Diastereoselective addition of alkenylchromium(III) reagents to Garner's aldehyde. The Nozaki-Hiyama-Kishi coupling approach to sphingosines and ceramides

Abstract

Intermolecular Nozaki-Hiyama-Kishi coupling between alkenylchromium(III) reagents, derived from either (E)-(2-bromoethenyl)benzene or (E)-1-iodo-1-pentadecene, and the conformationally rigid Garner's aldehyde resulted in the stereoselective formation of Felkin-type allylic alcohols in good yields, thus providing an easy access to sphingosines. In addition, when the protecting group in the Garner's aldehyde was changed (from Boc to N-octanoyl), a reversal of stereoselectivity was observed in the reaction with (E)-1-pentadecenylchromium(III), probably as the result of hydrophobic interactions between the long carbon chains of the reaction partners.