Highly Enantioselective Construction of Strained Spiro[2,3]hexanes through a Michael Addition/Ring Expansion/Cyclization Cascade.

Zhao, Chuan‐Gang; Feng, Zhi‐Tao; Xu, Guo‐Qiang; Gao, Ang; Chen, Jing‐Wei; Wang, Zhu‐Yin; Xu, Peng‐Fei

We herein report a general organocatalytic enantioselective strategy for the construction of highly strained spiro[2,3]hexane skeletons from methylenecyclopropanes and a broad selection of α,β‐unsaturated aldehydes. The reaction proceeds through a Michael addition followed by ring expansion of methylenecyclopropanes and nucleophilic attack of an enamine to realize the construction of spiro[2,3]hexanes. Key to the success of this approach are the utilization of an electron‐deficient difluoro‐substituted secondary amine catalyst and the intrinsic reactivity of methylenecyclopropanes.

SECONDARY amines; CONSTRUCTION; HEXANE; ALDEHYDES

Angewandte Chemie, 2020, Vol 132, Issue 8, p3082

0044-8249

Academic Journal

10.1002/ange.201912834