Transition-Metal-Catalyzed Direct C–H Alkenylation, Alkynylation, Benzylation, and Alkylation of (Hetero)arenes
Direct functionalization of (hetero)aromatic C-H bonds has recently emerged as a powerful tool for the functionalization of organic molecules. In the past decade, while many efforts have focused on the direct arylation of (hetero)arenes, much less attention has been devoted to the direct alkenylation, alkynylation, and benzylation of (hetero)arenes. This micro-review summarizes the development in this area to date, with the focus on how the substrate scope has been expanded through selection of more appropriate synthetic methods, such as the careful choice of catalysts, ligands, bases and reaction conditions.