Patent ID: 8084604

Claim:
A process for the preparation of a compound of formula (I) in which Ar represents aryl, in which aryl can be substituted by 1 to 3 substituents, where the substituents independently of one another are selected from the group consisting of alkyl, alkoxy, formyl, carboxyl, alkylcarbonyl, alkoxycarbonyl, trifluoromethyl, halogen, cyano, hydroxyl, amino, alkylamino, aminocarbonyl and nitro, in which alkyl can be substituted by 1 to 3 substituents, where the substituents independently of one another are selected from the group consisting of halogen, amino, alkylamino, hydroxyl and aryl, or two of the substituents on the aryl, together with the carbon atoms to which they are bonded, form a 1,3-dioxolane, a cyclopentane ring or a cyclohexane ring and an optionally present third substituent independently thereof is selected from the group mentioned, R 1 represents hydrogen, amino, alkyl, alkoxy, alkylamino, alkylthio, cyano, halogen, nitro or trifluoromethyl, R 2 represents hydrogen, alkyl, alkoxy, alkylthio, cyano, halogen, nitro or trifluoromethyl, R 3 represents amino, alkyl, alkoxy, alkylamino, alkylthio, cyano, halogen, nitro, trifluoromethyl, alkylsulphonyl or alkylaminosulphonyl or one of the radicals R 1 , R 2 and R 3 represents hydrogen, alkyl, alkoxy, cyano, halogen, nitro or trifluoromethyl and the other two, together with the carbon atoms to which they are bonded, form a 1,3-dioxolane, a cyclopentane ring or a cyclohexane ring, R 4 represents hydrogen or alkyl, R 5 represents hydrogen or alkyl or the radicals R 4 and R 5 are bonded to exactly opposite carbon atoms of the piperazine ring and taken together form a methylene bridge optionally substituted by 1 or 2 methyl groups, R 6 represents hydrogen, alkyl, alkoxy, alkylthio, formyl, carboxyl, aminocarbonyl, alkylcarbonyl, alkoxycarbonyl, trifluoromethyl, halogen, cyano, hydroxyl or nitro, R 7 represents hydrogen, alkyl, alkoxy, alkylthio, formyl, carboxyl, alkylcarbonyl, alkoxycarbonyl, trifluoromethyl, halogen, cyano, hydroxyl or nitro and R 8 represents hydrogen, alkyl, alkoxy, alkylthio, formyl, carboxyl, alkylcarbonyl, alkoxycarbonyl, trifluoromethyl, halogen, cyano, hydroxyl or nitro, comprising the steps of hydrolyzing a compound of formula (II) in which Ar, R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 have the meaning indicated above, and R 9 represents C 1 -C 4 -alkyl, using a base or an acid, and reacting a compound of formula (III) in which R 1 , R 2 , R 3 , R 6 , R 7 and R 8 have the meaning indicated above, and R 9 represents C 1 -C 4 -alkyl, in the presence of a base with a compound of formula (IV) in which Ar, R 4 and R 5 have the meaning indicated above, to form the compound of formula (II).