Practical syntheses of penciclovir and famciclovir from N2-acetyl-7-benzylguanine

摘要

We have established practical methods for the synthesis of penciclovir (PCV) and famciclovir (FCV) from readily available guanosine via N2-acetyl-7-benzylguanine. The alkylation of N2-acetyl-7-benzylguanine proceeded selectively at the N9 position to give the desired alkylated product in good yield in salt form. After conventional catalytic hydrogenolysis of the benzyl group and hydrolysis of the resulting acetate, pure PCV was obtained without the need for chromatography. As a side chain precursor, the mesylate was selected rather than a halide since the corresponding halides gave several impurities under the same reaction conditions. Two procedures for the synthesis of FCV from PCV and a derivative are also reported. (c) 2006 Elsevier Ltd. All rights reserved.