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
Synthetic studies towards naturally occurring γ-(<i>Z</i>)/(<i>E</i>)-alkylidenebutenolides through bimetallic cascade cyclization and an adventitious photoisomerization method
visible light-induced photoisomerization method of γ-(Z)-alkylidenebutenolides to their corresponding E-components was reported in this article. Initially, a series of naturally occurring enantiopure γ-(Z)-alkylidenebutenolides was synthesized by employing a “Pd–Cu” bimetallic cascade cyclization protocol. In the later part, the synthesized γ-(Z)-alkylidenebutenolides were photoisomerized in the presence
本文报道了一种通用且灵活的可见光诱导γ-( Z )-亚烷基丁烯内酯光致异构化为其相应的E-组分的方法。最初,通过采用“Pd-Cu”双金属级联环化方案合成了一系列天然存在的对映体纯 γ-( Z )-亚烷基丁烯内酯。在后面的部分中,合成的 γ-( Z )-亚烷基丁烯内酯在三重光敏剂存在下以合理可接受的产率对 γ-( E )-亚烷基丁烯内酯进行光异构化。采用所开发的方法实现了 goniobutenolides、hygrophorones、ramariolide D、melodorinols/乙酰-melodorinols、versicolactones 和 phomopsolidones 的全合成。