Title: Generation of Endocyclic Vinyl Carbene Complexes via Gold-Catalyzed Oxidative Cyclization of Terminal Diynes: Towards Naphthoquinones and Carbazolequinones

Authors: Chao Shu, Chong-Yang Shi, Qing Sun, Bo Zhou, Tian-You Li, Qiao He, Xin Lu, Rai-Shung Liu, and Long-Wu Ye

Abstract:

Carbene cascade reactions involving carbene/alkyne metathesis have attracted much attention over the past decades because this chemistry offers great potential to build complicated cyclic molecules. However, the formed vinyl metal carbenoids in these reactions are limited to exocyclic carbenes, and the generation of endocyclic vinyl carbene complexes remains unexplored. Here we report an unprecedented gold-catalyzed oxidative cyclization of terminal diynes. Importantly, the generation of endocyclic vinyl carbene complexes was involved in this oxidative cyclization, which is distinctively different from previous protocols. This method allows the facile synthesis of various valuable naphthoquinones and carbazolequinones from readily available diynes under exceptionally mild reaction conditions and features a broad substrate scope and wide functional group tolerance. Moreover, theoretical calculations provide further evidence on the divergent selectivity of this cyclization reaction.

Full-Link: https://pubs.acs.org/doi/10.1021/acscatal.8b04455