AU653364B2 - Xanthine derivatives - Google Patents

Description

OPI DATE 15/04/92 AOJP DATE 28/05/92 APPLN. TD 95413 /91 PCT NUMBER PCT/GB91/1i633 INTERNA TREATY (PCT) (51) International Patent Classification 5 (11) International Publication Number: WO 92/05175 C07D 473/06, A61K 31/52 Al (43) International Publication Date: 2 April 1992 (02.04.92) (21) International Application Number: PCT/GB91/01633 (74)Agent: RUTTER, Keith; Corporate Patent, SmithKline Beecham Pharmaceuticals, Great Burgh, Yew Tree Bot- (22) International Filing Date: 23 September 1991 (23.09.91) tom Road, Epsom, Surrey KT18 5XQ (GB).

Priority data: (81) Designated States: AT (European patent), AU, BE (Euro- 9020959.4 26 September 1990 (26.09.90) GB pean patent), CA, CH (European patent), DE (European patent), DK (European patent), ES (European patent), FR (European patent), GB (European patent), GR (71) Applicant (for all designated States except US): BEECHAM (European patent), IT (European patent), JP, KR, LU GROUP PLC [GB/GB]; SB House, Great West Road, (European patent), NL (European patent), SE (Euro- Brentford, Middlesex TW8 9BD pean patent), US.

(72) Inventors; and Inventors/Applicants (for US only) BUCKLE, Derek, Ri- Published chard [GB/GB]; SMITH, David, Glynn [GB/GB]; With international search report.

FENWICK, Ashley, Edward [GB/GB]; SmithKline Beecham Pharmaceuticals, Great Burgh, Yew Tree Bottom Road, Epsom, Surrey KT18 5XQ (GB).

(54)Title: XANTHINE DERIVATIVES 1

R

R

4

N

N

(57) Abstract A compound of formula or, if appropriate, a pharmaceutically acceptable salt thereof; or a pharmaceutically acceptable solvate thereof, wherein R 1 and R 2 each independently represent a moiety of formula -(CH2)m-A, wherein m represents zero or an integer 1, 2 or 3 and A represents a substituted or unsubstituted cyclic h-.drocarbon radical; R 3 represents NO 2 a halogen atom, a hydroxy group, an alkoxy group or a methyl group substituted with 1 or 2 groups of formula CO 2 R, wherein R in each group is independently hydrogen or alkyl or a group of formula O-L-A' wherein L is a bond or a linking group and Al is a saturated or unsaturated heterocyclic group, or R 3 represents a group of formula NRsRt, wherein Rs and Rt each independently represent hydrogen, alkyl, aralkyl, an unsaturated heterocyclic group or Rs and Rt together with the nitrogen to which they are attached form an unsaturated heterocyclic group; and R 4 represents an alkyl, aralkyl or an (unsaturated heterocyclyl)alkyl group; a process for preparing such a compound, a pharmaceutical composition containing such a compound and the use of such a compound or composition in medicine.

WO 92/05175 PCT/GB91/01633 -1- Xanthine derivatives.

The present invention relates to certain novel compounds having pharmacological activity, to a process for the preparation of such compounds, to pharmaceutical compositions containing such compounds and to the use of such compounds and compositions in medicine.

Molecular Pharmacology, Volume 6, No. 6, 1970, p.597-603 discloses 1,3-dimethyl-8-nitro-xanthine. This compound is disclosed as having lipolytic activity. Ann. Chim. 47, 362-365 (1957) discloses 1,3dimethyl-8-amino-xanthine and a process by which it may be prepared.

No pharmacological utility is disclosed for compound. Drug Res. 27(1) Nr 19, 1977, pages 4-14, Van K.H. Klingler discloses certain 1,3-dimethyl- 8-substituted xanthines as intermediates solely in the synthesis of phenylethyl aminoalkyl xanthines. Drug Res. 31 Nr. 12, 1981, R.G.

Werner et al, pages 2044-2048 discloses certain 1,3-dimethyl-8-substituted xanthines. No pharmacological activity is disclosed for these compounds.

European Patent Application, Publication Number 0369744 also discloses certain 1,3- or 1,3,7- 8-H cycloalkylalkylene xanthines, for use inter alia as bronchodilators in the treatment of asthma. European Patent Application, Publication Number 0389282 also discloses certain 8-substituted 1,3- dicycloalkylalkylene xanthines, for use inter alia in the treatment or prophylaxis of disorders associated with increased numbers of eosinophils.

It has now surprisingly been discovered that a novel series of substituted xanthines, some of which are generically but not specifically disclosed in EP 0389282, are indicated to be particularly effective as inhibitors of induced blood eosinophilia and that they are therefore potentially of particular use in the treatment and/or prophylaxis of disorders associated with increased numbers of eosinophils, such as asthma, and allergic disorders associated with atopy, such as urticaria, eczema and rhinitis.

In addition these compounds show activity as phosphodiesterase inhibitors: These compounds are indicated to have bronchodilator activity and thus to be of potential use in the treatment of disorders of the respiratory tract, WO 92/0)5175 PCT/GB91/01633 -2such as reversible airways obstruction and asthma.

These compounds have a protective effect against the consequences of cerebral metabolic inhibition. The said compounds improve data acquisition or retrieval following transient forebrain ischaemia and are therefore useful in the treatment of cerebral vascular and neuronal degenerative disorders associated with learning, memory and cognitive dysfunctions including cerebral senility, multi-infarct dementia, senile dementia of the Alzheimer type, age associated memory impairment and certain disorders associated with Parkinson's disease.

These compounds are also indicated to have neuroprotectant activity.

They are therefore useful in the prophylaxis of disorders associated with neuronal degeneration resulting from ischaemic events, including cerebral ischaemia due to cardiac arrest, stroke and also after cerebral ischaemic events such as those resulting from surgery and/or during childbirth. In addition treatment with these compounds is indicated to be of benefit for the treatment of functional disorders resulting from disturbed brain function following ischaemia.

These compounds are also active in increasing the oxygen tension in ischaemic skeletal muscle. This property results in an increase in the nutritional blood flow through ischaemic skeletal muscle which in turn indicates that the compounds of the invention are of potential use as agents for the treatment of peripheral vascular disease such as intermittent claudication.

These compounds are also of potential use in the treatment of proliferative skin disease in human or non-human mammals.

In addition these compounds may also have potential as inhibitors of the production of'tumour necrosis factor (TNF) and hence have potential for the treatment of human immunodeficiency virus (HIV), acute immune deficiency syndrome (AIDS), rheumatoid arthritis, rheumatoid spondylitis, osteoarthritis, gouty arthritis and other arthritic conditions; sepsis, septic shock, endotoxic shock, gram negative sepsis, toxic shock syndrome, adult respiratory distress syndrome, cerebral malaria, pulmonary inflammatory disease, bone resorption diseases, reperfusion WO 92/05175 PCT/GB9I/01633 -3injury, graft vs. host reaction, fever and myalgias due to infection, such as influenza, cachexia secondary to infection or malignancy, cachexia secondary to AIDS, keloid formation, scar tissue formation, Crohn's disease, ulcerative colitis, or pyresis.

Accordingly, the invention also provides a compound of formula 1

R

4

-RI

Ok N N

I

R

2 (I) or if appropriate a pharmaceutically acceptable salt thereof;wherein R 1 and R 2 each independently represent a moiety of formula -(CH2)m-A (a) wherein m represents zero or an integer 1, 2 or 3 and A represents a substituted or unsubstituted cyclic hydrocarbon radical;

R

3 represents NO 2 a halogen atom, a hydroxy group,an alkoxy group or a methyl group substituted with 1 or 2 groups of formula C02R wherein R in each group is independently hydrogen or alkyl or a group of formula

O-L-A

1 wherein L is a bond or a linking group and Al is a saturated or unsaturated heterocyclic group, or R 3 represents a group of formula NRSRt wherein R s and Rt each independently represent hydrogen, alkyl, aralkyl, an unsaturated heterocyclic group or R s and Rt together with the nitrogen to which they are attached form an unsaturated heterocyclic group; and

R

4 represents an alkyl, aralkyl or an (unsaturated heterocyclyl)alkyl group.

Suitably, A represents a substituted or unsubstituted alicyclic hydrocarbon radical.

Suitably, A is unsubstituted. Favourably, A represents a substituted or unsubstituted C 3 8 cycloalkyl group, especially a C 3 -6 cycloalkyl group.

WO 92/05175~ PCT/GB91/01633 -4- In particular, A represents a substituted or, preferably, unsubstituted cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl group.

Favourably, A represents a cyclopropyl group or a cyclobutyl group.

Particular aralkyl groups are benzyl and naphthylmethyl groups.

Particular substituents for the aryl moiety of any aralkyl group include

NO

2 and alkoxy, especially N02 and methoxy.

When R s and/or Rt represents aralkyl, examples include benzyl and nitrobenzyl, especially 2-nitrobenzyl.

When R 4 represents aralkyl examples include methoxybenzyl, such as 4-methoxybenzyl; trimethoxybenzyl, such as 3,4,5-trimethoxybenzyl; nitrobenzyl, such as 2- or 4-nitrobenzyl; and naphthylmethyl.

When L represents a bond, the saturated or unsaturated heterocyclic group represented by Al is attached by a ring carbon atom to the 0 atom of the group O-L-A 1 When L represents a bond, preferred carbon linked heterocyclic groups represented by Al are single ring heterocyclic groups having 6 ring atoms, which ring atoms comprise or 2, especially 1, heteroatoms, selected from 0 or N, preferably N, ,,icular examples include piperidinyl groups.

When L represents a linking group, a suitable linking group is a C1-6 alkylene chain, optionally interrupted by an oxygen atom.

An Example of a linking group L is -(CH 2 2

-O-(CH

2 2 When L represents a linking group, suitable heterocyclic groups represented by Al are single ring heterocyclic groups having 5- or 6- ring atoms which ring atoms comprise 1 or 2, especially 1, heteroatoms selected from 0 or N, preferably N; particular examples include piperazinyl groups, especially N-piperazinyl groups.

Particular substituents for the heterocyclic groups represented by A 1 WO 92/05175 PCT/GB91/01633 include aralkyl, especially benzyl, and alkyl carbonyl wherein the alkyl group may be substituted or unsubstituted, a particular substituent for the said alkyl group being a carboxy group or an alkyl ester thereof.

Examples of substituents for the heterocyclic group represented by Al are benzyl and -CO(CH 2 2

CO

2 H or an ester thereof.

When either RS or Rt represent an unsaturated heterocyclic group, particular groups are single ring, 6-membered heterocyclic groups which ring atoms comprise 1 or 2, preferably 1, heteroatoms selected from 0 or N, preferably N;suitable examples are heteroaryl groups such as pyridyl.

