2-Ethoxy-5,6-diphenylpyrazine

Ethoxy-3,6-dimethylpyrazine 4-oxide 5-Ethoxy-l,3-dimethyl-2(177)-pyrazinone 2-Ethoxy-3,6-diphenylpyrazine... 

Chloro-3,6-diphenylpyrazine (119, R = Cl) gave 2-ethoxy-3,6-diphenylpyra-zine (119, R = OEt) (EtONa, EtOH, reflux, 4 h 89%)82 or 2-phenoxy-3, 6-diphenylpyrazine (119, R = OPh) [(PhO)3PO, KOH, Me2NCHO, reflux, 1 h 81% substituted-phenoxy analogues were made likewise].192... 

Ethoxycarbonylmethyl-5,6-diphenylpyrazine 2-(l -Ethoxy carbonyl-1 -methylethyl)-5-phenylpyrazine... 

Ethoxypyrazine 1-oxide refluxed with 40% alcoholic hydrogen chloride yielded 2-ethoxy-5-hydroxypyrazine (1069). Ultraviolet irradiation of 2,5-dimethyl-pyrazine 1-oxide in water afforded 3-hydroxy-2,5-dimethylpyrazine (10%) and 2,5-diphenylpyrazine 1-oxide in benzene gave 3-hydroxy-2,5-diphenylpyrazine (3%) (742). A small yield of 2-ethyI-5-hydroxy-3,6-dimethylpyrazine has been isolated as by-product from the reaction of 2,5-dimethylpyrazine with ethyllithium in ether (615). 

Pyrolyses and thermal stabilities of 2-hydroxy-, 2-ethoxy-, and 2-isopropoxy-pyrazines have been studied. 2-Hydroxypyrazine was very stable, but the alkoxy-pyrazines underwent thermal elimination of olefin to yield 2-hydroxypyrazine (668a). Electrochemical reductions of l-methyl-2-oxo-5,6-diphenyl-l,2-dihydro-pyrazine and 54iydroxy(and 5-methoxy)-2,3-diphenylpyrazine are reported to involve the intermediate enamine, for example, 6-hydroxy-1-methyl-2,3-diphenyl-1,4-dihydropyrazine (54) (1096, cf. 1097). When tested on mice 2-carbamoyl-5-methoxypyrazine had less anti tubercular activity than did pyrazinamide (1098). 

Chloro-3,6-dipropylpyrazine 1-oxide 2-Chloro-5-ethoxy-3,6-dimethylpyr azine 2-Chloro-5-ethoxy-3,6-diphenylpyrazine 5-Chloro-6-ethoxy-3-guanidinocarbonyl-... 

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