(3-Methyl-1.2.4-oxadiazol-δ-yl)-6-(2-pyrιdyllmethyloxy-7.8 9.10- 10 tetrahvdro-(7,10-ethano)-1.2,4-tnazolo[3,4-a1phthalazιne The title-compound was prepared from Intermediate 1 and 2- pyπdylcarbinol using the procedure given for Example 4 part b, mp 182°C, Η NMR (360MHz, CDC1 3 ) δ 1.40-1.53 (4H, m, 2 of CH 2 ), 1.89-2.00 (4H, m, 2 of CH2), 2.60 (3H, s, Me), 3.61 (IH, s, CH), 4.02 (IH, s, CH), δ.66 (2H, s, lδ CH 2 ), 7.29 (IH, m, Ar-H), 7.72 (IH, t, J=7.8Hz, Ar-H), 7.77 (IH, dd, J=7.6 and 6.1Hz, Ar-H), 8.64 (IH, m, Ar-H); MS (ES + ) m/e 390 [MH] + ; Anal Found C, 61.56; H, 4.96; N, 24.72. C 2 oHi9N 7 O 2 . 0.1H 2 O req res C, 61.40, H, 4.95; N, 25.06%. 20 EXAMPLE 7 3-(3-Methyl-1.2.4-oxadιazol-5-yl)-6-(3-pyrιdyl)methyloxy-7.8.9.10- tetrahvdro-(7.10-ethano)-l,2,4-tπazolof3 4-alphthalazιne Sodium hydnde(63mg of a 60% dispersion in oil, l.βmmol) was 2δ added to a stirred solution of 3-pyrιdylcarbιnol (112mg, 1.03mmol) in DMF (8ml) at room temperature under nitrogen and the mixture stirred for 0.8h. After this time, Intermediate 1 (2δ0mg, 0 789mmol) was added and the reaction mixture stirred for 22h. Water (34ml) was added and the resulting precipitate stirred for 1.2δh before being collected by filtration 30 Flash chromatography on silica gel eluting with ethyl acetate followed by recrystal sation (ethyl acetate/diethyl ether) gave the tiύe-product (132mg, 43%), mp 167.δ-168°C; Η NMR (360MHz, CDC1 3 ) δ 1.36-1.52 (4H, m, 2 of CH 2 ), 1.89-2.00 (4H, m, 2 of CH ), 2.63 (3H, s, Me), 3.δ3 (IH, br s, CH), 4.01 (IH, br s, CH), δ.δ9 (2H, s, CH 2 ), 7.37 (IH, dd, J=7.6 and 5.0Hz, Ar-H), 8.02 (IH, br d, J=7.9Hz, Ar-H), 8.62 (IH, d, J=5.0Hz, Ar-H), 8.90 δ (IH, s, Ar-H); MS (ES + ) m/e 390 [MH] + ; Anal. Found C, 61.44; H, 4.94; N, 24.89. C..0H19N7O requires C, 61.69; H, 4.92; N, 25.18%. EXAMPLE 8 0 6-(5,6-Dimethylpyridin-2-yl)methyloxy-3-(3-methyl-l,2.4-oxadiazol-δ-yl)- 7.8.9.10-tetrahvdro-(7.10-ethano)-1.2.4-trιazolor3.4-alphthalazine The title-compound was prepared from Intermediate 1 and 2- hydroxymethyl-5,6-dimethylpyridine (prepared as described in patent WO 93/21158) using lithium hexamethyldisilylazide as base, following the 5 procedure given for Example 7, mp 139-141°C; Η NMR (250MHz, CDCI3) δ 1.38-1.60 (4H, m, 2 of CH 2 ), 1.86-2.00 (4H, m, 2 of CH 2 ), 2.31 (3H, s, Me), 2.55 (3H, s, Me), 2.61 (3H, s, Me), 3.60 (IH, br s, CH), 4.01 (IH, br s, CH), 5.61 (2H, s, CH 2 ), 7.48 (2H, s, Ar-H); MS (ES + ) m/e 418 [MH] + 0 EXAMPLE 9 6-(4,6-Dimethylpyridin-2-yl)methyloxy-3-(3-methyl-1.2.4-oxadiazoI-5-yl)- 7.8.9.10-tetrahvdro-(7.10-ethano)-1.2,4-triazolof3.4-a1phthalazine The title-compound was prepared from Intermediate 1 and 2- δ hydroxymethyl-4,6-dimethylpyridιne (prepared in an analogous manner to that described in J. Am. Chem. Soc, 19δ4, 76, 1286) using the procedure given for Example 8, mp 204-20δ°C; MS (ES + ) m/e 418[MH] + . EXAMPLE 10 3-(3-Methyl-1.2.4-oxadiazol-δ-yl)-6-(2-αuinolino)methyloxy-7,8.9.10- tetrahvdro-(7.10-ethano)-1.2.4-triazolof3,4-a]phthalazine δ a) 2- (Hvdroxymethyl)α uinoline A mixture of 2-(chloromethyl)quinoline hydrochloride (1.50g, 7.00mmol) and sodium acetate trihydrate (2.86g, 21.0mmol) in DMF (40ml) was heated at 100°C under nitrogen for 6h. The reaction mixture 0 was poured into ether, washed with water (x3), dried (MgS0 4 ) and evaporated in vacuo. The residue was dissolved in methanol/water (9:1) (40ml), sodium hydroxide (O.δOg, 12.5mmol) added and the mixture heated at reflux for 0.75h. The solvent was evaporated in vacuo and the residue partitioned between dichloromethane and water. The organic layer was 5 separated, washed with water (xl), dried (MgS0 4 ) and evaporated in vacuo. The residue was flash chromatographed on silica gel, eluting with 4:1 ethyl acetate/hexane, to give the title-α/coΛo/ (0.85g, 76%); → - NMR (2δOMHz, CDCls) δ 4.51 (IH, br s, OH), 4.93 (2H, s, CH 2 ), 7.29 (IH, d, J=8.5Hz, Ar-H), 7.δδ (IH, t, J=6.9Hz, Ar-H), 7.73 (IH, m, Ar-H), 7.84 0 (IH, dd, J=8 and 1.3Hz, Ar-H), 8.09 (IH. d, J=8.4Hz. Ar-H). 8.14 (IH, d, J=8.δHz, Ar-H). b) 3-(3-Methyl-1.2.4-oxadiazol-δ-yl)-6-(2-Quinolino)methyloxy-7.8.9.10- tetrahvdro-(7.10-ethano)-l,2,4-triazolor3.4-a|phthalazine δ The title-compound was prepared from Intermediate 1 and the preceding alcohol using the procedure given for Example 7, mp 216-218°C; Η NMR (360MHz, CDCI3) δ 1.43-1.55 (4H, m, 2 of CH 2 ), 1.92-2.02 (4H, m, 2 of CH 2 ), 2.59 (3H, s. Me), 3.65 (IH, br s, CH), 4.03 (IH, br s. CH), 5.84 (2H, s, CH 2 ), 7.58 (IH, t, J=7.6Hz. Ar-H), 7.73-7.86 (2H. m, 3 of Ar-H). 