Benzannulation of 2‐Alkenylindoles using Aldehydes by Sequential Triple‐Relay Catalysis: A Route to Carbazoles and Carbazole Alkaloids

Abstract

Abstract Benzannulation of 2‐alkenylindoles with readily available aldehydes, under one‐pot sequential triple‐relay‐catalysis, provides an easy access to several structurally unique carbazoles including 2‐ and 3‐alkenylcarbazoles. This protecting group‐free method enabled one‐pot synthesis of alkaloids such as hyellazole and 6‐chlorohyellazole, and the formal syntheses of seven other alkaloids. Construction of the core structure, present in murastifoline A, murrafoline E, and related alkaloids was also demonstrated. Even conjugated 3,3′‐biscarbazoles can also be synthesized by one‐pot, two‐fold sequential triple‐relay catalysis . magnified image