DK175131B1 - 4- (9H-Purin-9-yl) -2-cyclopentenylcarbinols, pharmaceutical compositions containing the compounds and intermediates thereof - Google Patents

Description

in DK 175131 B1

The present invention relates to dideoxycarbocyclic nudeosidanaTo'gé. More specifically, the invention relates to carbocyclic Z Z ^-dideoxy-Z’₂B’-didehydropurine nudeoside analogues and their use in therapy, particularly as antiviral. 5 agents.

* Given the similarity between viral and host cellular functions, it is difficult to selectively attack a virus while leaving the host cell intact. Thus, there are relatively few agents that are effective against viruses persian, and it is difficult to find antiviral agents with an acceptable therapeutic index, ie. agents which have a meaningful antiviral effect at a dose level, at which the agent has an acceptable toxicity or side effect profile.

A group of viruses that have recently gained significant importance are the retroviruses responsible for the human acquired immunodeficiency syndrome (AIDS).

Such viruses have been previously designated by various terminologies but are now generally referred to as human immunodeficiency viruses (HIVs); two such viruses, HIV-I and HIV-II, have been reproducibly isolated from patients suffering from AIDS and related conditions such as AIDS-related complex (ARC) and persistent generalized lymphadenopathy.

Although a number of nudeosides have been described as helpful in treating conditions associated with HIV infections, only azidovudine (AZT,

Retrovir) received regulatory approval for the treatment of such conditions.

25 However, zidovudine is known to have serious side effects, causing bone marrow suppression, leading to a decrease in white blood cell count with consequent pronounced anemia, and there is therefore a need for effective agents that are less cytotoxic. 1

A novel class of antiviral nudeoside analogue has now been found. Accordingly, a first aspect of the invention relates to 4- (9H-purin-9-yl) -2-cydopentenylcarbinols of formula I

DK 175131 B1

By Λ \ Λ /

5 Z N N

HO-CH, I.

wherein X is hydrogen, NRR 1, SR, OR or halogen; Z is hydrogen, OR2 or NRR1; - R, R 1 and R 2 may be the same or different and are selected from hydrogen, C 1-4 alkyl and aryl; and pharmaceutically acceptable derivatives thereof, or pharmaceutically acceptable esters thereof selected from 15 carboxylic acid esters in which the non-carbonyl portion of the ester group is hydrogen, C 1-6 alkyl, C 1-6 alkoxy-C 1-6 alkyl, aryl C 1-6 alkyl, aryloxy-C 1-4 alkyl or optionally with halogen, C 1-4 alkyl or C 1-4 alkoxy substituted aryl; C1-18 alkyl or aryl C1-4 alkylsulfonyl esters; amino acid esters or triphosphate esters, or pharmaceutically acceptable salts of such esters.

EP-A-236935 discloses 2,3-dideoxynucleosides which exhibit anti-HIV activity.

However, surprisingly, it has been found that the present compounds exhibit a substantially higher activity, as well as exhibit a substantially higher therapeutic index.

It will be appreciated by those skilled in the art that the compounds of formula I are cis compounds, and further that the cyclopentene ring of the compounds of formula 1 contains two chiral centers (shown in formula I at *) and can therefore exist in the form of two optical isomers ( i.e., enantiomers) and mixtures thereof, including racemic mixtures.

All such isomers and mixtures thereof including racemic mixtures are within the scope of the invention. Thus, in the compounds of formula I, either the chiral center to which the base is attached is in R configuration and the chiral center to which the CH 2 OH moiety is attached is in S configuration (hereinafter referred to as the 35 D isomer). or the chiral center to which the base is attached is in konf configuration, and the center to which the CH2OH moiety is attached is in R configuration (hereinafter called the L isomer). The compounds are conveniently in the form of either a racemic mixture or substantially as the pure D isomer. The D-isomers can be represented by the formula la 5

X

/ Λ Λ T i \ Ia / w / \ /

10 2 N N

H01> xl

\ _J

15 wherein X and Z are as defined for Formula I. Reference hereinafter to compounds of Formula I comprises compounds of Formula Ia.

It will also be appreciated by those skilled in the art that certain of the compounds of formula I may exist as a number of tautomeric forms and all such tautomers are included in the scope of the invention.

As used herein, the term halogen refers to fluorine, chlorine, bromine and iodine; if X is halogen, it is preferably chlorine.

As used herein, C 1-4 alkyl represents a straight or branched alkyl group, for example methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl and t-butyl. C 1-4 alkyl is preferably methyl.

As used herein, aryl represents any mono- or polycyclic aromatic moiety and comprises unsubstituted and substituted aryl (such as phenyl, tolyl, xylyl, anisyl) and unsubstituted and substituted aralkyl, including ar (C 1-4) alkyl such as phenyl 4, for example, benzyl or phenethyl. In the compounds of formula I, Z is preferably amino.

In one preferred class of compounds of formula I, X represents OR, especially OH.

In a further preferred class of compounds of formula I, X is NRR1, especially NH2, or hydrogen.

Particularly preferred compounds of formula I are those in which Z is NH 2 and X is H, NH 2 or, in particular, OH. In particular, such compounds have particularly desirable therapeutic indices as antivirals.

By the term "pharmaceutically acceptable" in connection with the above-defined salts, esters or salts of such esters of a compound of formula I is meant a compound which, upon administration to the recipient, is capable of providing (directly or indirectly) a compound of formula I or an antivirally active metabolite or residue thereof.

15

Esters of compounds of formula I, as mentioned above, are carboxylic acid esters in which the non-carbonyl portion of the ester group is selected from hydrogen, straight chain or branched alkyl (e.g., methyl, ethyl, n-propyl, t-butyl, n-butyl ), alkoxyalkyl (e.g., methoxymethyl), aralkyl (e.g., benzyl), aryloxyalkyl (e.g., phenoxymethyl), aryl (e.g., phenyl optionally substituted with halogen, C1-4 alkyl or C1-4 alkoxy); sulfonate esters such as alkyl or aralkylsulfonyl (e.g. methanesulfonyl); amino acid esters (e.g., L-valyl or L-isoleucyl) and mono-, di- or triphosphate esters.

With respect to the esters described above, any alkyl moiety present preferably contains 1-4 carbon atoms. Advantageously, any aryl moiety present in such esters comprises a phenyl group.

Pharmaceutically acceptable salts of the compounds of formula I include those derived from pharmaceutically acceptable inorganic and organic acids and bases. Examples of suitable acids include hydrochloric, hydrochloric, sulfuric, nitric, perchloric, fumaric, maleic, phosphoric, glycolic, lactic, salicylic, succinic, toluene-p-sulfonic, tartaric, acetic, nitric, methanoic, -2-sulfonic acid and 35-benzenesulfonic acid. Other acids such as oxalic acid, although not inherently pharmaceutically acceptable, may be useful in the preparation of salts which are useful as intermediates for the preparation of the compounds of the invention and their pharmaceutically acceptable acid addition salts.

Salts derived from appropriate bases include alkali metal salts (e.g., sodium salts), alkaline earth metal salts (e.g., magnesium salts), ammonium salts, and NR 1 salts (where R is C 1-4 alkyl).

References below to a compound of the invention comprise both compounds of formula I and their pharmaceutically acceptable derivatives.

Specific compounds of formula I include: (1a, 4a) -4- (6-Chloro-9H-purin-9-yl) -2-cyclopentenylcarbinol; (1a, 4a) -4- (6-Hydroxy-9H-purin-9-yl) -2-cyclopentenylcarbinol; (La, 4a) -4- (6-Amino-9H-purin-9-yl) -2-cyclopentenylcarbinol; (La, 4a) -4- (6-Mercapto-9H-purin-9-yl) -2-cydopentenylcarbinol; (La, 4a) -4- (2-Amino-6-chloro-9H-purin-9-yl) -2-cyclopentenylcarbinol; (La, 4a) -4- (2-Amino * 6-hydroxy-9H-purin-9-yl) -2-cyclopentenylcarbinol; (1a, 4a) -4- (2,6-Diamino * 9H-purin-9-yl) -2-cyclopentenylcarbinol; in the form of a racemic mixture or single enantiomer.

The compounds of the invention either have antiviral activity per se and / or can be metabolized to such compounds. These compounds are particularly effective in inhibiting the replication of retroviruses, including human retroviruses such as human immunodeficiency viruses (HIVs) that cause AIDS.

Certain compounds of the invention, especially those in which Z is H, also have anticancer activity.

30

Accordingly, a further aspect of the invention is a compound of formula I for use as an active therapeutic agent, especially as an antiviral agent, for example in the treatment of retroviral infections, or as an anticancer agent.

6 DK 175131 B1

Thus, the invention enables a method of treating a viral infection, especially an infection caused by a retrovirus such as HIV, in a mammal, including humans, by which method an effective amount of an antiviral compound of the invention is administered.

In a further or alternative aspect, the invention also relates to the use of a compound of the invention for the manufacture of a medicament for the treatment of a viral infection or use as an anticancer agent.

Compounds of the invention with antiviral activity are also useful in the treatment of AIDS-related conditions such as AIDS-related complex (ARC), progressive generalized lymphadenopathy (PGL), AIDS-related neurological conditions (such as dementia or tropical parapheresis), anti-HIV disease. antibody positive and HIV positive conditions, Kaposi's sarcoma and thrombocytopenia purpura.

15

The antiviral compounds of the invention are also useful in preventing progression until clinical disease in individuals who are anti-HIV antibody or HIV anti-gene positive and in prophylaxis after exposure to HIV.

The antiviral compounds of formula I can also be used to prevent viral contamination of physiological fluids such as blood or semen in vitro.

Some of the compounds of formula I are also useful as intermediates in the preparation of other compounds of the invention.

