An efficient and concise synthesis of alpha-galactosylceramide

A concise and stereoselective synthesis of α-GalCer is described. The key features of the synthetic strategy are the use of a phytosphingosine in which the amine is masked as trichlorophthalimide, the diol as an isopropylidene acetal, and a galactosyl donor protected as a 4,6-benzylidene to improve the α selectivity of the glycosylation reaction. The pattern of protecting groups on the donor and the acceptor have proven to give an excellent match of reactivity allowing the glycosylation reaction to take place stereoselectively. The overall synthesis allowed to achieve α-GalCer in good yields and few steps.