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.

A general and efficient visible-light photoredox-catalysed decarboxylative radical coupling reaction of N-aryl amino acids with aldehydes or ketones for the synthesis of various 1,2-amino alcohols by using water as the solvent at room temperature is described. This protocol is characterised by broad substrate scopes, mild reaction conditions and amenability to gram-scale synthesis, which opens up a simple, mild but effective method to produce 1,2-amino alcohols from readily available starting materials.