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Abstract

The present invention provides a process for the preparation of a tetrazine derivative of formula (I), or a pharmaceutically acceptable salt thereof wherein R₁ represents a hydrogen atom, a straight or branched C₁-C₆ alkyl group, C₂-C₆ alkenyl group or C₂-C₆ alkynyl group, which C₁-C₆ alkyl group, C₂-C₆ alkenyl group and C₂-C₆ alkynyl group is unsubstituted or substituted with 1, 2 or 3 substituents selected from halogen atoms, straight or branched C₁-C₄ alkoxy groups, C₁-C₄ alkylthio groups, C₁-C₄ alkylsulphinyl groups, C₁-C₄ alkylsulphonyl groups and phenyl groups, which phenyl groups are unsubstituted or substituted with one or more substituents selected from C₁-C₄ alkyl groups, C₁-C₄ alkoxy groups and nitro groups; or R₁ represents a C₃-C₈ cycloalkyl group; and R₂ represents a group of formula —(C═O)NR₃R₄, wherein R₃ and R₄ are independently selected from hydrogen atoms, C₁-C₄ alkyl groups, C₂-C₄ alkenyl groups and C₃-C₈ cycloalkyl groups, which process comprises: i) providing a compound N of formula (III), wherein R₁ is as defined; R₁—N═C═O ii) absorbing the compound of formula (III) into a solvent to obtain a solution of the compound of formula (III); iii) adding to the thus obtained solution a compound of formula (II), to obtain a compound of formula (I), as defined above, wherein R₂ is as defined above; iv) decomposing any excess compound of formula (III) remaining by addition of water; and v) optionally salifying the thus obtained compound with a pharmaceutically acceptable acid, or base.

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First Claim