Synthesis and Diels–Alder reactions of the furo[3,4-b]pyrrole ring system. A new indole ring synthesis

The previously unknown furo[3,4-b]pyrrole ring system has been synthesized from the appropriate pyrrolo hydroxyketones by acid-catalyzed cyclodehydration. Diels–Alder reactions of these furo[3,4-b]pyrroles affords a new synthesis of indoles.