2,5-Diisobutylpyrazine 1-oxide

Oxidation of nuclear and extranuclear hydroxypyrazines (and derivatives) to their Af-oxides has been achieved with hydrogen peroxide in acetic acid, and with m-chloroperoxybenzoic acid in 1,2-dichIoroethane. 3-Hydroxy-2,5-diisobutyl-pyrazine was oxidized with 30% hydrogen peroxide in acetic acid at 70 to 3-hydroxy-2,5-diisobutylpyrazine 1-oxide (101), 3-hydroxy-2-(Af-methyl-A -phenyl-carbamoyl)pyrazine 1-oxide (90) was also prepared from the conesponding pyrazine [its A -4-methyl derivative was prepared similarly and also by methylation of (90) (1055)], and 3-hydroxy-2-(A -methyl-AAp-tolylcarbamoyl)pyrazine 1-oxide (1055) was synthesized analogously. 

The reactions of phosphoryl chloride and some hydroxypyrazine A-oxides with an unsubstituted position adjacent to the A-oxide function to give chlorohydroxy-pyrazines have been described in Section V.IG. In this way 3-hydroxy-2,5-diisobutylpyrazine 1-oxide was converted to 2-chloro-5-hydroxy-3,6-diisobutyl-pyrazine (101) and 2-hydroxy-3,5-diphenylpyrazine 1-oxide gave 2-chloro-6-hydroxy-3,5-diphenylpyrazine (873). 

Both 2-chloro-3,6-diisobutylpyrazine 1-oxide (181) and the isomeric 4-oxide (183) gave 2,5-diisobutylpyrazine 1-oxide (182) [Pd(PPh j4, HC02Na, Me2NCH0, 100°C, A, 2 h 90 and 87%, respectively note survival of the oxide entity) also analogous dechlorinations " However, if HCO2Na was replaced by MeCO Na, hydrogen appeared to be necessary for dehalo-... 

Ethoxycarbonyl vinyl)- 3,6-diethylpyrazine 4-oxide 2- (2-Ethoxycarbonyl vinyl)- 3,6-diisobutylpyrazine 2- (2-Ethoxycarbonyl vinyl)- 3,6-diisobutylpyrazine 4-oxide 2- (2-Ethoxycarbonyl vinyl)- 3,6-diisopropylpyrazine 2- (2-Ethoxycarbonyl vinyl)- 3,6-diisopropylpyrazine 4-oxide 2- (2-Ethoxycarbonyl vinyl)- 3,6-dimethylpyrazine 2- (2-Ethoxycarbonyl vinyl)- 3,6-dimethylpyrazine 4-oxide 2-(2-Ethoxycarbonylvinyl)-3, methyl-thiopyrazine... 

Ethyl 5-bromo-2-pyrazinecarboxylate 2-(2-Ethylbut-1 -enyl)-6-methylpyrazine Ethyl 5-carbamoyl-2-pyrazinecarboxylate Ethyl 5-chloro-2-pyrazinecarboxylate Ethyl 3-cyano-5,6-dimethyl-2-pyrazinecarboximidate Ethyl 3-cyano-5,6-dimethyl-2-pyrazinecarboxylate Ethyl 3,5-diami no-6-chloro-2-pyrazi necarboximidate Ethyl 6-diethylamino-2-pyrazinecarboxylate 2-Ethyl-3,6-diisobutyl-5-methylpyrazine 2-Ethyl-3,6-diisobutylpy razi ne 2-Ethyl-3,6-diisobutylpyrazine 1 -oxide 2-Ethyl-3,6-diisobutylpyrazine 4-oxide 2-Ethyl-3,6-diisopropylpyrazine /V-Ethyl-AyV -dimethyl-3,5-bismethylamino-2,6-pyrazinedicarboxamide Ethyl 3,6-dimethyl-5-oxo-4,5-dihydro-2-pyrazinecarboxylate... 

Chloro-3,6-diisobutylpyrazine 1-oxide 5-(l -Acetoxy-2 -methyl)propyl-3-chloro-2-isobutylpyrazine 113b... 

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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