Patent ID: 8569497

Claim:
A process for the preparation of a compound of general formula (I) wherein R 1 and R 2 represent independently C 1-6 alkyl with straight or branched chain optionally substituted with aryl group, or C 2-7 alkenyl group containing 1-3 double bonds, or monocyclic, bicyclic or tricyclic aryl group optionally substituted with one or more C 1-6 alkoxy, trifluoro-C1-6 alkoxy, C1-6 alkoxycarbonyl, C1-6 alkanoyl, aryl, C1-6 alkylthio, halogen or cyano groups, or a monocyclic, bicyclic or tricyclic cycloalkyl group, or R 1 and R 2 together with the adjacent nitrogen atom may form a saturated or unsaturated, monocyclic or bicyclic heterocyclic ring which may contain further heteroatoms selected from oxygen, nitrogen or sulphur atoms comprising reacting the compound of formula (III) with a carbamoylchloride of general formula (II) wherein R 1 and R 2 are as described above which comprises carrying out the reaction in a mixture of a solvent and concentrated aqueous solution of an alkali hydroxide at a temperature between 40-100° C. in the presence of a phase transfer catalyst, separating the phases and washing the organic layer then removing the solvent and drying the compound of formula (I) obtained until its weight is constant.