Kinetic and Mechanistic Study of Transition Metal Ion Catalyzed Vilsmeier–Haack Cyclization and Formylation Reactions with Acetanilides

Abstract

Vilsmeier–Haack reactions (VHR) with acetanilides afforded 2-chloro 3-formyl quinoline derivatives. The reactions obeyed second order kinetics with a first order dependence on VHR as well as acetanilide. Significant rate enhancements were observed when transition metal ions such as Cu(II), Ni(II), Co(II), and Cd(II) were used as catalysts in these reactions. The kinetic results in transition metal ion catalyzed reactions coupled with uv-visible spectrophotometric observations substantiated the participation of mixed ligand precursors of the type [M(II)S(VHR)] involving acetanilides and VH reagents in the rate limiting step. Activation parameters were computed and interpreted suitably.