Abstract: wherein Z1 is hydrogen or an amino-protecting group selected from the group consisting of acyl of the formula R—C(O)—, wherein R is alkyl of 1-6 carbon atoms; trityl, optionally substituted with methoxy; and N-(9-fluorenylmethoxycarbonyl); Y1 is halo, aralkyloxy or acyloxy, wherein acyl is as defined above; and Y2 is aralkyloxy. These intermediates are useful in a novel process for preparing the mono-L-valine ester of 2-(2-amino-1,6-dihydro-6-oxo-purin-9-yl) methoxy-1,3-propanediol (ganciclovir). The mono-L-valine ester of ganciclovir and its pharmaceutically acceptable salts are of value as antiviral agents with improved absorption.

Abstract: Process for preparing intermediates of formula (III) wherein Y1 is acyloxy, wherein acyl is of the formula R—C(O)—, wherein R is alkyl of 1-6 carbon atoms, Y2 is aralkyloxy, and Z is benzoyloxy or acyloxy, wherein acyl is as defined above. Intermediates of formula (III) are useful in a novel process for preparing the mono-L-valine ester of 2-(2-amino-1,6-dihydro-6-oxo-purin-9-yl)methoxy-1,3-propanediol (ganciclovir). The mono-L-valine ester of ganciclovir and its pharmaceutically acceptable salts are of value as antiviral agents with improved absorption.

Abstract: Intermediates of Formula (III) wherein Y1 is acyloxy, wherein acyl is of the formula R—C(O)—, wherein R is alkyl of 1-6 carbon atoms, Y2 is aralkyloxy, and Z is benzoyloxy or acyloxy, wherein acyl is as defined above. Intermediates of formula (III) are useful in a novel process for preparing the mono-L-valine ester of 2-(2-amino-1,6-dihydro-6-oxo-purin-9-yl)methoxy-1,3-propanediol (ganciclovir). The mono-L-valine ester of ganciclovir and its pharmaceutically acceptable salts are of value as antiviral agents with improved absorption.

Abstract: Process and novel intermediates for preparing the L-mono-valine ester of 2-(2-amino-1,6-dihydro-6-oxo-purin-9-yl)methoxy-1,3-propanediol and its pharmaceutically acceptable salts. The present process and intermediates provide for reduced impurities in the mono-valine ester end-product and lower overall production costs. The process involves the condensation of a silylated guanine compound with a substituted glycerol derivative and esterification of this product with an L-valine derivative. These mono-valine products are of value as antiviral agents with improved absorption.