Cross-dehydrogenative coupling of unactivated alkanes

Chemists have been seeking simple and efficient methods to form C–C bonds, which are paramount in organic synthesis, advanced materials, and life science. Towards this goal, cross-dehydrogenative coupling (CDC) between two different C–H bonds represents an ideal paradigm for C–C bond formation, wherein the CDCs of unactivated alkanes rank among the most challenging but rewarding transformations. This review summarises some recently developed strategies that allow C–C cross-couplings between an inert aliphatic C–H bond and another C–H bond. These contributions are organised based on their key C(sp³)–H functionalisation tactics, including hydrogen atom abstraction, in situ desaturation, directed metallation, and others. In each category, representative examples are given and discussed from their general mechanistic perspectives.