Other Derivatives of Mercaptopyrazines

1-Methyl-2-oxo-l, 2-dihydropyrazine with phosphorus pentasulfide in pyridine at reflux was converted into l-methyl-2-thio-l,2-dihydropyrazine (18) (821,1100), and 3-chloropyrazine 1-oxide with sodium hydrogen sulflde in ethanol at room temperature gave 3-mercaptopyrazine 1-oxide (19) (1035). Whereas 3-chloro-2,5-dimethyipyrazine 1-oxide reacted slowly with thiourea in ethanol, and the use of water in place of ethanol caused some increase in reaction rate, the reaction in 2A sulfuric acid at reflux for 30 minutes gave 3-mercapto-2,5-dimethylpyrazine 1-oxide (85%), and 3-mercapto-2-methylpyrazine 1-oxide was prepared similarly (905). 

2-Amino-3-cyano-5-(benzylthiomethyl)pyrazine 1-oxide has been prepared from j3-bromopyruvaldoxime, benzylmercaptan, and aminomalononitrile tosylate in propan-2-ol (542). 

2-Amino-5 [(p-chlorophenylthio)methy 1] -3-cyanopy razine 1-oxide (prepared 

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