25

It will be appreciated by those skilled in the art that reference herein to treatment extends to prophylaxis as well as to treatment of established infections or symptoms. 1 2 3 4 5 6

Furthermore, it will be appreciated that the amount of a compound of the invention 2 required for use in treatment will vary not only according to the 3 specifically selected compound, but also according to the route of administration, the nature of the condition being treated. , and the patient's age and condition and will ultimately be determined by the attending physician or veterinarian. However, in general 6, a suitable dose will be in the range of approx. 1 to approx. 750 mg / kg, e.g. from 7 DK 175131 B1 approx. 10 to approx. 750 mg / kg body weight per day such as from 3 to approx. 120 mg / kg body weight of the recipient per per day, preferably in the range of 6-90 mg / kg / day, especially in the range of 15-60 mg / kg / day.

The desired dose may conveniently be presented as a single dose or as divided doses administered at appropriate intervals, e.g., as 2, 3, 4 or more sub-doses per dose. day.

The compound is conveniently administered in unit dosage form; e.g. containing 10 10-1500 mg, suitably 20-1000 mg, especially 50-700 mg of active ingredient per day. unit dosage form.

Ideally, the active ingredient should be administered so as to obtain plasma peak concentrations of the active ingredient of from ca. 1 to approx. 75 µΜ, preferably 15 ca. 2-50 μΜ, especially from approx. 3 to approx. 30 μΜ. This can be achieved, for example, by intravenous injection of a 0.1-5% solution of the active ingredient, optionally in saline, or administered orally as a bolus containing from ca. 1 to approx. 100 mg of the active ingredient, desired blood levels, can be maintained by continuous infusion to give from ca. 0.01 to approx. 5.0 mg / kg / tyrene or with interrupted infusions containing from ca. 0.4 to approx. 15 mg / kg of the active ingredient.

While it is possible for use in therapy that a compound of the invention may be administered as the crude chemical, it is preferred to present the active ingredient as a pharmaceutical composition.

25

Thus, the invention further relates to a pharmaceutical composition comprising a compound of formula I together with one or more pharmaceutically acceptable carriers therefor and, optionally, other therapeutic and / or prophylactic ingredients. The carrier (s) must be "acceptable" in the sense that they are compatible with the other constituents of the preparation and are not harmful to the recipient.

Pharmaceutical compositions include those suitable for oral, rectal, nasal, topical (including buccal and sublingual), vaginal or parenteral (including intramuscular, subcutaneous, and intravenous) administration or in a form suitable for administration. B1 net for inhalation or insufflation administration. The compositions may, where appropriate, be conveniently presented in separate dosage units and may be prepared by any of the methods well known in the art. All methods include the step of contacting the active compound with liquid carriers or finely divided solid carriers or both and then, if necessary, forming the product into the desired composition.

Conveniently, pharmaceutical compositions suitable for oral administration may be presented as separate units such as capsules, letters or tablets, each containing a predetermined amount of the active ingredient; as a powder or as granules; as a solution, suspension or as an emulsion. The active ingredient may also be presented as a bolus, lathe or paste. Tablets and capsules for oral administration may contain conventional excipients such as binders, fillers, lubricants, explosives or wetting agents. The tablets may be coated according to methods well known in the art. Oral liquid preparations may be in the form of, for example, aqueous or oily suspensions, solutions, emulsions, syrups or elixirs or may be presented as a dry product for constitution with water or another suitable carrier prior to use. Such liquid compositions may contain conventional additives such as suspending agents, emulsifiers, non-aqueous carriers (which may include edible oils) or preservatives.

The compounds of the invention may also be formulated for parenteral administration (e.g., by injection, e.g., bolus injection or continuous infusion) and may be presented in unit dose form in ampoules, pre-filled syringes, small volume infusion or in multi-dose containers with an added preservative. The compositions may take such forms as suspensions, solutions or emulsions in oily or aqueous carriers and may contain formulation agents such as suspending, stabilizing and / or dispersing agents. Alternatively, the active ingredient may be in powder form obtained by aseptic isolation of sterile solid or by lyophilization from solution, for constitution with a suitable carrier, e.g. sterile pyrogen-free water, before use.

9 DK 175131 B1

For topical administration to the epidermis, the compounds of the invention may be formulated as ointments, creams or lotions or as a transdermal patch. Ointments and creams may, for example, be formulated with an aqueous or oily base with the addition of suitable thickening and / or gelling agents. Lotions may be formulated with an aqueous or oily base and will generally also contain one or more emulsifiers, stabilizers, dispersing agents, suspending agents, thickening agents or coloring agents.

Formulations suitable for topical oral administration include agents comprising an active ingredient in a flavored base, usually sucrose and acacia or tragacanth; lozenges comprising the active ingredient in an inert base such as gelatin and glycerine or sucrose and acacia; and mouthwashes comprising the active ingredient in a suitable liquid carrier.

Pharmaceutical compositions suitable for rectal administration, wherein the carrier is a solid, are preferably presented as unit dose suppositories. Suitable carriers include cocoa butter and other materials commonly used in the art, and the suppositories may conveniently be formed by mixing the active compound with the softened or melted carrier or carriers followed by cooling and molding.

Formulations suitable for vaginal administration may be present as pessaries, tampons, creams, gels, pastes, foams or sprays containing, in addition to the active ingredient, such carriers known in the art as relevant.

For intranasal administration, the compounds of the invention can be used as a liquid spray or in the form of drops.

Drops may be formulated with an aqueous or non-aqueous basis as well as comprising one or more dispersants, solubilizers or suspending agents.

Liquid sprays are conveniently delivered from pressure seals.

For administration by inhalation, the compounds of the invention are suitably dispensed from an insufflator, nebulizer, or a pressure pack or other suitable means for delivering an aerosol spray. Pressure gaskets may include a suitable propellant such as dichlorodifluoromethane, trichlorofluoromethane, dichloro-trifluoroethane, carbon dioxide or other suitable gas. In the case of a pressure aerosol, the dosage unit may be determined by providing a valve which delivers a metered amount.

Alternatively, for administration by inhalation or insufflation, the compounds of the invention may be in the form of a dry powder composition, e.g., a powder blend of the invention and a suitable powder base such as lactose or starch. The powder composition may be presented in unit dosage form in, for example, capsules or cartridges or, for example, gelatin or blister packs, from which the powder may be administered by means of an inhaler or insufflator.

If desired, the above-described compositions adapted to provide prolonged release of the active ingredient may be used.

The pharmaceutical compositions of the invention may also contain other active ingredients such as antimicrobial or preservatives.

2b The compounds of the invention may also be used in combination with other therapeutic agents, e.g., other anti-infective agents. In particular, the compounds of the invention can be used with known antiviral agents.

Thus, in a further aspect, the present invention relates to a combination comprising a compound of formula I together with another therapeutically active agent, in particular an antiviral agent.

The combinations referred to above may conveniently be presented for use in the form of a pharmaceutical composition, and pharmaceutical compositions comprising a combination as defined above together with a pharmaceutically acceptable carrier therefor thus constitute a further aspect of the invention.

Suitable therapeutic agents for use in such combinations include 35 acyclic nucleosides such as aciclovir, interferons such as α-interferon, renal excretion inhibitors such as probenicide, nucleoside transport inhibitors such as dipyridamole, 2 ', 3' dideoxynucleosides such as 2 ', 3' dideoxycytidine, 2 ', 3'-dide oxyadenosine, 2', 3'-dideoxyinozine, 2, 3'-dideoxythymidine and 2 ', 3'-dideoxy-2,3,3-didehydrothymidine and immunomodulators such as interleukin II (IL2) and granulocyte macrophage colony-stimulating factor (GM-CSF), erythropoietin and ampligen.

The individual components of such combinations can be administered either sequentially or simultaneously in separate or combined pharmaceutical preparations.

10

If the compound of formula I or a pharmaceutically acceptable derivative thereof is used in combination with another therapeutic agent which is active against the same virus, the dose of each compound may be different from the dose when the compound is used alone. Appropriate doses will be readily ascertainable by those skilled in the art.

15

The compounds of formula I and their pharmaceutically acceptable derivatives can be prepared by any method known in the art for preparing compounds of analogous structure. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Suitable methods for preparing compounds of formula I and their pharmaceutically acceptable derivatives are described below; groups X and Z are as defined 3 right above unless otherwise stated. It will be understood that the following 4 reactions may require the use of or suitably be applied to starting materials with protected functional groups, and deprotection may thus be necessary as an intermediate or final step to provide the desired compound. . Protection and deprotection of functional groups can be performed using conventional techniques. Thus, for example, amino groups 9 may be protected by a group selected from aralkyl (e.g. benzyl), acyl or aryl (e.g. 2,4-dinitrophenyl); Subsequent removal of the protecting group is carried out when desired by hydrolysis or hydrogenolysis, as appropriate, using 12 standard conditions. Hydroxy groups can be protected under 13 using any conventional hydroxy protecting group, eg 14 as described in "Protective Groups in Organic Chemistry", Ed. J.F.W. McOmie 15 (Plenum Press, 1973) or "Protective Groups in Organic Synthesis" by Theodora 16 W. Greene (John Wiley and Sons, 1981). Examples of suitable hydroxy protecting groups include groups selected from alkyl (e.g. methyl, t-butyl or methoxymethyl), aralkyl (e.g. benzyl, diphenylmethyl or triphenylmethyl), heterocyclic groups such as tetrahydropyranyl, acyl (e.g. acetyl or benzoyl) and silyl groups. such as trialkylsilyl (e.g. t-butyldimethylsilyl). The hydroxy protecting groups can be removed by conventional techniques. Thus, for example, alkyl, silyl, acyl and heterocyclic groups can be removed by solvolysis, for example, by hydrolysis under acidic or basic conditions. Aralkyl groups such as triphenylmethyl can similarly be removed by solvolysis, for example, by hydrolysis under acidic conditions. Aralkyl groups such as benzyl may be removed by hydrogenolysis in the presence of a precious metal catalyst such as palladium on charcoal. Silyl groups may also conveniently be removed using a fluorine source such as tetra-n-butylammonium fluoride.

