The Transition Metal-catalyzed N-Alkylation and N-Heterocyclization. A Reductive Transformation of Nitroarenes into (Dialkylamino)arenes and 2,3-Dialkyl-substituted Quinolines Using Aliphatic Aldehydes under Carbon Monoxide

The catalytic N-alkylation and N-heterocyclization of nitroarenes occur at 180 °C under a carbon monoxide pressure of 70 atm and in the presence of aldehyde and such transitionmetal complexes as rhodium and palladium complexes, thus giving 2,3-dialkyl-substituted quinolines and (dialkylamino)arenes in good yields. The product selectivity depends greatly on the catalysts: a binary catalyst, RhCl(PPh3)3 and PdCl2, is effective for the N-heterocyclization, while [Rh2Cl2(cod)2] is effective for the N-alkylation.