上海科技大学知识管理系统

Expedient assembly of unprecedented molecular scaffolds from readily accessible starting materials in a sustainable fashion is highly pursued in modern organic chemistry. Herein, the first catalytic intramolecular dearomative [2 + 2] cycloaddition of indoles or pyrroles with alkynes is achieved via visible-light-mediated energy transfer catalysis. This method enables the synthesis of cyclobutene-fused indolizidines, which are otherwise challenging to access, in high yields with exclusive selectivity. The reaction profiles are well documented by DFT calculations. In addition, this protocol could be extended to the synthesis of cyclobutane-fused indolizidines and related structural analogs. Diverse elaborations of the products are achieved.