When R s and Rt together with the nitrogen atom to which they are attached form an unsaturated heterocyclic group, suitable heterocyclic groups are single ring, 5- or 6- membered heterocyclic groups optionally comprising 1 or 2, preferably 1, additional heteroatoms in the ring; particular examples include imidazolyl groups.

When R 4 represents an (unsaturated heterocyclyl)alkyl group, suitable examples are heteroarylalkyl groups such as heteroarylmethyl groups, the unsaturated heterocyclyl group suitably being a single ring, 6-membered heterocyclyl group which ring atoms comprise 1 or 2, preferably 1, heteroatoms selected from 0 or N, preferably N; particular examples include pyridylmethyl groups.

Suitably, R 3 represents nitro, a halogen atom, an alkoxy group, such as an ethoxy group, or a group NRSRt wherein R S and Rt each independently represent hydrogen or alkyl, especially hydrogen.

When R 3 represents RSRt, in one particular aspect R s represents hydrogen and Rt represents alkyl, aralkyl or an unsubstituted heterocyclic group.

When R 4 is alkyl suitable examples include C1- 4 alkyl such as methyl.

Preferably, A represents a cyclopropyl group.

Preferably R 3 represents NH 2 WO 92/05175 PCT/GB91/01633 -6- Suitably R 4 represents an alkyl or aralkyl group. Preferably R 4 represents an aralkyl group, especially a benzyl group. Favourably, m represents 1.

Suitable pharmaceutically acceptable solvates are those used conventionally such as hydrates.

Suitable pharmaceutically acceptable salts are pharmaceutically acceptable base salts and pharmaceutically acceptable acid addition salts.

Suitable pharmaceutically acceptable base salts of the compounds of formula include base salts including metal salts, such as alkali metal salts for example sodium salts, or organic amine salts such as that provided with ethylenediamine.

Suitable acid addition salts of the compounds of formula are the acid addition salts including pharmaceutically acceptable inorganic salts such as the sulphate, nitrate, phosphate, borate, hydrochloride and hydrobromide and pharmaceutically acceptable organic acid addition salts such as acetate, tartrate, maleate, citrate, succinate, benzoate, ascorbate, methanesulphonate, a-keto glutarate, a-glycerophosphate and glucose-1phosphate. Preferably the acid addition salt is a hydrochloride salt.

The pharmaceutically acceptable salts and/or soivates of the compounds of formula are prepared using conventional procedures.

When used herein the term 'cyclic hydrocarbon radical' includes single ring and fused ring, alicyclic hydrocarbons comprising up to 8 carbon atoms in each ring, suitably up to 6 carbon atoms, for example 3, 4, 5 or 6 carbon atoms.

Suitable optional substituents for any cyclic hydrocarbon radical includes a C 1 -6 alkyl group or a halogen atom.

When used herein the term 'alkyl' (whether used alone or when used as part of another group for example as in an alkylcarbonyl group) includes straight and branched chain alkyl groups, containing from 1 to 12 carbon atoms, suitably 1 to 6 carbon atoms, for example methyl, ethyl, propyl or butyl. Optional substituents for alkyl groups include those mentioned WO 92/05175 PCT/GB91/01633 -7herein for aryl groups.

When used herein the term 'aryl' (whether used alone or when used as part of other groups for example as in an aralkyl group) includes phenyl and naphthyl optionally substituted with up to five, preferably up to three, groups selected from halogen, alkyl, phenyl, alkoxy, halo alkyl, hydroxy, amino, nitro, carboxy, alkoxycarbonyl, alkoxycarbonylalkyl,alkylcarbony'oxy, or alkylcarbonyl groups.

The term 'heterocyclic' or 'heterocyclyl' when used herein refers to groups comprising single or fused rings which rings each comprise 4 to 7, suitably or 6 ring atoms, which ring atoms comprise up to 4 hetero atoms selected from 0, N or S.

Optional substituents for any 'heterocyclic' or 'heterocyclyl' group include alkyl, alkoxy, halo, carboxy or an alkyl ester thereof, aralkyl or alkyl carbonyl wherein the alkyl group may be substituted or unsubstituted.

When used herein the expression 'proliferative skin diseases' means benign and malignant proliferative skin diseases which are characterized by accelerated cell division in the epidermis, dermis or appendages the'-to, associated with incomplete tissue differentiation. Such diseases include: psoriasis, atopic dermatitis, non-specific dermatitis, primary irritant contact dermatitis, allergic contact dermatitis, basal and squamous cell carcinomas of the skin, lamellar ichthyosis, epidermolytic hyperkeratosis, premalignant sun induced keratosis, non-malignant keratosis, acne, and seborrheic dermatitis in humans and atopic dermatitis and mange in domesticated animals.

The compounds of formula are preferably in pharmaceutically acceptable form. By pharmaceutically acceptable form is meant, inter alia, of a pharmaceutically acceptable level of purity excluding normal pharmaceutical additives such as diluents and carriers, and including no material considered toxic at normal dosage levels. A pharmaceutically acceptable level of purity will generally be at least 50% excluding normal pharmaceutical additives, preferably 75%, more preferably 90% and still more preferably WO 92/05175 PCT/GB91/01633 -8- The invention further provides a process for the preparation of a compound of formula which process comprises reacting a compound of formula (II): la R 0 H R 3

I

R

2 a (11) wherein Rla repre,_ its R 1 as defined in relation to formula or a group convertible to R 1 and R2a represents R 2 as defined in relation to formula or a group convertible thereto and R3a represents R 3 as defined in relation to formula or a group convertible thereto, with a compound of formula (III): R4-L1 (III) wherein R 4 is as defined in relation to formula and L 1 represents a leaving group; and thereafter, if required carrying out one or more of the following optional steps: converting any group R l a to R 1 and/'or R2a to R 2 and/or R 3 a to R 3 (ii) converting a compound of formula into a further compound of formula (iii) converting a compound of formula into a pharmaceutically acceptable salt thereof.

A suitable leaving group L 1 is a halo atom, for example a bromine or chlorine atom.

The reaction between compounds of formulae (II) and (III) may be carried out using conventional alkylation conditions, for example in an aprotic solvent, such as dimethylformamide, tetrahydrofuran or dimethylsulphoxide, at any temperature providing a suitable rate of formation of the required product, for example in the range of from OOC to WO 92/05175 PCT/GB91/01633 -9- 1000C, conveniently at ambient temperature.

Preferably,, in the reaction between compounds (II) and (III), the compound of formula (II) is in an activated form, suitably in an anionic form such as a salted form, for example an alkali metal salted form.

The activated form of the compound of formula (II) is conveniently prepared by treating a compound of formula (II) with a base, suitably an alkali metal alkoxide, for example potassium t-butoxide, or an alkali metal hydride, for example sodium hydride.

A compound of formula (II) may be prepared by reacting a compound of formula (IV): la 0 R a H

H

2a R

(IV)

wherein R l a represents R 1 as defined in relation to formula or a group convertible to R 1 and R 2 a represents R 2 as defined in relation to formula or a group convertible thereto, with a reagent capable of substituting the C-8 hydrogen of the compound of formula (IV) with a group R3b wherein R3b represents R 3 a as defined above in relation to formula or a group convertible thereto; and thereafter, if required carrying out one or more of the following optional steps: converting any group R l a to R 1 and/or R 2 a to R 2 (ii) when R3b is not R 3 a, converting R3b to R 3 a.

For compounds of formula (II) wherein R 3 a represents nitro, R3b preferably represents R 3 a i.e. nitro.

For compounds of formula (II) wherein R 3 a represents other than nitro, R3b preferably represents a group convertible to R3a.

One preferred group R3b is a nitro group which may then if required be WO 92/05175 PCT/GB91/01633 converted to groups R 3 a other than nitro.

Suitable reagents for substituting the C-8 hydrogen of the compound of formula (IV) with a group R3b are the appropriate conventional reagents.

The conditions of reaction for the substitution of the C-8 hydrogen of the compound of formula (IV) will of course depend upon the particular reagent chosen, and in general the conditions used will be those which are convent lonal for the reagent used.

One particularly suitable reagent is a nitrating agent.

The nitration of compound (II) may be carried out using any suitable, conventional nitrating agent, for example a nitric acid/acetic acid mixture in an inert solvent, such as dichloromethane, at any temperature providing a convenient rate of formation of the required product, conveniently at ambient temperature.

In one convenient form of the abovementioned process the compound of formula (IV) is reacted with a suitable nitrating agent to provide a compound of formula wherein R3a represents a nitro group and then converting the nitro group into a halogen atom or a group of the abovedefined formula -NRSRt, suitably via the halogen atom.

For example, when R 3 a represents a nitro group, suitable conversions of the nitrli group into another group R 3 a include the following: converting the nitro group into a halogen atom; (ii) converting the nitro group into an amine group; (iii) converting the nitro group into a halogen atom followed by conversion of the halogen atom into the above defined group -NRsRt; (iv) converting the nitro group into a halogen atom and thereafter converting the halogen atom into a methyl group substituted with 1 or 2 groups of formula CO 2 R, wherein R is as defined above.

WO 92/05175 PCT/GB91/01633 -11converting the nitro group into a halogen atom and thereafter converting the halogen atom into the above defined group O-L-A 1 (vi) converting the nitro group into an amino group and thereafter alkylating the amino group to provide the above defined group -NRsRt; and (vii) converting the nitro group into an halogen atom, and thereafter converting the halogen atom into a hydroxy group or an alkoxy group.

A nitro group may be converted into a halogen atom by using any convenient halogenating agent.

One suitable halogenating agent is a hydrogen halide, suitably reacted in aqueous conditions for example by using concentration hydrochloric acid at an elevated temperature, for example in the range of from 50 to 1500C.

A further suitable halogenating agent is a phosphorous oxyhalide, such as phosphorous oxychloride or phosphorous oxybromide, which may be reacted in any suitable solvent, such as dimethylformamide, suitably at an elevated temperature for example in the range of from 500C to 1500C.

A nitro group may conveniently be converted into an amino group by conventional reduction methods for example by using tin powder and concentrated hydrochloric acid at ambient temperature or by using sodium dithionite in aqueous methanol at ambient temperature.

When R3a represents a halogen atom, it may be converted into a methyl gror substituted with 1 or 2 groups of formula CO 2 R wherein R is as defined above, by reacting the required compound of formula (II) wherein R3a is halogen, with the appropriate mono or bis malonate wherein the esterifying moiety is a group R as defined above, in the presence of a base such as sodium hydride in an aprotic solvent at any temperature providing a suitable rate of formation of the required product, conveniently at an elevated temperature such as in the range of 40°C to 120°C, for example 800C.

When R 3 a in the compound of formula (II) represents a halogen atom it WO 92/05175 PCT/GB91/01633 -12may be converted into a group -O.L-A 1 wherein L -i Al are as defined in relation to formula by reaction with a reagend of formula or, preferably, an activated form thereof: Al-L-OH

(V)

wherein Al and L are as defined above.

