Stoichiometric to catalytic reactivity of the aryl cycloaurated species with arylboronic acids: insight into the mechanism of gold-catalyzed oxidative C(sp2)–H arylation

摘要

Based on the well-defined five-membered aryl gold( III ) complexes, [Au(tpy)X _(2) ] ( 3a and 3b ) and [AuBr(Ph)(tpy)] ( 7 ), as well as the aryl gold( III ) complex [AuCl _(2) (Ph)(tpy)] ( 8 ) (tpy = 2-( o -tolyl)pyridine) as reliable models, we present a detailed study of the mechanism for gold( III )-catalyzed oxidative cross-coupling reactions between cycloaurable arenes and arylboronic acids. Here we report the direct evidence for a mechanistic proposal including arene C–H activation, transmetallation and biaryl reductive elimination. The chelation-assisted C–H activation strategy has been used for the development of the gold( III )-catalyzed C–H bond arylation of arenes with aryl reagents to forge extended π-conjugated systems.