Asymmetric syntheses of spiro[benzofuro-cyclopenta[1,2-b]indole-indoline] scaffolds via consecutive cyclization
Heng Zhang1, Xu-Kai Guan, Dong-Yang Sun
1College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun 130012, People's Republic of China. suoqin@jlu.edu.cn.
Abstract:
An efficient method to construct enantioenriched spiro[benzofuro-cyclopenta[1,2-b]indole-indoline] scaffolds via consecutive cyclization is described here. The new scaffolds possess five successive chiral stereogenic centers and two spiroheterocycles. A range of highly enantioenriched scaffolds has been obtained with up to 93% yield, 99% ee and >19 : 1 d.r. catalyzed by Brønsted acid catalysts.
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