PROCESS FOR PRODUCING VALACYCLOVIR

摘要

A production process capable of efficiently obtaining valacyclovir of high purity chemically and optically is provided. The process for producing valacyclovir represented by the formula (4) or a salt thereof comprising the steps of: neutralizing acyclovir represented by the formula (2) and an organic amine salt of an N-protected valine represented by the formula (1) (wherein R<SUP>1</SUP> represents an alkyl group, an aryl group or an alkoxyl group, R<SUP>2</SUP> represents a hydrogen atom or an alkyl group, and R<SUP>3</SUP> represents an alkyl group), or an alkali metal salt or alkaline earth metal salt of the N-protected valine, subjecting them to a condensation reaction in the presence of a condensing agent thereby to obtain N-protected valacyclovir represented by the formula (3), and deprotecting the resulting N-protected valacyclovir. (The respective symbols in the formulae have the same meanings as in the description.)