A C-H Insertion Approach to Functionalized Cyclopentenones.

Cyclopentenones are synthetically versatile structures, and their straightforward construction from alkynone substrates by employing synthetically streamlining C–H insertion is conceptually appealing and of high synthetic potential. But, its implementation is very limited. Herein we report a Au-catalyzed version, which affords 2-bromocyclopent-2-en-1-ones with a broad scope and synthetically desirable diastereoselectivities. The proposed key intermediate capable of the observed insertion into unactivated C–H bonds is a fully functionalized gold vinylidene, which is generated via a novel intermolecular strategy. This flexible access of likely gold vinylidenes opens various opportunities to explore their versatile reactivities.