| abstract |
A process for preparing piperazinedione derivatives of the formula I n n n n n n n n n n in whichn R 1 is hydrogen, alkyl, alkenyl, alkynyl and alkylcarbonyl, R 2 is hydrogen, alkyl, alkenyl, C 3 -C 4 -alkynyl and C(═O)R 11 , R 3 , R 4 are each hydrogen, alkyl and haloalkyl, where the groups may be substituted, which comprises reacting amines of the formula II nn H 2 N—R 1 IIn n in whichn R 1 is hydrogen and alkyl which may optionally be substituted with N-acylated amino acid derivatives of the formula III nn n n n n n n n n n in whichn X is halogen, Y is halogen, alkoxy or phenyloxy which may be substituted and R 2 , R 3 and R 4 are each as defined at the outset,n nunder basic conditions in an aqueous solvent. |