New Syntheses of Pyrrolo[3,4-<i>b</i>]indoles, Benzo[<i>b</i>]furo[2,3-<i>c</i>]pyrroles, and Benzo[<i>b</i>]thieno[2,3-<i>c</i>]pyrroles. Utilizing the Reaction of Münchnones (1,3-Oxazolium-5-olates) with Nitroheterocycles

Abstract

1,3-Dipolar cycloaddition of münchnones (mesoionic 1,3-oxazolium-5-olates) 3 and 4 with 2- and 3-nitroindoles, 2-nitrobenzo[b]furan, and 3-nitrobenzo[b]thiophene affords the corresponding pyrrolo[3,4-b]indoles, benzo[b]furo[2,3-c]pyrroles, and benzo[b]thieno[2,3-c]pyrroles, respectively, in one operation in good to excellent yields.