2-Carbamoyl-3-chloro-5,6-diphenylpyrazine

Cyano-6-methylaminopyrazine was also prepared from the chloro compound with methylamine hydrochloride and sodium hydroxide in aqueous dioxane (945) and 2-cyano-6-(2, 2 -dimethylhydrazino)pyrazine was prepared similarly (945). 2-Chloro-6-cyanopyrazine with methanol (and similarly with ethanol) and triethylamine gave 2-methoxy-6-(C-methoxyformidoyl)pyrazine (32) [see Section 5D(2)], and 2-chloro-6-carbamoylpyrazine with concentrated aqueous ammonia at 170-175° gave 2 -amino-b-carboxypyrazine (744). 2-Chloro-3-cyano-5,6-diphenylpyrazine with ammonium hydroxide and potassium iodide formed 2-amino-3-carbamoyl-5,6-diphenylpyrazine, but on fusion with ammonium acetate it gave 2-amino-3-cyano-5,6-diphenylpyrazine (848). 

A -Alkyl(thiocarbamoyl)]pyrazines have also been obtained by heating the 2-(A -alkylcarbamoyl)pyrazine with phosphorus pentasulfide and potassium sulfide in xylene at 100° (1268) and 2-amino-3-carbamoyl-5,6-diphenylpyrazine refluxed with phosphorus pentasulfide in pyridine gave 2-amino-5,6-diphenyl-3-thiocarbamoylpyrazine and the 3-A -butyl(thiocarbamoyl) analogue was prepared similarly (455). 2-Amino-5-chloro-3-(C-imino-C-methylthiomethyl)pyrazine with hydrogen sulfide in pyridine gave 2-amino-5-chloro-3-thiocarbamoylpyrazine (1218). 

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