中科院上海有机所Jinghan Gui和浙江大学Xin Hong等带领的合作组，在天然产物Bufospirostenin A和Ophiopogonol A全合成研究中取得进展。相关论文发表在2022年9月20日出版的《美国化学会杂志》上。

在该文中，团队首次报道了在非Curtin-Hammett条件下精确控制环癸烯酮构象，以影响第一个顺式选择性跨环Prins环化，这使得从廉价的起始原料仅用7步就可以简捷合成5(10→1)阿贝类固醇Bufospirostenin A和Ophiopogonol A。计算结果表明，关键环化反应受动力学控制，根据反应条件的不同可通过Prins路径或羰基-烯路径进行。此外，构象异构化对决定产物的立体化学性质也起着至关重要的作用。

据了解，由于中等尺寸环的柔性和环张力效应，控制其构象具有一定的挑战性。

附：英文原文

Title: Syntheses of Bufospirostenin A and Ophiopogonol A by a Conformation-Controlled Transannular Prins Cyclization

Author: Peicheng Yang, Yan-Yu Li, Hailong Tian, Gan-Lu Qian, Yun Wang, Xin Hong, Jinghan Gui

Issue&Volume: September 20, 2022

Abstract: Controlling the conformation of medium-sized rings is challenging because of their flexibility and ring strain effects. Herein, we report non-Curtin–Hammett conditions for the precise control of the conformation of cyclodecenones to effect the first cis-selective transannular Prins cyclization, which enabled concise syntheses of the 5(10→1)abeo-steroids bufospirostenin A and ophiopogonol A in only seven steps from inexpensive starting materials. Computational results indicated that the key cyclization was kinetically controlled and proceeded via either a Prins pathway or a carbonyl–ene pathway, depending on the reaction conditions. Moreover, conformational isomerization played a critical role in determining the stereochemistry of the products.

DOI: 10.1021/jacs.2c07944

Source: https://pubs.acs.org/doi/10.1021/jacs.2c07944