8.11 0 (IH, d, J=8.6Hz. Ar-H), 8.24 (IH. d, J=8.3Hz, Ar-H): MS (ES + ) m/e 440 [MH] + ; Anal. Found C, 64.81; H, 4.51; N, 21.74. C 24 H 21 N 7 O2.0.3H 2 O requires C, 64.79; H, 4.89; N, 22.04%. EXAMPLE 11 3- ( 3-Methyl-1.2.4-oxadiazol-δ-yl ) -6- ( 2- p yridyl-N-oxide)methyloxy-7.8.9.10- tetrahvdro-(7.10-ethano)-1.2,4-triazolo[3.4-alphthalazine m-Chloroperbenzoic acid (62mg of a 55% purity sample, 0.20 mmol) was added to a stirred solution of 3-(3-methyl-l,2,4-oxadiazol-δ-yl)-6-(2- pyridyl)methyloxy-7,8,9,10-tetrahydro-(7,10-ethano)-l,2,4-triazolo[3,4- a]phthalazine (43mg, O.llmmol) in dichloromethane (3ml) at room temperature under nitrogen. After stirring for 17h, the mixture was diluted with dichloromethane, washed with saturated potassium carbonate solution (x2) and water (xl), dried (MgSO ) and evaporated in vacuo. The residue was chromatographed on silica gel, eluting with 5% methanol/dichloromethane, and then recrystallised (ethyl acetate/hexane) to give the title-product (21mg, 47%), mp 225-227°C; J H NMR (360MHz, CDC1 3 ) δ 1.42-1.54 (4H, m, 2 of CH 2 ), 1.92-2.02 (4H, m, 2 of CH 2 ), 2.60 (3H, s, Me), 3.62 (IH, br s, CH), 4.03 (IH, br s, CH), δ.8δ (2H, s, CH 2 ), 7.31-7.33 (2H, m. 2 of Ar-H), 7.86 (IH. m, Ar-H), 8.33 (IH, m. Ar-H); MS (ES T ) m/e 406 [MH] + ; Anal. Found C, 56.54; H, 4.69; N, 22.91. C 2 oH,oN 7 θ3.H2θ requires C, 56.73; H, 4.99; N, 23.15%. EXAMPLE 12 6-(2-Imidazolyl)methyloxy-3-(3-methvI-l,2.4-oxadiazol-5-yl)-7,8.9,10- tetrahvdro-(7.10-ethano)-1.2.4-triazoiof3.4-a)phthalazine a) 2-(Hvdroxymethyl)-l- 2-(trimethylsilyl)ethoxylmethv -imidazole Sodium borohydride (0.42g, llmmol) was added to a stirred solution of l-{[2-(trimethylsilyl)ethoxy]methyl -lH-imidazole-2-carboxaldehyde (7.45g, 33mmol) (prepared as described in J. Org. Chem., 1986, 51, 1891) in methanol (30ml) at 0°C. The solution was stirred at 0°C for 0.67h, brine (15ml) added and the mixture stirred at room temperature for 0.2δh. The methanol was evaporated in vacuo and the aqueous solution washed 5 with ethyl acetate (3x50ml). The combined organic layers were dried (Na 2 SO ) and evaporated in vacuo to yield an oil which crystallised at 0°C. The solid was washed and recrystallised (hexane) to give the title- imidazole as colourless crystals (1.99g, 26%); Η NMR (250MHz, CDC1 3 ) δ 0.00 (9H, s, SiMe 3 ), 0.93 (2H, t, J=8.2Hz, CH 2 ), 3.54 (2H, t, J=8.2Hz, CH 2 ), 10 4.73 (2H, s, CH 2 ), 4.77 (IH, br s, OH), 5.39 (2H, s, CH 2 ), 6.94 (IH, d, J=1.4Hz, Ar-H), 7.00 (IH, d, J=1.4Hz, Ar-H); MS (ES + ) m/e 229 [MH]~. b) 3-(3-Methyl-1.2.4-oxadiazol-5-vI)-6-f2-(l-f2- (trimethylsilyl)ethoxylmethyl)imidazolyl]methyloxy-7.8,9,10-tetrahvdro- lδ (7.10-ethano)-1.2,4-triazolor3,4-a1phthalazine The title -compound was prepared from Intermediate 1 and the preceding alcohol using the procedure given for Example 7, J H NMR (360MHz, CDCI3) δ 0.00 (9H, s, SiMe 3 ), 0.91 (2H, t, J=8.lHz. CH 2 ), 1.40- 1.56 (4H. m. 2 of CH 2 ), 1.89-2.02 (4H, m, 2 of CH 2 ), 2.62 (3H, s, Me). 3.53- 20 3.58 (3H. m, CH and CH 2 ), 4.05 (IH, br s, CH), 5.50 (2H, s, CH 2 ), δ.72 (2H, s, CH 2 ), 7.14 (IH, d, J=1.4Hz, Ar-H), 7.16 (IH, d. J=1.4Hz, Ar-H); MS (ES + ) m/e 509 [MH] + . c) 6-(2-Imidazolyl)methyloxy-3-(3-methyl-1.2.4-oxadiazol-5-yl)- 25 7.8.9.10-tetrahvdro-(7.10-ethano)-1.2.40-triazolor3.4-alphthalazine A stirred solution of the preceding product (35δmg, 0.698mmol) in δN HCl (14ml) was heated at 40°C for 2.3h. Ethanol was added and the mixture evaporated in vacuo. The residue was azeotroped with ethanol (x2), partitioned between dichloromethane and water and basified with 30 saturated potassium carbonate solution. The organic layer was separated and the aqueous phase re-extracted with dichloromethane (xl). The combined organic extracts were washed with water (xl), dried (MgSO 4 ) and evaporated in vacuo, and the residue recr stallised (ethyl acetate- hexane) to give the title -compound (190mg, 72%), mp 187°C; ! H NMR (360MHz, CDCls) δ 1.36-1.50 (4H, m, 2 of CH 2 ), 1.88-2.00 (4H, m, 2 of 5 CH 2 ), 2.66 (3H, s, Me), 3.δ6 (IH, br s, CH), 4.01 (IH, br s, CH), δ.δ8 (IH, br s, CH ), 7.10 (2H, s, 2 of Ar-H); MS (ES + ) m/e 379 [MH] + ; Anal. Found C, δ7.30; H, 4.84; N, 29.14. Ci8Hi8N 8 O 2 . 0.0δH 2 O requires C, δ7.00; H, 4.81; N, 29.54%. 0 EXAMPLE 13 6-f2-(l-Methyl)imidazoivnmethyloxy-3-(3-methyl-1.2.4-oxadiazol-δ-yl)- 7,8,9.10-tetrahvdro-(7.10-ethano)-1.2.4-triazolor3,4-alphthalazine The title-compound was prepared from Intermediate 1 and 1- lδ methyl-2-(hydroxymethyl)imidazole using the procedure given for Example 7, mp 215-216°C; Η NMR (360MHz, CDCI3) δ 1.36-1.53 (4H, , 2 of CH 2 ), 1.86-1.99 (4H, m, 2 of CH 2 ), 2.58 (3H, s, M), 3.50 (IH, br s, CH), 3.80 (3H, s, Me), 4.02 (IH, br s, CH), 5.6δ (2H, s, CH ), 6.98 (IH, d, J=l.lHz, Ar-H), 7.10 (IH, d, J=1.4Hz, Ar-H); MS (ES + ) m/e 393 [MH] + ; 20 Anal. Found C, 57.91; H, δ.02; N, 28.07. C19H20N8O2.O.2H2O requires C, δ7.62; H. 5.19; N, 28.29%. EXAMPLE 14 2δ 6-f2-(Cvano)phenyl1methyloxy-3-(3-methvi-1.2.4-oxadιazol-δ-yl)-7.8.9.10- tetrahvdro-(7.10-ethano)-1.2.4-triazolof3.4-a1phthalazιne a) 2-Cvanobenzyl alcohol Sodium borohydride (0.87g, 23.0mmol) was added to a stirred 30 suspension of 2-cyanobenzaldehyde (3.00g, 22.9mmol. in ethanol (20ml) at 0°C under nitrogen. The mixture was stirred at room temperature for 0.8h and the solvent then evaporated in vacuo. The residue was partitioned between dichloromethane (60ml) and water (60ml) and the aqueous layer separated and re-extracted with dichloromethane (60ml). The combined