An efficient glycosylation reaction for the synthesis of asialo GM2 analogues

We investigated the coupling reaction of glycosyl donors N-trichloroethoxycarbonyl-galactosamine-O-trichloroacetimidate (2a) and N-p-nitrobenzyloxycarbonyl-galactosamine-O-trichloroacetimidate (2b) with the 4′-OH of lactose derivatives (3a–d) to synthesize key intermediates of asialo GM2 analogues, and found that the glycosylation yield with 2a was 90% or more in all investigated cases.