Patent ID: 6162923
Filing Date: 2000-12-19
Classification: C07D

Abstract:
A process for the preparation of a compound of general formula (I): ##STR5## wherein R.sup.1 represents a hydrogen atom or an alkyl group of 1-6 carbon atoms, and their salts, wherein the compound of formula (II): ##STR6## is reacted with a compound of formula (III): ##STR7## wherein R represents an alkyl group of 1-4 carbon atoms and R.sup.1 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): ##STR8## wherein R and R.sup.1 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.