organic extracts were dried (MgSO 4 ) and evaporated in vacuo, and the residue chromatographed on silica gel, eluting with 5% methanol/dichloromethane, to give the title-α coΛo (1.71g, 56%), Η NMR (250MHz, CDCla) δ 5.32 (2H, s, CH 2 ), 7.39-7.66 (3H, m, 3 of Ar-H), 7.88 (IH, d, J=7.5Hz, Ar-H). b) 6-f2-(Cvano)phenyl1methyloxy-3-(3-methvI-1.2.4-oxadiazol-5-vI)- 7.8.9.10-tetrahvdro-(7.10-ethano)-1.2.4-triazolor3.4-alphthalazine The title-compound was prepared from Intermediate 1 and the preceding alcohol using the procedure given for Example 7, mpl97-198°C; Η NMR (360MHz, CDCls) δ 1.42-1.53 (4H, m, 2 of CH2), 1.90-1.99 (4H, m, 2 of CH 2 ), 2.62 (3H, s, Me), 3.60 (IH, br s, CH), 4.01 (IH, br s. CH), 5.73 (2H, s, CH 2 ), 7.49 (IH, t, J=7.6Hz, Ar-H), 7.64 (IH, dt, J=l.l and 7.6Hz, Ar-H) 7.76 (IH, d, J=7.6Hz, Ar-H), 7.87 (IH, d, J=7.6Hz, Ar-H); MS (ES + ) m/e 414 [MH] + ; Anal. Found C, 63.62; H. 4.40; N, 23.38. C22H10N7O2 requires C. 63.91; H, 4.63; N, 23.72%. EXAMPLE 15 6-(2-Bromophenyl ) methyloxy-3-(3-methvI-l,2.4-oxadiazol-5-yl)-7.8.9.10- tetrahydro-(7.10-ethano)-l,2.4-triazolof3,4-a1phthalazine The title-compound was prepared from Intermediate 1 and 2- bromobenzyl alcohol using the procedure given for Example 7. mp 217- 218°C; NMR (360MHz, CDCls) δ 1.38-1.53 (4H, m. 2 of CH 2 ), 1.88-1.99 (4H, m, 2 of CH 2 ), 2.61 (3H, s, Me), 3.57 (IH, br s, CH).4.01 (IH, br s, CH). 5.63 (2H, s. CH 2 ), 7.25 (IH, dt, J=1.8 and 7.6Hz. Ar-H). 7.35 (IH. m. Ar-H). 7.64 (IH. dd, J=l.l and 7.9Hz, Ar-H), 7.74 (IH, dd, J=1.4 and 7.6Hz. Ar- H); MS (ES + ) m/e 467 [MH] + . SUBSTΓΓUTE SHEET (RULE 26) EXAMPLE 16 3-(3-Methyl-1.2.4-oxadiazol-5-yl)-6-(4-thiazolo)methyloxy-7.8.9.10- tetrahvdro- (7.10-ethano)- 1.2.4- triazolo f 3.4- a]phthalazine The title-compound was prepared from Intermediate 1 and 4- hydroxymethylthiazole (prepared in an analogous manner to that described in J. Am. Chem. Soc, 19δ4, 76, 1286) using the procedure given for Example 8, mp 119-121°C; MS (ES + ) m/e 418 [MH] + . EXAMPLE 17 3-(3-Methyl-1.2.4-oxadiazol-δ-yl)-6-(N-pyrrolidinylcarbonyl)methyloxy- 7.8.9.10-tetrahvdro-(7.10-ethano)-1.2.4-triazolor3.4-a1phthalazine a) N-Hvdroxymethylcarbonylpyrrolidine A stirred solution of methyl glycolate (2.0g, 22.2mmol) in pyrrolidine (16.0g, 225mmol) was heated at 90°C for 3h. The pyrrolidine was removed by distillation and the residue partitioned between dichloromethane (150ml) and 2N HCl (30ml). The aqueous layer was separated and re-extracted with dichloromethane (x2). The combined organic layers were dried (Na2SO 4 ) and evaporated in vacuo to afford the title-pyrrolidine (2.0g, 70%); Η NMR (250MHz, CDCla) δ 1.84-2.0δ (4H, m, 2 of CH2), 2.9δ (IH, br s, OH), 3.28 (2H, t, J=6.8Hz, CH 2 N), 3.δδ (2H, t, J=6.8Hz, CH 2 N). 4.08 (2H, CH 2 O). b) 3-(3-Methyl-1.2.4-oxadιazol-δ-yl)-6-(N- pyrrolidinylcarbonyl)methyloxy-7.8.9,10-tetrahvdro-(7,10-ethano)- 1.2,4- triazolo[3.4-a1phthalazine The title-compound was prepared from Intermediate 1 and the preceding alcohol using the procedure given for Example 7, mp 234-23δ°C: Η NMR (360MHz, CDC1 3 ) δ 1.48-1.50 (4H, m. 2 of CH2). 1.89-1.99 (6H, m, 3 of CH 2 ), 2.09-2.16 (2H, quintet, J=6.8Hz, CH 2 ), 2.5δ (3H, s, Me), 3.δl (2H, t, J=6.8Hz, CH2N), 3.64-3.67 (3H, m, CH 2 N and CH), 4.01 (IH, br s, CH), 5.09 (2H, s, CH 2 O); MS (ES + ) m/e 410 [MH] + ; Anal. Found C, 58.47; 5 H, 5.72; N, 23.47. C20H23N7O3. 0.15 H 2 O requires C, 58.28; H, 5.70; N, 23.79%. EXAMPLE 18 10 3-(3-Ethyl-1.2.4-oxadiazol-5-yl)-6-(6-methylpyπdin-2-yl)methvIoxy- 7.8.9.10-tetrahvdro-(7.10-ethano)-1.2.4-triazolor3.4-a hthalazine The title -compound was prepared from propionamide oxime using the procedure described for Example δ, mp 169-171°C; Η NMR (360MHz, lδ CDCI3) δ 1.40-1.54 (7H, m, 2 of CH2 and Me), 1.90-2.00 (4H, m, 2 of CH 2 ), 2.60 (3H, s, Me), 2.97 (2H, q, J=7.6Hz, CH 2 ), 3.61 (IH, br s, CH), 4.01 (IH, br s, CH), 5.62 (2H, s, CH2), 7.14 (IH, d, J=7.9Hz, Ar-H), 7.49 (IH, d, J=7.6Hz, Ar-H), 7.64 (lH,t, J=7.6Hz, Ar-H); MS (ES + ) m/e 418 [MH] + ; Anal Found C, 63.28; H, 23.49; N, 23.24. C22H23N7O2 requires C, 63.29; H. 5.55; 20 N. 23.49%. EXAMPLE 19 3-(3-Isopropyl-1.2.4-oxadiazol-5-yl)-6-(6-methvipyridin-2-yl)methvioxy- 25 7.8.9,10-tetrahvdro-(7.10-ethano)-1.2.4-tnazolof3.4-alphthalazine The title -compound was prepared from 2-methylpropionamide oxime using the procedure described for Example δ, mp 185-187°C; l H NMR (360MHz, CDCI3) δ 1.40-1.52 (10H, m. 2 of CH 2 and CHMe 2 ), 30 1.88-2.00 (4H. m, 2 of CH 2 ), 2.60 (3H, s, Me), 3.30 (IH. septet, J=6.8Hz, CHMe 2 ), 3.61 (IH, br s. CH), 4.01 (IH, br s, CH). 5.62 (2H. s, CH 2 ), 7.14 (1H, d, J=7.6Hz, Ar-H), 7.50 (IH, d, J=7.6Hz, Ar-H), 7.63 (IH, t, J=7.8Hz, Ar-H); MS (ES + ) m/e 432 [MH] + ; Anal. Found C, 63.68; H, 5.45; N, 22.38. C23H25N7O2 requires C, 64.02; H, 5.84; N, 22.72%. 