Claims for Patent: 4,642,346

Summary for Patent: 4,642,346

Title:	Anhydrous crystalline 9-(1,3-dihydroxy-2-propoxymethyl)guanine
Abstract:	Novel anhydrous crystalline 9-(1,3-dihydroxy-2-propoxymethyl)guanine useful as an antiviral agent.
Inventor(s):	Chan; Tai W. (Palo Alto, CA), Nguyen; Huong T. (Saratoga, CA)
Assignee:	Syntex (U.S.A.) Inc. (Palo Alto, CA)
Application Number:	06/747,631
Patent Claims:	1. Anhydrous crystalline 9-(1,3-dihydroxy-2-propoxymethyl)guanine. 2. The anhydrous crystals of claim 1 further characterized by water of hydration of less than 1% w/w. 3. The anhydrous crystals of claim 2 further characterized by m.p. 243.degree. C.-245.degree. C. 4. The anhydrous crystals of claim 3 characterized by the powder X-ray diffraction pattern shown in FIGS. IA, IB or IC. 5. The process for preparing the anhydrous crystals of claim 1 which comprises (i) adding 9-(1,3-dihydroxy-2-propoxymethyl)guanine to a heated oxygen-containing solvent; (ii) cooling the mixxture formed in step (i) to room temperature; and (iii) recovering the crystals formed in step (ii). 6. The process of claim 5 wherein the oxygen-containing solvent is dimethyl acetamide or water. 7. The process of claim 6 wherein the solvent is warmed to 60.degree. to 100.degree. C. 8. The process of claim 7 which further comprises adding methanol or acetone to the warm solution. 9. The process of claim 5 wherein the oxygen-containing solvent is an alcohol of one to four carbon atoms. 10. The process of claim 9 wherein the solvent is warmed to 40.degree. to 80.degree. C. 11. A process for preparing the anhydrous crystals of claim 1 which comprises heating a suitable form of 9-(1,3-dihydroxy-2-propoxymethyl)guanine. 12. The process of claim 11 wherein the suitable form is 9-(1,3-dihydroxy-2-propoxymethyl)guanine hydrate. 13. The process of claim 12 wherein the hydrate is heated to 200.degree.-220.degree. C.