Asymmetric Büchner reaction and arene cyclopropanation via copper-catalyzed controllable cyclization of diynes
Yan-Xin Zheng1, Li-Gao Liu2, Tian-Qi Hu1
1State Key Laboratory of Physical Chemistry of Solid Surfaces, Key Laboratory of Chemical Biology of Fujian Province, and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, China.
Abstract:
The asymmetric Büchner reaction and related arene cyclopropanations represent one type of the powerful methods for enantioselective dearomatization. However, examples of asymmetric Büchner reactions via a non-diazo approach are quite scarce, and the related arene cyclopropanation based on alkynes has not been reported. Herein, we disclose an asymmetric Büchner reaction and the related arene cyclopropanation by copper-catalyzed controllable cyclization of N-propargyl ynamides via vinyl cation intermediates, leading to chiral tricycle-fused cycloheptatrienes and benzonorcaradienes in high yields and enantioselectivities. Importantly, this protocol represents an asymmetric arene cyclopropanation reaction of alkynes and an asymmetric Büchner reaction based on vinyl cations.
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