Facile synthesis of 2-arylpyrroles from 4-oxo-butanoic acids and their use in the preparation of bis(pyrrolyl)methanes

Abstract

A range of 3-aroyl-propionic acids have been cyclised to unsaturated lactones which, upon reduction using DIBAL-H and reaction with an ammonia source, gave 2-arylpyrroles (Ar = Ph, 1-naphthyl, o-phenoxyphenyl and 4-methyl-2-methylsulfanylphenyl) in excellent yields. Reaction of 2,6-disubstituted aroylpropanals (Ar = 2,4,6-Me3C6H2, anthracenyl and 2-Me-naphthalen-1-yl) with an ammonia source failed to generate pyrroles. The arylpyrroles react readily with ketones or aldehydes in ethanol or under eutectic mix melt conditions to give bis-(pyrrolyl)methanes in excellent isolated yields. © 2006 The Japan Institute of Heterocyclic Chemistry.