Bischler-Napieralski reaction of N-(4-Aryl-4-hydroxybutyl)benzamides: Synthesis and X-ray structure of (E)-3-arylmethylidene-4,5-dihydro-3H-pyrroles

Abstract

The N-(4-aryl-4-hydroxybuty1)benzamides (3a,b) have been cyclized under Bischler-Napieralski conditions to the 3-arylmethylidene-4,5-dihydro-3H-pyrroles (4a,b). These products are consistent with the formation of N-(4-aryibut-3-enyl)benzamide intermediates. The structure of the 3,4-dimethoxyphenyl derivative (4a) was confirmed by X-ray crystallographic analysis, which established its configuration as the E-isomer.