| abstract |
The present invention relates to a process for the preparation of compounds of formula (I) wherein R 1 , R 2 and R 3 are each independently of the others hydrogen or methyl, by reaction of compounds of formula (II) wherein R 1 , R 2 and R 3 are as defined for formula (I) and X is bromine or chlorine, with ammonia in the presence of a catalytic amount of at least one copper-containing compound. |