Chitosan: an efficient recyclable catalyst for transamidation of carboxamides with amines under neat conditions

A novel chitosan-catalyzed transamidation of carboxamides with amines under solvent-free conditions is described. A series of amide derivatives as well as more challenging aryl and alkyl amines with long-chain alkyl substituents could be selectively converted into the corresponding transamidation products, which are frequently found in biologically active compounds and pharmaceuticals. Under similar reaction conditions benzo[d]heterocycles were also obtained via a one-pot synthesis through transamidation and subsequent dehydration. Recyclability of chitosan was demonstrated, with quantitative yields of products obtained without any loss of catalytic activity.