5 EXAMPLE 20 6-(6-Methylpyridin-2-yl)methyloxy-3-r3-(pyridin-3-yl)-1.2.4-oxadiazol-5-vn- 7.8.9.10-tβtrahvdro-(7,10-ethano ' )-1.2.4-triazoloI3.4-a1phthalazine 10 a) 3-Pyridylcarboxamide oxime A solution of 3-cyanopyridine (10.0g, 96mmol) in ethanol (100ml) was added to a stirred solution of hydroxylamine hydrochloride (13.3g, 192mmol) and potassium carbonate (15.9g, 120mmol) in ethanol (150ml). The mixture was heated at reflux for 16h, then added to room lδ temperature, filtered through a pad of Celite and evaporated in vacuo to give the title-ozάme, Η NMR (360MHz, d δ -DMSO) 5.97 (2H, br s), 7.40 (0.55H, m), 7.50 (0.45H, m), 8.02 (0.5H, m), 8.20 (0.5H, m), 8.56 (0.55H, m), 8.70 (0.45H, m), 8.86 (0.55H, m), 9.04 (0.45H, m), 9.77 (IH, br s). 20 b) Ethyl-f3-(Pyridin-3-yl)-1.2.4-oxadiazol-5-yllcarboxylate A mixture of the preceding amide oxime (3.0g, 22mmol) and 4A molecular sieves in THF (120ml) was stirred vigorously at room temperature under nitrogen. Sodium hydride (0.96g of a 60% dispersion in oil, 24mmol) was added, the mixture stirred for O.lh and then ethyl 25 oxalyl chloride (3.0g, 22mmol) added. The mixture was heated at reflux for lh, cooled to room temperature and filtered through celite. The solvent was evaporated in vacuo and the residue dissolved in dichloromethane, washed with water (x2), dried (MgS0 4 ) and evaporated in vacuo. The residue was chromatographed on silica gel, eluting with ethyl 30 acetate/hexane (1:1) to give the title-product (1.30g, 28%), Η NMR (360MHz, CDCI3) 1.51 (3H, t, J=7.0Hz, Me), 4.59 (2H, q, J=7.1Hz, CH 2 ), 7.47 (IH, m, Ar-H), 8.43 (IH, m, Ar-H), 8.78 (IH, m, Ar-H), 9.39 (IH, m, Ar-H). c) 6-(6-Methylpyrιdin-2-yl)methyloxy-3-r3-(pyrιdin-3-yl)-1.2.4- δ oxadιazol-5-vn-7.8.9.10-tetrahvdro-(7.10-ethano)-1.2.4-trιazolo[3.4- alphthalazine The title-compound was prepared from the preceding ester using the procedure described for Example 5, steps b-c, mp 202-204°C; Η NMR (250MHz, CDCls) δ 1.42-1.58 (4H, m, 2 of CH 2 ), 1.90-2.08 (4H, m, 2 of 0 CH 2 ), 2.61 (3H, s, Me), 3.64 (IH, br s, CH), 4.05 (IH, br s, CH), 5.67 (2H, s, CH 2 ), 7.16 (IH, d, J=7.5Hz, Ar-H), 7.49-7.δ2 (2H, m, Ar-H), 7.6δ (IH, t, J=7.6Hz, Ar-H), 8.δ6 (IH, m, Ar-H), 8.80 (IH, m, Ar-H), 9.51 (IH, br s, Ar- H); MS (ES + ) m/e 467 [MH] + ; Anal. Found C, 5δ.0δ; H, 5.18; N, 20.45. C25H22N8O2.I.2H2O.I.5HCI requires C, 55.31; H, 4.81; N, 20.64%. 5 EXAMPLE 21 6-(6-Methylpyridin-2-yl)methyloxy-3-r3-(pyridin-4-yl)-l,2.4-oxadiazoI-δ-vn- 7.8.9.10-tetrahvdro-(7.10-ethano)-1.2,4-trιazolof3.4-a1phthalazme 0 The title-compound was prepared from 4-cyanopyridine using the procedure described for Example 20, mp 272-274°C; *H NMR (2δOMHz, CDCI3) δ 1.42-1.58 (4H, m, 2 of CH 2 ), 1.90-2.05 (4H, m, 2 of CH 2 ), 2.61 (3H, s, Me), 3.64 (IH, br s, CH), 4.05 (IH, br s, CH), 5.67 (2H, s, CH 2 ), 7.16 (IH, 5 d, J=7.8Hz, Ar-H), 7.49 (IH, d, J=7.8Hz, Ar-H), 7.64 (IH, d, J=7.7Hz, Ar- H), 8.13-8.16 (2H, m, Ar-H), 8.84-8.86 (2H, m, Ar-H); MS (ES + ) m/e 467 [MH] + ; Anal. Found C, 64.80; H, 4.δ6; N, 23.62. C25H22N8O2.O.KCH2CI2) requires C, 64.37; H, 4.56; N, 24.02%. EXAMPLE 22 6-(δ.6-DimethvI p yridin-2-yl)methyloxy-3-r3-(pyridin-3-yl)-l,2.4-oxadiazol- 5-yll-7.8.9.10-tetrahvdro- ( 7.10-ethano ) -l,2,4-triazolor3.4-alphthalazine The title -compound was prepared from ethyl-[3-(pyridin-3-yl)-l,2,4- oxadiazol-δ-yl]carboxylate, 3-chloro-6-hydrazino-4,5- diazatricyclo[6.2.2]dodeca-2(7),3,δ-triene and 2-hydroxymethyl-δ,6- dimethylpyridine using the procedure described for Example δ step b and Example 9, mp 21δ-216°C; Η NMR (360MHz, CDC1 3 ) δ 1.42-1.54 (4H, m, 2 of CH2), 1.89-2.02 (4H, m, 2 of CH 2 ), 2.30 (3H, s, Me), 2.53 (3H, s. Me), 3.62 (IH, br s, CH), 4.03 (IH, br s, CH), 5.63 (2H, s, CH2), 7.42-7.51 (3H, m, 3 of Ar-H), 8.δ6 (IH, m, Ar-H), 8.80 (IH, m, Ar-H), 9.51 (IH, br s, Aril); MS (ES + ) m/e 481 [MH] + ; Anal. Found C, 65.14; H, 4.75; N, 23.12. C2GH24N8O2 requires C, 64.99; H, 5.03; N, 23.32%. EXAMPLE 23 3-(2-Methyloxazol-4-yl)-6-(2-pyridyl)methyloxy-7.8.9.10-tetrahvdro-(7.10- ethano)-1.2.4-triazolo[3,4-a1phthalazine a) Ethyl (2-methyl-2-oxazolin-4-yl)carboxylate Triethylamine (8.2ml, 59mmol) was added to a stirred mixture of L-serine ethyl ester hydrochloride (δ.OOg, 29.δmmol) and ethyl acetimidate hydrochloride (3.64g, 29.δmmol) in dichloromethane (IδOml) at 0°C under δ nitrogen. The mixture was stirred at 0°C for 1.2δh and at room temperature for 19h and then partitioned between dichloromethane and water. The organic layer was separated, washed with water (x3), dried (MgS0 4 ) and evaporated £71 vacuo and the residue chromatographed on silica gel, eluting with diethyl ether, to give the title-ester (2.68g, 37%), 0 Η NMR (360MHz, CDCI3) δ 1.31 (3H, t, J=7Hz, Me), 2.04 (3H, s, Me), 4.16-4.51 (4H. m, 2 of CH 2 ), 4.70 (IH, m, CH); MS (ES + ) m/e 158 [MH] + . b) Ethyl (2-methyloxazol-4-yl)carboxylate A stirred mixture of the preceding compound (2.18g, 13.9mmol) and N-bromosuccinimide (3.70g, 20.8mmol) in dichloromethane (90ml) at -lδ°C δ under nitrogen was irradiated for 7h. A second portion of N- bromosuccinimide (0.4δg, 2.