Chemoselective Alkylation of 3- and 4-(5-Amino-4-hetaryl-2,3-dihydro-3-oxopyrrol-1-yl)benzoic Acids

Alkylation of 3- and 4-(5-amino-4-hetaryl-2,3-dihydro-3-oxopyrrol-1-yl)benzoic acids with phenacyl bromides or chloroacetanilides in DMF in the presence of triethylamine occurs at the carboxy group with high selectivity and yields the corresponding phenacyl and arylcarbamoylmethyl esters. The initial pyrrolylbenzoic acids were synthesized by reaction of 3- and 4-aminobenzoic acids with 4-chloro-2-hetaryl-3-oxo-butyronitriles.