title: Construction of dispirocyclohexanes via amine-catalyzed [2 + 2 + 2] annulations of Morita-Baylis-Hillman acetates with exocyclic alkenes.
abstract: Amine-catalyzed [2 + 2 + 2] annulations of one molecule of Morita-Baylis-Hillman (MBH) acetates 1 with two molecules of 2-(arylmethylidene)indane-1,3-diones 2 or methyleneindolinones 4 have been developed under very mild conditions, which produce multistereogenic dispirocyclohexanes 3 and 5, respectively, in moderate to excellent yields and good diastereoselectivity. This amine-catalyzed annulation constitutes a novel and efficient method for the construction of dispirocyclohexane motifs, and also showcases the divergent catalysis between amines and phosphines with regard to the corresponding phosphine-catalyzed [3 + 2] annulations.
authors.affiliation: The State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), 94 Weijin Road, Tianjin 300071, P. R. China. zhengjiehe@nankai.edu.cn.
authors.forename: Rongshun
authors.initials: R
authors.lastname: Chen
authors.forename: Silong
authors.initials: S
authors.lastname: Xu
authors.forename: Xia
authors.initials: X
authors.lastname: Fan
authors.forename: Hanyuan
authors.initials: H
authors.lastname: Li
authors.forename: Yuhai
authors.initials: Y
authors.lastname: Tang
authors.forename: Zhengjie
authors.initials: Z
authors.lastname: He