2-Amino-5,6-dicyano-3-methoxypyrazine

Q-(p-Toluenesulfonyloxyiinino)malononitrile (104), when treated with malono-nitrile in basic conditions, has been shown to give salts of l,l,3,3-tetracyano-2-azapropenide (105), which with concentrated sulfuric acid in methanol gave 2-amino-3,5-dicyano-6-methoxypyrazine (106) (484) and with hydrochloric acid in acetone gave 2-amino-6-chloro-3,5-dicyanopyrazine (485, 486). Catalytic cyclization of 2-(2 -aminobutylamino)butanol with Raney nickel has been found to give a mixture of 2,5-diethylpiperazine (25% yield) and 2,5-diethylpyrazine (8%) (487). 

The condensation of DAMN with 1,2-diimino-l, 2-dimethoxyethane (70) gives 2-amino-5,6-dicyano-3-methoxypyrazine (71) (385), but as in the condensation of DAMN with DISN the control of acid concentration is critical. The condensation of DAMN with chloroacetone or pyruvaldehyde has been shown to give 23-dicyano-5-methylpyrazine (385) and DAMN with methylsulfinylmethyl phenyl ketone refluxed in ethanol gave 23-dicyano-5-phenylpyrazine (386a). A, 7V -Dichlorodi-iminosuccinonitrile (a2DISN) (72) reacts with some olefins to give pyrazines. Thus with styrene (73, R = Ph, R = H) in benzene it gave 23-dicyano-5-phenyl-pyrazine (74, R = Ph, R = H). Similar reactions were observed with /J-methyl-styrene and 23-dihydropyran (387). 

Dicyano-3,6-dimethylpyrazine shaken with sodium ethoxide at room temperature for 10 hours produced 2-cyano-5-ethoxy-3,6-dimethylpyrazine (288). Bromination of 2-methoxy-3-sulfanilamidopyrazine (39) in methanol led to 5-(4 -amino-3, 5 -dibromobenzenesulfonimido)-6-hydroxy-2,3-dimethoxy-2,3,4,5-tetrahydropyrazine (32) which with 2 N sodium hydroxide gave 3-(4 -amino-3, 5 -dibromobenzenesulfonamido)-2-hydroxy-5 nethoxypyrazine (40) (816). The preparation of 2-amino-3,5-dicyano-6-methoxy(and ethoxy)pyrazine from a-(p-toluenesulfonyloxyiminomalononitrile and malononitrile has been described in Section II.7 (484). 2-Methoxycarbonyl(and cyano)-5-pyridiniopyrazine chloride (41) is reported (conditions not stated) to give 2-carboxy(and carbamoyl)-5-methoxypyrazine (765). 

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