Convenient Iodonium-Promoted Stereoselective Synthesis of 2-Deoxy-α-glycosides by Use of<i>S</i>-(2-Deoxyglycosyl) Phosphorodithioates as Donors

Abstract

S-(2-Deoxyglycosyl) O,O-diethyl phosphorodithioates, easily accessible from glycals, are convenient precursors for glycosylation in the presence of promoters such as N-iodosuccinimide or iodonium bis (2,4,6-trimethylpyridine) perchlorate. In a series of transformations both the α- and β-glycosyl donors were attached stereoselectively to acceptor sugar molecules [1,2: 3,4-di-O-isopropylidene-α-D-galactopyranose (1), benzyl 3-O-benzyl-2,6-dideoxy-β-L-ribo-hexopyranoside (2) or benzyl 4-O-benzyl-2,6-dideoxy-β-L-ribo-hexopyranoside (3)] in primary and secondary positions in short reaction times and generally convincing yields.