Recent advances in rhodium-catalysed cross-dehydrogenative-coupling between two C(sp2)–H bonds

Rhodium-catalysed cross-dehydrogenative coupling (CDC) has received considerable attention in recent years. This modern technology has been considered as an attractive synthetic tool for selective C–C bond formation due to the following reasons: (1) no pre-functionalised starting materials (i.e. no organometallic reagents or organohalides) are required that eliminates the generation of stoichiometric amounts of metallic wastes, and hence, the CDC reaction is a more environmentally benign and sustainable process and (2) it is a more straightforward synthetic approach using simple materials, resulting in better step- and atom economy. In this review, recent remarkable achievements in rhodium-catalysed CDC reactions between two C(sp2)–H bonds are overviewed, particularly in the period of 2016 to 2021.