The reaction between the compound of formula (II) w4 en R 3 a is halogen and the compound of formula may be carried out under analogous conditions to the above described reaction between compounds of formulae (II) and (III).

Suitable activated forms of the compound of formula are salted forms such as alkali metal salted forms.

In one convenient aspect the activated form of compounds of formula (V) are prepared by treating the compound of formula (III) with a base, suitably an alkali metal base such as those referred to above.

When R 3 a in the compound of formula (II) represents a halogen atom it may be converted into a group -NRSRt by reacting with a reagent of formula (VI): HNRSRt

(VI)

wherein R s and Rt are as defined above.

The reaction between the compound of formula (II) and the compound of formula (VI) may be carried out in any suitable solvent, such as toluene, at any temperature providing a convenient rate of formation of the product, but suitably at an elevated temperature, such as in the range of from 500 to 1800C, at atmospheric or an elevated pressure.

Suitable alkylation methods for use in the abovementioned conversions include those used conventionally in the art, for example methods using halides, preferably iodides, in the presence of a base such as potassium carbonate in any convenient solvent for example acetonitrile or toluene.

WOo 92/05175 PCT/GB91/01633 -13- In the conversion the nitro group may be converted into the halogen atom as described above. The conversion of the halogen atom into an alkoxy group may be effected by any conventional alkoxylation procedure, for example treating the halogen with a source of alkoxy ions, such as a sodium alkoxide.

Suitable conversions of a compound of formula into another compound of formula generally include converting one group R 3 into another group R 3 Conversions of one group R 3 into another group R 3 include the following: the abovementioned conversions of R 3 when nitro or halogen into other groups R 3 and (ii) the conversion of one group NRSRt into another group NRSRt.

An example of a conversion of one group NRSRt into another group is that wherein NRSRt represents a piperidinyloxy group, which may thereafter be converted into an (N-4-oxo-butanoic acid) piperidinyloxy group, by treatment with succinic hydride in dry dimethylformamide, or into an (N-benzyl) piperidinyloxy group, by conventional benzylation procedures.

A compound of formula (IV) may be prepared according to methods disclosed in EP 0369744.

Suitable values for R l a and R 2 a include R 1 and R 2 respectively or nitrogen protecting groups such as silyl groups.

When R l a or R 2 a represents other than R 1 or R 2 repectively, the abovementioned conversions of R l a into R 1 and R 2 a to R 2 may be carried out using the appropriete conventional procedure.

The protection of any reactive group or atom, such as any of the xanthine nitrogen atoms may be carried out at any appropriate stage in the aforementioned processes. Suitable protecting groups include those used conventionally in the art for the particular group or atom being protected, WOa 92/05175 W C'r/CG91/01633 -14for example suitable protecting groups for the xanthine nitrogen atoms are silyl groups, especially trialkyl silyl groups such as t-butyl dimethyl silyl or trimethyl silyl groups.

Protecting groups may be prepared and removed using the appropriate conventional procedure: For example, N-benzyl protecting groups may be prepared by treating the appropriate compound of formula (II) with benzyl chloride in the presence of a base such as triethylamine, bases such as potassium t-butoxide may also be used. The N-benzyl protecting groups may be removed by catalytic hydrogenation over a suitable catalyst, such as palladium on activated charcoal, in a suitable solvent, such as ethanol conveniently at an elevated temperature, or by treatment with anhydrous aluminium chloride in dry benzene at ambient temperature. Trialkylsilyl protected nitrogen groups may be prepared by treating the appropriate compound with a trialkylsilyl halide, for example trimethylsilyl chloride, in the presence of a base such as potassium t-butoxide. The N-trialkylsilyl protecting group may be removed by mild basic hydrolysis or by treatment with a source of fluoride ions such as tetrabutylammoniumfluoride.

Compounds of formulae (II) are novel compounds and as such form part of the present invention.

Compounds of formula (III), and (VI) are known compounds or are prepared according to methods used to prepare known compounds for example these disclosed in J. March, Advanced Organic Chemistry, 3rd Edition (1985), Wiley Interscience.

As mentioned above the compounds of the invention are indicated as having useful therapeutic properties: the present invention accordingly provides a compound of formula or where appropriate a pharmaceutically acceptable salt thereof; or a pharmaceutically acceptable solvate thereof, for use as an active therapeutic substance.

Thus the present invention provides a compound of formula or where appropriate a pharmaceutically acceptable salt thereof; or a pharmaceutically acceptable solvate thereof, for use in the treatment of WO 92/05175 PCT/GB91/01633 and/or prophylaxis of disorders associated with increased numbers of eosinophils, such as asthma, and allergic disorders associated with atopy, such as urticaria, eczema and rhinitis.

In a further aspect the present invention also provides a compound of formula or where appropriate a pharmaceutically acceptable salt thereof; or a pharmaceutically acceptable solvate thereof, for use as a phosphodiesterase inhibitor.

In a particular aspect, as indicated hereinbefore, the present invention provides a compound of formula or where appropriate a pharmaceutically acceptable salt thereof; or a pharmaceutically acceptable solvate thereof, for use in the treatment of disorders of the respiratory tract, such as reversible airways obstruction and asthma.

In a further particular aspect, the present invention provides a compound of formula or where appropriate a pharmaceutically acceptable salt thereof; or a pharmaceutically acceptable solvate thereof, for use in the treatments mentioned hereinbefore, such as cerebral vascular and neuronal denerative disorders associated with learning, memory and cognitive dysfunctions, peripheral vascular disease or proliferate skin disease or for the prophylaxis of disorders associated with neuronal degeneration resulting from ischaemic events or for the inhibition of the production of tumour necrosis factor in for example the treatment of human immunodeficiency virus.

A compound of formula or where appropriate a pharmaceutically acceptable salt thereof; or a pharmaceutically acceptable solvate thereof, may be administered pr, se or, preferably, as a pharmaceutical composition also comprising a pharmaceutically acceptable carrier.

Accordingly, the present invention provides a pharmaceutical composition comprising a compound of formula or where appropriate a pharmaceutically acceptable salt thereof; or a pharmaceutically acceptable solvate thereof, and a pharmaceutically acceptable carrier.

The active compound may be formulated for administration by any suitable route, the preferred route depending upon the disorder for which WO 92/05175 PCT/GB91/01633 -16treatment is required, and is preferably in unit dosage form or in a form that a human patient may administer to himself in a single dosage.

Advantageously, the composition is suitable for oral, rectal, topical, parenteral, intravenous or intramuscular administration or through the respiratory tract. Preparations may be designed to give slow release of the active ingredient.

The compositions of the invention may be in the form of tablets, capsules, sachets, vials, powders, granules, lozenges, suppositories, reconstitutable powders, or liquid preparations such as oral or sterile parenteral solutions or suspensions. Topical formulations are also envisaged where appropriate.

In order to obtain consistency of administration it is preferred that a composition of the invention is in the form of a unit dose.

Unit dose presentation forms for oral administration may be tablets and capsules and may contain conventional excipients such as binding agents, for example syrup, acacia, gelatin, sorbitol, tragacanth, or polyvinylpyrrolidone; fillers, for example lactose, sugar, maize-starch, calcium phosphate, sorbitol or glycine; tabletting lubricants, for example magnesium stearate; disintegrants, for example starch, polyvinylpyrrolidone, sodium starch glycollate or microcrystalline cellulose; or pharmaceutically acceptable wetting agents such as sodium lauryl sulphate.

The solid oral compositions may be prepared by conventional methods of blending, filling, tabletting or the like. Repeated blending operations may be used to distribute the active agent throughout those compositions employing large quantities of fillers.

Such operations are of course conventional in the art. The tablets may be coated according to methods well known in normal pharmaceutical practice, in particular with an enteric coating.

Oral liquid preparations may be in the form of, for example, emulsions, syrups, or elixirs, or may be presented as a dry product for reconstitution with water or other suitable vehicle before use. Such liquid preparations WO 92/0517S PCr/GB9I/01633 -17may contain conventional additives such as suspending agents, for example sorbitol, syrup, methyl cellulose, gelatin, hydroxyethylcellulose, carboxymethylcellulose, aluminium stearate gel, hydrogenated edible fats; emulsifying agents, for example lecithin, sorbitan monooleate, or acacia; non-aqueous vehicles (which may include edible oils), for example almond oil, fractionated coconut oil, oily esters such as esters of glycerine, propylene glycol, or ethyl alcohol; preservatives, for example methyl or propyl p-hydroxybenzoate or sorbic acid; and if desired conventional flavouring or colouring agents.

Compositions may also suitably be presented for administration to the respiratory tract as a snuff or an aerosol or solution for a nebulizer, or as a microfine powder for insufflation, alone or in combination with an inert carrier such as lactose. In such a case the particles of active compound suitably have diameters of less than 50 microns, such as from 0.1 to microns, preferably less than 10 microns, for example from 1 to Smicrons, 1 to 5 microns or from 2 to 5 microns. Where appropriate, small amounts of other anti-asthmatics and bronchodilators, for example sympathomimetic amines such as isoprenaline, isoetharine, salbutamol, phenylephrine and ephedrine; corticosteroids such as prednisolone and adrenal stimulants such as ACTH may be included.

For parenteral administration, fluid unit dosage forms are prepared utilizing the compound and a sterile vehicle, and, depending on the concentration used, can be either suspended or dissolved in the vehicle.

In preparing solutions the compound can be dissolved in water for injection and filter sterilized before filling into a suitable vial or ampoule and sealing.

Advantageously, adjuvants such as a local anaesthetic, a preservative and buffering agents can be dissolved in the vehicle. To enhance the stability, the composition can be frozen after filling into the vial and the water removed under vacuum. Parenteral suspensions are prepared in substantially the same manner, except that the compound is suspended in the vehicle instead of being dissolved, and sterilization cannot be accomplished by filtration. The compound can be sterilized by exposure to ethylene oxide before suspending in the sterile vehicle. Advantageously, a surfactant or wetting agent is included in the composition to facilitate WO 92/05175 PCT/GB91/01633 -18uniform distribution of the compound.

The compositions may contain from 0.1% to 99% by weight, preferably from 10-60% by weight, of the active material, depending on the method of administration.

Compounds of formula or if appropriate a pharmaceutically acceptable salt thereof, may also be administered as a topical formulation in combination with conventional topical excipients.

Topical formulations may be presented as, for instance, ointments, creams or lotions, impregnated dressings, gels, gel sticks, spray and aerosols, and may contain appropriate conventional additives such as preservatives, solvents to assist drug penetration and emollients in ointments and creams. The formulations may contain compatible conventional carriers, such as cream or ointment bases and ethanol or oleyl alcohol for lotions.

