Synthesis of linear ethyl 9-methoxy-1H-benz[f]indole-2-carboxylate

Abstract

This paper describes a synthesis of genuine ethyl 9-methoxy-1H-benz[f]indole-2-carboxylate (6). The genuine synthetic specimen has different physical properties from those of the indole reported as ethyl 9-methoxy-1H-benz[f]indole-2-carboxylate, which was obtained by Fischer indolisation of ethyl pyruvate 2-(1-methoxy-2-naphthylhydrazone)(9) by Goldsmith and Lindwall.

Our synthetic method includes the Friedel–Crafts acylation of ethyl pyrrole-2-carboxylate (13) with phthalic anhydride and a new selective N-debenzylation of N-benzylindole derivatives having a methoxy group in their molecule with aluminium chloride in anisole at room temperature.