Effective, high-yielding, and stereospecific total synthesis of D-erythro-(2R,3S)-sphingosine from D-ribo-(2S,3S,4R)-phytosphingosine.

The synthesis of naturally occurring D-erythro-(2R,3S,4E)-sphingosine from commercially available D-ribo-(2S,3S,4R)-phytosphingosine is described. The key step in the reaction sequence comprises TMSI/DBN promoted regio- and stereoselective oxirane opening of intermediate 2-phenyl-4-(S)-[(1S,2S)-1,2-epoxyhexadecyl]-1,3-oxazoline followed by the in situ trans-elimination of 2-phenyl-4-(S)-[(1S,2R)-1,2-dideoxy-2-iodo-1-trimethylsilyloxyhexadecyl]-1,3-oxazoline.