2′-Modified Neamine Analogues from Thiomannosides through Glycosidation-Stereoinversion

Abstract

Conveniently protected neamine analogues were synthesized with a free 2′-OH group for further functionalization. An approach was investigated involving a stereoselective α-glycosidation reaction of 3,4-O-dimethoxybutanediyl-2-O-silyl protected thiomannosides with a 2-deoxystreptamine derivative. Subsequent 2-O-deprotection followed by anoxidation–reduction sequence led to α-glucosides withstereoinversion at C-2′. The scope of the procedure for the syntheses of α-glucosides was explored with three distinct model acceptors. Thiomannoside coupling, 2-O-deprotection, and oxidation were straightforward, whereas the outcome of the reduction step was clearly acceptor-dependent.