An efficient aqueous N-heterocyclization of aniline derivatives: Microwave-assisted synthesis of N-aryl azacycloalkanes

ORGN 16

Rajender S. Varma, Varma.Rajender@epa.gov and Yuhong Ju, Ju.Yuhong@epa.gov. Sustainable Technology Division, National Risk Management Research Laboratory, U. S. Environmental Protection Agency, 26 West Martin Luther King Drive, MS 443, Cincinnati, OH 45268
N-aryl azacycloalkanes, an important class of building blocks in natural product and pharmaceuticals, are synthesized via an efficient and simple eco-friendly protocol that involves double N-alkylation of aniline derivatives. The reaction is accelerated by exposure to microwaves in aqueous medium in the presence of a mild base, potassium carbonate. The methodology shortens the reaction time significantly, utilizes readily available aniline derivatives, alkyl dihalides or ditosylates to assemble two C-N bonds in a SN2-like heterocyclization protocol which can not be fully realized under conventional reaction conditions. The approach circumvents the need for a multi-step process or the use of expensive metal catalysts. Further, this new method affords excellent product yields and in view of the mild reaction conditions accommodates reactive functional groups such as carbonyl, hydroxyl and ester etc.