In a first process (A), compounds of formula I and pharmaceutically acceptable derivatives thereof can be prepared by a compound of formula II

Ϊ A Λ N · I i 20 / \\ / \ 2 N NH, | Λ • ·

1_I

(Wherein X and Z are substituents of the meaning of formula I or are protected forms thereof and Y is OH or a protected form thereof) or a pharmaceutically acceptable derivative thereof reacted with a reagent selected from formic acid and reactive derivatives thereof, if necessary, followed by the removal of undesirable groups introduced by said reagent and / or by removal of any protecting groups present.

Examples of suitable derivatives of formic acid which may be used in process (A) above include orthoformates (e.g., triethyl orthoformate), dialkoxymethyl acetates 13 (175131 B1 (e.g., diethoxymethyl acetate), dithiomyric acid, formamide, s-triazine or formamine acetate).

Adverse groups introduced by formic acid or a reactive derivative thereof can conveniently be removed by mild hydrolysis, for example using an inorganic acid such as aqueous hydrochloric acid.

If a trialkyl orthoformate such as triethyl orthoformate is used, this is suitably also solvent for the reaction. Other solvents which may be used include amides (e.g., dimethylformamide or dimethylacetamide), chlorinated hydrocarbons (e.g., dichloromethane), ethers (e.g., tetrahydrofuran), or nitriles (e.g., acetonitrile).

In certain cases (e.g., if a trialkyl orthoformate such as triethyl orthoformate is used), the reaction may conveniently be carried out in the presence of a catalyst such as a strong acid (e.g., concentrated hydrochloric acid, hydrochloric acid or sulfuric acid). The reaction can be carried out at a temperature in the range of -25 ° C to + 150 ° C, eg 0-100 ° C and conveniently at ambient temperature.

In another process (B), compounds of formula I and pharmaceutically acceptable derivatives thereof or a protected form thereof are subjected to an interconversion reaction, whereby substituent X present initially is replaced by another substituent X and / or that group Z, which is initially present, is replaced by another group Z, if necessary, followed by the removal of any 25 protecting groups present.

Conditions for converting halides to secondary and tertiary amines are also described by I.T. Harrison et. al., Compendium of Organic Synthetic Methods, Wiley-Interscience, New York (1971) on pages 250-252.

In another embodiment of process (B), compounds of formula I in which X is a group OR (wherein R is as defined above) can be prepared by displacing the halogen atom (e.g. chlorine) with a suitable anion RO ". is a hydrogen atom, the displacement reaction can be carried out by hydrolysis which can be carried out in water or in a mixture of water and a water miscible solvent such as an alcohol (e.g., methanol or ethanol), an ether (e.g., dioxane or tetrahydrohydrocarbon). furan), a ketone (e.g., acetone), an amide (e.g., dimethylformamide) or a sulfoxide (e.g., dimethylsulfoxide), conveniently in the presence of an acid or base. Suitable acids include organic acids such as p Suitable bases include inorganic bases such as alkali metal hydroxides or carbonates (e.g., sodium or potassium hydroxide or carbonate). Aqueous acid or base can also be used as a reaction solvent. n can conveniently be performed at a temperature in the range of -10 ° C to + 150 ° C, for example at reflux. If R is a C 1-4 alkyl or aryl group, the anion RO * is conveniently formed from a corresponding alcohol ROH using an inorganic base such as an alkali metal (e.g., sodium metal) or an alkali metal hydride (e.g., sodium hydride). The reaction with the in situ formed anion may conveniently be carried out at ambient temperature. In a further embodiment of process (B), compounds of formula I wherein 2 X is a group SH may be prepared by substituting thiourea with the halogen compound of formula I in a suitable solvent such as an alcohol (e.g. n-4 propanol) at elevated temperature (e.g. reflux) followed by alkaline hydro 5 lysis. Suitable bases which can be used include alkali metal hydroxides (e.g., sodium hydroxide). The reaction may conveniently be carried out according to the method described by G.G. Urquart et. al., org. Vision. Coll. Vol. 3, 363 (1953), for example, by refluxing the intermediate with aqueous NaOH for from ca. 0.25 to approx.

5 hours.

In yet another embodiment of process (B), compounds of formula I, which X is a hydrogen atom, can be prepared by reducing the halogen compound of formula I using a reducing system which will not affect the rest of the molecule. Suitable reducing agents which can be used to effect the desired dehalogenation reaction include zinc metal / water using the method described by J.R. Marshall et. al., J. Chem. Soc., 1004 (1951). Alternatively, the reaction can be carried out by photolysis in a suitable solvent such as tetrahydrofuran containing 10% triethylamine and suitably in a Raoynet photochemical reactor (2537A) according to the method described by V. Nair et. al., J. Org. Chem., 52, 1344 (1987).

In yet another embodiment of process (B), compounds of formula I wherein X is halogen can be prepared from another halogen compound of formula I by conventional halide-halide replacement methods. Alternatively, if X is chlorine, this substituent may be replaced by other halogen atoms using various p- (halogen) benzenediazonium chlorides in accordance with well known procedures.

Compounds of formula I in which X is a group SR wherein R is C 1-6 alkyl or aryl can be prepared from the corresponding thiols using standard alkylation or arylation methods, for example, as described in U.S. Pat.

4383114.

Compounds of formula I wherein Z is a hydroxy group may conveniently be prepared from a corresponding compound of formula I in which Z is NH 2 / by reaction with hydrochloric acid, for example, using the procedure described by J.

Davoll, J. Amer. Chem. Soc., 73, 3174 (1951).

Many of the reactions described above have been extensively reported in the context of purine nucleoside synthesis, e.g., in Nucleoside Analogs-Chemistry, Biology and Medical Applications, edited by R.T. Walker et. eel,

Plenum Pless, New York (1979) on pages 193-223, to which reference is made.

Pharmaceutically acceptable salts of the compounds of the invention may be prepared as described in U.S. Patent No. 4,383,114 to which reference is made. For example, if it is desired to prepare an acid addition salt of a compound of formula I, the product of any of the above processes can be converted to a salt by treating the resulting free base with a suitable acid using conventional acid. methods. Pharmaceutically acceptable acid addition salts 5 can be prepared by reacting the free base with an appropriate acid, optionally in the presence of a suitable solvent such as an ester (e.g., ethyl acetate) or an alcohol (e.g., methanol, ethanol, or isopropanol). Inorganic basic salts can be prepared by reacting the free base with a suitable base such as an alkoxide (e.g. sodium hydroxide), optionally in the presence of a solvent such as an alcohol (e.g. methanol). Pharmaceutically acceptable salts may also be prepared from other salts, including other pharmaceutically acceptable salts, of the compounds of formula I using conventional methods.

A compound of formula I may, as appropriate, be converted to a pharmaceutically acceptable phosphate or other ester by reaction with a phosphorylating agent such as POCl 3 or a suitable esterifying agent such as an acid halide or anhydride. An ester or salt of a compound of formula I can be converted to the parent compound by, for example, hydrolysis.

Compounds of formula II and salts thereof are novel compounds and constitute a further aspect of the present invention.

The compounds of formula II in which Z is hydrogen or hydroxy may be prepared directly from the compound 2a 25 -ΤΛΡ # o I_I 2a 30

by reaction with an excess of a pyrimidine of formula III

35 17 DK 175131 B1

X

in NH 111 N · I I * · ς / \\ / \

5 Z N Y

wherein Y is halogen, e.g., chlorine, and Z is hydrogen or hydroxy, in the presence of an amine base such as triethylamine and in an alcoholic solvent (e.g., n-butanol), preferably at reflux.

10

Compounds of formula II in which Z is NH 2 can be prepared using the compound of formula 2a by reacting with an excess of a pyrimidine of formula IV

15

X

! /% T i iv • e / w / \

20 H2N N Y

wherein Y is as defined in formula III above, under conditions similar to those described just above for the preparation of compounds of formula II, in which Z is hydrogen or hydroxy, to form a compound of formula V

X

0 // \ N · \ I o> 30 Λ Λ H2N N NH v

Htw% Λ • ·

1 _I

35 18 DK 175131 B1

which can be diazotized using a diazonium salt ArN2 + E '(wherein Ar is an aromatic group, e.g. p-chlorophenyl, and E' is an anion, e.g., a halide such as chloride) in a solvent such as water, an organic acid such as acetic acid or a mixture thereof, conveniently at about ambient temperature, to form a compound of formula VI

X

i N = N-Ar // \ / ΐ; • · 10 H2f / V \ h

ho-ch2x 7 · χ VI

Wherein Ar is as defined just above which can be converted to the desired compound of formula II by reduction using, for example, a reducing metal such as zinc in the presence of an acid, eg acetic acid. It will be clear that the choice of reducing agent will depend on the nature of the group X.

The compound 2a can be prepared from the widely applicable precursor 1a-acetyl-20-amino-3a-acetoxy-methylcyclopent-2-ene (1a) by hydrolysis in the presence of a mild base such as an alkaline earth metal hydroxide.

A particularly convenient synthesis of compounds of formula I via 6-chloro compounds of formula II is outlined below.

DK 175131 B1 19 | 51 Λ / NH * N ·

! B

Λ Λ

1 H HH

NHAc NH-

• “">%] “^ λΙ --IA

1—1 -> I I -i-> I \ la 2nd in 'ir f1 ^ fwo; - tV a \

A - * “/ v \ _> / vV

Tf Tv τΐ 15 LJ i =. Li 5a A 6β (I) t f1

A

2 ° ΐ ί Λ Λ π2ν Ν \ Μ0-ΐΛ.

I_ 25 * 4β

Compound 2a and compounds of formulas V and VI are novel intermediates and constitute further aspects of the present invention.

