化学
对映选择合成
立体化学
立体选择性
绝对构型
炔基化
分子内力
筑地反应
全合成
烷基化
天然产物
催化作用
立体异构
有机化学
作者
Jianwei Bian,Matthew Van Wingerden,Joseph M. Ready
摘要
The nigellamine alkaloids are dolabellane diterpenes displaying potent lipid metabolism-promoting activity. Total synthesis of (+)- and (−)-nigellamine A2 has been accomplished. Absolute stereochemistry of synthetic nigellamine A2 was established through an intramolecular asymmetric allylic alkylation using a Pd(phosphinooxazoline) catalyst. Other notable transformations include a radical alkynylation, a diastereoselective Nozaki−Hiyama−Kishi cyclization, and a regio- and stereoselective catalytic epoxidation. On the basis of X-ray crystallographic analysis of an optically active intermediate, we have confirmed the assigned absolute stereochemistry of the natural product. Minor modifications of the synthetic sequence outlined here should provide access to the other nigellamine alkaloids.
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