An Efficient and Concise Synthesis of α-Galactosylceramide

A concise and stereoselective synthesis of α-galactosylceramide (α-GalCer) is described. The key features of the synthetic strategy are the use of a phytosphingosine in which the amine is masked as a tetrachlorophthalimide and the diol as an isopropylidene acetal, and the galactosyl donor is 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 gave α-GalCer in good yields and in few steps.