δmmol) was added and the mixture irradiated for a further 4 h. The reaction mixture was filtered and the filtrate diluted with dichloromethane, washed with water (x3), dried (MgS0 ) and evaporated in vacuo. The residue was chromatographed on silica gel, 10 eluting with diethyl ether/hexane (70:30), to give the title-ester (0.9δg, 44%), 'H NMR (2δOMHz, CDC1 3 ) δ 1.38 (3H, t, J=7.3Hz, Me), 2.δ2 (3H, s, Me), 4.39 (2H, J=7Hz, CH 2 ), 8.13 (IH, s, Ar-H); MS (ES + ) m/e lδ6 [MH] + . c) 2-Methyloxazole-4-carboxylic acid lδ A solution of sodium hydroxide (0.97g, 24mmol) in water (10ml) was added to a stirred solution of the preceding ester (0.94g, 6.1mmol) in methanol (6ml). After 1.2δh at room temperature, the methanol was evaporated in vacuo and the aqueous solution cooled to 0-δ°C and acidified to pH 1 with δN HCl. Ethanol was added, the solvents evaporated 0 in vacuo and the residue azeotroped with ethanol. The resulting solid was mixed with ethanol, filtered and evaporated in vacuo. The process was repeated to give the title-αcid (0.776g, 100%), Η NMR (360MHz, d 6 - DMSO) δ 2.44 (3H, s, Me), 8.60 (IH, s, Ar-H); MS (ES + ) m/e 128 [MH] + . 2δ d) 6-Chloro-3-(2-methyloxazol-4-yl)-7.8.9.10-tetrahvdro-(7.10-ethano)- 1.2.4-triazolof3,4-a1phthalazine l,l'-Carbonyldiimidazole (l.Ollg, 6.23mmol) was added to a stirred solution of the preceding acid (0.7δδg, δ.94mmol) in DMF (20ml) at room temperature under nitrogen. The solution was stirred for l.lh before 30 adding 3-chloro-6-hydrazino-4,δ-diazatricyclo[6.2.2.2.7]dodeca-2(7), 3,5- triene (1.335g, 5.94mmol). After 2.5h, the solvent was evaporated in vacuo and the residue triturated with water. The solid was filtered off, washed with water and hexane, and dried in vacuo to give the ketohydrazine (1.64δg, 83%), MS (ES + ) m/e 334 [MH] + . A solution of the ketohydrazine (1.8δ5g, 5.56mmol) and triethylamine hydrochloride (0.186g, O.δδβmmol) δ in xylene (28ml) was heated at reflux for 3h. The solution was cooled to room temperature and the solvent evaporated in vacuo. The residue was dissolved in dichloromethane, washed with water (x3), dried (MgS0 ) and evaporated in vacuo, and the crude product was chromatographed on silica gel, eluting with 7% methanol/dichloromethane, to give the title- 0 phthalazine (0.917g, δ2%), Η NMR (2δOMHz, CDC1 3 ) δ 1.42- 1.56 (4H, m, 2 of CH ), 1.92-2.04 (4H, m, 2 of CH 2 ), 2.62 (3H, s, Me), 3.58 (IH, br s, CH), 4.09 (IH, br s, CH), 8.59 (IH, s, Ar-H); MS (ES + ) m/e 316 [MH] + . e) 3-(2-Methyloxazol-4-yl)-6-(2-pyridyl)methyloxy-7.8.9.10-tetrahvdro- 5 (7.10-ethano)-l,2,4-triazolo[3,4-a1phthalazine The title-compound was prepared from the preceding phthalazine and 2-pyridylcarbinol using the procedure given for Example 7, mp 222- 224°C; Η NMR (360MHz, CDCI3) 1.42-1.53 (4H, m, 2 of CH 2 ), 1.90-1.98 (4H, m, 2 of CH 2 ), 2.59 (3H, s, Me), 3.59 (IH, br s, CH), 4.00 (IH, br s, CH), 0 5.62 (2H, s, CH 2 ), 7.30 (IH, m, Ar-H), 7.51 (IH, d, J=7.9Hz, Ar-H), 7.76 (IH, m, Ar-H), 8.47 (IH, s, Ar-H), 8.68 (IH, m, Ar-H); MS (ES + ) m/e 389 [MH] + ; Anal. Found C, 65.04; H, 5.11; N, 21.33. C21H20N6O2 requires C, 64.94; H, 5.19; N, 21.64%. 5 EXAMPLE 24 3-(2-Methyloxazol-4-yl)-6-(6-methylpyridin-2-yl ' )methyloxy-7.8.9.10- tetrahvdro-(7.10-ethano)-1.2,4-triazolof3,4-alphthalazine The title-compound was prepared from 6-chloro-3-(2-methyloxazol- 0 4-yl)-7,8,9,10-tetrahydro-(7,10-ethano)-l,2,4-triazolo[3,4-a]phthalazine and 6-methyl-2-pyridylcarbinol using the procedure given for Example 7, mp 195-197°C; 360MHz (Η NMR, CDCI3) δ 1.42-1.54 (4H, m, 2 of CH2), 1.90- 1.98 (4H, m, 2 of CH 2 ), 2.δ9 (3H, s, Me), 2.64 (3H, s, Me), 3.δ8 (IH, br s, CH), 4.00 (IH, br s, CH), δ.60 (2H, s, CH 2 ), 7.15 (IH, d, J=7.6Hz, Ar-H), 7.32 (IH, d, J=7.6Hz, Ar-H), 7.65 (IH, t, J=7.6Hz, Ar-H), 8.56 (IH, s, Ar- δ H); MS (ES + ) m/e 403 [MH] + ; Anal. Found. C, 65.36; H, 5.51; N, 21.02. C 22 H 22 N G 0 2 requires C, 6δ.66; H, δ.δl; N, 20.88%. EXAMPLE 25 10 3-(5-Methylisoxazol-3-yl)-6-(2-pyridv methyloxy-7.8,9, 10-tetrahvdro-(7, 10- ethano)-1.2.4-triazolor3,4-alphthalazine The title-compound was prepared from 6-chloro-3-(5-methylisoxazol-3-yl)- 7,8,9, 10-tetrahydro-(7, 10-ethano)-l,2,4-triazolo[3,4-a]phthalazine and lδ 2-pyridylcarbinol using the procedure given for Example 1, part b, Η NMR (360 MHz, CDCI3) δ 1.40-1.52 (4H, m, 2 of CH 2 ), 1.86-1.98 (4H, m, 2 of CH 2 ), 2.57 (3H, s, Me), 3.58 (IH, br s, CH), 3.98 (IH, br s, CH), 5.63 (2H, s, CH 2 ), 6.83 (IH, s, Ar-H), 7.29 (IH, m, Ar-H), 7.68 (IH, d, J = 7.7 Hz, Ar-H), 7.76 (IH, m, Ar-H), 8.66 (IH, m, Ar-H); MS (ES + ) m/e 389 [MH] + . 20 EXAMPLE 26 3-(5-Methylisoxazol-3-yl)-6-(2-cvanophenyl)methyloxy-7.8,9.10-tetrahydro- (7.10-ethano)-1.2.4-triazolo 3.4-alphthalazine 25 The title -compound was prepared from 6-chloro-3-(5-methylisoxazol-3-yl)- 7.8,9, 10-tetrahydro-(7,10-ethano)-l,2,4-triazolo[3,4-a]phthalazine and 2-cyanobenzyl alcohol using the procedure given for Example 1. part b, Η NMR (250MHz, CDCI3) δ 1.38-1.52 (4H, m, 2 of CH 2 ), 1.84-1.98 (4H, m, 30 2 of CH 2 ), 2.59 (3H, s, Me), 3.