Halogen derivatives antimitotic alkaloids of vinca

The invention concerns novel halogenated derivatives of the vinblastine and vinorelbine family, corresponding to general formula (1) and their therapeutically acceptable salts. The invention also concerns the application of these compounds in therapy and their methods of preparation. The invention further concerns a novel method for preparing vinflunine or 20',20'-difluoro-3',4'-dihydrovinorelbine, of formula (a).