Details for Patent: 5,856,481

Title:	2-(2-amino-1,6-dihydro-6-oxo-purin-9-yl)methoxy-1,3-propanediol derivative
Abstract:	The L-monovaline ester derived from 2-(2-amino-1,6-dihydro-6-oxo-purin-9-yl)methoxy-1,3-propanediol and its pharmaceutically acceptable salts are of value as antiviral agents with improved absorption.
Inventor(s):	Nestor; John Joseph (Cupertino, CA), Maag; Hans (Menlo Park, CA)
Assignee:	Syntex (U.S.A.) Inc. (Palo Alto, CA)
Filing Date:	Mar 04, 1997
Application Number:	08/812,989
Claims:	1. A process for preparing the compound 2-(2-amino-1,6-dihydro-6-oxo-purin-9-yl)methoxy-3-hydroxy-1-propanyl-L-val inate or a pharmaceutically acceptable salt thereof, comprising: (a) removal of the amino- and hydroxy-protecting groups from a compound of the formula ##STR15## where: P.sup.1 is hydrogen or a hydroxy-protecting group, P.sup.2 is an amino-protecting group, P.sup.3 is hydrogen or P.sup.2, and the asterisk denotes an asymmetric carbon atom; to afford the compound 2-(2-amino-1,6-dihydro-6-oxo-purin-9-yl)-methoxy-3-hydroxy-1-propanyl-L-va linate; optionally followed by (b) conversion of the 2-(2-amino-1,6-dihydro-6-oxo-purin-9-yl)-methoxy-3-hydroxy-1-propanyl-L-va linate into a pharmaceutically acceptable salt thereof. 2. The process of claim 1 where P.sup.1 is hydrogen. 3. The process of claim 2 where P.sup.2 is C.sub.1-4 alkanoyl, trityl, trifluoroacetyl, N-(9-fluorenylmethoxycarbonyl), allyloxycarbonyl, N-benzyloxycarbonyl, t-butyloxycarbonyl, or phthalyl. 4. The process of claim 2, where step (a) is carried out under acidic conditions or by hydrogenolysis. 5. The process of claim 2 where a pharmaceutically acceptable salt of 2-(2-amino-1,6-dihydro-6-oxo-purin-9-yl)methoxy-3-hydroxy-1-propanyl-L-val inate is prepared. 6. The process of claim 5 where the pharmaceutically acceptable salt is the hydrochloride. 7. A process for preparing the compound 2-(2-amino-1,6-dihydro-6-oxo-purin-9-yl)methoxy-3-hydroxy-1-propanyl-L-val inate or a pharmaceutically acceptable salt thereof, comprising: (a) removal of the amino- and hydroxy-protecting groups from a compound of the formula ##STR16## where: P.sup.1 is a hydroxy-protecting group, P.sup.2 is an amino-protecting group, P.sup.3 is hydrogen or P.sup.2, and the asterisk denotes an asymmetric carbon atom; to afford the compound 2-(2-amino-1,6-dihydro-6-oxo-purin-9-yl)-methoxy-3-hydroxy-1-propanyl-L-va linate; optionally followed by (b) conversion of the 2-(2-amino-1,6-dihydro-6-oxo-purin-9-yl)-methoxy-3-hydroxy-1-propanyl-L-va linate into a pharmaceutically acceptable salt thereof. 8. The process of claim 7 where P.sup.2 is C.sub.1-4 alkanoyl, trityl, trifluoroacetyl, N-(9-fluorenylmethoxycarbonyl), allyloxycarbonyl, N-benzyloxycarbonyl, t-butyloxycarbonyl, or phthalyl. 9. The process of claim 7 where step (a) is carried out under acidic conditions or by hydrogenolysis. 10. The process of claim 7 where a pharmaceutically acceptable salt of 2-(2-amino-1,6-dihydro-6-oxo-purin-9-yl)methoxy-3-hydroxy-1-propanyl-L-val inate is prepared. 11. The process of claim 10 where the pharmaceutically acceptable salt is the hydrochloride. 12. A process for preparing the compound 2-(2-amino-1,6-dihydro-6-oxo-purin-9-yl)methoxy-3-hydroxy-1-propanyl-L-val inate or a pharmaceutically acceptable salt thereof, comprising: (a) removal of the amino- and hydroxy-protecting groups from a compound of the formula ##STR17## where: P.sup.1 is a hydroxy-protecting group removable under acidic conditions or by hydrogenolysis, P.sup.2 is an amino-protecting group, P.sup.3 is hydrogen or P.sup.2, and the asterisk denotes an asymmetric carbon atom; to afford the compound 2-(2-amino-1,6-dihydro-6-oxo-purin-9-yl)-methoxy-3-hydroxy-1-propanyl-L-va linate; optionally followed by (b) conversion of the 2-(2-amino-1,6-dihydro-6-oxo-purin-9-yl)-methoxy-3-hydroxy-1-propanyl-L-va linate into a pharmaceutically acceptable salt thereof. 13. The process of claim 12 where P.sup.1 is benzyl, trityl, allyl, tetrahydropyranyl, silyl, or trialkylsilyl. 14. The process of claim 12 where P.sup.2 is C.sub.1-4 alkanoyl, trityl, trifluoroacetyl, N-(9-fluorenylmethoxycarbonyl), allyloxycarbonyl, N-benzyloxycarbonyl, t-butyloxycarbonyl, or phthalyl. 15. The process of claim 14 where P.sup.1 is benzyl, trityl, allyl, tetrahydropyranyl, silyl, or trialkylsilyl. 16. The process of claim 12 where a pharmaceutically acceptable salt of 2-(2-amino-1,6-dihydro-6-oxo-purin-9-yl)methoxy-3-hydroxy-1-propanyl-L-val inate is prepared. 17. The process of claim 16 where the pharmaceutically acceptable salt is the hydrochloride. 18. The process of claim 12 were P.sup.1 is benzyl, P.sup.2 is N-benzyloxycarbonyl, and P.sup.3 is hydrogen. 19. The process of claim 18 where a pharmaceutically acceptable salt of 2-(2-amino-1,6-dihydro-6-oxo-purin-9-yl)methoxy-3-hydroxy-1-propanyl-L-val inate is prepared. 20. The process of claim 19 where the pharmaceutically acceptable salt is the hydrochloride.