Abstract: The invention is concerned with the preparation of 2-[4-(3-oxo- cyclohexyl)phenyl] propionic acid and of its derivatives. This preparation consists in transforming 4-(3,3-ethylenedioxo- cyclohexyl) acetophenone or its derivatives of the general formula: ##STR1##in which A.sup.1 represents a group ##STR2##and B represents a group ##STR3##and R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, which can be identical or different, represent each a hydrogen or an alkyl group into the desired compound of the general formula: ##STR4##in which A.sup.4 represents a group ##STR5##This method offers the advantage of being easier to implement on an industrial scale and of having a better yield than the methods of preparation of the compounds of formula (I) according to prior art.