Suitable cream, lotion, gel, stick, ointment, spray or aerosol formulations that may be used for compounds of formula or if appropriate a pharmaceutically acceptable salt thereof, are conventional formulations well known in the art, for example, as described in standard text books of pharmaceutics and cosmetics, such as Harry's Cosmeticology published by Leonard Hill Books, Remington's Pharmaceutical Sciences, and the British and US Pharmacopoeias.

Suitably, the compound of formula or if app-opriate a pharmaceutically acceptable salt thereof, will comprise from about 0.5 to by weight of the formulation, favourably from about 1 to 10%, for example 2 to The dose of the compound used in the treatment of the invention will vary in the usual way with the seriousness of the disorders, the weight of the sufferer, and the relative efficacy of the compound. However, as a general guide suitable unit doses may be 0.1 to 1000mg, such a5.0:5 to 200, 0.5 to 100 or 0.5 to 10 mg, for example 0.5, 1, 2, 3, 4 or 5 mg; and such unit doses may be administered more than once a day, for example 2, 3, 4, 5 or 6 times a day, but preferably 1 or 2 times per day, so that the total daily dosage for a 70kg adult is in the range of about 0.1 to 1000 mg, that is in WO 92/05175 PCT/GB91/01633 -19the range of about 0.001 to 20 mg/kg/day, such as 0.007 to 3, 0.007 to 1.4, 0.007 to 0.14 or 0.01 to 0.5 mg/kg/day, for example 0.01, 0.02, 0.04, 0.05, 0.06, 0.08, 0.1 or 0.2 mg/kg/day; and such therapy may extend for a number of weeks or months.

When used herein the term 'pharmaceutically acceptable' encompasses materials suitable for both human and veterinary use.

No toxicological effects have been established for the compounds of formula in the abovementioned dosage ranges.

The following pharmacological data and examples illustrate the invention.

The following preparations illustrate the preparation of intermediates to the novel compounds of formula WO 92/05175 PTG9/13 PCr/GB91/01633 8-Amino-7-benzvl- 1.3-di(cvlopronvylmethflxanthine CH 2

K

N N NH Potassium t-butoxide(0.12g,llmmole)was added to a solution of 8-amino- 1,3-di(cyclopropylmethyl)xanthine (O.27g, immole) in DMF(3m1) and the resulting mixture was stirred for lhir at ambient temperature.

Benzyl bromide (0.24m1,2mmole) was added to the dark orange/red solution which turned cherry red. After stirring for lhr at ambient temperature the reaction mixture was added to ethyl acetate(80m1)and the organic solution washed with water(2x25m1), dried(MgSO 4 )and the solvent removed under reduced pressure to give a red solid(0.43g).

Chromatography on silica (acetone/hexane 1:5) gave 8-amino-7-benzyl- 1,3-di~cyclopropylmethyl) xanthine(0.3 lg,84%),m.p. 1580C, vmax (KBr) 3369(w), 3330(w), 169 1(m),1639(s),1526(m) and 1432(m)cm-1; B(CDCl 3 0.39-0.52(8H,m), 1.25- 1.36(2H,m), 3.89 (4H,t(overlapping J=6.5Hz) ,4.66(2H,brs),5 .39(2H,s), 7.26-7.41 mle 365(M+,100%),91(60),214(30), 55(20),220(11), 337(8); Found: C, 65.43; H, 6.15; N, 19.10. C 2 0

H

2 3

N

5 0 2 requires C, 65,73; H, 6.34; N, 19.17%.

WO 92/05175 WO 9205175PCT/GB91/01633 -21- 8-Amino-i .3-di(cvclouronvylmethvl)-7-(4-methoxvbenzvl)-xanthine, 0 /CH OMe <N N NH 0 1 Potassium t-butoxide(1.34g,l2mmnole)was added to a solution of 8-amino- 1,3-di(cyclopropylmethyl)xanthine (2.7g, l0mmole)in DMF(25xn1)and the resulting mixture was stirred for 0.5hr at ambient temperature. 4-Methoxybenzyl chloride( 1.56g, 1.35xn1 mmole) was added to the red solution which lightened to an orange colour. After stirring for lhr at ambient temperature the mixture was added to ethyl acetate (200m1), washed with dilute hydrochloric acid(50m1),water(50m1) and dried (MgSO 4 Removal of the solvent under reduced pressure gave a solid which was chromatographed on silica (hexane/acetone, gradient)to give 8-amidno- 1,3-di(cyclopropylmethyl)-7-(4-methoxybenzyl) xanthine (2.55,64%) m.p.176 0 C, Vmax 3434(w), 1691(m),1639(s),1527(m) and 1456(m)cm- 1 8(CDCl 3 )0.43S-0.53(8H,m), 1.26-1.35(2H,m),3.79(3H,s),3.89 (4H,t(overlapping d), J=7.OHz),4.55(2H,brs),5.32(2H,s),6.90(2H,d,J=9.OHz)7.30(2H,d,J=9.H 2 395(M+,20); Found C, 63.64; H, 6.36; N, 17.77. C 2 1

H

2 5

N

5 0 3 requires C, 63.78; H, 6.37; N, 17.71%.

WO 92/05175 WO 9205175PCT/GB91 /01633 -22- 8-Amno.L-di(vclouropvlmethvfl)-7-methylxanthine 0 m NH 2 Potassium t-butoxide (1.34glnmole) was added to a solution of 8-amino-i ,3-di(cyclopropylmethyl)xanthine 7g, 10mmole) in DMIF (25m1) and the resulting mixture was stirred for 0.5hr at ambient temperature. Methyl iodide (1.78g,0.78m1, 12.5mmole) was added to the red solution, an exothermic reaction resulted and a precipitate formed.

After stirring for 10 minutes the mixture was added to ethyl acetate (200m1), washed with dilute hydrochaloric acid (50m1), water(50ml) and dried (MgSO 4 Removal of the solvent under reduced pressure gave a solid which was chromatographed on silica (acetone/hexane gradient) to give 8-amino-i, 3-di(cyclopropyhnethyl)-7-methylxanthine (1.5g,52%), m.p.204-5 0 C, vmax 3405(w), 3343(w), 1689(m),1649(s), 1638(s),1534(m) and 1464(m) cm- 1 8(CDCl 3 0.41-0.50(8H,m), 1.26-1.36(2H,m), 3.75(3H,s), 3.90mn (4H,d,J=7.0Hz), 4.'77(2H,brs); m/e 289(M+,55%),15 1(30), 55(13),26 1(12); Found C, 58.00; H, 6.50; N, 24.08. C 14 Hj 9

N

5 0 2 requires C, 58.11; H, 6.62; N, 24.21%.

Exampje 4 1 .3-Di(cvcloropylmethvl)-8-ethoxv-7-(4-methoxvbenzyl-xanthine 0 CH 2 /\OMe 0 Etz 0,KN N WO 92/05175 WO 2/0175PCr/GB91/*G-.633 -23- Sodium ethoxide (3m1 of a 1M solution in ethanol, 3mmol) was added to a solution of 8-chloro- 1,3- di(cyclopropylmethyl)-7-(4-methoxybenzyl)xanthine (1.0g, 2.4rnmol) in dry ethanol (5m1) and the reaction mixture was heated at refiux for 16 hours. The solution was allowed to czool and the solvent wa'% removed under reduced pressure. The residue wa3 suspended in methanol/dicbloromethane and the solvent decanted from the sodium chloride.

Purification by column chromatography over silica gel in the same solvent system, afforded 1,3-di(cyclopropylmethyl)-8-ethoxy-7-(4methoxybenzyl)xanthine (0.87g, 85%) which was recrystallised from ethylacetate-hexane to afford a white crystalline solid, m.p. 112-1130C, v'max (KBr) 2953(m), 2836(s), 1697(s), 1651(s), 1609(s), 1514(s), 1454(s) and 1427(s); 1 H8 (270 MHz, CDCl 3 0.45 (8H, in), 1.29 (2H, in), 1.45 (3H, t, J 7.15Hz), 3.77 (3H, 3.87 (2H, d, J 7.4Hz), 3.90 (2H, d, J 7.4Hz), 4.52 (2H, q, J 7MHz), 5.20 (2H, 6.84 (2H, d, J 8.8Hz) and 7.42 (2H, d, J 8.Hz); m/e 424 121 (100) Found: 65.02; 6.68; N, 13.42. C 2 3

H

2 8

N

4 0 4 requires C, 65.07; H, 6.65; N, 13.20%.

Exml 8-Q Woro- 1.3-di-(cyclopropylmethyl)-7-(4-methoxybenzyj)xanthine 0 CH2 m N

C

/C

0

N

Sodium hydride (2.11g of a 60% suspension in oil, S3mmol) was added portionwise to a solution of 8-chloro-1,3-di(cyclopropylmethyl)xanth-ine (14.4g, 44mmol) in anhydrous dimethylsulphoxide, (lO0mi). After 1 hour, 4-methoxybenzyl chloride (6.5in1, 48mmol) was added and stirring continued for 16 hours. The reaction mixture was quenched with water (lO0mi) and extracted into ethyl acetate. The combined organic extracts were washed with water, dried over magnesium sulphate, filtered and concentrated. The solid residue was recrystallised from hexane to afford WO 92/05175 WO 9205175PCr/GB9I /01633 -24- 8-chloro-1,3- di(cyclopropylmethyl)-7-(4-methoxybenzyl)xanthfir -a (15.0g, 82%) as a white solid, m.p. 1,35-1360C, Vmax 1704(s), 1663(s), 1612(m), 1533(m), 1514(m) and 1453(m) cm-1; IH8 (270 M~z CDCl 3 0.46 (8H, in), 1.30 (2H, in), 3.78 (3H, 3.92 (4H, dd, J 1.38, 7.2 Hz), 5.48 (2H, 6.86 (2H, el, J 9Hz), 7.42 (2H, d, J= 9Hz); nile 414 121 (100) Found: C, 60.57; H, 5.41; N, 13.72. C 2 1

H

2 3

N

4 0 3 C1 requires C, 60.8; H, 5.6; N, 13.50%.

0 N N 0 <N N>

H

2-Hydroxyethylpyridine (0.32g, 1.1 equiv) was added dropwise to a suspension of 8-chloro- 1,3-di(cyclopropylmethyl)-7-(4methoxybenzyl)xanthine (1g, 2.41 minol) and sodium hydride (0.15g of a dispersion in oil, 1.5 equivs) in dry DMSO (20m1A) and was heated at 80"C for 16h. The reaction mixture was poured into water, neutralized and extracted into ethyl acetate The combined organic solutions were dried, filtered and concentrated. The residue was purified by column chroinatograihy over silica gel in 0.5-1% methanol/dichloromethane to afford 1,3-di(cyclopropylmethyl)-8-hydroxy-7-(4-methoxybenzyl)xanthine (0.4g, 84% based on recovered starting material), mp 24700 (ethyl acetate/chioroform/hexane). 8 (CDCl 3 0.39-0.63 (8H,rn), 1.23-1.40 (2H,m), 3.77 3.85 (2H,d J=7.lHz), 3.89 (2H, d J=7.lHz), 5.13 6.83 (2H, d J=8.8Hz), 7.50 (2H, d J=8.8Hz), 13.14 (1H,s).

