POLYMORPH The present invention relates to heterocyclyl substituted adenosine derivatives. More particularly the invention is concerned with particular physical forms of (2S, 3S, 4R, 5R)-2- (5- tert-butyl- [1, 3, 4]-oxadiazol-2-yl)-5- [6- (4-chloro-2-fluorophenylamino)-purin-9-yl]- tetrahydrofuran-3, 4-diol, pharmaceutical formulations thereof and their use in therapy.

(2S, 3S, 4R, 5R)-2- (5-tert-butyl- [1, 3, 4]-oxadiazol-2-yl)-5- [6- (4-chloro-2-fluorophenylamino)- purin-9-yl]-tetrahydrofuran-3, 4-diol has activity at the adenosine A1 receptor.

W099/67262 (Glaxo Group Limited) discloses certain heterocyclyl adenosine derivatives including (2S, 3S, 4R, 5R)-2- (5-tert-butyl- [1, 3, 4]-oxadiazol-2-yl)-5- [6- (4-chloro-2- fluorophenylamino)-purin-9-yl]-tetrahydrofuran-3, 4-diol, Example 14 of W099/67262, the structure of which is indicated below as the compound of formula (A) : (A) The preparation of the compound of formula (A) is described in W099/67262. The compound of formula (A) may be prepared by the reaction of 4-chloro-2-fluoroaniline with an appropriate purinyl derivative having a suitable leaving group in the 6-position of the purine ring, optionally in the presence of a solvent at elevated temperatures. Alternatively the compound of formula (A) may be prepared by treating 9- { (3aR, 4R, 6S, 6aR)-6- [5-tert- butyl-1, 3, 4-oxadiazol-2-yl]-2, 2-dimethyltetrahydrofuro [3,4-d] [1,3] dioxol-4-yl}-N-(4-chloro-2- fluorophenyl)-9H-purin-6-amine with trifluoroacetic acid followed by treatment with sodium bicarbonate. Extraction of the product into ethyl acetate followed by evaporation in vacuo provides the compound of formula (A) as a buff solid.

We have now surprisingly found that the compound of formula (A) can be obtained in polymorphic forms. We have further found that the compound of formula (A) may be obtained by crystallisation under certain conditions in the form of polymorphic form V (hereinafter Polymorph V).

There is thus provided as a first aspect of the invention (2S, 3S, 4R, 5R)-2- (5-tert-butyl- [1,3, 4]-oxadiazol-2-yl)-5- [6- (4-chloro-2-fluorophenylamino)-purin-9-yl]-tetrahydrofuran-3 , 4- diol as polymorphic form V.

Polymorph V is particularly suitable for bulk preparation and handling and thus may be useful in the preparation of pharmaceutical formulations.

Polymorph V may be useful in the preparation of pharmaceutical formulations.

In a preferred aspect the invention provides (2S, 3S, 4R, 5R)-2- (5-tert-butyl- [1, 3,4]- oxadiazol-2-yl)-5- [6- (4-chloro-2-fluorophenylamino)-purin-9-yl]-tetrahydrofuran-3 , 4-diol in the form of Polymorph V as herein defined.

(2S, 3S, 4R, 5R)-2- (5-tert-Butyl- [1, 3, 4]-oxadiazol-2-yl)-5- [6- (4-chloro-2-fluorophenylamino)- purin-9-yl]-tetrahydrofuran-3, 4-diol may be prepared in polymorphic form V by crystallisation of the compound under suitable conditions.

Polymorph V may be prepared substantially free from alternative polymorphs by controlling crystallisation conditions.

In a further aspect the invention provides (2S, 3S, 4R, 5R)-2- (5-tert-butyl- [1, 3, 4]-oxadiazol-2- yl)-5- [6- (4-chloro-2-fluorophenylamino)-purin-9-yl]-tetrahydrofuran-3 , 4-diol in the form of Polymorph V as herein defined substantially free of any other polymorph.

In a further aspect the invention provides (2S, 3S, 4R, 5R)-2- (5-tert-butyl- [1, 3, 4]-oxadiazol-2- yl)-5- [6- (4-chloro-2-fluorophenylamino)-purin-9-yl]-tetrahydrofuran-3 , 4-diol in the form of Polymorph V as herein defined substantially free of impurities.

By"substantially free"is meant containing less than 10%, preferably less than 5%, more preferably less than 2%, of alternative polymorph or impurity.

In general, (2S, 3S, 4R, 5R)-2- (5-tert-butyl- [1, 3, 4]-oxadiazol-2-yi)-5- [6- (4-chloro-2- fluorophenylamino)-purin-9-yl]-tetrahydrofuran-3, 4-diol in the form of Polymorph V may be obtained by treating 9- { (3aR, 4R, 6S, 6aR)-6- [5- (tert-butyl)-1, 3, 4-oxadiazol-2-yl]-2, 2- dimethyltetrahydrofuro [3,4-d] [1,3] dioxol-4-yl)-N- (4-chloro-2-fluorophenyl)-9H-purin-6-amine (less than 98% pure, preferably 96-98% pure) with trifluoroacetic acid/water followed by neutralisation with aqueous ammonium hydroxide in the presence of methanol, maintaining a temperature of less than 25°C, preferably 20-25°C.

