| abstract |
The present invention relates to a process for the preparation of compounds of the formula (I) by using a compound of formula (II) in the presence of a palladium or platinum-containing catalyst, in the presence or absence of a solvent with hydrogen at 0 to 120 ° C, wherein the radicals R 1 , R 2 , R 3 and R 4 in the formula (I) have the same meaning as in the formula (II) and R 1 is Cl or F, R 2 , R 3 and R 4 are independently the same or different and are H, F, Cl, CF 3 , OCF 3 , C 1 -C 4 alkyl or C 1 -C 4 alkoxy. |