EASY SYNTHESIS OF 5,6-DISUBSTITUTED ACYCLOURIDINE DERIVATIVES

Ethyl 2-ethyl-3-oxo-4-phenylbutyrate is synthesized in a high yield fr om the corresponding benzyl cyanide and ethyl 2-bromobutyrate or by re action of the potassium salt of ethyl 2-ethylmalonate with phenylacety l chloride. Condensation of the 3-oxo ester with thiourea, desulfuriza tion with chloroacetic acid and finally condensation with acetals or 1 ,3-dioxolanes using trimethylsilyl triflate (TMS triflate) as a cataly st or with chloromethyl ethyl ether afforded the 5-ethyl-6-benzyl acyc louridine derivatives.