SYNTHESIS OF 4 STEREOISOMERIC TETROSE DERIVATIVES FROM PROPARGYL ALCOHOL - ONE-CARBON HOMOLOGATION OF VINYLSILANES VIA ALPHA,BETA-EPOXY SILANES

Silicon-mediated synthesis of stereoisomeric tetroses 1, 2, 3, and 4, from propargyl alcohol, is described. An allylic alcohol bearing the trimethylsilyl group in the gamma-position, rac-9b, was subjected to the Sharpless kinetic resolution to give (2S)-9b and the (2S,3S,4S)-epoxide 10a of very high enantiomeric purity (greater-than-or-equal-to 97% ee). Compound (2S)-9b was epoxidized with tert-butyl hydroperoxide and vanadyl acetylacetonate to give epoxide 14a as the major product. Epoxy silanes 10a and 14a were treated with benzenethiol in the presence of silica gel to give the corresponding sulfides (11a and 16a). Sulfides 11b and 16b were oxidized to sulfoxides which, without isolation, were subjected to the Pummerer rearrangement followed by hydrolysis. Intermediate vinylsilane 9a was prepared from vinylsilane 6 via epoxy silane 7 using a novel homologation method.