Abstract: A process for the preparation of alpha-(N-pyrrolyl)-derivative acids, the salts and esters thereof, of the formula ##STR1## in which R, R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are hydrogen atoms or substituted or unsubstituted alkyl, aryl, alkylaryl or heterocyclic radicals and R' is a metal cation, an organic base or an organic radical, wherein the corresponding amino ester is reacted with a dialkoxytetrahydrofuran or a derivative thereof. Certain compounds comprised among those corresponding to the above formula, particularly the DL, D and L-alpha-(N-pyrrolyl)-phenylacetic acids and certain esters thereof. Therapeutical compositions containing such compounds as active ingredient and therapeutical applications of said compounds.