Palladium-Catalyzed Dearomatization of Indoles with Alkynes: Construction of Spirocyclohexaneindolenines.

A palladium-catalyzed dearomatization of indoles with alkynes has been developed, providing an efficient route to access a variety of synthetically useful spirocyclohexaneindolenines in moderate to good yields. The current method features a simple catalytic system, operational simplicity, and good functional group compatibility, which will contribute substantially to the development of dearomatization to access spiro compounds. Besides, the ubiquitous existence of spiro molecules, including spirocyclohexaneindolenines, in drugs and biological active molecules suggests the potential application of this methodology in medicinal chemistry.