One Substrate, Two Modes of C–H Functionalization: A Metal-Controlled Site-Selectivity Switch in C–H Arylation Reactions

A unique site-selectivity switch has been achieved in the ruthenium-catalyzed C–H arylation reaction of N-acetyl-1,2-dihydroisoquinolines. This metal-mediated switch is antipodal to the previous report on the palladium-mediated C-4 C–H arylation on the same substrate. Mechanistic details reveal interesting aspects of the reaction pathway, and kinetic studies bring out the difference in the modes of C–H activation adopted by the two catalytic systems.