Microwave assisted aminocatalyzed [3 + 2] annulation between α-iminonitriles and succinaldehyde: synthesis of pyrrole-3-methanols and related polycyclic ring systems

A quick and highly efficient method for the synthesis of substituted pyrrole-3-methanols from α-iminonitriles and succinaldehyde under microwave irradiation is reported. This one-pot method involves aminocatalyzed direct Mannich reaction-cyclization-dehydrocyanation followed by NaBH4 reduction sequence in good yields (up to 75%). Further applications of this method are demonstrated through the rapid synthesis of polycyclic heterocycles such as pyrrolo-dihydrochromene and pyrrolo-dihydroquinoline compounds.