The self-condensation of 3,4-dimethylpyrrole: an alternative reaction pathway

Abstract

Treatment of 3,4-dimethylpyrrole with 6N-hydrochloric acid in the cold for a short time gives a dimer which is formulated as 3,4-dimethyl-2-(3,4-dimethyl-3-pyrrolin-2-yl)pyrrole (II). The reaction is reversible. This appears to be the first example of an acid-catalysed pyrrole self-condensation where it is necessary to envisage an α-protonated (as opposed to a β-protonated) pyrrole as a reactant.