A versatile synthesis of pyrrolo-, furo- and thienopyridines via photocyclization of 3-amino-2-alkene imines in an acid medium

We describe the synthesis of pyrrolo-, furo- and thieno[3,2-b]pyridines sub stituted by alkyl-, arylamino or NH2 groups from irradiation of 2-pyrrolyl- , 2-furyl-, and 2-thienylalkene imines under mild reaction conditions. We a lso describe the irradiation of 3-pyrrolyl-, 3-furyl-, and 3-thienylalkene imines, which yields pyrrolo[3,2-c]pyridines in all cases. The mechanism fo r this procedure is proposed. The compounds obtained can potentially be use d in medicinal chemistry. (C) 1999 Elsevier Science Ltd. All rights reserve d.