Abstract
Methyl 3-benzoylthio-5-O-tert-butyldiphenylsilyl-2,3-dideoxy-beta-D- erythro-pentofuranoside (4) and its corresponding alpha anomer 5 were synthesized in four steps from 2-deoxy-D-ribose and used as substrates for the synthesis of nucleosides by condensation with silylated thymidine and N-6-isobutyryladenine. The nucleosides were deprotected by treatment with Bu(4)NF in THF followed by reaction with MeONa in MeOH to give 3'-deoxy-3'-mercaptothymidine (8), 2',3'-dideoxy-3'mercaptoadenosine (15) and its corresponding alpha anomer 16. In the latter reactions it was important to use degassed solvents to minimize formation of the corresponding disulfides of purine nucleosides. Using Bu(4)NF, without subsequent reaction with MeONa in the deprotection reaction, resulted in intermolecular transesterification reactions.