Synthesis of benzyl and benzyloxycarbonyl base-blocked 2'-deoxyribonucleosides

Abstract

Acylimidazolium salts, particularly benzyloxycarbonylimidazolium salts, are shown: to be effective agents for the direct N-protectionof nucleoside bases as their acyl derivatives.These acyl nucleosides are also available in two steps via thiocarbamate intermediates.In addition, chlorothioformates are shown to be effective for converting the 6-oxygen of 2'-deoxy guanosine to a thioether, which then can be transformed to a number of -' 6-substi tuted 2'-deoxyguanos i ri~;,.--~