Patent ID: 8609868

Claim:
A process for preparing a compound of general formula (I) in which R 1 and R 2 are identical or different and are selected from the group consisting of hydrogen; C 1 -C 8 -alkyl, which is optionally substituted one or more times by halogen, —OR 3 , or —COR 4 ; C 3 -C 7 -cycloalkyl, which is optionally substituted one or more times by halogen, C 1 -C 4 -alkyl or C 1 -C 4 -haloalkyl; and aryl or aryl-(C 1 -C 4 -alkyl), each of which is optionally substituted one or more times by halogen, C 1 -C 4 -alkyl, C 1 -C 4 -haloalkyl, —COR 4 or sulphonylamino, R 3 is hydrogen, C 1 -C 4 -alkyl, C 1 -C 4 -alkylcarbonyl or is aryl which is optionally substituted one or more times by halogen, C 1 -C 4 -alkyl or C 1 -C 4 -haloalkyl, R 4 is hydroxyl, C 1 -C 4 -alkyl or C 1 -C 4 -alkoxy, wherein a compound of formula (VI) in which R is R 1 or R 2 is reacted with thiourea in water, optionally in the presence of a phase transfer catalyst, in the absence of an organic solvent to give the compound of formula (I).