Interconversion of polymorph V to other polymorphs can occur under certain circumstances.

The methods for the preparation of Polymorph V described herein constitute a further aspect of the present invention.

Description of Figures: Figure I shows X-Ray diffraction data obtained for Polymorph V.

Figure II shows a Raman spectrum of Polymorph V.

Figure III shows an infrared spectrum of Polymorph V.

Polymorph V has been characterised by X-ray powder diffraction (XRPD) studies, Raman spectroscopy and infrared spectroscopy.

Polymorph V is characterised by having signals in its Infrared spectra substantially at 3432,3427, 3423,3419, 860 and 856 cm-1.

Infrared peaks are quoted to the nearest cm-1.

Polymorph V is characterised by having peaks in its Raman spectra substantially at 3420,1616, 1586 and 1294 cm-1.

Raman peaks are quoted to the nearest cm-1.

Polymorph V is characterised by having an XRPD pattern with signals substantially at 5.42, 7.99, 8.89, 9.66, 10.34 10.89, 11.84 and 12.37 (degrees 2-theta).

The skilled person will recognise that XRPD peak positions are affected by differences in sample height. The peak positions quoted herein are thus subject to a variation of +/-0.15 degrees 2-theta.

It will be recognised that spectra and diffraction data will vary slightly according to various factors such as the temperature, concentration and instrumentation used. In order to account for this variability, signals and peak positions are quoted herein as being "substantially"at specific values.

The present invention also provides (2S, 3S, 4R, 5R)-2- (5-tert-butyl- [1, 3,4] oxadiazol-2-yl)-5- [6- (4-chloro-2-fluorophenylamino)-purin-9-yl]-tetrahydrofuran-3 , 4-diol characterised in that it: i) provides an XRPD spectrum substantially as illustrated in Figure I ; and/or ii) provides a Raman spectrum substantially as illustrated in Figure II ; and/or iii) provides an infrared spectrum substantially as illustrated in Figure iii.

The present invention further provides (2S, 3S, 4R, 5R)-2- (5-tert-butyl- [1, 3,4] oxadiazol-2-yl)- 5- [6- (4-chloro-2-fluorophenylamino)-purin-9-yl]-tetrahydrofuran-3 , 4-diol characterised in that it: i) provides an XRPD spectrum with signals substantially at 5.42, 7.99, 8.89, 9.66, 10.34 10.89, 11.84 and 12.37 (degrees 2-theta); and/or ii) provides a Raman spectrum with signals substantially at 3420,1616, 1586 and 1294 cm-1 ; and/or iii) provides an infrared spectrum with signals substantially at 3432,3427, 3423,3418, 860 and 856 cm-1.

This invention further provides for a pharmaceutical composition comprising (2S, 3S, 4R, 5R)-2- (5-tert-butyl- [1, 3,4] oxadiazol-2-yl)-5- [6- (4-chloro-2-fluorophenylamino)- purin-9-yl]-tetrahydrofuran-3, 4-diol in polymorphic form V, and a pharmaceutical acceptable carrier and/or excipient.

Suitable pharmaceutically acceptable carriers and excipients are described in WO 99/67262.

(2S, 3S, 4R, 5R)-2- (5-tert-Butyl- [1, 3, 4]-oxadiazol-2-yi)-5- [6- (4-chloro-2-fluorophenylamino)- purin-9-yl]-tetrahydrofuran-3, 4-diol in polymorphic form V may be used for decreasing plasma free fatty acid concentration; reducing heart rate; or treating ischemic heart disease, peripheral vascular disease, stroke, pain (for example inflammatory pain and neuropathic pain), migraine, CNS disorder, or sleep apnoea, as described in WO 99/67262.

In a further aspect the present invention therefore provides (2S, 3S, 4R, 5R)-2- (5-tert-butyl- [1,3, 4]-oxadiazol-2-yl)-5- [6- (4-chloro-2-fluorophenylamino)-purin-9-yl]-tetrahydrofuran-3 , 4- diol in polymorphic form V for use in decreasing plasma free fatty acid concentration; reducing heart rate; or treating ischemic heart disease, peripheral vascular disease, stroke, pain, migraine, CNS disorder, or sleep apnoea.

