AN ALTERNATIVE STRATEGY FOR THE SYNTHESIS OF 3'-AZIDO-2',3'-DIDEOXY-4'-THIONUCLEOSIDES STARTING FROM D-XYLOSE

Methyl ideoxy-4-thio-alpha,beta-D-erythro-pentofuranoside and -dideoxy -4-thio-alpha,beta-D-erythro-pentofuranose were prepared in twelve and thirteen steps, respectively, by an efficient route starting from D-x ylose. Both compounds were easily converted into an anomeric mixture o f pyrimidine nucleosides by reaction with the 2,4-bi(trimethylsilyloxy ) derivative in the presence of a Lewis acid. The anomeric mixtures we re separated by chromatography. The 4'-thio analogue of AZT and relate d uridine nucleosides have been prepared by a novel and more efficient approach.