2.3- Dichloro-5-methoxycarbonylpyrazine

Chlorination of 2-amino-3-methoxycarbonylpyrazine in aqueous acetic acid at about 40° has been shown to give 5-chloro-2-chloroamino-3-methoxycarbonyl-pyrazine and thence 2-amino-5-chloro-3-methoxycarbonylpyrazine (150, 378a, 432a, 778-787), but in the presence of polar aprotic solvents (such as acetonitrile and dichloroethane) at temperatures between room temperature and reflux it gave 2-amino-5,6 -dichloro-3 -me thoxycarbonyIpyrazine (788). 

Chlorination of 2-methoxycarbonyl-3-methylaminopyrazine gave 2,3-dichloro-5-methoxycarbonyl-6-methylaminopyrazine (789), 5-chloro-2-(2 -dimethylamino-ethylamino)-3-methoxycarbonylpyrazine at room temperature gave 2,3-dichloro-5-... 

In reactions with amines the 2-halogeno substituent was replaced from 2,5-dihalogeno-3-methoxycarbonylpyrazines (35) and 2,3-dichloro-5-methoxycarbonyl-... 

Methoxypyrazines (31) have been prepared by diazomethane methylation of 2-hydroxy-3-isobutylpyrazine (60, 311, 367), 2-hydroxy-3-isopropylpyrazine (59, 367), 2-hydroxy-3-propyl(ethyl or hexyl)pyrazine (367), 3-hydroxy-2-isobutyl-5(and 6)methylpyrazine and 2-hydroxy-3-isobutyl-5,6-dimethylpyrazine (368), 2,3-dihydroxypyrazine (832), 2-hydroxy-5-methoxy- and 2,5-dihydroxy-3,6-diphenyl-pyrazine (832), 2-hydroxy-6-methoxy(and benzyloxy)pyrazine (832), 2,6-dihydroxy-3,5-diphenylpyrazine (873), 2,3,5-trifluoro-6-hydroxypyrazine (851), 2-chloro-6-hydroxy-3,5-diphenylpyrazine (873), 2-chloro-6-hydroxy-5-methyl-3-phenylpyrazine (873), 2-chloro-6-hydroxy-3-methyl-5-phenylpyrazine (873), 5,6-dichloro-1 -cyclohexyl-34iydroxy-2-oxo-l, 2-dihydropyrazine (853), 2-chloro-5-hydroxy-3-methoxy-6-methoxycarbonylpyrazine (881), 2-(4 -amino-3, 5 -dibromo-phenylsulfonamido)-3Tiydroxy-6-methoxypyrazine (881), 2-amino-3-hydroxy-... 

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