A novel O -fucosylation strategy preactivated by ( p -Tol) 2 SO/Tf 2 O and its application for the synthesis of Lewis blood group antigen Lewis a

Based on a preactivation strategy using ( p -Tol) 2 SO/Tf 2 O, a new O -fucosylation method with thioglycoside as donor under mild conditions was reported. High yields and excellent α-stereoselectivities of the fucosylation were obtained with secondary sugar alcohol as acceptors. Moreover, the novel fucosylation strategy was successfully applied to the synthesis of an important Lewis blood group antigen Lewis a , which was obtained in nine linear steps with 27% overall yield.