Copper-catalyzed Buchner reaction and phenyl cyclopropanation through diyne cyclization†

The Buchner 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 Buchner reaction almost relies on using explosive diazo compounds as carbene precursors. Herein, we disclose a copper-catalyzed Buchner reaction through diyne cyclization, and bicycle-fused cycloheptatrienes bearing all carbon quaternary stereogenic centers are obtained in moderate to excellent yields with a broad substrate scope. In addition, norcaradiene derivatives can also be selectively produced by substrate control through a phenyl cyclopropanation reaction, thus constituting a copper-catalyzed controllable cyclization of diynes.