CoIII-Catalyzed C–H Alkenylation and Allylation with Cyclopropenes via Sequential C–H/C–C Bond Activation

An atom-economical strategy for the C–H alkenylation and C–H allylation of arenes by employing cyclopropenes as versatile alkenylating and allylating reagents is reported, catalyzed by cobalt. The Co-catalyzed C–H alkenylation process involves sequential C–H and C–C bond cleavage. Under the optimized conditions, broad-ranging alkenylated (hetero)­arenes were synthesized with complete (E)-stereoselectivity (up to 91%). The consecutive C–H allylation proved viable under basic conditions via double-bond migration of the initially generated alkenyl (hetero)­arenes, thus leading to allylated (hetero)­arenes with high stereoselectivity of olefin (E/Z ratio = 91:9 to 100:0).