The cationic iridium complex ([Ir(cod)2]OTf + rac-BINAP) efficiently catalyzed a sequential process of ortho-C-H bond functionalization, cyclization and dehydration, leading to a concise preparation of 1-methylene indene (benzofulvene) derivatives. The iridium complex operated as a catalyst in the ortho-C-H bond alkenylation of aryl ketones with alkynes and as a Lewis acid catalyst in the cyclization of the alkenylated product and the subsequent dehydration.
A highly efficient and practical synthesis of benzofulvenes was developed via ketone-directed Cp*Co(III)-catalyzed sequential C–H activation, addition, cyclization, and dehydration cascade processes between simple aromaticketones and alkynes. The reaction tolerates a variety of functional groups, and various benzofulvenes were efficiently synthesized in 42–92% yields.