Novel cyclization reactions of dichloroazodienes

The novel cyclization reactions of the in;situ generated 1-carboxyethyl-3-phenyl-4,4-dichloroazodiene were found to give N-aminopyrroles and pyridazines when combined with acyclic enamines,Table 1. However, reactions with cyclic enamines gave the N-aminopyrroles, pyridazines, a dihydropyridazine as products as well as the non-cyclized enamine intermediates, Table 2. The enamines 10c and 11c could be converted to the N-aminopyrroles 10a and 11a simply upon heating to higher temperatures indicating a stepwise mechanism. The examples described here are the first reported cyclization reactions for dichloroazodienes.