| abstract |
The present invention relates to a process for the preparation of compounds of formula (I) wherein R1, R2 and R3 are each independently of the other hydrogen or methyl, by the reaction of compounds of formula (II) wherein R1, R2 and R3 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. |