δδ (IH, br s, CH), 3.97 (IH. br s. CH). δ.70 (2H, s, CH 2 ), 6.8δ (IH, s, Ar-H), 7.49 (IH, m, Ar-H), 7.65 (IH, m. Ar-H), 7.7δ (IH, d, J = 7.6Hz, Ar-H), 7.89 (IH, d, J = 7.1Hz, Ar-H); MS (ES + ) m/e 413 [MH] + ; Anal. Found C, 64.52; H, 4.90; N, 19.40. C23H2 0 N 6 O 2 .O.9H2O requires C, 64.44; H, 5.13; N, 19.61%. EXAMPLE 27 6-(3-Methylpyridin-2-yl)methyloxy-3-(2-pyraz nyl)-7,8,9.10-tetrahvdro- (7,10-ethano)-l,2,4-triazolof3,4-alphthalazme The title-compound was prepared from 6-chloro-3-(2-pyrazmyl)-7,8,9,10- tetrahydro-(7,10-ethano)-l,2,4-tnazolo[3,4-a]phthalazιne and 3-methyl-2- pyridylcarbinol using the procedure given for Example 1, part b, Η NMR (360MHz, CDCI3) δ 1.38-l.δ4 (4H, m, 2 of CH 2 ), 1.8δ-1.98 (4H, m, 2 of CH 2 ), 2.44 (3H, s, Me), 3.50 (IH, br s, CH), 4.02 (IH, br s, CH), 5.64 (2H, s, CH 2 ), 7.24 (IH, m, Ar-H), 7.57 (IH, d, J = 7.4Hz, Ar-H), 8.49 (IH, m, Ar- H), 8.68 (IH, m, Ar-H), 8.82 (IH, m, Ar-H), 9.74 (IH, d, J = 1.5Hz, Ar-H); MS (ES + ) m/e 400 [MH] + ; Anal. Found C, 66.39; H, 5.36; N, 24.53. C22H21N7O2 requires C, 66.15; H, 5.30; N, 24.55%. EXAMPLE 28 3-(2-Pyrazιnyl)-6-(2-pyrιdyl)methyloxy-7,8.9.10-tetrahvdro-(7,10-ethano)- 1.2,4-trιazolor3.4-a1phthalazιne The title-compound was prepared from 6-chloro-3-(2-pyrazιnyl)-7,8,9,10- tetrahydro-(7,10-ethano)-l,2,4-trιazolo[3,4-a]phthalazιne and 2- pyridylcarbmol using the procedure given for Example 1, part b, Η NMR (250MHz, CDCls) δ 1.41-1.57 (4H, m, 2 of CH 2 ), 1.89-2.02 (4H, m, 2 of CH 2 ), 3.60 (IH, br s, CH), 4.03 (IH, br s, CH), 5.63 (2H, s, CH 2 ), 7.29 (IH, m, Ar-H), 7.59 (IH, d, J = 7.8Hz, Ar-H), 7.87 (IH, td, J = 7.7 and 1.7Hz, Ar-H), 8.66-8.70 (2H, m, Ar-H), 8 83 (IH, m, Ar-H), 9 65 (IH, d, J = 1.2Hz, Ar-H); MS (ES + ) m/e 386 [MH] + ; Anal. Found C, 64.34; H, 4.99; N, 24.74. C 2 iH 19 N 7 O.0.δH 2 O requires C, 63.9δ; H, 5.11; N, 24.86%. EXAMPLE 29 5 3- ( δ-Methylisoxazol-3-vi)-6-(2-p y ridyl ) methyloxy-7.8.9.10-tetrahvdro-(7.10- methano)-1.2.4-triazolo[3.4-a]phthalazine a) 3-ChloiO-6-hvdrazino-4.5-diazatricvclo[6.2.1.2.71undeca-2(7).3.5- 10 triene Prepared using the procedures described for Reference Example 1, steps a-c, with 2-norbornene-2,3-dicarboxylic anhydride being used instead of bicyclo[2.2.2.]oct-2-ene-2,3-dicarboxylic acid anhydride in step a, l H lδ NMR (2δOMHz, CDC1 3 ) δ 1.10-1.24 (2H, m, CH 2 ), 1.58 (IH, m, CH 2 ), 1.80 (IH, m, CH 2 ), 1.96-2.10 (2H, m, CH 2 ), 3.49 (IH, d, J = 1.8Hz, CH), 3.5δ (IH, d, J = 1.6Hz, CH). b) 3-(5-MethvIisoxazol-3-yl)-6-(2-pyridyl)methyloxy-7.8.9.10- 20 tetrahvdro-(7, 10-methano)-l,2,4-triazolor3,4-a]phthalazine The preceding hydrazine was coupled with δ-methylisoxazole-3- carboxylic acid using the procedure described for Example 1, part a. The resultant triazolopyridazine was reacted with 2-pyridylcarbinol using the 2δ procedure given for Example 1, part b, to afford the title-compound, ! H NMR (360MHz, CDCI3) δ 1.22-1.34 (2H, m, CH 2 ), 1.69 (IH, d, J = 9.2Hz, CH2), 1.95 (IH, d, J = 9.2Hz, CH 2 ), 2.05-2.16 (2H, m, CH 2 ), 3.76 (IH. br s, CH), 4.13 (IH. br s, CH), 5.62 (IH, d, J = 13.1Hz, CH 2 ), 5.66 (IH, d, J = 13.2Hz, CH 2 ), 6.81 (IH, d, J = 0.7Hz, Ar-H), 7.30 (IH, t, J = 6.2Hz. 30 Ar-H), 7.72 (IH, d, J = 7.6Hz, Ar-H), 7.78 (IH, m, Ar-H), 8.66 (IH, m. Ar-H); MS (ES + ) m/e 37δ [MH] + ; Anal. Found C, 63.08, H, 4.67; N, 21.61. C2θH 18 N 6 θ2.0.4δ H 2 O requires C, 62.88; H, 4.98; N, 21.97%. EXAMPLE 30 3-(δ-Methylisoxazol-3-yl)-6-(6-methylpyridin-2-yl)methvIoxy-7.8.9.10- tetrahvdro-(7,10-methano)-1.2.4-triazolor3,4-alphthalazine 3-Chloro-6-hydrazino-4.δ-diazatricyclo[6.2.1.2,7]undeca-2(7),3,δ-triene was coupled with δ-methylisoxazole-3-carboxylic acid using the procedure given for Example 1, part a. The resultant triazolopy idazine was reacted with 6-methyl-2-pyridylcarbinol using the procedure given for Example 1, part b, to afford the title-compound, Η NMR (360MHz, CDCI3) δ 1.22-1.33 (2H, , CH 2 ), 1.69 (IH, br d, J = 9.2Hz, CH 2 ), 1.95 (IH, br d, J = 9.2Hz, CH 2 ), 2.05-2.18 (2H, m, CH 2 ), 2.57 (3H, d, J = 0.8Hz, Me), 2.60 (3H. s, Me), 3.76 (IH, br s, CH), 4.13 (IH, br s, CH), δ.58 (2H, s, CH 2 ), 6.83 (IH, d, J = 0.8Hz, Ar-H), 7.14 (IH, d, J = 7.6Hz, Ar-H), 7.4δ (IH, d, J = 7.8Hz, Ar-H), 7.64 (IH, t, J = 7.8Hz, Ar-H); MS (ES + ) m/e 389 [MH] + . EXAMPLE 31 3-(3-Furyl)-6-(2-pyridyl)methyloxy-7.8.9.10-tetrahvdiO-(7.10-methano)- 1.2.4-triazolo[3.4-a phthalazine 3-Chloro-6-hydrazino-4.δ-diazatricyclo[6.2.1.2,7]undeca-2(7),3,5- triene was coupled with 3-furoic acid using the procedure given for Example 1, part a. The resultant triazolopyridazine was reacted with 2-pyridylcarbinol using the procedure given for Example 1, part b, to afford the title-compound, Η NMR (360MHz, CDCI3) δ 1.24-1.34 (2H, m, CH 2 ), 1.68 (IH, m, CH 2 ), 1.95 (IH, m, CH 2 ), 2.04-2.20 (2H, m, CH 2 ), 3.76 (IH, br s, CH), 4.13 (IH, br s, CH), 5.60 (IH, d, J = 14.2Hz, CH 2 ). 5.64 (IH, d, J = 14.0Hz, CH 2 ), 7.25-7.30 (2H, m, 2 of Ar-H), 7.51-7.66 (2H, m, 2 of Ar-H), 7.76 (IH, m, Ar-H), 8.45 (IH, d, J = 1.1Hz, Ar-H), 8.66 (IH, m, Ar-H); MS (ES + ) m/e 360 [MH] + ; Anal. Found C, 65.04; H, 4.60; N, 18.77%. C2θH 17 N5θ2.0.6 H 2 0 requires C, 64.89; H, 4.96; N, 18.92%.

