Distinct roles of Ag(I) and Cu(II) as cocatalysts in the intramolecular cyclization of N-methyl-N-phenylanthranilic acid: A theoretical investigation

Abstract

• The selectivity is controlled by the additive employed in this reaction. • The silver oxide promotes C(sp 3 )−H activation and C−O cyclization to provide 1,2-dihydro-(4H)−3,1-benzoxazin-4-one. • The copper acetate contributes to C(sp 2 )−H activation and decarboxylative arylation to afford carbazole. • The origins of the selectivity could be attributed to the cation-π interaction between Ag and the substrate arene ring. The mechanisms of the intramolecular cyclization of N-methyl-N-phenylanthranilic acid catalyzed by Pd(OAc) 2 were investigated by employing the density functional theory (DFT) calculations. The selectivity is controlled by the additive employed in this reaction. Silver oxide promotes C(sp 3 )−H activation and C−O cyclization to provide 1,2-dihydro-(4H)-3,1-benzoxazin-4-one, while copper acetate contributes to C(sp 2 )−H activation and decarboxylative arylation to afford carbazole. The origins of the selectivity could be attributed to the cation-π interaction between Ag and the substrate arene ring, which significantly lowers the activation energy for C(sp 3 )−H deprotonation. The distinct roles of Ag(I) and Cu(II) as cocatalysts were clarified through our calculations.