2-Ethyl-3-methylquinoxaline

Ethyl 2-methyl-3-oxo-3,4-dihydro-6-quinoxalinecarboxylate Ethyl 3-methyl-2-oxo-l,2-dihydro-6-quinoxalinecarboxylate Ethyl 4-methyl-3-oxo-3,4-dihydro-2-quinoxalinecarboxylate Ethyl 8-methyl-3-oxo-3,4-dihydro-2-quinoxalinecarboxylate 2-Ethyl-3-methylquinoxaline... 

Ethyl 3-methyl-2-quinoxalinecarboxylate 1-oxide Ethyl 3-methyl-2-quinoxalinecarboxylate 4-oxide 2-Ethyl-3-methylquinoxaline 1,4-dioxide... 

Quantitative determination of diacetyl and 2,3-pentanedione during beer fermentation was achieved by GC/MS method as 2,3-dimethylquinoxaline and 2-ethyl-3-methylquinoxaline, respectively, after reacting with 1,2-diamino-benzene <2006MI52>. 

In boiling ethanol, under nitrogen and in the presence of palladized charcoal, 2-acetyl-l,4-dihydro-3-methylquinoxaline (30) undergoes dismutation to give a mixture of 2-acetyl-3-methylquinoxaline, 2-acetyl-l,2,3,4-tetrahydro-3-methylquinoxaline (33), and 2-l -hydroxy-ethyl-3-methylquinoxaline (34), The latter compound is the product of sodium borohydride or Meerwein-Ponndorf reduction of 2-acetyl-3-methylquinoxaline. 

Chloro-3-methylquinoxaline 4-oxide gave 3-chloro-2-quinoxalinecarbalde-hyde 1-oxide (172) (SeOi, PhH, reflux, h 72%) dioxane may be used as solvent for such oxidations yielding, for example, 3-amino-2-quinoxaline-carbaldehyde ethyl acetate may also be so used. 

Hydroxy ethyl)-3- methylquinoxaline 2-(2-Hydroxyethyl)-3-methylquinoxaline 2-(l-Hydroxyethyl)-3-pivalamidoquinoxaline 2- (2- Hydroxy ethyl) quinoxaline 2-(2-Hydroxyethyl)quinoxaline 1,4-dioxide 2-(2-Hydroxyethyl)-3,6,7-trimethylquinoxaline... 

Elina and co-workers have extensively investigated the reactions of 2-methylquinoxaline 1,4-dioxide and 2,3-dimethylquinoxaline 1,4-dioxide with aldehydes.206 Under alkaline conditions formalin gives hydroxy-ethyl derivatives, and aryl aldehydes form styrylquinoxalines. As expected, 2,3-dimethylquinoxaline 1-oxide yields 3-methyl-2-styrylquin-oxaline 1-oxide.207... 

Intermediate 6-substituted quinoxalin-2(l//)-one 4-oxides can be converted into 6-substituted 3-methylquinoxalin-2(l//)-one 4-oxidcs in a one-pot reaction involving dehydration, deacetylation and decarboxylation using ethyl acetoacetate. ... 

In the case of 2-methylquinoxalines (system A) there is no evidence for the existence of tautomeric form B with an exocyclic double bond. The UV and IR spectroscopic properties of ethyl 3-methylquinoxalin-2-yl pyruvate (24) suggest that it exists as the enamine (25) rather than as the enol (26). ... 

Benzofuroxan (150) on reaction with ethyl acetoacetate provides the methylquinoxaline 151, which on bromination gives the bromomethyl derivative 152. Treatment of this compound with amines gives the monooxopyrrolo compound 154. The 2-methyl derivative 154 (R = Me) was also prepared directly from benzofuroxan by reaction with the JV-methylpyrrolinone 153. The products 154 are claimed to be antibacterials and animal growth promotants. ... 

The influence of acid on these additions is considerable. In ethanol, for example, ethyl nicotinate is converted into the corresponding 6a-hydroxyethylpyridine, whereas in acidified solution the 6-ethylpyridine derivative is obtained.147 The function of the acid may, of course, simply be to promote dehydration of the intermediate 6a-hydroxyethyldihydropyridine. Phthalazine and quinoxaline are converted by irradiation in acidified methanol into 1-methylphthalazine and 2-methylquinoxaline, respectively.148 In this case, however, there is evidence to suggest that the alkylations proceed by way of electron transfer from the solvent to an excited state of the protonated diazines in neutral solution, a hydrogen... 

Reduction of the quinoxalines 5 leads to hydropyrroloquinoxalines 6-8 (Nelson and Boyer 1950 Okumura and Shigemitsu 1965). The pyrrolo[l,2-a]quinoxaline system (compound 6) was first obtained by this method (Okumura and Shigemitsu 1965). During the reductive cyclization of ethyl quinoxalin-2-yl- and 3-methylquinoxalin-2-ylpyruvates 5 in the presence of copper chromite at high temperature, the perhydropyrrolo[l,2-a]quinoxalines 7 and 8 are formed (Scheme 3.2). 

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