Found: C, 63.40; H, 6.12; N, 14.00. C 2 1

H

2 4 0 4

N

4 requires 0, 63.62; H, 6.10; N, 14.13%.

WO 92/05175 WO 92O5I7~PCr/GB91/01633 Eza1Q-z 8-Amino-i .3-di(cvcglonrovvlmethfl)-7-(3 OMe OMe 8-Amino- 1,3-di(cyclopropylniethyl)-7-(3 ,4,5-trimethoxybenzyl)xanthine mp 173-174'C was -prepared. in 84% yield in a similar manner to the compound of E~xample 2 using 8-amino- 1,3-di~cyclopropylmethyl)xanthine and 3,4,5-trimethoxybenzyl chloride; 8 (CDCl 3 0.44-0.49 1.29- 1.32 3.82 C9H,s), 3.89 (2H, d, J=6.9Hz), 3.92 (2H,d, J=6.9Hz), 4.82 C2H,s), 5.30 (2H,s) and 6.57 v (KBr) 3414 Cm), 1694 Cs), 1646 1633 Cs), 1525 Cs), 1456 Cs) and 1127 cm- 1 m/e (FAB) 181 (100%), 456 observed 455.2169, C 2 3

H

2 9

N

5 0 5 requires 455.2156; Found: 0, 60.55; H, 6.23; N, 15.27. 0 2 3

H

2 9

N

5 0 5 requires C, 60.64; H, 6.42; N, 15.38%.

WO 92/05175 WO 9205175PCT/GB9I /01633 -26- I .3-Di(cyclopropylmethvl)-7-(4-methoxybenzl)-8-(4iddvlamino)xanthine O OMe 0-0 NN

H

This compound was prepared according to the procedure of Example 9 but with 4-aminopyridine replacing imidazole. Purification by column chromatography afforded 1 ,3-di(cyclopropylnethyl)-7-(4-methoxybenzyl)- 8-(4-pyridylzimino)xanthine mp, 207-208'C (decomp, ethylacetate/hexane). 8 (CDCl 3 /DMSO-d 6 0.32-0.57 1.26-1.40 3.19 (1H,brs), 3.74 3.86 (2H, d J=7.l5Hz), 3.96 (2H, d 5.57 6.82 (2H, d J=8.8Hz), 7.29 (2H, d J=8.8Hz), 7.62 (2H, d J=6.5Hz), 8.36 (2H,brs).

Found: C, 66.28; H, 5.77; N, 17.94. C 2 6

H

2 8

N

6 0 3 requires C, 66.08; H, 5.97; N, 17.78%.

WO 92/05175 WO 92/05175PCr/GB91/01633 -27- 1 .3-Di(cvclovropV methyl)-8-imidazoyl-7-(4-methoxybenzyl)xanthine 0 N

N

A solution of 8-chloro-1,3-di(cyclopropylrnethyl)-7-(4methoxybenzyl)xanthi.ne (0.5g, 1.21 x 10-3 moles), potassium t-butoxi,de (0.15g, 1.1 equiv) and irnidazole (0.090g, 1.1 equivs) in dry dimethyl sulphoxide (l0mi) was heated at 80'0 for 16h. The reaction mixture was allowed to cool, poured into water and extracted into ethyl acetate (x3).

The combined organic solutions were dried over magnesium sulphate, filtered and concentrated. The crude residue was purified by column chromatography over silica gel in 1% ruethanol/dichloromethane to afford 1,3-di(cyclopropylmethyl)-8-imidazoyl-7-(4-methoxybenzyl)xanthine (0.32g, mp 117-119'C (ethyl acetate/hexane). 8 (CDCl 3 0.41-0.56 1.26-1.40 3.77 3.96 (2H,d J=7.lHz), 3.97 (2H,d J=7.lHz), 5.48 6.82 (2H,d J=8.8Hz), 6.98 (2H,d J=8.5Hz), 7.20 7.26 (1H,s) and 7.78 (1H,s).

Accurate Mass: Found 446.2065. C 2 4

H

2 6

N

6 0 3 requires 446.2066.

Found: C, 64.48; H, 5.94; N, 18.81. C 2 4

H

2 6

N

6 0 3 requires C, 64.55; H, 5.87; N, 18.82%.

WO 92/05175 WO 9205175PCT/G19 1/01633 -28- 8-Chloro- 1 di cclprylmethvl)-7-(3 Dyri dvlmethyvbxanthine 0 O N HCt

N

8-Chloro-1,3-d.i(cyclopropylmethyl)-7-(3 pyridylmethy' )xanthine was prepared from 3-chioromethylpyridine and 8-chloro-iL,3di(cyclopropylrnethyl)xanthine according to the procedure of Example 14, except that the reaction mixture was heated at 80TC for 16h. The free base was dissolved in dry ether and the solution was saturated with hydrogen chloride gas. 8-Chioro- 1,3-di(cyclopropylmethyl)-7-(3pyridylmethyl)xanthine hydrochloride, m.p. >20000 (methanol/ether), was precipitated. 5 (DMSO-d 6 0.29-0.51 1.11-1.27 3.77 (2H,d J=6.8Hz), 3.84 (2H, d J=7.lHz), 4.5-6.0 (1H, hr 5.68 7.83 (1H,t), 8.22 (1K, d J=8.51-z), 8.76 (1H, d J=4.4Hz), 8.85 (1H,s).

Accurate Mass: Found 386.1365. C 1 9

H

2 1

N

5 0 2 C1 requires 386.1384.

Found: C,53.82; H, 5.17; N, 16.60. C 1 9

H

2 1

N

5 0 2 C1 2 requires C, 54.03; H, 5.01; N, 16.58%.

WO 92/05175 WO 9205175PCI'/G19 1/01633 -29- E~xample1 8-Choro-1 .3-di(cyclotropylmethl)-7-(a.4.5-trnethoxybenzvl)xpntl'n

N

8-Chloro- 1,3-di(cyclopropylmethyl)-7-(3 m.p. 109-110'C, was prepared in 62% yield from 3,4,5-trimethoxybenzyl chloride and 8-chloro-1,3-di(cyclopropylmethyl)xanthine using the procedure of Example 14. 5 (CDCl 3 0.42-0.51 (8H, in), 1.25-1.36 (2H, in), 3.82 (3H, 3.84 (6H, 3.93 (4H, 2xd J=7.l5Hz), 5.45 (2H, 6.82 (2H,

S)

Found: C, 58.33; H, 5.47; N, 11.72. C 2 3

H

2 7

N

4 0 5 C1 requires C, 58.16; H, 5.73; N, 11.80%.

WO 92/05175 WO 9205175PCr/G1191/01633 Examnles 12 and 13 8-Amino-i .3-di(cvclouroplmethvl)-7-(2-nitrobenzyl)xanthine (Example 12) and 1 cvlonronvylmethfl-8-(2-nitrobenzylamino)-7-(2nitrobenzyV)xanthine (Examnle 13)

NO

2 N0 2 0 0 0 NN'N N H 0 ~N N N0 2 Example 12 Example 13 8-Amiino- 1,3-di(cyclopropylmethyl)xanthine was reacted with 2nitrobenzyl bromide in a similar manner to that for the compound of Example 2 to give, after chromatography on silica (hexane/acetone gradient), 1 ,3-di(cyclopropylmethyl)-8-(2-nitrobenzylamino)-7-(2nitrobenzyl)xanthine rn.p. 198-9'C; 8 (CDCl 3 0.32-0.58 (8H, in), 1.17-1.1L3 (111, in), 1.33-1.40 (1H, in), 3.82 (2H, d, J=7.lHz), 3.94 (2H, d, J=7.lHz), 4.83 (2H, d, 5.63 (1H, t, J=6.3Hz), 5.73 (2H, 7.03 (1K, d, J=7.7Kz), 7.42-7.64 (5H, in), 7.83 (1H, d, J=8.0Hz), 8.10 (1K, d, J=8.OHz); v x (KIBr) 1695(s), 1652(s), 1619(s), 1570(m), 1526(s), 1476(m), 1340(m), 1302(m), 1275(m) and 727(m) cm- 1 m/e (FAB) 546 (MIH+, 100%), 136(43), 55(28), 91(15), 78(12), and 530(10); Found: C, 59.16; H, 5.04; N, 18.08. C 2 7

H

2 7

N

7 0 6 requires C, 59.44; H, 4.99; N, 19.97% followed by 8-amino- 1,3-di(cyclopropylmethyl)-7-(2-nitrobenzyl)xanthine m.p. 240-1'C, 8 (CDCI 3 0.35-0.42 (4H, in), 0.45-0.53 (4H, mn), 1.21- 1.36 (1K, in), 1.37-1.42 (1K, mn), 3.82 (2H, d, J=7.lHz), 3.93 (2H, d, J=7.lHz), 5.83 (2H, 6.05 (2H1, brs), 6.94 (1H, dd, J=1.1, 8.0Hz), 7.11:- 7.62 (2H1, mn), 8.17 (1H, dd, J=1.1, 8.0Hz) vmax (KBr) 1695(s), 1638(s), 1.525(s), 1452(s), 1338(m), 1275(m) and 728(w) cm- 1 zn/e (FAB) 411 (MH+, 100%, 55(50), 136(35), 357(18), 91(14); Found: C, 58.30; H, 5.43; N, 20.55. C 2 0

K

2 2

N

6 0 4 requires C, 58.52; H, 5.40; N, 20.48%.

WO 92/05175 WO 9205175Pcr/Gll91 /01633 -31- Example 14 8-Chloro- 1.3-dli(cycloprouvlImethyl)-7-(4-nitrobenzvbIxanthine N0 2 0 0 N N 0 4<N Sodium hydride (0.16g of a 60% suspension in oil, 1.2 equivs) was added to a solution of 8-chloro-1,3-di(cyclopropylmethyl)xanthine (1g, 3.40 x 1moles) in dry DMS0 (25m1). After 1 h, 4-nitrobenzyl bromide (0.88g, 1.2 equivs) was added and the solution was stirred at ambient temperature for 16 h. The reaction mixture was poured into water and extracted into.

ethyl acetate The combined organic solutions were dried, filtered and concentrated. The crude residue was purified by colun chromatography over silica gel in 1% methanolldichloromethane to afford 8-chloro-1 ,3-di(cyclopropylmethyl)-7-(4-nitrobenzyl)xanthine (0 .93g, 64%) as a white solid m.p. 111-1120C (ethyl acetate/hexane). 5 (CDCI 3 0.38- 0.55 (8H1,m), 1.22-1.39 3.90 (2H,d J=7.15Hz), 3.95 (2H, d 6.4 7.58 (2H,d J=8.8Hz), 8.23 (2H, d J=8.8Hz).