The compound 1a is a known compound disclosed in U.S. Patent No. 4,138,562.

If the compound of formula I is desired as a single isomer, it can be obtained either by cleavage of the final product or by stereospecific synthesis from isomerically pure starting material or any convenient intermediate.

20 DK 175131 B1

Therefore, cleavage of the final product or an intermediate product or starting material can be carried out by any suitable method known in the art: see, for example, "Stereochemistry of Carbon Compounds" by E.L. Eliel (McGraw Hiil, 1962) and "Tables of Resolving Agents" by S.H. Wilen.

5

A convenient method of obtaining chirally pure compounds of formula I is by enzymatic conversion of a racemic mixture of the compound or a precursor thereof. In such a method, both (+) and (-) compounds of formula I can be obtained in optically pure form. Suitable enzymes include deaminases such as adenosine deaminase.

The invention is further illustrated with reference to the following detailed examples in which elemental analyzes were performed by N-H-W Laboratories,

Phoenix, Arizona, USA. Melting points were determined on a Mel-Temp apparatus and are corrected. Nuclear magnetic resonance spectra were recorded on Jeol FX 90QFT or Nicollet NT300 spectrometers and were recorded in DMSO-D6. Chemical shift values are expressed in ppm downfield relative to Me4Si. IR spectra were determined as KBr pellets with a Nicollet 50XC FT-IR spectrometer and UV spectra were determined on a Beckmann DU-8 spectrophotometer. Mass spectra were recorded using an AEI Scientific Apparatus Limited MS-30 mass spectrometer.

Thin layer chromatography (TLC) was performed on 0.25 mm layer of Merck silica gel (0.063-0.037 mm, 230-400 mesh). All chemicals and solvents are reagent grade unless otherwise stated. The term "active ingredient" as used in the Examples denotes a compound of formula I or a pharmaceutically acceptable derivative thereof.

Example 1 (±) - (1α, 4a) -4 - [(5-Amino-6-chloro-4-pyrimidinyl) amino] -2-cyclopentenylcarbinol (3a)

A mixture of 1a-acetylamino-3-a-acetoxymethyl-cydopent-2-ene (1a) (3.0 g, 15 mmol) and aqueous barium hydroxide (0.5N, 300 ml) was refluxed overnight. After cooling, the mixture was neutralized with dry ice. The precipitate was filtered off and the aqueous solution was concentrated to dryness. The residue was extracted with absolute ethanol and concentrated again to give 2a as a colorless syrup, 1.6 g (14 mmol).

To this syrup was added 5-amino-4,6-dichloropyrimidine (4.59 g 28 mmol), triethylamine (4.2 g, 42 mmol) and n-butanol (50 ml) and the mixture was refluxed. - for 24 hours. The volatile solvents were removed and the residue was absorbed on silica gel (7 g), packed in a flash column (4.0 x 12 cm) and eluted with CHCh-MeOH (20: 1) to give 2.69 g ( 74%) of compound 3a; mp 10 130-132 ° C. An analytical sample was obtained by recrystallization from ethyl acetate (EtOAc), mp 134-135 ° C, MS (30 ev, 200 ° C); m / e 240 and 242 (M + and M ++ 2), 209 (M + * 31), 144 (B +); IR: 3600-2600 (OH), 1620, 1580 (C = C, C = N); Analysis (C 10 H 13 ClN 4 O) C, Η, N.

Example 2 (±) - (1a, 4a) -4 - [(2-Amino-6-chloro-4-pyrimidinyl) amino] -2-cydopentenylcarbinol (4a)

To 14 mmol of crude 2a (Example 1) was added 2-amino-4,6-dichloropyrimidine (3.74 g, 22.8 mmol), triethylamine (15 ml) and n-butanol (75 ml) and reflux for 48 hours. The volatile solvents were removed and the residue was treated with methanol to separate the undissolved by-product (the double pyrimidine nudeoside). The methanol solution was absorbed on silica gel (8 g), packed in a column (4.0 x 14 cm) and eluted with CHCl 3 -MeOH (40: 1) to give 1.52 g (42%) of crude 4a. The product was recrystallized from ethyl acetate to give 4a; mp 132-134 ° C, MS (30 ev, 200 ° C); m / e 30 240 and 242 (M + and M ++ 2), 209, (M + '31), 144 (B +); IR: 3600-3000 (NH 2, OH), 1620, 1580 (C = C, C = N); analysis (C 10 H 3 ClN 4) C, Η, N.

(±) - (1a, 4a) -4 - [(2-Amino-6-chloro-5 (4-chlorophenyl) -azo] -4-pyrimidinylamino) -2-cydopentenylcarbinol (5a) EXAMPLE 3 22 DK 175131 B1

A cold diazonium salt solution was prepared from p-chloroaniline (1.47 g, 11.5 mmol) in 3N HCl (25 mL) and sodium nitrite (870 mg 12.5 mmol) in water (10 mL).

This solution was added to a mixture of 4a (2.40 g, 10 mmol), acetic acid (50 ml), water (50 ml) and sodium acetate trihydrate (20 g). The reaction mixture was stirred overnight at room temperature. The yellow precipitate was filtered off and washed with cold water until a neutral reaction, then air-dried in a fume hood to give 3.60 g (94%) of 5a, mp 229 ° C (dec.). The analytical sample was obtained from acetone-methanol (1: 2), mp 241-243 ° C (dec.). MS (30 ev, 260 ° C): m / e 15 378 and 380 (M + and M ++ 2), 282 (B +); IR: 3600-3000 (NH 2, OH), 1620, 1580 (C = C, C = N); Analysis (C16H16Cl2N60) C, Η, N.

EXAMPLE 4 (±) - (1a, 4a) -4 - [(2,5-Diamino-6-chloro-4-pyrimidinyl) amino] -2-cyclopentenylcarbinol (6a) 1 2 3 4 5 6 35

A mixture of 5a (379 mg, 1 mmol), zinc dust (0.65 g, 10 mmol), acetic acid 2 (0.32 ml), water (15 ml) and ethanol (15 ml) was refluxed under nitrogen for 3 hours. hours. The zinc was removed and the solvents evaporated. The residue 4 was absorbed on silica gel (2 g), packed in a column (2.0 x 18 cm) and eluted with 5 CHCl 3 -MeOH (15: 1). A pink syrup was obtained. Further purification from 6 methanol-ether gave 6a as pink crystals, 170 mg (66%), m.p., 168-170 ° C, MS (30 ev, 220 ° C); m / e 255 and 257 (M + and M ++ 2), 224 (M + '31), 159 (B +); IR: 3600-3000 (NH 2, OH) 1620, 1580 (C = C, C = N); analysis (C10HhCIN5) C, Η, N.

(±) - (1a, 4a) -4 - [(6-Chloro-9H-purin-9-yl) -2-cydopentenylcarbinol (7a) EXAMPLE 5 A mixture of 3a (1.30 g, 5.4 mmol), triethyl orthoformate (30 ml) and hydrochloric acid (12N, 0.50 ml) were stirred overnight at room temperature. The solvent was removed at 35 ° C in vacuo. To the residue was added hydrochloric acid (0.5 N, 30 ml) and the mixture was stirred for 1 hour, then the mixture was neutralized to pH 7-8 with 1N sodium hydroxide and absorbed on silica gel (8 g), packed 10 in a column (4.0 x 8 cm) and eluted with CHCl 3 -MeOH (20: 1) to give white crystals of 7a, 1.12 g (82%). The crude product was recrystallized from ethyl acetate to give 7a, mp 108-110 ° C, MS (30 ev, 200 ° C); m / e 250 and 252 (M + -2), 219 (M + '31), 154 (B +); IR; 3600-2800 (OH), 1600 (C = C, C = N); Analysis (CnHuCl2) C, Η, N.

Example 6 (±) - (1a, 4a) -4 - [(6-Hydroxy-9H-purin-9-yl) -2-cyclopentenylcarbinol (8a)

A mixture of 7a (251 mg, 1 mmol) and aqueous sodium hydroxide (0.2N, 10 ml) was refluxed for 3 hours. After cooling, the reaction mixture was adjusted to pH

5-6 with acetic acid. The reaction mixture was absorbed on silica gel (2 g), packed in a column (2.0 x 11 cm) and eluted with CHCl 3 -MeOH (10: 1) to give 105 mg (45%) of 8a. The crude white product was recrystallized from water-methanol (3: 1) to give 8a, mp 248-250 ° C (dec.), MS (30 ev, 300 ° C); m / e 232 (M +), 214 (M + 18), 136 (B +); IR; 3600-2600 (OH), 1680, 1600 (C = 0, C = C, C = N); Analysis (C11H12N4O2) C, Η, N.

EXAMPLE 7 (± Hla, 4a) -4 - [(6-Amino-9H-purin-9-yl) -2-cyclopentenylcarbinol (9a) Liquid ammonia was introduced into a bomb containing a solution of 7a (250 mg, 1 mmol) in methanol (5 ml) at -80 ° C. The bomb was sealed and heated at 60 ° C for 24 hours. Ammonia and methanol were evaporated and the residue was recrystallized from water to give off-white crystals of 9a, 187 mg (81%), mp 198-200 ° C, MS 10 (30 ev, 210 ° C): m / e 231 (M +), 213 (M + 18), 135 (B +); IR: 3600-2600 (NH 2, OH), 1700, 1600 (C = C, C = N); Analysis (CnH13NsO) C, Η, N.

