新的手性源——5-(1-(艹孟)氧基)-2(5-H)-呋喃酮的合成及其不对称 Michael 反应的研究

Studies on the Synthesis and Asymmetric Michael Reation of 5-(1-Menthyloxy)-2(5-H)-Furanone

近年来,手性的丁烯内酯类化合物在合成杂环和天然产物方面起了很重要的作用,我们利用新的手性源,5-(1-氧(艹孟)基)-2(5-H)-

A new chiral source,5-(1-Menthyloxy)-2(5-H)-Furanone (4 a) has been conveniently synthesized in 71% overall yield with a de>99%,and used as an efficient chiralMichael aceeptor.The optically pure γ-menthyloxylactone (4 a) is readily available throughsinglet oxygen photooxygenation of furfural followed by etherification of the resulting 4-hydroxybutenolide epimeric mixture with 1-menthol and subsequent crystallization from pe-trolether.The asymmetric Michael reaction of 5-(1-Menthyloxy)-2(5-H)-Furanone has beenfurther investigated.The bulky γ-menthyloxysubstituent favours the attack of thiols andamines to 4a from the less hindered face.Complete diastereoselecti control 1,4-conjugativeaddition is deduced from the spectroscopic analyses of adducts 5 and 6.This indicates a dia-stereometric excess (de)>99% for all aminoactones 5 and thiolactones 6 prepared.A newsynthetic route to optically active 2-amino (thio)-1,4-diols based on the reduction of enan-tiomerically pure 4-amino(thio)-5-menthyloxy-butyrolctone is described.