Accurate Mass: Found 430.1285. C 2 0

H

2 jN 5 0 4 CI requires 430.1282.

Found C,55.91; H, 4.81; N, 16.22. C 2 0

H

2

ON

5 0 4 CI requires C,55.88; H,4.69; N, 16.29%.

WO 92/05175 WO 9205175PCT/G1191 /01633 -32- 8-Amino-i. .di(cvclopronvylmethvbl'-7-( 1-naphthylmethvl)xanthine 0 0 0

>-NH

2 0~

N

K>

Potassium t-butoxide (0.48g, 1.2equiv) was added to a suspension of 8amino- 1,3- di(cycl opropylmethyl)xanthine (1g, 3.63 x 10-3 moles) in dry ethylene glycol dimethyl ether (25m1). After 0.5h 1chloromethylnaphthalene (0.77g, 1.2 equivs) was added and stirring continued for a further 16 h. The reaction mixture was poured into water, neutralised, and extracted into ethyl acetate The combined organic extracts were dried over magnesium sulphate, filtered and concentrated.

The crude residue was purified by column chromatography over silica gel in 1% methanolldichloromethane to afford 8-amino-1,3di(cyclopropylmethyl)-7-(1-naphthylmethyl)xanthine (0.82g, 54%) as a pale pink solid m.p. 215-216.'C. 8 (CDCl 3 0.33-0.56 1.2-1.44 3.82 (2H,d J=7.15Hz), 3.93 (2H,d J=7.l5Hz), 5.67 (2H,br 5.90 6.96 (1H,d J=7.lHz), 7.40 (1H,t J=7.lHz), 7.55 7.79 (1H,d J=8.2Hz), 7.85 1HAd), 8.07 (1H,d).

Accurate Mass: Found 416.2066. C 2 4

H

2 6

N

5 0 2 requires 416.2087.

WO 92/05175 WO 9205175PCT/GB91/01633 -33- 8-Chloro-1 .3-ci(cvclopronvlmethy vD-7-( 1-nauhthylmethvl)xanthine

K>

8-C hioro- 1 ,3-di(cyclopropylmethyl)-7-( 1-napthyl methyl)xanthine, m.p.

187-188TC (hexane), was prepared in 32% yield, from 1chloromethylnaphthalene and 8-chloro-1,3-diQcyclopropymethyl)xanthine using the procedure of Example 14. 8 (CDCl 3 0.37-0.59 1.21- 1.46 3.87 (2H,d J=7.l4Hz), 4.01 (2H,d J=7.14Hz), 6.10 6.76 (1H, d J-,7.l4Hz), 7.38 7.58 7.81 (1H, d J=:8.3Hz), 7.91 (1H, d J=7.7Hz), 8.06 (1H,d J=8.2Hz).

Found C,66,14; H, 5.23; N, 12.85. C 2 4

H

23

IN

4

O

2 CIl requires C,66.27; H, 5.32; N, 12.80%.

Accurrate Mass: Found 435.1588. C 2 4

H

2 3

N

4 0 2 CI requires 435.1588.

WO 92/051-75 WO 92OS~75PCF/GB91/01633 -34- 8-Amino-i, :3di(cvclonronlmethyvl)-7-(4-nitrobenzyl)xpnthine N0 2 0 0

NH

2

K>

Sodium hydride (0.17g of a 60% dispersion in oil, 1.2 equivs) was added to a suspension of 8-amino- 1,3-di(cyclopropylmethyl)xanthine (1g, 3.63 x 3 moles) in dry DMSO (25m1). After stirring for 1 h at ambient temperature 4-nitrobenzyl bromide (0.94g, 1.2 equivs) was added. After 16 h the reaction mixture was poured into water, neutralised and extracted with ethyl acetate Wx). The combined organic extracts were dried over magnesium sulphate, fitered and concentrated. The crude residue was purified by column chromatography over silica gel in 2% methanolIdichloromethane to afford 8-armino-1,3-di(cyclopropylmethyl)-7- (4-nitrobenzyl)xanthine (1.03g, 69%) as a pale yellow solid, m.p. 136- 137"C. 5 (CDC1 3 0.36-0.54 1.23-1.39 3.88 (4H,t,J=6.75Hz), 4.59 5.47 7.47 (21-T,d,J=8.8Hz), 8.21 (2H,d of t J=8.8Hz).

Accurate Mass: Found 411.1781. C 2 0 11 2 3

N

6 0 4 requires 411.1781.

WO 92/05175 PC/GB9I /01633 Example 18 I .3-Di(cVclopropvlmethl)-7-(4-methoxvbenzvl)-8-r2-(2-N- 1jerizinvl1ethox)ethoxvyxanthine sesuimaleate sesauihydrate C0 2

H

OMe 1.51 1.5H 2 0 0 CO 2

H

N N 0 0 N

N

NN

This compound was prepared according to the procedure of Example 6 using 2-(2-(N-piperizinyl)ethoxy)ethano and 8-chioro-I,3di(cyclopropylmethyl)-7-(4-methoxybenzyl]xanthine. Purification by column chromatography over silica gel using 4% methanot/dichioromethane afforded I,3-di(cyclopropylmethyl)-7-(4methoxybenzyl)-8-[2-(2-[N-piperizinyl]ethoxy)ethoxy]xanthine as an oil. 8 (CDC1 3 0.43-0.48 (8H, 1.29 (2H, 1.95 (1H, brs), 2.50(4H, i), 2.60 (2H, t, J=5.8Hz), 2.90 (4H, 3.66 (2H, t, J=5.8Hz), 3.77 (3H, 3.77- 3.91 (6H, 4.61 (2H, 5.22 (21, 6.83 (2H, d, J=8.5Hz), 7.44 (2H, d, Accurate Mass: Found: 552.5878 C 2 9 H40N 6 0 5 requires 552.306C Treatment of the above oil with maleic acid gave the sesquimaleate sesquihydrate m.p. 150-5'C (decomp. ethanol/diisopropyl ether).

WO 92/05175 WO 9205175PCTr/GB91 /01633 -36- ExamlPk19 1 .3-Di(cyc'liopylmethvl)-7-(4-methoxvbenzyl)-8-(4-piperi dinyloxy)xanthine maleate O OMe N COOH 0 C0 2

H

N

:N H 1 ,3-Di(cyclopropylmethyl)-7-(4-methoxybenzyl)-8-(4piperidinyloxy)xanthine maleate was prepared according to the procedure of Example 6 but with 4-hydroxypiperidine replacing 2hydroxyethylpyridine. Purification by column chromatography ov'er silica gel afforded 1,3-di(cyclopropylmethyl)-7-(4-methoxybenzyl)-8-(4piperidinyloxy)xanthine as an oil. 5 (DMSO-d 6 0.3 1-0.48 (8H,m), 1.15-1.23 1.54-1.66 1.93 2.51-2.62 2.87- 2.94 3.72 3.77 (2H,d J=7.l5Hz) 3.78 (2H, d J=7.iSHz), 4.95-5.01 (1H,m) 5.16 6.90 (2H, d J=8.8Hz), 7.30 (2H, d J=8.8Hz).

The maleate salt was prepared and recrystallised from methanolldiisopropyl ether to afford the pure material, mp 165-166TC.

Found. C, 60.34; H, 6.39; N, 11.77 C 3 0

H

3 7 0 8

N

5 requires C, 60.49; H, 6.26; N, 11.76%.

WO 92/05175 WO 9205175PCI'/GB91/01633 -37- 4-r4-(8- r 1.3-Di (gvclopropvlm ethyl 7-(4-methoxvbenzv1I)xanthin- Ylx-ieiiy)14ejtni acid hemihvdratq 0

C)

N N> ONCOCH 2

CH

2

CO

2

H

Succinic anhydride (0.23g, 1.2 equivs) was added to a solution of 1,3di(cyclopropylmethyl)-7-(4-methoxybenzyl)-8-(4-piperidinyloxy)xanthine (0.92g, 1.92 mmoles) in dry THF (20m1). After 48h the sclvent, was removed by evaporation to give 4 1,3-di(cyclopropylmethyl)-7-(4methoxybenzyl )xanthinyloxyjipiperidinyl)]-4-oxo-butanoic acid hemihydrate, (0.62g, nip 141-142'C (ethyl acetate/hexane). 8 (CDCl 3 0.43-0.52 1.25-1.29 1.91-2.02 2.71 3.49-3.71 3.77 3.87 (2H,d J=7.4Hz), 3.91 (2H, d J=7.2Hz), 5.23 6.85 (2H, d J=8.8Hz), 7.37 d Found: C, 60.82; H, 6.32; N,'11.82 C 3 0

H

3 7 0 7

N

5 0.5H 2 0 requires C, 61.20; H, 6.50; N, 11.89%.

WO 92/05175 WO 9205175PCTF/GB91 /01633 -38- Example 1 8-r4-(N-jEri-zyl )ineridinvloxvl- 1.3-di(cyclonropylmethyl methoxyvbenzvi~anthine rnaleate 0 ra Ome C C 2

H

N N 0-NHP 0 2

H

0 AN

N

Benzyl bromide (0.17g, 1.2 equivs), triethylamine (0.21g, 2.5 equivs), and 1 ,3-di(cyclopropylmethyl)-7-(4-methoxybenzyl)-8-(4piperidinyloxy)xanthine (0.40g, 8.4 x 10- 4 mmole) were stirred in dry tetrahydrofairan (l0mi) for 16h. The reaction mixture was poured into aqueous sodium bicarbonate solution an'i extracted into dichioromethane.

The combined organic solutions were dried over magnesium sulphate, filtered and concentrated and the residue was purified by column chromatography over silica gel in 1% methanol/dichioromethane to afford 8-[4-(N-benzyi)piperidinyloxyl-1,3-di(cyclopropylmethyl)-7-(4methoxybenzyl)xanthine (0.36g, 8 (CDCl 3 0.43-0.48 1.26- 1.32 1.86-1.94 (2H,rn), 2,03-2.,09 (211,m), 2.35-2.41 2.66 3.54 3.78 3.87 (2H, d J=11.82Hz), 3.90 (2H, d J=.,11.5Hz), 5.00-5.21 5.20 (21I,s), 6.85 (2H, d J=8.79Hz), 7.26-7.39 and 7.42 (2H, d J=8.8Hz). Accurate Mass: Found 569.2919.

C

3 3

H

3 9

N

5 0 4 requires 569.3002.

The maleate salt was prepared and recrystallised from methanolldiisopropyl. ether to afford the pure material as a white solid mp 160-161 0

C.

Found: C, 64.71; HI, 6.42; N, 9.93. C 3 7

H

4 3 0 8

N

5 requires C, 64.80; H, 6.32; N, 10.21%.