Example 8 (±) - (1a, 4a) -4 - [(6-Mercapto-9H-purin-9-yl) -2-cyclopentenylcarbinol (10a) 1 2 3 4 5 6 7 8 9 10 11

A mixture of 7a (125 mg, 0.5 mmol), thiourea (40 mg, 0.64 mmol) 2 and n-propanol (5 ml) was refluxed for 2 hours. After cooling, the precipitate 3 was isolated by filtration, washed with n-propanol and dissolved in sodium hydroxide (1N, 4 ml). The solution was adjusted to pH 5 by acetic acid. The pure compound 5 10a (90 mg, 73%) was isolated again, m.p. 260-262 ° C (decomposition) and 6 was recrystallized from Ν, Ν-dimethylformamide to give 10a, mp 7 263-265 ° C (decomposition). , MS (30 ev, 290 ° C): m / e 248 (M +), 230 (M + 18), 152 (B +); IR: 3600-3200 (OH), 3100, 2400 (SH), 1600 (C = C, 9 C = N); Analysis (C11H12N4OS) C, Η, N.

11 (±) - (1a, 4a) -4 - [(2-Amino-6-chloro-9H-purin-9-yl) -2-cyclopentenylcarbinol (13a) EXAMPLE 9 A mixture of 6a ( 1.41 g, 5.5 mmol), triethyl orthoformate (30 ml) and hydrochloric acid (12N, 1.40 ml) were stirred overnight. The suspension was dried in vacuo. Dilute hydrochloric acid (0.5N, 40 ml) was added and the mixture was reacted at room temperature for 1 hour. The mixture was neutralized to pH 8 with 1N sodium hydroxide and absorbed in silica gel (7.5 g), packed in a column (4.0 x 10 cm) and eluted with CHCl 3 -MeOH (20: 1) to give off -white crystals of compound 13a, 1.18 g (80%). The crude product was recrystallized from ethanol to give 13a, mp 145-147 ° C, MS (30 ev, 220 ° C): m / e 265 and 267 (M + and M ++ 2), 235 (M + * 30) , 169 (B +); IR: 3600-2600 (NH 2, OH), 620-1580 (C = C, C = N); Analysis (ΟπΗ, 2Ν5οα.3 / 4 H2 O) C, Η, N.

EXAMPLE 10 (±) - (1a, 4a) -4 - [(2-Amino-6-hydroxy-9H-purin-9-yl) -2-cydopentenylcarbinol (14a)

A mixture of 13a (266 mg, 1 mmol) and aqueous sodium hydroxide (0.33N) was refluxed for 5 hours, absorbed on silica gel (2 g), packed in a column (2.0 x 7.5 cm) and eluted with CHCl 3 -MeOH (5: 1). The crude product was recrystallized from methanol-25 water (1: 4) to give white crystals of compound 14a, 152 mg (61%), mp 254-256 ° C (dec.), MS (30 ev, 200 ° C): m / e 247 (M +), 217 (M + '30), 151 (B +); IR: 3600-2600 (NH 2, OH), 1700, 1600 (C = O, C = C, C = N); analysis (0 „, 3Ν502.3 / 4H₂O) C, Η, N. 1 (±) - (1α, 4a) -4 - [(2,6-Diamino-9H-purin-9-yl) -2 -cydopentenylcarbinol (15a) EXAMPLE 11 26 Liquid ammonia was introduced into a solution of 13a (265 mg, 1 mmol) in methanol (10 ml) at -80 ° C in a bomb. The bomb was sealed and heated at 75 ° C for 48 hours. Ammonia and methanol were evaporated. The residue was absorbed on silica gel (2 g), packed in a column (2.0 x 10 cm) and eluted with CHCl 3 -MeOH (15: 1). The crude product was recrystallized from ethanol to give 196 mg 10 (80%) of 15a, mp 152-155 ° C, MS (30 ev, 200 ° C): m / e 246 (M +), 229 (M + '17 ), 216 (M + '30), 150 (B +); IR: 3600-3000 (NH 2, OH), 1700, 1650, 1600 (C = O, C = C, C = N); analysis (CnHHN60) C, Η, N.

Example 12 (1S, 4R) -4 (2,6-Diamino-9H-purin-9-yl) -2-cyclopentenylcarbinol [(1S, 4R) -4- (2,6-Diamino-9H-purin-9 -Yl) - 2-cyclopentene methanol] (a) Intermediate 1: (1R, 2S, 3R, 5R) -3- [6-Amino-9H-purin-9-yl] -5 - [((1,1- dimethylethyl) dimethylsilyloxy (methyl) -1,2-cyclopentanediol (-) Aristeromycin (12.505 g), tert-butyldimethylsilyl chloride (7.8 g) and imidazole (12.96 g) in dry dimethylformamide (85 ml) stirring at ambient temperature for 2 1/2 hours. The resulting solution was diluted with ethyl acetate (500 mL) and then washed with water (3 x 100 mL) and brine (50 mL) before a white solid crystallized out. This was collected by filtration, washed with ethyl acetate and then dried in vacuo to give the title product (3.92 g); * H 30 p.m. (DMSO-d6) 8.15 (1H), 8.09 (1H), 7.19 (2H), 5.00 (1H), 4.72 (1H), 4.69 (1H), 4.36 (1H), 3.85 (1H), 3.67 (2H), 2.23 (1H), 2.09 (1H), 1.79 (1H), 0.89 (9H), 0.07 ( 6H).

35

Journal of the American Chemical Society 1983, vol 105, 4049-4055.

Intermediate 2: (4R, 3aS, 6R, 6aR) -4- [6-Amino-9H-purin-9-yl] -6 - [((1,1-dimethylethyl) - dimethylsilyloxy) methyl] -3a, 5,6,6a-tetrahydro-4H-cyclopenta-1,3-dioxol-2-thione A stirred suspension of intermediate 1 (3.45 g) in dry dimethylformamide (56 ml) was treated. with Ι, Ι'-thiocarbonyldiimidazole (3.3 g) to give a yellow solution. After 15 1/2 hours at ambient temperature, the resulting solution was combined with the corresponding solution from a previous experiment (scale 6%) and the solvent removed by evaporation. The remaining oil 10 was diluted with ethyl acetate (100 ml), then washed with water (2 x 20 ml) and brine (2 x 20 ml), dried (MgSO 4) and evaporated to a yellow solid. This was washed with diethyl ether (25 ml) collected by filtration, washed further with ether (25 ml) and then dried in vacuo to give the title compound as a light cream solid (3.61 g); Xmax (ethanol) 240, Onm (E1% lcm 459); IH n.m.r.

(DMSO-d6) 8.27 (1H), 8.13 (1H), 7.33 (2H), 5.81 (1H), 5.37 (1H), 5.28 (1H), 78 (2H), 2.60 (1H), 2.28 (2H), 0.90 (9H), 0.09 (6H).

(c) Intermediate 3: (rR, 4'S) -9- [4 - (((1,1-Dimethylethyl) dimethylsilyloxy) -methyl) -2-cyclopenten-1-yl] -9H-purin-6-amine

A solution of intermediate 2 (3.57 g) in dry tetrahydrofuran (25 ml) was treated with a solution of 1,3-dimethyl-2-phenyl-1,3,2-diazaphospholidine (4.94 g) in dry tetrahydrofuran (10 ml) and then stirred at ambient temperature for 8 3/4 hours. The solvent was removed by evaporation. The remaining oil was combined with the corresponding oil from a previous experiment (scale 40%) and then subjected to column chromatography on silica gel (200 g, Merck 7734) eluted with chloroform and then chloroform-ethanol mixtures to give a white solid. This solid was washed with diethyl ether (25 ml) and then collected by filtration. The solid was further washed with ether (10 ml) and then dried in vacuo to give the title product (1.47 g); Xmax (ethanol) 261.4nm (E1% 1cm 443); IH n.m.r. (DMSO-d6) 8.14 (1H), 8.00 (1H), 7 (2H), 6.12 (1H), 5.95 (1H), 5.60 (1H), 3.66 (1H) 2H), 2.96 (1H), 2.69 (1H), 1.65 (1H), 0.74 (9H), 0.02 (6H).

(D) Intermediate 4: (rR, 4'S) -9- [4 - (((1,1-Dimethylethyl) dimethylsilyloxy) -methyl) -2-cyclopenten-1-yl] -9H-purine-6 amine, l-oxide

A solution of intermediate 3 (1.37 g) in chloroform (30 ml) was treated with 80-90% m-chloroperoxybenzoic acid (1.29 g) and then stirred at ambient temperature for 3 hours. Solvent was removed by evaporation and the remaining gum was dissolved in ethyl acetate (10 ml). A white substance crystallized out. This solid and material recovered by evaporation of the filtrate were dissolved in chloroform (100 ml) and then washed with saturated aqueous sodium hydrogen carbonate solution (3 x 10 ml) and brine (2 x 10 ml). The aqueous wash phases were back extracted with chloroform (50 ml). The combined organic solutions were dried (MgSO 4) and then evaporated to a solid. This solid was washed with diethyl ether (25 ml) and then collected by filtration. The white solid was further washed with ether (10 ml) and then dried in vacuo to give the title product (1.16 g); lmax (ethanol) 235.4nm (E1% iCm 1324), 263.2nm (E1% lcm 248), 300.2nm (E1% Km 75); lH n.m.r. (CDCl 3) 8.72 (1H), 8.02 (1H), 7.16 (2H), 6.21 (1H), 5.87 (1H), 5.72 (1H), 3.68 (2H) ), 3.04 (1H), 2.82 (1H), 1.74 (1H), 0.89 (9H), 0.06 (6H).

(E) Intermediate 5: (1'R, 4'S) -7- [4 - (((1,1-Dimethylethyl) dimethylsilyloxy) methyl) -2-cydopenten-1-yl] -2-imino-1, 2-dihydro- [l, 2,4] oxadiazole [3,2-i] -9H-purine hydrobromide

A stirred ice-cooled suspension of intermediate 4 (1.08 g) in methanol (20 ml)

25 was treated with a solution of cyanogen bromide (0.34 g) in methanol (20 ml) added over 5 minutes. After 15 minutes, the suspension was allowed to warm to ambient temperature to give a solution. After 90 minutes, the solvent was removed by evaporation. The residue was washed with diethyl ether (25 ml) and then collected by filtration. The solid was further washed with ether (25 ml) and then dried in vacuo to give the title product (1.37 g); λ + χ (ethanol) 228.2nm (E,% lcm 530), 285.2nm (Em1Cm 445); H

n.m.r. (CDCl 3) 10.20 (1H), 10.02 (1H), 8.37 (1H), 6.25 (1H), 6.01 (1H), 5.90 (1H), 3.69 (2H) ), 3.05 (1H), 2.86 (1H), 1.73 (1H), 0.86 (9H), 0.03 (6H).

