Ruthenium‐Catalyzed C–Heteroatom Bond Formation Through C(sp ² )H Functionalization

Abstract

This article describes recent advances in C–heteroatom bond formation via ruthenium‐catalyzed proximal or remote C(sp 2 )H functionalization. This ruthenium catalysis is particularly fascinating not only because of the low cost of the metal, but also because it allows for a wide range of transformations. The excellent reactivity of the ruthenium catalysts is attributed to the highly active CH ruthenated intermediate, which can perform oxidative addition or electrophilic substitution at the ortho position as well as radical addition at distal meta or para positions. Diverse strongly or weakly coordinating directing groups, such as N ‐containing heterocycles, aldehydes, ketones, carboxylic acids, amides, sulfamides, carbamates, and phosphines, can assist the ruthenium‐catalyzed functionalization of ortho, meta, and even, para positions via CN, CO, C–halogen, CSi, CS/Se, and CB bond‐forming reactions. Typically, [RuCl 2 ( p ‐cymene)] 2 is used for C–heteroatom bond construction, but the octahedral Ru catalysts RuHCl(CO)(PPh 3 ) 3 and Ru 3 (CO) 12 have been used for ortho CSi and meta CN bond formation, respectively. In addition, this article details representative applications of Ru‐catalyzed C(sp 2 )H functionalization in the preparation and late‐stage modification of important synthetic building blocks and pharmaceuticals.