Ruthenium(II)/N-Heterocyclic Carbene Catalyzed [3+2] Carbocyclization with Aromatic N—H Ketimines and Internal Alkynes

摘要

Transition-metal-catalyzed direct functionalization of C—H bonds has become a powerful method for chemical synthesis over the past two decades. A major strategy for catalytic C—H activation is to utilize heteroatom-based neighboring functional groups by formation of cyclometalated reactive intermediates.One of the most influential advancements for this directed C—H activation strategy was achieved by Murai etal., who, in 1993, reported ruthenium-catalyzed C—H alkylation of aromatic ketones with olefins. Since this seminal discovery, a variety of transition metal catalysts have been developed to exploit various directing groups for selective functionalization of C-H bonds.