Process for preparing alkyl ethers of 1-alkyl- or 1,4-dialkyl-1H - pyrrole-2-acetic acid.

摘要

The invention relates to a new process for the preparation of 1-alkyl- or 1,4-dialkyl-1H-pyrrole- -2-acetic acid, esters of the general formula (I) IMG (I) wherein R1 is hydrogen or an alkyl group having from 1 to 4 carbon atoms, R2 and R3 each independently represent an alkyl group having from 1 to 4 carbon atoms, by selective desalkoxycarbonylation of the corresponding 1-alkyl- and 1,4-dialkyl-3-alkoxycarbonyl-1H-pyrrole- -2-acetic acid esters of the general formula (II) IMG (II) wherein R1, R2 and R3 have the same meaning as defined above, by heating in the presence of a concentrated mineral acid or an aliphatic or aromatic sulfonic acid. Compounds of the general formula (I) are known pharmaceutically active materials, which can be prepared by this process in a single reaction step selectively, without the formation of by-products.