King’s reaction

Methyl- and 2,3-dimethylpyrazine 1,4-dioxide when heated with pyridine and iodine undergo King s reaction from 2-methylpyrazine 1,4-dioxide the quaternary salt, 2-pyridiniomethyIpyrazine 1,4-dioxide iodide (41, R = H) was obtained, and this with p-nitrosodimethylaniline in alkaline medium gave the nitrone (42, R = H) (763). 

The Vilsmeier reaction on 2-methylpyrazine has been described in Section IV.2C(7) (717), and King s reaction on 2-methyl(and 23-dimethyl)pyrazine 1,4-dioxide has been described in Section IV.3C(7) (763). Pyrazine with A, jV-dimethyl-acetamide, ammonium peroxydisulfate, and ferrous sulfate gave 2-(A -acetyl-iV-methylaminomethyl)pyrazine (1188). 

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See also in sourсe #XX -- [ , ]

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