First Asymmetric Synthesis of 6-Hydroxy-4-Sphingenine-Containing Ceramides. Use of Chiral Propargylic Alcohols To Prepare a Lipid Found in Human Skin
作者:Jiong Chun、Hoe-Sup Byun、Robert Bittman
DOI:10.1021/jo026240+
日期:2003.1.1
present here the first synthesis of the 6S and 6R diastereoisomers 2 and 3, which represent analogues of (2S,3R)-ceramide (1) having two allylic hydroxyl groups. Chiralpropargylicalcohols 8 and 11, which were prepared by asymmetric dihydroxylation of alpha,beta-unsaturated ester 13 and allylic chloride 22, respectively, were employed as precursors of 2 and 3. Nucleophilic addition of lithiated TBS-protected
has been isolated and subsquently synthesized in enantiomerically pure form. The total synthesis includes a Sharpless asymmetric dihydroxylation protocol as the stereodifferentiating step, followed by two diastereoselective aldol-type reactions. The approach allows the unambiguous control of all three stereogenic centres, and, furthermore, unequivocal determination of the relative and absolute configuration