Claims: CLAIMS 1. A compound of formula I: (I) wherein: L is O, S or NH; X is: NR 2 R 3 ; phenyl optionally substituted by one or two groups independently chosen from R 6 , halogen, CN and OR G , where R G is d-βalkyl, C2-6alkenyl, C2-Galkynyl or CF3, or by a methylenedioxy or ethylenedioxy group; or a δ-membered heteroaromatic ring containing 1, 2, 3 or 4 heteroatoms independently chosen from oxygen, nitrogen and sulphur, at most one of the heteroatoms being oxygen or sulphur, or a 6-membered heteroaromatic ring containing 1, 2, 3, or 4 nitrogen atoms, the ring being optionally fused to a benzene ring and optionally substituted by one or more groups independently chosen from R 7 , OR 7 , OCOR 7 , NR 8 R 9 , NR 8 COR 9 , CN and CF 3 where R 7 is independently as defined for R G , R 8 is independently as defined for R 2 and R 9 is independently as defined for R 3 , when the 6-membered heteroaromatic ring is pyridine it is optionally in the form of the N-oxide; Y is optionally branched d -ialkylidene optionally substituted by an oxo group; Z is pyrazine, pyrimidine or a 5-membered heteroaromatic ring containing at least one nitrogen or an oxygen and optionally 1, 2 or 3 other heteroatoms independently selected from oxygen, nitrogen and sulphur, at most one of the other heteroatoms being oxygen or sulphur, the ring being optionally substituted by a group R 1 , NR 2 R 3 , NR 2 COR 3 , CN, CF 3 , phenyl, benzyl or pyridyl or a 5-membered heteroaromatic ring containing at least one nitrogen or an oxygen and optionally 1, 2 or 3 other heteroatoms independently selected from oxygen, nitrogen and sulphur, at most one of δ the other heteroatoms being oxygen or sulphur; R 1 is d.θalkyl, C 2 -6alkenyl, C^alkynyl or CF 3 ; R 2 and R 3 are each independently hydrogen, d-calkyl, C2-6alkenyl, C 2 .6alkynyl or CF3 or R 2 and R 3 , together with the nitrogen atom to which they are attached, form a 4-7 membered ring; and 0 n is 1 or 2; or a pharmaceutically acceptable salt thereof or a prodrug thereof. 2. A compound according to claim 1 of formula II: 5 wherein Z is defined in claim 1; X 1 is: a 6-membered heteroaromatic ring containing one or two nitrogen atoms optionally substituted by one or two Cι-6 alkyl groups which ring is optionally fused to a benzene ring and when the 6-membered heterocycle is pyridine it is optionally in the form of 0 the N-oxide; a δ-membered heteroaromatic ring containing one or two nitrogen atoms and optionally one additional heteroatom selected from nitrogen, oxygen or sulphur and optionally substituted by Ci-calkyl; an amine of the formula NR 10 R n where R 10 and R 11 are independently hydrogen or d-6alkyl or are joined to form together with the nitrogen atom δ to which they are attached to form a 4-7 membered ring; or a phenyl ring optionally substituted by Br or CN; and Y 1 is CH 2 or CHCO; or a pharmaceutically acceptable salt thereof. 3. A compound according to claim 1 of formula I " : L" — Y" X" wherein L" is 0; δ X" is pyridyl which is unsubstituted or substituted by d-calkyl; Y" is CH 2 ; and Z" is a furan, isoxazole or pyrazine which is unsubstituted or substituted by Ci-calkyl; or a pharmaceutically acceptable salt thereof. 10 4. A compound which is: 3-(δ-methylisoxazol-3-yl)-6-(6-methylpyridin-2-yl)methyloxy-7,8,9,10- tetrahydro-(7,10-ethano)-l,2,4-triazolo[3,4-a]phthalazine; 3-(3-furyl)-6-(6-methylpyridin-2-yl)methyloxy-7,8,9,10-tetrahydro-(7,10- ethano)-l,2,4-triazolo[3,4-a]phthalazine; lδ 3-(2-furyl)-6-(2-pyήdyl)methyloxy-7,8,9,10-tetrahydro-(7,10-ethano)-l,2,4- triazolo[3,4-a]phthalazine; 6-(6-methylpyrιdin-2-yl)methyloxy-3-(2-pyrazinyl)-7,8,9,10-tetrahydro- (7,10-ethano)-l,2,4-triazolo[3,4-a]phthalazine; 3-(3-methyl-l,2,4-oxadiazol-δ-yl)-6-(6-methylpyridin-2-yl)methyloxy- 20 7,8,9,10-tetrahydro-(7, 10-ethano)-l,2,4-triazolo[3,4-a]phthalazιne; 3-(3-methyl-l,2,4-oxadiazol-δ-yl)-6-(2-pyridyl)methyloxy-7,8,9, 10- tetrahydro-(7,10-ethano)-l,2,4-triazolo[3,4-a]phthalazιne; 3-(3-methyl-1.2,4-oxadiazol-δ-yl)-6-(3-pyridyl)methyloxy-7,8,9,10- tetrahydro-(7,10-ethano)-l,2,4-triazolo[3,4-a]phthalazme; 2δ 6-(δ,6-dimethylpyridin-2-yl)methyloxy-3-(3-methyl-l,2,4-oxadiazol-5-yl)- 7,8,9,10-tetrahydro-(7, 10-ethano)-l,2,4-triazolo[3,4-a]phthalazιne; 6-(4,6-dimethylpyridin-2-yl)methyloxy-3-(3-methyl-l,2,4-oxadιazol-5-yl)- 7,8,9,10-tetrahydro-(7,10-ethano)-l,2,4-trιazolo[3,4-a]phthalazme; 3-(3-methyl-l,2,4-oxadiazol-δ-yl)-6-(2-quinolino)methyloxy-7,8,9,10- tetrahydro-(7,10-ethano)-l,2,4-triazolo[3,4-a]phthalazine; 