2- Methoxy-6-phenylpyrazine 4-oxide

Chloro-6-phenylpyrazine 4-oxide (129, R = Cl) gave 2-methoxy-6-phenylpyrazine 4-oxide (129, R = OMe) (MeONa, MeOH, reflux, 20 h ... 

Alkoxy groups again direct attack to the more remote nitrogen site, probably for steric reasons. Thus, 2-ethoxypyrazine gave 45% and 2-methoxy-3-methylpyrazine 82% of the 4-oxides (64JOC2623). Isolation of an almost quantitative yield of 4-oxide from 2-methoxy-3-phenylpyrazine oxidation... 

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... 

Methoxy-6-phenyl-2-pyrazinecarbonitrile 2-Methoxy-3-phenylpyrazine 4-oxide 2-Methoxy-5-phenylpyrazine 4-oxide... 

The following alkoxypyrazines have been prepared from the corresponding dichloropyrazines and alkoxide ions 2,3-dimethoxy-5,6-dimethyl(and diphenyl) (797) 2,3-dibenzyloxy (sodium benzyl oxide in benzyl alcohol at reflux for 24 hours (883)] [but 23-dichloropyrazine with sodium hydride and benzyl alcohol in xylene gave l,4-dibenzyl-2,3-dioxo-l,2,3,4-tetrahydropyrazine)(988)] 2-chloro-5-methoxy (838) 2,5-diethoxy-3,6-dimethyl (872) 2methanolic sodium methoxide refluxed for 2 h) 2,5-dimethoxy-3-phenyl (817) 2-chloro-5-methoxy(and ethoxy)-3,6-diphenyl (817) 2,5-dimethoxy-3,6-dimethyl (and diisopropyl) (844) 2,5-dimethoxy-3-isopropyl-6-methyl (methanolic potassium methoxide at reflux for 6 days) (844) 2(5)-s-butyl-3-chloro-6-ethoxy-5(2)-isobutyl (93) 2-chloro-6-methoxy (838, 883) 2,6-dimethoxy (reflux for 8h) (832) 2,6-diethoxy (reflux for 14 h) (883) 2-benzyloxy-6-chloro (1 equiv. of sodium hydride and benzyl alcohol in benzene at reflux) (832) 2,6-dibenzyloxy (5 equiv. of sodium benzyloxide in benzene at reflux gave 70%) (832) and 3,5-dimethoxy-2-methyl (535). 

Alkoxypyrazine A-oxides may also be prepared by oxidation of the alkoxypyrazine with peroxyacetic acid. In this way the following have been prepared 3-ethoxypyrazine 1-oxide (100°/20h) (978) 3-(trideuteromethoxy)pyrazine 1-oxide (757l9h) (975) 3-ethoxy-2-methylpyrazine 1-oxide (65-75724h) (978) 3-methoxy-2-phenylpyrazine 1-oxide (55720 h) (817) 3-ethoxy-2,5-dimethyl-pyrazine 1-oxide (56716 h) (872) 3-carbamoyl-2-methoxypyrazine 1-oxide (80720h) (881) and 2-cyano-5-ethoxy-3,6-dimethylpyrazine A-oxide (55720h) (288). 

---