DIASTEREOSELECTIVE SYNTHESIS OF D-ERYTHRO-SPHINGOSINE

A twelve-step, diastereoselective synthesis of D-erythro-C-18-sphingos ine [(2S,3R,4E)-2-amino-1,3-dihydroxy-4-octadecane, 1] is described (1 2 steps, 10% overall yield), starting from 2,3-O-isopropylidene-D-glyc eraldehyde 3. The first step was the crossed addition of oxycarbonyl)- 2-(tert-butyldimethylsilyloxy)pyrrole (TB-SOP, 2) to 2,3-O-isopropylid ene-D-glyceraldehyde 3 (a vinylogous variant of the Mukaiyama-aldol re action) producing a seven-carbon lactam intermediate 4, which was then shortened by three carbon atoms to furnish the aldehydo-erythrose der ivative 10. Wittig elongation of 10 with the appropriate C-14 ylide, f ollowed by photoinduced Z to E double bond isomerization and removal o f the protecting groups, completed the synthesis. (C) 1997 Elsevier Sc ience Ltd.