ethyl (5-formyl-2,4-dimethyl-1H-pyrrole)-3-carboxylate
3,5-dimethyl-1H-pyrrole-2,4-dicarboxylic acid 4-ethyl ester
2,4-dimethyl-1H-pyrrole-3-carboxylic acid ethyl ester
4-ethoxycarbonyl-3,5-dimethyl-pyrrole-2-sulfonic acid
2,4-Dimethyl-5-(4-nitro-phenylazo)-pyrrol-3-carbonsaeure-ethylester