A simple route to tetracyclic oxazepine-fused pyrroles via metal-free [3+2] annulation between dibenzo[b,f][1,4]oxazepines and aqueous succinaldehyde

Abstract

A direct method for the synthesis of new tetracyclic oxazepine-fused pyrroles has been developed through [3+2] annulation between aqueous succinaldehyde and dibenzo[b,f][1,4]-oxazepines under metal-free conditions. This one-pot synthetic protocol involves proline-catalyzed direct Mannich/cyclization between aqueous succinaldehyde and seven-membered oxazepine-imines, followed by an IBX-mediated oxidation sequence with high yields (up to 90%).