Theoretical investigation of gold-catalyzed oxidative Csp3-Csp2 bond formation via aromatic C-H activation

The mechanisms of Selectfluor-mediated Au-catalyzed intramolecular C-sp3-C-sp2 cross-coupling reaction involving direct aryl C-sp2-H functionalization have been investigated theoretically. Several pathways involving the oxidation of alkylgold(I) (Cycle I), phosphine Au(I) precatalyst (Cycle II), gold(I) pi-alkene complex (Cycle III) and arylgold(I) (Cycle IV) by Selectfluor, respectively, were examined. Our calculation results suggested the following: (1) Cycles I and II are preferred over Cycles III and IV, and the reaction would undergo the energy favored pathways (Cycles I and II), which is further confirmed by stereochemical analysis; (2) Cycle I is competitive with Cycle II, and the rate-determining steps of these two cycles are oxidation of Au(I) species by Selectfluor; (3) water has been found to participate in the catalytic reaction and decrease the activation energy barrier of the reductive elimination.