Process for the preparation of imidazolones

PCT No. PCT/HU98/00065 Sec. 371 Date Apr. 26, 2000 Sec. 102(e) Date Apr. 26, 2000 PCT Filed Jul. 22, 1998 PCT Pub. No. WO99/05118 PCT Pub. Date Feb. 4, 1999The present invention relates to a process for the preparation of a compound of general formula (I), wherein R1 represents a hydrogen atom or an alkyl group of 1-6 carbon atoms, and their salts, wherein the compound of formula (II): is reacted with a compound of formula (III): wherein R represents an alkyl group of 1-4 carbon atoms and R1 is the same as defined above, by heating their neutral pH mixtures at the boiling temperature of the mixture, and the resulting compound of general formula (IV): wherein R and R1 are the same as defined above, is cyclized into the compound of general formula (I) by further elevating the temperature of the neutral mixture, and if desired, the compounds of general formula (I) are transformed into their salts, or the compounds of general formula (I) are liberated from their salts.