Attempts to prepare 3-substituted pyrroles.

Abstract

I-Benzylpyrrole was prepared and subjected to bromination, nitration and formylation and the products isolated and identified. l-Benzyl-3-bromopyrrole was converted to l-benzyl-3-pyrrolecarboxylic acid and to methyl l-benzyl-3-pyrrolecarboxylate; l-benzyl-3-nitropyrrole was converted to l-benzyl-3-acetamidopyrrole. I-Benzyl-3-pyrrolecarboxaldehyde was oxidized to the 3-acid and l-benzyl-2-pyrrolecarboxaldehyde was converted to the nitrile and thus to the 2-acid and the acid esterified to its methyl ester. -- Identification of the compounds has been accomplished primarily by interpretation of nuclear magnetic resonance spectra in conjunction with infrared spectra and elemental analysis. Some interconversions of the derivatives were also successfully performed. Further evidence for the assigned structures of the 2- and 3-esters has been furnished by the synthesis of these compounds by unequivocal routes. -- The catalytic reductive debenzylation of methyl I-benzyl-3-pyrrolecarboxylate was attempted, but with no success. -- Attempts were made to prepare l-benzenesulfenylpyrrole and 1-(2,4-dinitrobenzenesulfenyl)-pyrrole but without success, the 2-substituted products being obtained in each case. The formylation of 1-(2,4-dinitrobenzenesulfenyl)-pyrrole gave only the 5-formyl derivative.