InCl3-catalyzed four-component reaction: a novel synthesis of N-carbazolyl dihydropyridines

We have developed a simple, efficient, and environmentally benign microwave-assisted InCl3-catalyzed synthesis of N-carbazolyldihydropyridines via a four-component reaction of 3-amino-9-ethylcarbazole, malononitrile, aromatic aldehydes, and acetylenic esters. The use of microwave heating allowed for reduced reaction times and resulted in higher yields. This four-component reaction is atom-efficient, high-yielding, and applicable to a wide variety of four-component reactions. (C) 2011 Elsevier Ltd. All rights reserved.