3-(3-methyl-l,2,4-oxadiazol-δ-yl)-6-(2-pyridyl-N-oxide)methyloxy-7,8,9, 10- tetrahydro-(7,10-ethano)-l,2,4-triazolo[3,4-a]phthalazine; δ 6-(2-imidazolyl)methyloxy-3-(3-methyl-l,2,4-oxadiazol-δ-yl)-7, 8,9,10- tetrahydro-(7,10-ethano)-l,2,4-triazolo[3,4-a]phthalazine; 6-[2-(l-methyl)imidazolyl]methyloxy-3-(3-methyl-l,2,4-oxadiazol-δ-yl)- 7,8,9,10-tetrahydro-(7,10-ethano)-l,2,4-triazolo[3,4-a]phthalazine; 6-[2-(cyano)phenyl]methyloxy-3-(3-methyl-l,2,4-oxadiazol-δ-yl)-7,8,9,10- 10 tetrahydro-(7, 10-ethano)-l,2,4-triazolo[3,4-a]phthalazine; 6-(2-bromophenyl)methyloxy-3-(3-methyl-l,2,4-oxadiazol-δ-yl)-7,8,9,10- tetrahydro-(7,10-ethano)-l,2,4-triazolo[3,4-a]phthalazine; 3-(3-methyl-l,2,4-oxadiazol-δ-yl)-6-(4-thiazolo)methyloxy-7,8,9,10- tetrahydro-(7,10-ethano)-l,2,4-triazolo[3,4-a]phthalazine; lδ 3-(3-methyl-l,2,4-oxadiazol-δ-yl)-6-(N-pyrrolidinylcarbonyl)methyloxy- 7,8,9, 10-tetrahydro-(7,10-ethano)-l,2,4-triazolo[3,4-a]phthalazine; 3-(3-ethyl-l,2,4-oxadiazol-δ-yl)-6-(6-methylpyridin-2-yl)methyloxy- 7,8,9,10-tetrahydro-(7,10-ethano)-l,2,4-triazolo[3,4-a]phthalazine; 3-(3-isopropyl-l,2,4-oxadiazol-5-yl)-6-(6-methylpyridin-2-yl)methyloxy- 20 7,8,9,10-tetrahydro-(7,10-ethano)-l,2,4-triazolo[3,4-a]phthalazine; 6-(6-methylpyridin-2-yl)methyloxy-3-[3-(pyridin-3-yl)-l,2,4-oxadiazol-5-yl]- 7,8,9,10-tetrahydro-(7,10-ethano)-l,2,4-triazolo[3,4-a]phthalazine; 6-(6-methylpyridin-2-yl)methyloxy-3-[3-(pyridin-4-yl)-l,2,4-oxadiazol-δ-yl]- 7,8,9, 10-tetrahydro-(7,10-ethano)-l,2,4-triazolo[3,4-a]phthalazine; δ 6-(δ,6-dimethylpyridin-2-yl)methyloxy-3-[3-(pyridin-3-yl)-l,2,4-oxadiazol- δ-yl]-7,8,9,10-tetrahydro-(7,10-ethano)-l,2,4-triazolo[3.4-a]phthalazine; 3-(2-methyloxazol-4-yl)-6-(2-pyridyl)methyloxy-7,8,9,10-tetrahydro-(7,10- ethano)-l,2,4-triazolo[3,4-a]phthalazine; 3-(2-methyloxazol-4-yl)-6-(6-methylpyridin-2-yl)methyloxy-7,8,9,10- 30 tetrahydro-(7, 10-ethano)-l,2,4-triazolo[3,4-a]phthalazine; and pharmaceutically acceptable salts and prodrugs thereof. δ. A compound which is: 3-(δ-methylisoxazol-3-yl)-6-(2-pyridyl)methyloxy-7,8,9,10-tetrahydro-(7,10- ethano)-l,2,4-triazolo[3,4-a]phthalazine; 3-(5-methylisoxazol-3-yl)-6-(2-cyanophenyl)methyloxy-7,8,9,10-tetrahydro- δ (7 , 10-ethano) - 1 , 2, 4-triazolo [3 , 4-a]phthalazine ; 6-(3-methylpyridin-2-yl)methyloxy-3-(2-pyrazinyl)-7,8,9,10-tetrahydro- (7 , 10-ethano)- 1,2, 4-triazolo [3 , 4-a]phthalazine ; 3-(2-pyrazinyl)-6-(2-pyridyl)methyloxy-7,8,9,10-tetrahydro-(7,10-ethano)- 1 , 2, 4-triazolo [3 , 4-a]phthalazine ; 0 3-(δ-methylisoxazol-3-yl)-6-(2-pyridyl)methyloxy-7,8,9,10-tetrahydro-(7, 10- methano)-l,2,4-triazolo[3,4-a]phthalazine; 3-(δ-methylisoxazol-3-yl)-6-(6-methylpyridin-2-yl)methyloxy-7,8,9,10- tetrahydro-(7,10-methano)-l,2,4-triazolo[3,4-a]phthalazine; 3-(3-furyl)-6-(2-pyridyl)methyloxy-7,8,9, 10-tetrahydro-(7,10-methano)- 5 l,2,4-triazolo[3,4-a]phthalazine; and pharmaceutically acceptable salts and prodrugs thereof. 6. A pharmaceutical composition comprising a compound according to any one of claims 1 to 5 or a pharmaceutically acceptable salt thereof and a pharmaceutically acceptable carrier. 0 7. A compound as claimed in any one of claims 1 to δ or a pharmaceutically acceptable salt thereof for use in therapy. 8. The use of a compound as claimed in any one of claims 1 to 5 or a pharmaceutically acceptable salt thereof for the manufacture of a medicament for the enhancement of cognition. 5 9. A method of treatment of a subject suffering from a cognition deficit which comprises administering to that subject an effective amount of a compound as claimed in any one of claims 1 to δ or a pharmaceutically acceptable salt thereof. 10. A process for the preparation of a compound as claimed in any one 0 of claims 1 to δ, which process comprises reacting a compound of formula III with a compound of formula IV: (IV) (HI) wherein n, L, X, Y and Z are as defined above and G is a leaving group.

Inventors: CARLING WILLIAM ROBERT, MACLEOD ANGUS MURRAY, MCKERNAN RUTH, REEVE AUSTIN JOHN, STERNFELD FRANCINE, STREET LESLIE JOSEPH, CARLING, WILLIAM, ROBERT, MACLEOD, ANGUS, MURRAY, MCKERNAN, RUTH, REEVE, AUSTIN, JOHN, STERNFIELD, FRANCINE, STREET, LESLIE, JOSEPH
Applicants: CARLING WILLIAM ROBERT, MACLEOD ANGUS MURRAY, MCKERNAN RUTH, MERCK SHARP & DOHME, REEVE AUSTIN JOHN, STERNFIELD FRANCINE, STREET LESLIE JOSEPH, CARLING, WILLIAM, ROBERT, MACLEOD, ANGUS, MURRAY, MCKERNAN, RUTH, MERCK SHARP & DOHME LIMITED, REEVE, AUSTIN, JOHN, STERNFIELD, FRANCINE, STREET, LESLIE, JOSEPH
Application year: 1997
Main classification: C07D487
IPC codes: A61K31, A61P25, C07D487