Process for the preparation of 2,3-pyridinedicarboximides

A process for the preparation of a 2,3-pyridinedicarboximide having the structural formula I

• 23
• wherein
• R is hydrogen, C1-C6alkyl or C1-C6alkoxymethyl;
• R1 is hydrogen, C1-C6alkyl, C(O)R2,
• phenyl optionally substituted with any combination of from one to four halogen, C1-C4alkyl, C1-C4alkoxy, nitro or cyano groups,
• benzyl optionally substituted on the phenyl ring with any combination of from one to four halogen, C1-C4alkyl, C1-C4alkoxy, nitro or cyano groups, or
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• R2 is C1-C6alkyl, benzyl or
• phenyl optionally substituted with any combination of from one to four halogen, C1-C4alkyl, C1-C4alkoxy, nitro or cyano groups;
• R3 and R4 are each independently C1-C4alkyl;
• and
• R5 is cyano or CONH2,
• which process comprises reacting an oxime or hydrazone having the structural formula II
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• wherein
• R is as described above;
• R6 is C1-C6alkyl;
• R7 is OR8 or NR9R10;
• R8 is hydrogen, C1-C6alkyl, C(O)R11,
• phenyl optionally substituted with any combination of from one to four halogen, C1-C4alkyl, C1-C4alkoxy, nitro or cyano groups, or
• benzyl optionally substituted on the phenyl ring with any combination of from one to four halogen, C1-C4alkyl, C1-C4alkoxy, nitro or cyano groups;
• R11 is C1-C6alkyl, OR12, NR12R13, benzyl or
• phenyl optionally substituted with any combination of from one to four halogen, C1-C4alkyl, C1-C4alkoxy, nitro or cyano groups;
• R12 and R13 are each independently hydrogen, C1-C6alkyl, benzyl or
• phenyl optionally substituted with any combination of from one to four halogen, C1-C4alkyl, C1-C4alkoxy, nitro or cyano groups;
• and
• R9 and R10 are each independently hydrogen, C1-C6alkyl, benzyl or
• phenyl optionally substituted with any combination of from one to four halogen, C1-C4alkyl, C1-C4alkoxy, nitro or cyano groups,
• with a maleimide having the structural formula III
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• wherein R1 is as described above.