A Catalyst- and Solvent- Free Synthesis of Tetra-Substituted Pyrroles by Multicomponent Reaction

A facile, catalyst- and solvent- free, three-component reaction was developed for the synthesis of tetrasubstituted pyrroles at room temperature and under white light. The reaction proceeds via enamine formation between primary amines with 1,3-dicarbonyl compounds followed by Michael addition with beta-nitro styrene and subsequent intramolecular cyclization and aromatization to yield 1,2,3,4-tetrasubstituted pyrroles in good to excellent yields. Further, the present strategy is highly atom-economical and environmentally benign. The preliminary in vitro cytotoxic studies on a set of compounds were performed against Hepatocellular carcinoma cells (HepG2) and one of the compounds 4 ac showed significant activity with an IC50 value of 17.82 mu M.

Automated summary

A facile and environmentally benign three-component reaction was developed to synthesize tetrasubstituted pyrroles under white light at room temperature without catalysts or solvents. The reaction involved enamine formation between primary amines and 1,3-dicarbonyl compounds, followed by Michael addition with beta-nitro styrene and subsequent intramolecular cyclization and aromatization, resulting in good to excellent yields of 1,2,3,4-tetrasubstituted pyrroles. Preliminary in vitro cytotoxic studies demonstrated significant activity of one compound (4 ac) against Hepatocellular carcinoma cells (HepG2), with an IC50 value of 17.82 μM.