WO 92/05175 PTG9/13 PCr/GB91/01633 -39- Diethyl 1 .3-di(cvdlovropvlmethyl)-74 4-methoxybenzvl )xanthin- Yf1lmanp.

0 OMe N N C0 2 Et 0a N

CO

2

EI

Sodium hydride (1.48g of a 60% suspension in oil, 37 mmol) was added portionwise to a solution of diethyl malonate (5.4g, 34 mmol) in anhydrous DMSO (70 ml) and stirring continued for 1h at ambient temperature. 8- Chloro- 1,3-di(cyclopropylmethyl)-7-(4-methoxybenzyl)xanthine (71.Og-, 16.9 mmol) was added and the reaction mixture was heated to 80 TC. After 16h the solution was allowed to cool, poured into water and extracted with ethyl acetate. The combined organic extracts were dried over magnesiumr sulphate, filtered and concentrated under reduced pressure. The residue was purified by column chromatography over silica gel in methanolldichloromethane to afford diethyl 8-[1,3-di(cyclopropylmethyl)- 7-(4-methoxybenzyl)xanthinyllmalonate (8 .95g, m.p. 134- 135'C (CDCl 3 0.39-0.50 1.22 (6H, t, J=7.lHz), 1.31 (2H, in), 3.77 (3H, s), 3.92 (2H, d, J=7.lHz), 3.95 (2H, d, J=7.lHz), 4.14 (4H, in), 4.79 (1H, s), 5.52 (2H1, 6.85 (2H, ai, J=8.8Hz), 7.13 (2H, d, J=8.8Hz). Found: C, 62.40; H, 6.39; N, 10.35. C 2 8

H

3 4

N

4 0 5 requires C, 62.40; H, 6.30; N, 10.4% WO 92/05175 PCr/GB91/01633 Procedure 1 1.3-Di-cvcloropyDvl methyl-8-nitro xanthine 1,3-Di-cyclopropylmethyl xanthine (20g, 0.076mol) was dissolved in acetic acid (33ml) and then treated with concentrated nitric acid (13.2g) at 870C.

After 1 hour, the mixture was cooled to 50C and the resulting yellow precipitate filtered off. The yellow crystals were dissolved in dichloromethane and washed with water. The separated organic layer was then dried over anhydrous sodium sulphate and concentrated in vacuo. The product crystallized from the concentrate to yield a yellow crystalline product yield 12.2g, m.p. 2070C (with decomposition).

1H NMR (CDC1 3 ppm: 0.35-0.7 8H), 1.1 -1.7 2H), 3.95-4.2 4H), 9.0-11.0 (br.

exchanges with D 2 0, 1H).

Procedure 2 1.3-Di"cyc~; o rouvlmethvl-8-amino xanthine 1,3-Di-cyclopropylmethyl-8-nitro xanthine (4g, 0,014mol), suspended in of concentrated hydrochloric acid,was treated with small portions of tin (8g) at room temperature. The mixture was then stirred at room temperature for two hours.

The resulting precipitate was filtered off and crystallised from ethanol to give white crystals of the title product, yield 0.9g m.p. 2810C.

In an alternative procedure, using sodium dithionite as reducing agent (in methanol-water mixture). The yield was 36% (compare Example 13).

1 H NMR (CDC13): ppm: 0.3-0.6 1.0-1.6 3.7-4.0 5.75 (br,2H), 10.84 (br. exchanges with D 2 0, 1H).

Brpamration 3 WO 92/05175 WO 9205175PCT/GB9I /01633 -41- 8-ChlWoro- 1 3-di(cvclopropy-lmethvl)xanthine 1,3-Di(cyclopropylmethyl)-8-nitroxanthine (50g, l64nunol) was dissolved in dry dimethylformamide (300m1) and to this phosphorus oxychioride 536mmo1) was added dropwise with caution. After 16h, the reaction mixture was poured onto ice and the precipitate was collected and washed with water. The solid was dissolved in dichioromethane, and dried (MgSO 4 The solution was filtered and concentrated and the crude product was recrystallised from ethyl acetate/hexane to afford 8-'chloro-1,3-di(cyclopropylmethyl)xanthine (31g, 64%) as a white ci-ystailnie solid. 1 H NMR (CDC1 3 IDMSO-d6) d 0.40-0.53 in), 1.31 (2H, in), 2.76 (1H, br.s), 3.89 (2H, d, J 7.15Hz), 3.94 (2H, d, J 7.42Hz); max (KBr) 3438(s), 1707(s), 1648(s), 1601(m), 1545(s), and 1465(s) cm- 1 m/e 294 55 (100) Found: C, 52.97; H, 5.04; N, 19.02. C 13

H

1 5

N

4 C10 2 requires C, 52.97; H, 5.09; N, 19.01%.

WO 92/05175 PCT/GB91/01633 -42- PHARMACOLOGICAL DATA 1) Induction of blood eosinophilia and the effects of drugs.

Animals Male Charles River Sprague Dawley rats weighing between 270 to 400g were used.

The method used was a modification of that described by Laycock et al (Int. Arch. Appl. Immunol, (1986). 81, 363).

Sephadex G200, particle size 40 to 120 micron, was suspended in isotonic saline at 0.5mg/ml, and stored for 48h at 4oC. 1ml of the suspension was given intravenously to rats on days 0,2 and 5. A control group received saline. The test compound was given before the Sephadex on each occasion, with a contact time expected to give maximum activity at the time of the Sephadex administration. Blood was taken from the tail vein of the rats on day 7 for the determination of total and differential leucocyte counts.

A control group of at least 6 animals was included each time a compound was evaluated. The control group received Sephadex and the vehicle without test compound. The results in the drug treated animals were compared with the control group.

Total and differential leucocte counts.

samples of blood, taken from the tail vein of the rats, were added to 10ml of Isoton II and, within 30min, Zaponin (3 drops) was added, to lyse the erythrocytes. Five minutes later the total cell count was determined using a Coulter Counter Model DN. Differential leucocyte counts were carried out by fixing and staining a blood smear on a microscopic slide with May-Grunwald and Giemsa stains. A minimum of 400 cells were counted on each slide.

WO 92/05175 PCT/GB91/01633 -43- Statistics Probability values were calculated using the Student's t test.

The effect of the test compound upon Sephadex induced eosinophilia in the rat is set out below. The test compound was given orally 30 minutes before each injection of Sephadex.

Test Compound Dose mg/kg (orally -30 mins) of Control Mean SEM (n=16 Vehicle dosed control sephadex i.v Negative control saline i.v.

100 13 14 1 49 13* 60+ 12* Example 2 Example 3 p<0.

0 p< 0.001 WO 92/05175 PCT/GB91/01633 -44- 2) Inhibition of PhosDhodiesterase Isolation of phosphodiesterases The Ca2+/calmodulin-stimulated PDE (PDE I, see Table 1 and Beavo and Reifsynder (1990) for nomenclature) was prepared from bovine cardiac ventricle. Following chromatography on a Mono Q column, the fractions showing stimulation of PDE activity by Ca 2 and calmodulin were pooled and further purified on a calmodulin-affinity column. cGMP-stimulated PDE (PDE II), cGMP-inhibited PDE (PDE III) and cAMP-specific PDE (PDE IV) were all isolated from guinea-pig cardiac ventricle. Initial chromatography on a 20 ml Mono Q column resolved PDE III from a peak that contained both PDE II and PDE IV. The latter were separately rechromatographed on a 1 ml Mono Q column. cGMP-selective PDE (PDE V) was obtained from porcine lung using chromatography on DEAEcellulose and Mono Q columns; a calmodulin-affinity column was used to remove residual PDE I activity.

Characteristics of phosphodiesterase isoenzvmes With the exception of PDE II, which displayed positive cooperativity, all the preparations showed simple Michaelis-Menton kinetics (see Table 1).

PDE I The activity of this isoenzyme was stimulated by the Ca 2 calmodulin complex. The isoenzyme could hydrolyse both cAMP and cGMP, the latter was the preferred substrate.

PDE II The activity of this isoenzyme with cAMP as a substrate was stimulated by cGMP. The isoenzyme could hydrolyse both cAMP and cGMP, the latter was the preferred substrate under basal conditions. The activity of this isoenzyme was unaffected by the Ca 2 +-calmodulin complex.

PDEIII The activity of this isoenzyme with cAMP as a substrate was inhibited by cGMP. The isoenzyme could hydrolyse both cAMP and cGMP, the former was the preferred substrate. The activity of this isoenzyme was unaffected by the Ca 2 calmodulin complex.

WO 92/05175 PCT/GB91/01633 PDE IV This isoenzyme had high affinity for cAMP, the hydrolysis of which was not inhibited by cGMP. The activity of this isoenzyme was unaffected by the Ca2-calmodulin complex.

PDE V This isoenzyme had high affinity for cGMP. The activity of this isoenzyme was unaffected by the Ca 2 +-calmodulin complex.

Assay of phosphodiesterase activity PDE activity was assayed by the boronate column method as previously described (Reeves et. al., 1987). The enzymes were assayed by incubation at 37°C for 4-30 min. in 50 mM Tris, 5 mM MgC12, pH 7.5 with 3

H-

labelled cyclic nucleotide (4 x 105 disintegrations min and 14 C-labelled nucleotide 5'-monophosphate (3 x 103 disintegrations min-1). The assay was stopped by boiling and the 3 H-labelled 5'-monophosphate product separated from substrate on boronate columns. The reaction mixture was diluted with 0.5 mL 100 mM HEPES [N-(2-hydroxyethyl)piperazine-N1-2-ethanesulfonic acid], 100 mM NaC1, pH 8.5, and applied to the column. The column was extensively washed with the same buffer, and the 5'-nucleotide eluted with 6 mL of 0.25 M acetic acid. The recovery of product as judged by 1 4 C-recovery was approximately 80%. All assays were linear with time of incubation and concentration of enzyme over the range used in these experiments.

IC

5 0 values (the concentration of inhibitor required for 50% inhibition of activity) were obtained by incubation of the isoenzyme using 1 mM cGMP as a substrate for PDE I (in the absence of Ca 2 and calmodulin), PDE II and PDE V and with 1 mM cAMP as a substrate for PDE III and PDE IV.

A range of inhibitor concentrations from 0.1 x IC 5 0 to 100 x IC50 was used.

References BEAVO, J.A. and D.H. REIFSNYDER, Primary sequence of cyclic nucleotide phosphodiesterase isozymes and the design of selective inhibitors. Trends. Pharmacol. Sci. 11, 150-155 (1990).

WO 92/05175 WO 9205175PCT/GB9l /0 1633 -46- REEVES B.K. LEIGH and P.J. ENGLAND, The identification of a new cyclic nucleotide phosphodiesterase activity in human and guinea-pig cardiac ventricle. Biochem. J. 241, 535-541 (1987).

