Studies towards the total synthesis of solanoeclepin A: synthesis of the 7-oxabicyclo[2.2.1]heptane moiety and attempted seven-membered ring formation
作者:Jorg C. J. Benningshof、Richard H. Blaauw、Angeline E. van Ginkel、Jan H. van Maarseveen、Floris P. J. T. Rutjes、Henk Hiemstra
DOI:10.1039/b201987f
日期:2002.7.11
This paper details studies towards the total synthesis of solanoeclepin A (1), the most active natural hatching agent of potato cyst nematodes. The first goal was the preparation of the tetracyclic left-handed substructure 2 in enantiopure form. The 7-oxabicyclo[2.2.1]heptane moiety was obtained via a diastereoselective intramolecular Diels–Alder strategy by using (R)-phenylglycinol as a chiral auxiliary as pioneered by Mukaiyama. A chromium-mediated nickel-catalysed coupling of aldehyde 5 with vinyl triflate 6 gave α,β-unsaturated lactone 18 as a single stereoisomer. The seven-membered ring was expected to arise from a McMurry coupling of dialdehyde 4. Surprisingly, oxidation of diol 24 did not lead to the desired dialdehyde 4, but to the eight-membered ring lactone 25.
本文详细介绍了对马铃薯胞囊线虫最有效的天然孵化剂——索拉诺克利宾A(1)的全合成研究。第一个目标是制备对映纯形式的四环左旋子结构2。7-氧杂双环[2.2.1]庚烷部分是通过 Mukaiyama 首创的分子内迪尔-阿尔德不对称策略,使用(R)-苯甘氨醇作为手性助剂获得的。醛 5 与乙烯基三氟甲磺酸酯 6 的铬介导镍催化偶联反应产生了α,β-不饱和内酯 18 作为单一立体异构体。七元环预计由二醛 4 的麦克马利偶联反应产生。令人惊讶的是,二醇 24 的氧化反应并未产生预期的二醛 4,而是产生了八元环内酯 25。