Stereoselective Glycosylation for 1,2--Aminoglycoside Assembly by Cooperative Atom Transfer Catalysis.

We report here a new catalytic method for exclusively 1,2--α-selective glycosylation that assembles a wide variety of 1,2--aminoglycosidic linkages in complex glycans and glycoconjugates. Mechanistic studies revealed a unique glycosylation mechanism in which the iron catalyst activates a glycosyl acceptor and an oxidant when it facilitates the cooperative atom transfer of both moieties to a glycosyl donor in an exclusively -selective manner. This catalytic approach is effective for a broad range of glycosyl donors and acceptors, and it can be operated in a reiterative fashion and scaled up to the multigram scale.