Process for the preparation of 1-alkyl- or 1,4-dialkyl-5-aroyl-1H-pyrrole-2-acetic acids and derivatives thereof

For the preparation of compounds of the formula I in which Ar denotes a phenyl group which is optionally substituted by halogen atoms or alkyl or alkoxy groups having 1 to 4 carbon atoms, R denotes an alkyl group having 1 to 4 carbon atoms, R denotes hydrogen or an alkyl group having 1 to 4 carbon atoms, X denotes an imino group and R denotes hydrogen or an alkyl group having 1 to 4 carbon atoms, or X denotes oxygen and R denotes hydrogen and of acid addition salts of the imino compounds of the formula I and of alkali metal or alkaline earth metal salts of the carboxylic acids of the formula I, pyrrole derivatives of the formula II in which Y denotes a -COOR group where R = a C1 to C4 alkyl group with an aromatic nitrile of the formula III Ar-CN (III> to give ketimic acid alkyl esters of the formula I in the form of the hydrochloride salt. Where compounds of the formula I are prepared in which R denotes hydrogen and X is imino or oxygen, and the abovementioned salts of these compounds, these esters are subjected to hydrolysis.