Iridium-catalyzed Direct Bolylation of Benzene with Diboron. A Theoretical Study

摘要

From theoretical calculations, full catalytic cycle was proposed for direct borylation of benzene with diboron, B_2(eg)_2(eg=OCH_2_2CH_2O)Not iridium(I)boryl complex, Ir(Beg)(bpy)but iridium(III)tris(boryl)complex, Ir(Beg)_3(bpy), is an active species.The C-H sigma-bond of benzene is activated by Ir(Beg)_3(bpy)to afford an unusual iridium(V)complex, Ir(Beg)3(H)(Ph)(bpy).From this iridium(V)complex, the reductive elimination of the B-C bond easily takes place to afford borylbenzene Ph-Beg with concomitant formation of Ir(Beg)_2(H)(bpy).Ir(Beg)_2(H)(bpy)further reacts with diboron to regenerate Ir(Beg)_3(bpy)with formation of borane H-Beg, when diboron exists in the solution.When diboron is consumed and borane exists in the solution, Ir(Beg)_2(H)(bpy)reacts with borane to regenerate Ir(Beg)_3(bpy)with formation of H_2.