Pyrazinecarboxamides dehydration

Note The dehydration of pyrazinecarboxamides may be accomplished with a variety of reagents as exemplihed here. 

All the major routes to pyrazinecarbonitriles have been discussed already by primary synthesis in Chapters 1 and 2 by cyanolysis of halogenopyrazines in Sections 4.2.8 and 4.4 by deoxidative cyanation of pyrazine N-oxides in Section 5.5.2.4 by the rare cyanolysis of nitropyrazines in Section 7.1.2 by cyanolysis of trimethylammoniopyrazine salts no recent examples by dehydration of pyrazinecarboxamides in Section 8.4.2 and by passenger introduction of a cyano group in a variety of ways, for example, by cyanoalkylation. 

Cyanopyrazines were previously prepared by treatment of bromopyrazines with copper(I) cyanide in refluxing 4-picoline <56JA2i4i>. These compounds can also be synthesized by palladium-catalyzed cyanation of the less reactive chloropyrazines with potassimn cyanide (Section 6.03.5.4.2). Sodium dicyanocuprate is similarly effective for the cyanation of 2-amino-3-bromopyrazine, the halogen of which is almost inert to copper(I) cyanide. Dehydration of pyrazinecarboxamides with phosphoryl chloride, acetic anhydride or phosphorus pentoxide gives the carbonitriles. 

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See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ ]

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