Copper-catalyzed Büchner reaction and phenyl cyclopropanation through diyne cyclization

Abstract

Büchner reaction, as an exclusive category of expansive dearomatization, represents a powerful approach for the construction of valuable functionalized cycloheptatrienes in a direct manner from readily available aromatic precursors. However, the traditional Büchner reaction almost relies on using explosive diazo compounds as the carbene precursors. Herein, we disclose a copper-catalyzed Büchner reaction through diyne cyclization, and bicycle-fused cycloheptatrienes bearing all carbon quaternary stereogenic centers are obtained in moderate to excellent yields with broad substrate scope. In addition, norcaradiene derivatives can also be selectively produced by a substrate control through a phenyl cyclopropanation reaction, thus constituting a copper-catalyzed controllable cyclization of diynes.