(F) Intermediate 6: (rR, 4'S) -9- [4 - (((1,1-Dimethylethyl) dimethylsilyloxy) methyl-yl) -2-cyclopenten-1-yl] -6-cyanoimino l, 6-dihydro-l-methoxy-9H-purine

A solution of intermediate 5 (1.36 g) in dimethylformamide (10 ml) was stirred at ambient temperature and then treated with triethylamine (1.2 ml). After 40 minutes, iodomethane (0.54 ml) was added to give a yellow solution.

After 3 3/4 hours, the solvent was removed by evaporation. The residue was partitioned between ethyl acetate (100 ml) and water (20 ml). The organic solution was further washed with water (2 x 20 ml) and brine (20 ml), dried (MgSO 4) and evaporated to a solid. This solid was washed with diethyl ether (25 ml) and then collected by filtration. This white solid was further washed with ether (10 ml) and then dried in vacuo to give the title product (0.865 g);

Xmax (ethanol) 227.2nm (E1% icm m 449), 287, Onm (E1% icm m 544); * H n.m.r. 8.23 (1H), 7.96 (1H), 6.24 (1H), 5.85 (1H), 5.65 (1H), 4.21 (3H), 3.66 (2H), 3.04 (1H), 2.77 (1H), 1.68 (1H), 0.88 (9H), 0.05 (6H).

(g) Intermediate 7: (1'R, 4'S) -9- [4 - (((1,1-Dimethylethyl) dimethylsilyloxy) -methyl-2 * cyclopenten-1-yl] -6-methoxyamino-9H-purine 2-amine 20

A solution of intermediate 6 (802 mg) and 1,8-diazabicydo [5,4,0] undec-7-ene (0.45 ml) in ethanol (80 ml) was stirred and heated at reflux. Heating was stopped after 9 hours and the solution was allowed to stand at ambient temperature overnight. Solvent was removed by evaporation. The residual oil was combined with the oil of a previous experiment (scale 4%) and then subjected to column chromatography on silica gel (40 g, Merck 9385) eluted with chloroform and then chloroform-ethanol mixtures to give a foam.

This foam was triturated with diethyl ether (10 mL) and the resulting solid was collected by filtration. The solid was further washed with ether 30 (5 ml) and then dried in vacuo to give the title product (594 mg);

Xmax (ethanol) 282.2 nm (EI% 1cm 409); H-N.M.R. (DMSO-d6) 9.76 (1H), 7.32 (1H), 6.53 (2H), 6.08 (1H), 5.88 (1H), 5.26 (1H), 3.72 (3H), 3.61 (2H), 2.90 (1H), 2.50 (1H), 1.52 (1H), 0.83 (9H), 0.02 (6H).

Intermediate 8: (1S, 4R) -4- [2-Amino-6-methoxyamino-9H-purin-9-yl] -2-cy-dopentene-methanol

A solution of intermediate 7 (356 mg) in tetrahydrofuran (35 ml) was stirred at ambient temperature and then treated with tetra-butylammonium fluoride (1.0M solution in tetrahydrofuran, 1.4 ml). After 90 minutes, the reaction was quenched with water (1 mL) and the solvents removed by evaporation. The residual oil was subjected to column chromatography on silica gel (20 g, Merck 7734) eluted with chloroform and then chloroform-ethanol mixtures to give the title product as a solid (243 mg);

Xmax (pH 6 buffer) 280.2 nm (E,% lcm 534); lH n.m.r. (DMSO-d6) 9.75 (1H), 7.39 (1H), 6.52 (2H), 6.10 (1H), 5.84 (1H), 5.27 (1H), 4.73 (1H), 3.40 (2H), 2.83 (1H), 2.55 (1H), 1.52 (1H).

(1S, 4R) -4- [2,6-Diamino-9H-purin-9-yl] -2-cyclopentenecarbinol

A stirred ice-cooled solution of intermediate 8 (210 mg) in water (10 ml) and tetrahydrofuran (50 ml) was treated with aluminum amalgam [from aluminum (237 mg) and 0.5% aqueous mercuric chloride solution] added in small pieces over the course of 20 minutes. of 15 minutes. After 40 minutes, the stirred mixture was allowed to warm to ambient temperature. After 15 hours, the resulting mixture was filtered through diatomaceous earth to remove insoluble proportions. These were washed with water / tetrahydrofuran (1: 5, 60 ml). The combined filtrates were evaporated. The residue was subjected to column chromatography on silica gel (10 g, Merck 9385) and eluted with chloroform-ethanol mixtures to give the title product as a foam (159 mg); [α] D -81 ° (c 1.04, methanol);

λπ, βχ (PH 6 buffer) 255.0 nm (E1% lcm m 302), 280.8 nm (E1% lcm 381), * H

n.m.r. (DMSO-d6) 7.61 (1H), 6.66 (2H), 6.10 (1H), 5.87 (1H), 5.76 (2H), 5.38 (1H), 4.76 (1H), 3.45 (2H), 2.87 (1H), 2.60 (1H), 1.60 (1H).

EXAMPLE 13 311 (1S, 4R) -4- (2-Amino-6-hydroxy-9H-purin-9-yl) -2-cydopentenylcarbinol (1,1,4, S) -2-Amino-1 9-dihydro-9- [4-hydroxymethyl-2-cyclopenten-1-yl] .6H-pyrin-5-6-one

An cloudy solution of the title compound of Example 12 (144 mg) in 0.1 M pH 6 buffer (10 ml) (from 28.4 g disodium orthophosphate in 2 liters of water, adjusted with orthophosphoric acid) was treated with a solution of adenosine deaminase (0.5 mL, 10,778 units), in 50% glycerol / 0.01M potassium phosphate, pH 6.0, and then stirred and heated to 37 ° C. After 18 1/2 hours, the resulting suspension was cooled in the refrigerator. The collected solid was recrystallized from water to give the title product as a white solid (86 mg); [a) D-49 ° (c 0.5, dimethyl sulfoxide); λΦβχ (pH 6 buffer) 252.6 nm (Ε1% Κφ 531), * H 15 n.m.r. (DMSO-d6) 10.60 (1H), 7.60 (1H), 6.47 (2H), 6.10 (1H), 5.86 (1H), 5.33 (1H), 4.72 (1H), 3.45 (2H), 2.59 (1H), 1.58 (1H).

EXAMPLE 14 20

Preparation of Enantiomers of (1a, 4a) -4- (2-Amino-6-hydroxy-9H.purin-9-yl) -2-cyclopentenylcarbinol (a) (1S, 4R) -4- (2-Amino-6 -hydroxy-9H-purin-9-yl) -2-cyclopentenylcarbinol

The diamine analog (100 mg) (Example 11) was dissolved in 3 ml of 0.05 M K 2 PO 4 buffer (pH 7.4) under heating (50 ° C). The solution was cooled to room temperature and 40 units of adenosine deaminase (Sigma, type VI, calf intestinal mucosa) was added. After 3 days of incubation at room temperature, precipitate 30, which was removed by filtration, yielded 18.2 mg. The filtrate was concentrated to 1.5 ml and cooled in the refrigerator for 2 days. An additional solid was obtained by filtration, yield 26.8 mg. The two solid fractions were recrystallized from water to give the pure title product, mp 269-272 ° C, [α] M0 - 62.1 ° (c 0.3 MeOH).

B1 (b) (1R, 4S) -4- (2-Amino-6-hydroxy-9H-purin-9-yl) -2-cydopentenylcarbinol

The filtrates from the preparation of the 1S, 4R isomer (Example 14a) were combined and evaporated to dryness. The unchanged diamine starting material was separated on a silica gel flash column using 10% methanol / chloroform. The diamino compound was dissolved in 0.05 M K 2 PO 4 buffer, pH 7.4 (15 ml) and 800 units of adenosine deaminase added. The solution was incubated for 96 hours at 37 ° C.

TLC indicated some residual unreacted product. The solution was heated in boiling water for 3 minutes and filtered to remove denatured protein. An additional 800 units of adenosine deaminase was added and the process was repeated.

The deprotected solution was evaporated to dryness and the product crystallized from water. The title product as a white solid was collected by filtration from water, mp 265-247 ° C. [α] 24D + 61.1 ° (c 0.3 MeOH).

Example 15 (±) -1,4,4a) -4 - [(2-Amino-6-hydroxy-9H-purin-9-yl) -2-cyclopentenylacetoxycarbinol

For a suspension of the product of Example 10 (130 mg, 0.50 mmol) and 4-dimethylaminopyridine (5 mg, 0.04 mmol) in a mixture of acetonitrile (6 ml) and triethylamine (0.09 ml Acetic anhydride (0.06 mL, 0.6 mmol) was added. The mixture was stirred at room temperature for 3 hours. 25 methanol (1 ml) was added to quench the reaction. The solution was concentrated and absorbed on silica gel (1.5 g), packed on a column (2.0 x 12 cm) and eluted with CHCl 3 -MeOH (20: 1). The product fractions were collected and concentrated to give a white solid. The solid product was washed with MeOH-AcOEt: Yield 123 mg (85%). Further purification from ethanol gave the title product as needle-like crystals, mp 237-239 ° C, analysis (C 13 H 15 N 5 O 3) C, Η, N.

