Cyanolysis of Nuclear Halogenopyrazines

The displacement of a nuclear halogeno substituent by a cyano group can be done fairly readily in the pyrazine series, usually by treatment with cuprous cyanide, potassium cyanide plus cuprous iodide, or potassium cyanide in the presence of a palladium catalyst. The following examples illustrate these procedures  

2-Chloro-3-dimethylamino-6-nitropyrazine (184) gave 3-dimethylamino-6-nitro-2-pyrazinecarbonitrile (185) (CuCN, Me2NCIIO, 155°C, 18 h 62%).1313 

5-Dibromo-2-pyrazinamine (186, R = Br) gave selectively 3-amino-6-bromo-2-pyrazinecarbonitrile (186, R = CN) (CuCN, NaCN, IV NCHO, 120°C, 2.5 h 64%).222 

5-l)ichloro-1 -mc(hyl-2( I //)-pyrazitione (188, R = Cl) gave selectively 6-chloro-4-methyl-3-oxo-3,4-diliydro-2-pyrazinecarboiiitrile (188, R = CN) [CuCN, l-methyl-2-pyrrolidinone (solvent), 150°C, 6h 68%].370 

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