Kinetic properties of phosphodiesterase isoenzymes Isoenzyme Km M) Vmax cAMP cAMP cGMP Vmax cGMP I. Ca 2 +/calmodulin- 36 5 stimulated HI. cGMP-stimulated 45 14 1 III. cGMP-inhibited 0.5 0.1 IV. cAMP-specific 2 >n.d.

V. cGMP-specific >1 NAd a enzyme displayed positive cooperativity Km >100 mM n.d. not determined, due to inability of PDE to hydrolyse one of the substrates.

Inhibition of: Example PD lY PDE V No. IC 5 0 (pM) IC 5 0 (pM) 1 7.0 0.8 2 3.0 1 3 17 20.0 4 2.0 0.1 0.8 0.08 46a Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

e i i s t 6 tl

I

94070 I.p:\opu=da.85413.spc,46

Claims (14)

1. A compound of formula R 4 I R2(I) or, if appropriate, a pharmaceutically acceptable salt thereof; or a pharmaceutically acceptable solvate thereof, wherein R 1 and R 2 each independently represent a moiety of formula -(CIH2)m-A (a) wherein m represents zero or an integer 1, 2 or 3 and A represents a substituted or unsubstituted cyclic hydrocarbon radical; R 3 represents NO 2 a halogen atom, a hydroxy group,an alkoxy group or a methyl group substituted with 1 or 2 groups of formula CO 2 R wherein R in each group is independently hydrogen or alkyl or a group of formula O-L-A 1 wherein L is a bond or a linking group and Al is a saturated or unsaturated heterocyclic group, or R 3 represents a group of formula NRRt wherein R s and Rt each independently represent hydrogen, alkyl, aralkyl, an unsaturated heterocyclic group or R S and Rt together with the nitrogen to which they are attached form an unsaturated heterocyclic group; and R 4 represents an alkyl, aralkyl or an (unsaturated heterocyclyl)alkyl group.

2. A compound according to claim 1, wherein A represents a substituted or unsubstituted C 3 8 cycloalkyl group.

3- 3. A compound according to claim 1 or claim 2, wherein A represents an unsubstituted cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl group. WO 92/05175 PCT/GB91/01633 -48-

4. A compound according to any one of claims 1 to 3, wherein A represents a cyclopropyl group. A compound according to any one of claims 1 to 4, wherein R 3 represents nitro, a halogen atom, an alkoxy group, or a group NRsRt wherein RS and Rt each independently represent hydrogen er alkyl.

6. A compound according to any one of claims 1 to 5, wherein R 3 represents NH 2

7. A compound according to any one of claims 1 to 6, wherein R 4 is an alkyl or aralkyl group.

8. A compound according to any one of claims 1 to 7, wherein R 4 represents benzyl.

9. A compound according to claim 1, selected from the group consisting of: 8-amino-7-benzyl- 1,3-di(cyclopropylmethyl)xanthine; 8-amino-1 ,3-di(cyclopropylmethyl)-7-(4-methoxybenzyl)-xanthine; 8-amino-1,3-di(cyclopropylmethyl)-7-methylxanthine; 1,3-di(cyclopropylmethyl)-8-ethoxy-7-(4-methoxybenzyl-xanthine; 8-chloro-1,3-di-(cyclopropymethyl)-7-(4-methoxybenzyl)xantbine; 1,3-di(cyclopropylmethyl)-8-hydroxy-7-(4-methoxybenzyl)xanthine; 8-amino-1,3-di(cyclopropylmethyl)-7-(3,4,5-trimethozxybenzyl)xanthine; l, 3 -di(cyclopropylmethy)-7-(4-methoxybenzyl)-8-(4-pyridylamino)- xanthine; 1,3-di(cyclopropylmethyl) xantbine; WO 92/05175 WO 9205175PCF/GB91/01633 -49- 8-chioro. 1,3-di(cyclopropylmethyl)-7-(3 pyridylmethyl)xanthine hydrochloride; 8-chioro- 1,3-di(cyclopropyhnethyl)-7-(3,4,5-trimethoxybenzyl)xanthine; 8-amino-1,3-di(cyclopropyimethyl)-7-(2-niitrobenzyl)xanthine 1,3-di(cyclopropylmethyl)-8-(2-nitrobenzylamino)-7-(2-nitrobenzyl)- xanthine; 8-chioro- 1,3-di(cyclopropylmethyl)-7-(4-nitrobenzyl)xanthine; 8-amino-1,3-di(cyclopropylmethyl)-7-(-naphthylmethyl)xanthine; 8-chioro- 1,3-di(cyclopropylinethyl)-7-( 1-naphthylmethyl)xanthine; 8-amino-1,3-di(cyclopropylmethyl)-7-(4-nitrobenzyl)xanthine; 1,3-di(cyclopropylmethyl)-7-(4-methoxybenzyl)-8-[2-(2-[N- piperizinyllethoxy)ethoxylxantbine; 1,3-di(cyclopropylmethyl)-7-(4-methoxybeknzyl)-8-(4-piperidin- yloxy)xanthine maleate; 4-[4-(8-[1,3-di(cyclopropylmethyl)-7-(4-methoxybeiu~yl)xanthin- yloxylpiperidinyl)]-4-oxo-butanoic acid; 8-[4-(N-benzyl)piperidinyloxy]-1,3-di(cyclopropylmethyl)-7-(4- methoxybenzyl)xantbine maleate; and diethyl 8-I[i,3-di(cyclopropylmethyl)-7-(4-methoxybenzyl)xanthin- yllmalonate; or if appropriate a pharmaceutically acceptable salt thereof;, or a pharmaceutically acceptable solvate, thereof. c.A~co~ A process for the preparation of a compound of fo~la or where appropriate, a pharmaceutically acceptable salt thereof; or a WO 92/05175 PCT/GB91/01633 pharmaceutically acceptable solvate thereof, which process comprises reacting a compound of formula (II): la R 0 H 12a R (II) wherein R l a represents R 1 as defined in relation to formula or a group convertible to R 1 and R 2 a represents R 2 as defined in relation to formula or a group convertible thereto and R 3 a represents R 3 as defined in relation to formula or a group convertible thereto, with a compound of formula (III): R4-L1 (IH) wherein R 4 is as defined in relation to formula and L 1 represents a leaving group; and thereafter, if required carrying out one or more of the following optional steps: converting any group R l a to R 1 and/or R 2 a to R 2 and/or R3a to R 3 (ii) converting a compound of formula into a further compound of formula (iii) converting a compound of formula into a pharmaceutically acceptable salt thereof; or a pharmaceutically acceptable solvate thereof.

11. A pharmaceutical composition comprising a compound of formula V o av,..oe c.a \coq or where appropriate a pharmaceutically acceptable salt thereof; or a pharmaceutically acceptable solvate thereof, and a pharmaceutically acceptable carrier. -51

12. A method for the treatment of and/or prophylaxis of disorders associated with increased numbers of eosinophils, and allergic disorders associated with atopy which comprises administering an effective amount of a compound of formula (I) according to any one of claims 1 to 9; or where appropriate a pharmaceutically acceptable salt thereof; or a pharmaceutically acceptable solvate thereof to a subject in need thereof.

13. A method according to claim 12, wherein the disorder associated with increased numbers of eosinophils is asthma.

14. A method according to claim 12, wherein the allergic 6, disorder associated with atopy is urticaria, eczema or rhinitis.

15. The use of a compound of formula according to any one S, of claims 1 to 9; or where appropriate a pharmaceutically acceptable salt thereof; or a pharmaceutically acceptable 20 solvate thereof, for the manufacture of a medicament.

16. Compounds of formula processes for their preparation, pharmaceutical compositions containing them or methods or uses involving them, substantially as hereinbefore described with reference to the Examples. DATED this 1st day of July, 1994 Beecham Group p.l.c. By Its Patent Attorneys DAVIES COLLISON CAVE 94070 1,p:\operdb.8543.spe5 I INTERNATIONAL SEARCH REPORT International Application No PCT/GB 91/01633 1. CLASSIFICATION OF SUBJECT MATTER (it several Classification symbols apply, indicate 311)5 According ta International Patent Classification (IPC) or to both National Classification and IPC C 07 D 473/06, A 61 K 31/52 II. FIELDS SEARCHED Minimum Documentation Searched7 Classification System Classification Symbols C07 C Documentation Searched other than Minimum Documentztion to the Extent that such Documents arm Included in Fields Searched 1 Ill. DOCUMENTS CONSIDERED TO BE RELEVANT 9 Category Citation of Document, 11 with Indication, where appropriate, of the relevant passages 12 IRelevant to Claim No. 13 A,P EP,- A2, 0389282 (BEECHAM*I- WUELJFING GMBH CO. KG 1-14 ET AL) 26 September 1990, see the whole document A EP, A2, 0369744 (BEECHAM WUELFING ('9BH CO KG) 1-14 23 May 1990, see the whole document A WO, Al, 8805775 (SANDOZ-ERFINOUNGEN 1-14 VERWALTUNGSGESELLSCHAFT M.B.H.) 11 August 1988, see the whole document Spacial categories of cited doctunents: 10 1T later dopument published altar the iliternational filing date orprority data and not in conflict with the 2ppl cal on but W' docupient defining the general state of the art which is not pited to understand the principle or theory underlying the considered to be oa particular relevance invention fearlier document but published an or altar the international ~dcmn fpjlua eeactecamc neto fiig dataledcmn fprtclrrlvne hecamc neto ontbe considered novel or cannot be considered to LV doilumentwhich may throw doubts pn priority claim(s) or lovean inventive step wCh is cited to esablish the publication dlate of another Youeto atcirlvne h lie neto citaionor oherageial easn (s spcifed)cannot be considered to avolve an Inventive step when the document referring to an oral disclosure, uMe exhibition or document is combined with gne or more other such dou Dechbe art. International Searching Authority Signature of Authorized Officer EUROPEAN PATENT OFFICE Mmne N. KUPER Form POTMIAJ2IO5 (second sheet) (January 1185) ANNEX TO THE INTERNATIONAL SEARCH REPORT ON INTERNATIONAL PATENT APPLICATION NO.PCT/GB 91/01633 SA 51702 This annex lists the patent family members relating to the patent documents cited in the above-mentioned international search report. The members are as contained in the European Patent Office EDP file on 3 1/10/91 The European Pater,' office is in no way liable [or theseparticulars which are merely given for the purpose of information. Pa tent document cited in search report Publica tion date I Patent family member(s) Publication date EP-A2- 0389282 26/09/90 AU-D- CN-A- JP-A- 5208390 1047502 2273676 EP-A2- 0369744 23/05/90 JP-A- 4466789 2178283 27/09/90 05/12/90 08/11/90 17/05/90 11/07/90 02/08/90 03/03/88 02/03/88 WO-Al- 8805775 11/08/88 *AU-B- AU-D- EP-A- 600021 7744587 0258191 For more details about this annex see Official Journal of the European patent Office, No. 12182 EPO FORM P0470