Enantioselective Syntheses of Pachastrissamine and Jaspine A<i>via</i>Hydroxylactonization of a Chiral Epoxy Ester
作者:Hiroyuki URANO、Masaru ENOMOTO、Shigefumi KUWAHARA
DOI:10.1271/bbb.90670
日期:2010.1.23
A new enantioselective total synthesis of pachastrissamine (jaspine B) was achieved from a known α,β-unsaturated aldehyde by utilizing Córdova’s asymmetric epoxidation as the chirality-inducing step. The 2,3-cis stereochemistry of pachastrissamine was established via intramolecular epoxide ring opening of a γ,δ-epoxy-α,β-unsaturated ester intermediate coupled with oxy-Michael cyclization. Treatment of pachastrissamine with tetrahydro-2-furanol under acidic conditions led to smooth oxazolidine ring formation, furnishing jaspine A in a high yield.
实现了从已知的α,β-不饱和醛出发的新型对映选择性全合成的pachastrissamine(jaspine B),采用了Córdova的不对称环氧化反应作为产生手性的步骤。通过γ,δ-环氧-α,β-不饱和酯中间体的分子内环氧开环结合氧-迈克尔环化,确定了pachastrissamine的2,3-cis立体化学。在酸性条件下,用四氢-2-呋喃醇处理pachastrissamine,实现了顺利的噁唑烷环的形成,获得了高产率的jaspine A。