Total Synthesis of Pyrrolnitrin. IX. Synthesis of Dialkyl 3-Aryl-2, 5-pyrroledicarboxylates and Alkyl β-Aryl-5-methyl-2-pyrrolecarboxylates

Abstract

Synthetic methods of dialkyl 3-aryl-2, 5-pyrroledicarboxylates (VI) and alkyl β-aryl-5-methyl-2-pyrrolecarboxylates, intermediates to pyrrolnitrin (I), were investigated. VI were prepared by introduction of an ethoxycarbonyl group to ethyl 3-aryl-2-pyrrolecarboxylate (III) and by condensation of arylglyoxals with dimethyl acetyliminodiacetate. Alkyl β-aryl-5-methyl-2-pyrrolecarboxylates were prepared by methylation of alkyl β-aryl-2-pyrrolecarboxylates and by introduction of a methoxycarbonyl group to 2-methyl-3-arylpyrrole.