Stereoselective synthesis of novel 1′-substituted 2′-deoxy-4-thionucleosides

Abstract

Oxidation of 2′-deoxy-5-ethyl-4-thiouridine with sodium metaperiodate afforded a separable mixture of (R)- and (S)-sulfoxides. These were converted, after protection as their tert-butyldimethylsilyl ethers, by reaction with LDA to the 1′-anion which was reacted with a number of electrophiles to furnish a range of novel nucleoside analogues. Deprotection of the (R)-sulfoxide of 2′-deoxy-5-ethyl-1′-methyl-4′-thiouridine with triethylamine–trihydrogen fluoride under very mild conditions gave the unprotected sulfoxide.