3- Hydroxy-2,5-diisobutylpyrazine 1 -oxide

V-Hydroxy-6-propylthio-2-pyrazinecarboxamide V-Hydroxy-6-propylthio-2-pyrazinecarboxamidine 2- (3-Hydroxyprop-1 -ynyl)-3,6-diisobutylpyrazine 2- (3-Hydroxyprop-1 -ynyl)-3,6-diisobutylpyrazine 4-oxide 2- (3-Hydroxyprop-1 -ynyl)-3,6-diisopropylpyrazine 2- (3-Hydroxyprop-1 -ynyl)-3,6-diisopropylpyrazine 4-oxide 2- (3-Hydroxyprop-1 -ynyl)-3,6-dimethylpy razi ne 2-(3-Hydroxyprop-1 -y nyl)-3,6-dimethylpyrazine 4-oxide 2-(3-Hydroxyprop-l-ynyl)-3,5-diphenylpyrazine 2-(3-Hydroxyprop-l-ynyl)-3,6-diphenylpyrazine 2-(3-Hydroxyprop-l-ynyl)-5,6-diphenylpyrazine 2-(3-Hydroxyprop-l-ynyl)-5,6-diphenylpyrazine 4-oxide 2-(3-Hydroxyprop-l-ynyl)-6-methoxy-5-(2-methylprop-l-enyl)pyrazine 2- (3-Hydroxyprop-1 -ynyl )-6-methoxypyrazine N-Hydroxy-2-pyrazinecarboxamide Af-Hydroxy-2-pyrazinecarboxamide 4-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. 

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... 

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). 

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