dimethyl 3-(4-methylphenyl)-1H-pyrrole-2,4-dicarboxylate

dimethyl 3-thiophen-2-yl-1H-pyrrole-2,4-dicarboxylate

methyl 5-(2-acetamidophenyl)-1,3-oxazole-4-carboxylate

(E)-Methyl 2-(formylamino)-2-butenoate

methyl 2-formamidobut-2-enoate