Modifications to the Vilsmeier‐Haack formylation of 1,4‐dimethylcarbazole and its application to the synthesis of ellipticines

Abstract

Abstract An improved method for the preparation of 3‐formyl‐1,4‐dimethylcarbazole, a key intermediate in the synthesis of ellipticine, is presented. Conditions of the Vilsmeier‐Haack reaction have been modified to facilitate the production of 3‐formyl‐1,4‐dimethylcarbazole as a major product leading to an overall improvement in yield of ellipticine from 3% to 14%. This approach was also applied to the synthesis of 6‐methylellipticine and 9‐methoxyellipticine. J. Heterocyclic Chem., (2011).