Treatment of compound 2, 3, or 4 under the conditions described also afforded ester 5. Thus the reaction pathway can be envisioned as a series of hydrolysis-esterification equilibria followed by decarboxylations to produce compound 5 and the completely decarboxylated pyrrole 7 (Scheme I). To confii this sequence, a mixture of diester 1, sulfuric acid, ethanol, and water maintained at 60" C was sampled regularly, and the samples were analyzed by ...
