Enantioselective All-Carbon (4+2) Annulation by <i>N</i>-Heterocyclic Carbene Catalysis
作者:Lisa Candish、Alison Levens、David W. Lupton
DOI:10.1021/ja508542n
日期:2014.10.15
The enantioselective vinylogous Michael/aldol cascade is an underdeveloped approach to cyclohexenes. Herein we describe a highly enantioselective (most >= 98:2 er) and diastereoselective (all >= 15:1 dr) N-heterocyclic carbene catalyzed cycloisomerization of acyclic dienyl esters to cyclohexyl beta-lactones. Derivatizations avail cyclohexenes bearing four contiguous stereogenic centers, while mechanistic studies support olefin isomerization prior to cyclization.