Recent advances in chelation-assisted site- and stereoselective alkenyl C–H functionalization

Abstract

Olefinic C–H functionalization represents an atom- and step economic approach to valuable olefin derivatives from simpler ones, but controlling the selectivity remains a challenge. Remarkable progress has been made in the site-selective C–H functionalization of arenes and alkanes, but there are still limited examples of selective C–H functionalization of olefins presumably due to the lability and easy decomposition of the alkenyl moiety. Chelation-assisted C–H activation represents an efficient protocol for site- and stereo-selective construction of carbon–carbon and carbon–heteroatom bonds. This review highlights recent advances in vicinal- and geminal-group-directed olefinic C–H functionalization, including alkenylation, arylation, alkynylation, alkylation, halogenation, silylation, cyanation and annulation by the formation of exo-/endo-metallocycles. In particular, geminal-group-directed C–H functionalization is covered for the first time, as well as distal-selective alkenyl C–H functionalization under palladium/norbornene cooperative catalysis, which provides novel disconnections in retrosynthetic analysis and represents the future trend in green chemistry.