Phase Transfer Catalysis as a General and Stereoselective Entry into Glycosyl Azides from Glycosyl Halides

Abstract

Peracetylated glycosyl- and glycobiosyl bromides and chlorides 1-5 including acetochloroneuraminic acid 6 were converted to their corresponding glycosyl azides 7-12 in 93-98% yields under phase transfer catalyzed conditions. The stereoselective reactions occurred with complete inversion at the anomeric centers to provide a general, high-yielding entry into 1,2-trans-glycosyl azides together with α-sialic acid azide.