(2S, 3S, 4R, 5R)-2- (5-tert-butyl- [1, 3, 4]-oxadiazol-2-yl)-5- [6- (4-chloro-2-fluorophenylamino)- purin-9-yl]-tetrahydrofuran-3, 4-diol in polymorphic form V may be used in the manufacture of a medicament for use in decreasing plasma free fatty acid concentration; reducing heart rate; or treating ischemic heart disease, peripheral vascular disease, stroke, pain (for example inflammatory pain and neuropathic pain), migraine, CNS disorder, or sleep apnoea, as described in WO 99/67262.

In a yet further aspect the present invention provides the use of (2S, 3S, 4R, 5R)-2- (5-tert- butyl- [1, 3, 4]-oxadiazol-2-yl)-5- [6- (4-chloro-2-fluorophenylamino)-purin-9-yl]- tetrahydrofuran-3, 4-diol in polymorphic form V in the manufacture of a medicament for use in decreasing plasma free fatty acid concentration; reducing heart rate; or treating

ischemic heart disease, peripheral vascular disease, stroke, pain (for example inflammatory pain and neuropathic pain), migraine, CNS disorder, or sleep apnoea.

In another aspect the present invention also provides a method of treating a patient suffering from a condition where there is an advantage in decreasing plasma free fatty acid concentration; or reducing heart rate; or treating a patient suffering from ischemic heart disease, peripheral vascular disease, stroke, pain (for example inflammatory pain and neuropathic pain), migraine, CNS disorder, or sleep apnoea comprising administering a therapeutical effective amount of of (2S, 3S, 4R, 5R)-2- (5-tert-butyl- [1, 3, 4]-oxadiazol-2- yl)-5- [6- (4-chloro-2-fluorophenylamino)-purin-9-yl]-tetrahydrofuran-3 , 4-diol in polymorphic form V.

WO 99/67262 (Glaxo Group Limited) is incorporated by reference herein as though fully set forth.

The following examples illustrate the invention but are not intended as a limitation thereof.

EXAMPLES 9- { (3aR, 4R, 6S, 6aR)-6- [5- (tert-butyl)-1, 3, 4-oxadiazol-2-yl]-2, 2-dimethyltetrahydrofuro [3,4- d] [1,3] dioxol-4-yl)-N- (4-chloro-2-fluorophenyl)-9H-purin-6-amine was prepared according to the methods described in W099/67262, in particular intermediate 63.

Example 1-Preparation of Polvmorph V 9- { (3aR, 4R, 6S, 6aR)-6- [5- (tert-butyl)-1, 3, 4-oxadiazol-2-yl]-2, 2-dimethyltetrahydrofuro [3,4- d] [1,3] dioxol-4-yl)-N- (4-chloro-2-fluorophenyl)-9H-purin-6-amine (purity 96.6%) was dissolved in 3.8 volumes of 9: 1 v/v trifluoroacetic acid/water and the mixture stirred for 3 hours under ambient conditions, when the reaction is 95% complete by liquid chromatography. The reaction mixture was neutralised by careful addition to 5M aqueous NH40H in the presence of methanol, maintaining a temperature of 20-25°C. The mixture was then cooled to 5°C to complete precipitation of the product, (2S, 3S, 4R, 5R)-2- (5-tert- butyl- [1, 3, 4]-oxadiazol-2-yl)-5- [6- (4-chloro-2-fluorophenylamino)-purin-9-yl]- tetrahydrofuran-3, 4-diol. The solid is then filtered off, washed with aqueous methanol, stirred in water and dried in vacuo at 40-50°C.

X-Ray Powder Diffraction The sample preparation and acquisition conditions were as follows : Samples were lightly ground and packed (top-filling) into sample cups. Instrumentation consisted of a Bruker D8 Advance X-Ray powder diffractometer configured with a Cu anode (40 kV 40 mA), variable divergence slit, primary and secondary Soller slits, and a position sensitive detector. Data were acquired over the range 2-35 degrees 2-theta using a step size of 0.0145 degrees 2-theta (time per step: 1 s). Samples were rotated.

Data obtained for Polymorph V are shown in Figure I.

Raman Spectroscopy Raman spectra were acquired using a Nicolet 960 ESP FT-Raman spectrometer.

Samples were held in glass vials ; spectra of 5 different points on a sample were averaged.

Data collection parameters include : Laser power: 400 mW, Resolution: 4 cm-1, Sample gain: 1.0, Detector: InGaAs, Beamsplitter : CaF2, Correction: none, Zero filling : none, Apodization: Happ-Genzel, Phase correction: Power spectrum.

Raman spectra of Polymorph V is shown in Figure II.

Infrared Spectroscopy

Infrared spectra of the samples were obtained as Nujol mulls using a Perkin-Elmer 2000 FT-IR spectrometer. Spectra were recorded by averaging 2 scans and using a resolution of 2cm-1, scan interval of 0.5cm-1 and a spectral range of 4000-450cm-1.

An infrared spectrum of Polymorph V is shown in Figure Ill.