Example 16 33 B1 (1S, 4R) -4- [2-Amino-9H-purin-9-yl] -2-cyclopentenylcarbinol A stirred ice-cooled solution of (1S, 4R) -4- [2-amino 6-Methoxyamino-9H-purin-9-yl] -2-cyclopenten-methanol (Intermediate 8, Example 12) (1,202 g) in tetrahydrofuran (250 ml) and water (50 ml) was treated with aluminum amalgam (from aluminum (1.761 g) and 0.5% aqueous mercurichloride solution) added in small pieces over 1 hour and 47 minutes. After 35 minutes, the stirred mixture was allowed to warm to ambient temperature. After 16 hours and 50 minutes, more aluminum amalgam (from 235 mg of aluminum) was added over 14 minutes.

After a further 4 hours and 10 minutes, the resulting mixture was filtered through diatomaceous earth to remove soluble proportions. These were washed with tetrahydrofuran / water (5: 1, 300 ml). The combined filtrates were evaporated leaving a yellow foam. The foam was subjected to column chromatography on silica gel (33.8 Merck 7734) prepared in chloroform and eluted with chloroform-ethanol mixtures to give several fractions (578 mg, 420 mg and 40 mg). The two largest fractions were crystallized separately from isopropanol. The filtrates were combined with the smallest column fraction and subjected to preparative thin layer chromatography (Merck 5717) developed three times in 10: 1 chloroform / methanol.

The plates were eluted with ethyl acetate and ethyl acetate-ethanol (1: 1) to give a brown solid (45 mg). The solid was subjected to column chromatography on silica gel (2.7 g of Merck 7734) prepared in chloroform and eluted with chloroform-methanol-triethylamine mixtures to give a gum (17 mg). After crystallization without success from isopropanol and treatment with charcoal in methanol, an aqueous solution of the recovered material was lyophilized to give the title compound (15 mg). H NMR (DMSO-d 6) 1.62 (1H), 2.63 (1H), 2.89 (1H), 3.45 (2H), 4.73 (1H), 5.48 (1H), 5.91 (1H), 6.14 (1H), 6.50 (2H), 7.98 (1H), 8.57 (1H). Mass spectrum [MH] +232.

EXAMPLE 17 Tablet Preparations 5 A. The following preparation is prepared by wet granulation of ingredients with a solution of povidone in water, drying and sieving followed by addition of magnesium stearate and pressing.

mg / tablet 10 (a) Active ingredient 250 (b) Lactose B.P. 210 (c) Povidon B.P. 15 (d) Sodium Starch Glycollate 20 15 (e) Magnesium Stearate 5 500 B. The following preparation is prepared by direct pressing; The lactose is of the direct compressible type.

mg / tablet

Active ingredient 250 Lactose 145

Avicel 100

Magnesium stearate 5 1 30 C. (Retarding preparation) The preparation is prepared by wet granulation of the ingredients (below) with a solution of povidone in water, drying and sieving followed by the addition of magnesium stearate and pressing.

DK 175131 B1 mg / tablet (a) Active ingredient 500 (b) Hydropropylmethylcellulose 112 5 (Methocel K4M Premium) (c) Lactose B.P. 53 (d) Povidon B.P. 28 (e) Magnesium Stearate 7 10 700 EXAMPLE 18 15 Capsule Preparation

A capsule preparation is prepared by mixing the ingredients below and filling them into a two-piece hard gelatin capsule.

20 mg / capsule

Active ingredient 125

Lactose 72.5

Avicel 50 Magnesium Stearate 2.5 250 EXAMPLE 19 30

Injectable preparation Active ingredient 0.200 g

Sodium hydroxide solution 0.1M q.s. to a pH of about 11 35 Sterile water q.s. to 10 ml 36 DK 175131 B1

The active ingredient is suspended in some of the water (which may be heated) and the pH is adjusted to approx. 11 with a solution of sodium hydroxide. The portion is then filled to volume and filtered through a sterilizing grade membrane filter into a sterile 10 ml glass vial and sealed with sterile shutter and top seal.

EXAMPLE 20 10

Suppository mg / suppository Active ingredient (63pm) 250

Hard fat, BP 1770 2002 20 One-fifth of the hard fat is melted in a steam cooker pot at a maximum of 45 ° C. The active ingredient is sieved through a 200 μπι sieve and added to the molten base under mixing using a high shear stirrer until a uniform dispersion is obtained. Keeping the mixture at 45 ° C, the remaining hard fat is added to the suspension and stirred to ensure a homogeneous mixture. The entire suspension is passed through a 250 µl stainless steel mesh and allowed to cool to 40 ° C with continuous stirring. At a temperature of 38-40 ° C, 2.02 g of the mixture is filled into suitable 2 ml plastic molds. The suppositories are allowed to cool to room temperature. Example 21 - Antiviral Activity (A) Anti-HIV Assay Compounds of formula I were screened for anti-HIV activity at the National Cancer Institute, Frederick Cancer Research Facility, Frederick, Maryland (FCRF), USA. The following are the currently existing operational screening procedures used by the FCRF. The protocol consists of 3 areas, namely, (I) preparation of infected cells and distribution to the test plates, (II) preparation of drug dilution plates and distribution to the test plates, and (III) XTT assay procedure. See D.A. Scudi-ero et al., "A New Simplified Tetrazolium Assay for Cell Growth and Drug Sensitivity in Culture," Cancer Res., 48, 4827 (1988).

I. Infection and Distribution of ATH8 Cells to Microtiter Trays 15

Cells to be infected (a normal lymphoblastoid cell line expressing CD4) are placed in 50 ml conical centrifuge tubes and treated for 1 hour with 1-2 µg / ml polybrene at 37 ° C. The cells are then pelleted for 8 minutes at 1200 rpm. minute. HIV virus, diluted 1:10 in media (RMP1-1640, 10% human serum or 15% fetal calf serum (FCS) with IL-2 and antibiotics) is added to give a MOI of 0.001. Medium alone is added to virus-free control cells. Assuming an infectious virus titer of 10'4, an MOI of 0.001 represents 8 infectious virus particles per 10,000 cells. Ca. 500,000 cells / tube are exposed to 400 μΙ of the virus dilution. The resulting mixture is incubated for 1 hour at 37 ° C in air-CO 2. The infected or uninfected cells are diluted to give 1 x 10'4 (with human serum) or 2 x 10'4 (with fetal calf serum) cells / 100 μΙ.

Infected or uninfected cells (100 μΙ) are distributed to appropriate wells in a 96 U-bottomed microtiter plate. Each compound dilution is tested in 30 assays with infected cells. Uninfected cells are examined for drug sensitivity in a single well for each compound dilution. Drug-free control cells, infected and uninfected, are run in triplicate. Wells B2-G2 served as reagent controls and received medium only. The plates are incubated at 3 ° C in air CC> 2 until the substance is added.

35 38 DK 175131 B1 II. Substance thinning and addition

Dilution plates (96 flat bottom microtiter plates) are treated overnight with phosphate buffered saline (PBS) or medium containing at least 5 1% FCS or 1% human serum (depending on the medium used in the test) and beginning the day before the assay. This "blocking" procedure is used to limit the adsorption of drug substance to the microtiter tray during the dilution process.

10 The wells are completely filled with the blocking solution and allowed to stand at room temperature in a humidified chamber in a fume cupboard.

The dilution process begins by first diluting the test compound 1:20. Blocked dilution plates are prepared by knocking out the blocking solution and dipping 15 on sterile gauze. All wells on each plate are then filled with 225 μΙ of the appropriate medium using a Cetus fluid handling system.

25 microliters (25 μΙ) of each 1:20 diluted compound are then manually added to row A on a blocked and filled dilution plate. Four compounds, sufficient to supply two test plates, are added per well. dilution. The four compounds 20 are then serially diluted 10 times from row A through row H using the Cetus fluid handling system. The initial dilution of each compound in row A at this time is 1: 200. The dilution plates are stored on ice until needed. 1 2 3 4 5 6 35

Using a 6-microtip multichannel pipette, 100 μΙ of 2 each substance dilution is transferred to the test plate, which already contains 100 μΙ medium plus cells. The final dilution, in the test plate, begins at 1: 400 (wells B4 through and 4 with G4). This dilution (to 0.25% DMSO) prevents the DMSO carrier from controlling cell growth. Drug-free or uninfected cells (wells B3 through and 6 with G3) and reagent controls (B2 through G2) receive medium alone. The last two compounds are then transferred from wells H7 through H12 to another test plate using the same procedure. The test plates are incubated at 37 ° C in air CC> 2 for 7-14 days or until virus controls are lysed as determined macroscopically.

39 DK 175131 B1 III. Quantification of Viral Cytopathogenicity and Substance Activity A. Materials 5 1. A solution of 2β-bis [2-methoxy-4-nitro-5-sulfophenyl] -5. [(Phenylamino) carbonyl] -2H-tetrazolium hydroxide. (XTT) - 1 mg / ml solution in medium without FCS. Store at 4 ° C. Made every week.

Phenazine methosulfonate (PMS) stock solution - this can be prepared and stored frozen at -20 ° C until use. It should be prepared in PBS to a concentration of 15.3 mg / ml.

B. Microculture Tetrazolium Assay (MTA) 15 1. Preparation of XTT-PMS Solution - XTT-PMS is prepared immediately prior to addition to the wells in the culture tray. The PMS stock solution is diluted 1: 100 (0.153 mg / ml). Enough diluted PMS is added to each ml of XTT to give a final PMS concentration of 0.02 mM. A 50 µl aliquot of the XTT-PMS mixture is added to each of the relevant wells and the plate is incubated for 4 hours at 20 ° C. The plate covers are removed and replaced with self-adhesive plate seals (Dyna-tech cat 001-010-3501). The sealed plate is shaken on a microculture plate shaker and the absorbance is determined at 450 nm.

