Total Synthesis of Pyrrolnitrin. VII. Synthesis of 2, 5-Dimethyl-3-arylpyrrole

Abstract

Preparation of 2, 5-dimethyl-3-arylpyrrole (IX) was accomplished by three different routes : at first alkyl 3-aryl-5-methyl-4-pyrrolecarboxylate (IV) was converted to IX by the series of reactions containing Mannich reaction, reduction and decarboxylation, and secondly IX was also prepared by the ringclosure of 3-aryl-2, 5-hexanedione (XIV) with ammonium acetate and thirdly the methiodide of a bis-Mannich base (XVIII) prepared by Mannich reaction of 3-arylpyrrole (XVII) was reduced with sodium borohydride to IX.