Pyrrole chemistry. XXII. A "one-pot" synthesis of some 4-acylpyrrole-2-carboxaldehydes from pyrrole

Abstract

The Vilsmeier–Haack intermediates formed from pyrrole and from 1-methylpyrrole may be acylated under normal Friedel–Crafts conditions. Hydrolytic work-up then gives 4-acylpyrrole-2-carboxaldehydes in good yield. The methoxide/methanol treatment of the 4-trichloroacetylated intermediate leads to methyl 2-formylpyrrole-4-carboxylate. These are all "one-pot" syntheses from pyrrole. The formyl group has been removed from several of the products thus affording some 3-acylpyrroles in two operations.