IV: Results 25

The data obtained were plotted as a percentage of test cells over infected cells (%) for both infected and uninfected cells as a function of the increasing concentration of the test compound. Such plots allow calculated by an effective concentration (EC50) for infected cells, an inhibitory concentration 30 (IC50) for normal cells, and a therapeutic index (TI50).

The inhibitory concentrations (in Mg / ml) against HIV determined as described above for the compounds of Examples 7, 9 10, 11 and 14 (b) are shown in Table 1.

40 DK 175131 B1

Table 1

Compound Example Cell line ED50 ID50 TI50 5 9a 7 MT-2 2.3 50 21.4 13a 9 MT-2 0.41 6.97 17.3 14a 10 MT-2 0.15 100 667 15a 11 MT-2 2, 9> 125> 42.7 (-) 14a 14 (b) CEM 0.66 189 284 10 __

The compounds of Examples 5 and 8 also exhibited antiviral activity in this screening.

An earlier assay performed on the compound of Example 10 at the Southern Research Institute yielded a TI 200 when MT-2 cells were cultured with H9 / HILV-IIIB.

(B) Cat Leukemia Virus Activity 20 Antiviral screening for FeLV-FAIDS activity was performed in 96-well plates (Corning) using 81C indicator cells in Iscove's modified Dulbec-co's medium supplemented with 10% heat-inactivated fetal bovine serum (FBS). Twenty hours prior to the assay, the plates were seeded with the 81C cells at 5 x 10 3 cells / well. On the day of the assay, the cells were pretreated for 30 min at 37 ° C with DEAE-dextran (25 ng / ml) in 0.1 ml Hanks balanced salt solution. This was removed and 0.1 ml of growth medium containing 32 TCID50 FeLV-FAIDS or 0.1 ml of growth medium alone was added to each well. The virus was allowed to absorb for 1 hour, after which 0.1 ml of test or positive control compound (2 ', 3'-dideoxycytidine; ddC) or growth medium was added. Plates were incubated at 30 ° C. Cells were fed fresh growth medium containing compound on day 4 after infection. Culture medium was completely replaced and replaced with fresh medium containing compound on day 7 after infection. On day 10 after infection, the cells were fixed with formalin, stained with 0.1% Coomassie Brilliant Blue R-250, and microscopically observed for CPE and drug cytotoxicity.

35 41 DK 175131 B1

The compound of Example 10 had an ED 50 of 1.9 pg / ml.

(C) Activity against murine AIDS

Five Falcon 6-well tissue culture plates were seeded at 1.75 x 10 5 cells per well. well in a total volume of 2.5 ml of EMEM containing 5% heat-inactivated FBS. Twenty hours after inoculation with the cells, the medium was decanted and 2.5 ml of DEAE-dextran (25 ng / ml in phosphate buffered saline) was added to each well. The cultures were incubated at 37 ° C for 1 hour, then the DEAE dextran solution was decanted off, and the cell layers were washed once with 2.5 ml of PBS. Normal cell controls were re-fed with 2.5 ml of medium alone (no virus or substance). Substance control cultures received 2.5 ml of medium containing substance but no virus. Virus-infected control cultures received 0.5 ml of the appropriate dilution of CAS-BR-M stock culture to give countable plaques plus 2.0 ml of medium. The test samples received 0.5 ml of the relevant virus dilution plus 2.0 ml of the drug dilution. Six concentrations of the test compound diluted in serial half-log dilutions were tested. Three concentrations of the positive control substance, ddC, were tested. Triple wells for each test compound concentration and 6 virus and 6 cell control cultures were included in each assay. On day 3 after viral inoculation, the toxicity of the substance to the SC-1 cells was determined by microscopic examination of stained cell and substance control duplicate cultures. The remaining test and control cultures were irradiated with an ultraviolet lamp for 20 seconds and XC cells were added to each culture (5 x 10 5 cells / well in 2.5 ml of EMEM containing 10% heat-inactivated FBS). On day 3 after UV irradiation, the cultures were fixed with formula and stained with crystal violet. The plaques were counted using a dissection microscope.

Antiviral activity in the CAS-BR-M plaque reduction was expressed as the reduction in the average number of plaques counted in the drug-treated, virus-infected cultures compared to the average number of plaques counted in the untreated, virus-infected control cultures (percent of control). The compound of Example 10 had an ED 50 of 1.1 ng / ml.

42 DK 175131 B1 (D) Activity against aberetrovirus SAIDS (SRV-2)

Antiviral screening against the SAIDS virus (D / Washington) was performed by a syncytia inhibition assay on Raji cells. The fabric was diluted in complete Iscove's medium, whereupon 100 μΙ of each dilution was added to the relevant wells on a 96 * well plate. Actively growing Raji cells, 5 x 10 V43 cells in 50 μΙ complete Iscove's medium, were then added to each well. This was followed by the addition of 50 μΙ of clarified supernatant from an SRV-2 / Raji cell co-culture. DDC was included in this assay as the positive control substance. Plates were incubated at 37 ° C in a humidified atmosphere containing 5% CO 2. Syncytia were counted on day 7 after infection. Dust toxicity was determined by comparing viable cell counts for the uninfected drug treated sample with the viability of the uninfected, untreated control. The compound of Example 10 had an ED 50 of 2.8 Mg / ml.

15 (E) Activity against Visna Maedi Virus

The antiviral activity against Visna Maedi Virus (VMV), strain WLC-1, was determined by measuring the reduction of virus-specific immunohistochemical staining. Monolayers of sheep choroid plexus cells were infected with VMV and overlaid with serial dilutions of test compounds. After incubation for 5 days, the monolayers were further incubated with virus-specific antisera conjugated to horseradish peroxidase (Horse Radish Peroxidase, HRP). Subsequent incubation of the monolayers with a chromogenic substrate from HRP stains areas of viral replication. These 25 discrete points were counted and the concentration of test compound needed to reduce the number of points to 50% of the number of drug-treated controls was calculated.

The compound of Example 13 had an ED 50 of 0.2 pg / ml.

30

Claims (11)

5 The compounds of Examples 5, 7 and 8 exhibited cytotoxic activity when tested against P388 mouse leukemia cell culture assay as described by R.G. Alonquist and R. Vince, J. Med. Chem., 16, 1396 (1973). The obtained EDSO values pg / ml were: Example 5 12 Example 7 40 Example 8 3 15 1. 4- (9H-Purin-9-yl) -2-cydopentenylcarbinols of the general formula I ·. 20 / γ \ i! > i / w / \ / Z N N H0-CH2 where X is hydrogen, NRR \ SR, OR or halogen; 30. is hydrogen, OR2 or NRR1; R, R 1 and R 2 may be the same or different and are selected from hydrogen, C 1-4 alkyl and aryl; and pharmaceutically acceptable derivatives thereof, or pharmaceutically acceptable esters thereof selected from DK 175131 B1 carboxylic acid esters in which the non-carbonyl portion of the ester group is hydrogen, C 1- 4-alkyl, aryloxy-C 1-4 alkyl or optionally with halogen, C 1-4 alkyl or C 1-4 alkoxy substituted aryl; C1-10 alkyl or aryl C1-4 alkylsulfonyl esters; 5 amino acid esters or triphosphate esters, or pharmaceutically acceptable salts of such esters. A compound of formula I according to claim 1, characterized in that 2 is H, OH or NH2, preferably NH2. 10 A compound according to claim 1 or 2, characterized in that X is hydrogen, chlorine, NH 2, SH or OH, preferably NH 2, especially OH. A compound selected from (1a, 4a) -4- (6-chloro-9H-purin-9-yl) -2-cydopentenylcarbinol; (La, 4a) -4- (6-hydroxy-9H-purin-9-yl) -2-cyclopentenylcarbinol; (La, 4a) -4- (6-Amino-9H-purin-9-yl) -2-cyclopentenylcarbinol; (La, 4a) -4- (6-mercapto-9H-purin-9-yl) -2-cydopentenylcarbinol; (1a, 4a) -4- (2-diamino-9H-purin-9-yl) -2-cydopentenylcarbinol; (La, 4a) -4- (2-amino-6-chloro-9H-purin-9-yl) -2-cyclopentenylcarbinol; and (1a, 4a) -4- (2-amino-9H-purin-9-yl) -2-cyclopentenylcarbinol. 5. (1a, 4a) -4- (2-Amino-6-hydroxy-9H-purin-9-yl) -2-cyclopentenylcarbinol; 25 A compound according to any one of claims 1-5, characterized in that it is in the form of essentially a racemic mixture. 1 A compound according to any one of claims 1-5, characterized in that it consists essentially of one optical isomer, preferably the D isomer. DK 175131 B1 A compound of formula I as defined in any one of claims 1-7 or a pharmaceutically acceptable derivative thereof for use as an active therapeutic agent. A compound of formula I as defined in any one of claims 1-7 in the manufacture of a medicament for the treatment of a viral infection. Pharmaceutical composition, characterized in that it comprises a compound as defined in any one of claims 1-7 together with a pharmaceutically acceptable carrier therefor. 11. Compound of the general formula II ί 15 Λ Λ N · I i ΛΛ. Wherein X is hydrogen, NRR1, SR, OR, halogen or protective forms thereof; Y is OH or a protected form thereof; 25. is hydrogen, OR2, NRR1 or protected forms thereof; R, R 1 and R 2 may be the same or different and are selected from hydrogen, C 1-4 alkyl and aryl; and pharmaceutically acceptable derivatives thereof, or pharmaceutically acceptable esters thereof selected from 30 carboxylic acid esters in which the non-carbonyl moiety of the ester group is hydrogen, C 1- -alkyl, aryloxy-C 1-4 alkyl or optionally with halogen, C 1-4 alkyl or C 1-4 alkoxy substituted aryl; C1-10 alkyl or aryl C1-4 alkylsulfonyl esters; amino acid esters or triphosphate esters, or pharmaceutically acceptable salts of side esters.