2-Hydroxy-3-isobutylpyrazine methylation

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-... 

When 2-hydroxy-3,5-diphenylpyrazine 1-oxide was heated under reflux with an excess of acetic anhydride, a crystalline triacetoxy compound was obtained which was thought to have an open chain structure [AcO-CH=CPh-N=CPh-C(OAc)=N-OAc], but when the 2-hydroxypyrazine-l-oxide was boiled with a mixture of acetic anhydride and acetic acid, 2,6-diacetoxy-3,5-diphenylpyrazine was obtained (873) which was hydrolyzed by potassium hydrogen carbonate in methanol to 2,6-dihydroxy-3,5-diphenylpyrazine (873). 2-Hydroxy-5-methyl-3-phenylpyrazine 1-oxide behaved differently and when refluxed with acetic anhydride gave 5-acetoxymethyl-2-hydroxy-3-phenylpyrazine (100) and 2-hydroxy-3-methyl-5-phenylpyrazine 1-oxide similarly gave 3-acetoxymethyl-2-hydroxy-5-phenylpyrazine (873). When 2- l-hydroxy-2 -methylpropyl)-5-isobutylpyrazine 1-oxide was heated with a mixture of acetic anhydride and sodium acetate on a water bath 2-(l -acetoxy-2 -methylpropyl)-5-isobutylpyrazine 1 oxide was obtained (760a). 

Dimethylamino-7V-hydroxy-2-pyrazinecarboxamide 6-Dimethylamino-7V-hydroxy-2-pyrazinecarboxamidine 2-Dimethylamino-5-iodopyrazine 2-Dimethylamino-6-iodopyrazine 2-Dimethylamino-5-iodopyrazine 4-oxide 2-Dimethylamino-3-isobutylpyrazine 2-Dimethylamino-6-isobutylpyrazine 2-Dimethylamino-5-methoxy-3,6-dimethylpyrazine 2-Dimethylaminomethyl-3,6-bismethylthiopyrazine 2-Dimethylamino-6-methyl-5-phenylpyrazine 4-oxide 2-Dimethylamino-3-methylpyrazine 2-Dimethylamino-6-methylpyrazine 2-Dimethylamino-3-methylpyrazine 4-oxide Dimethyl 5-amino-6-oxo-1,6-dihydro-2,3-pyrazinedicarboxylate 2-Dimethylamino-5-phenylpyrazine 2-(3-Dimethylaminopropyl)-6-methylpyrazine... 

Diazomethane methylation of 3-hydroxy-2,5-diisobutylpyrazine 1,4-dioxide has been shown to give the 4-methoxypyrazine 1-oxide, 2,5-diisobutyl4-methoxy-3-0X0-3,4-dihydropyrazine 1-oxide (96) (843, 980) [and some 3-methoxy-2,5-diisobutylpyrazine 1,4-dioxide (4 l)(980)] 5-s-butyl-3-hydroxy-2-isobutylpyrazine... 

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