Ethylene Glycol → 2-Amino-5-(4-bromophenyl)-6-methylpyrazine

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Another intermediate pyrazine compound, 2-amino-5-(4-bromophenyl)-6-methylpyrazine is synthesized starting with 1-(4-bromophenyl)-1,2-propanedione 2-oxime, which oxime is obtained by the same general procedure of Hartung et al., supra. This oxime is allowed to react with aminomalononitrile tosylate, and the product, the substituted pyrazine 1-oxide, is allowed to react with phosphoruc trichloride in tetrahydrofuran, according to the procedure of Taylor et al., J. Org. Chem. 38, 2817 (1973), to yield 2-amino-3-cyano-5-(4-bromophenyl)-6-methylpyrazine. This product is then hydrolyzed in sodium hydroxide and ethylene glycol and the 2-amino-3-carboxy-5-(4-bromophenyl)-6-methylpyrazine so obtained is decarboxylated by heating in tetrahydronaphthalene to yield 2-amino-5-(4-bromophenyl)-6-methylpyrazine.

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