Green, Catalyst‐Free Reaction of Indoles with β‐Fluoro‐β‐nitrostyrenes in Water

Abstract

The reaction of 2‐fluoro‐2‐nitrostyrenes with various indoles was investigated. We found that the reaction proceeds as a Michael addition in a highly regioselective manner to form 3‐(1‐aryl‐2‐fluoro‐2‐nitroethyl)‐1 H ‐indoles. Thus, a green and catalyst‐free synthesis of these compounds was developed using water as a reaction medium. The high effectiveness of this approach was demonstrated through the preparation of target products in up to 92 % isolated yield. Subsequent reduction of the nitro group was investigated. We found that due to the instability of the intermediate α‐fluoro amines, the reduction led to non‐fluorinated tryptamine derivatives.