Halogen-Bonding-induced Hydrogen Transfer to C=N Bond with Hantzsch Ester

Several bidentate dihydroimidazolines were prepared and investigated as catalysts for hydrogen transfer reduction of C=N bond with Hantzsch ester. Highly efficient reactions were observed for quinolines and imines with low catalyst loading of 2 mol %. The presence of halogen bonding was elucidated using NMR studies and isothermal calorimeric titrations. Binding constants of the XB donors were also measured using isothermal calorimeric titrations (ITC).