Oxidation, of 2-methylquinoxaline

Another example of industrially viable biooxidation of N-heterocycles side chain oxidation is the oxidation of 2-methylquinoxaline to 2-quinoxalinecar-boxylic acid by Pfizer [134]. [Pg.168]

Oxidation of 2,3-dimethylquinoxaline with selenium dioxide affords 3-methylquinoxaline-2-carbaldehyde in 41 % yield,and oxidation of 2-methylquinoxaline affords quinoxaline-2-carbaldehyde. ... [Pg.246]

Oxidation, of 2-methylquinoxaline to 2-methylpyrazine-5,6-dicar-boxylic acid, 30, 89 of naphthalene by chromic oxide,... [Pg.54]

The effect of substitution at the 2- and 3-positions is now broadly understood. Oxidation of 2-methylquinoxaline with perphthalic acid gives a mixture of 38% of the 1-oxide, 25% of the 4-oxide, and 13% of the... [Pg.29]

Selenium dioxide oxidation of 2-methylquinoxaline yields quinoxaline-2-carboxaldehyde, and 3-methylquinoxaline-2-carboxaldehyde has been similarly prepared from 2,3-dimethylquinoxaline. Dimethylsulfoxide oxidation of 2,3-bis(bromomethyl)quinoxaline yields the furoquinoxaline 45, and this on sublimation gives quinoxaline-2,3-dicarboxaldehyde. 3-Dibromomethylquinoxaline-2-carboxaldehyde (46) is a by-product of the oxidation reaction. Direct selenium dioxide oxidation of 2,3-dimethylquinoxaline appears to be a less satisfactory method of preparing the dialdehyde. ... [Pg.215]

Dimethylquinoxaline is however resistant to attempted nitration at 100° with mixed fuming nitric acid and concentrated sulfuric acid." Potassium permanganate oxidation of 2-methylquinoxaline under carefully controlled conditions yields 70-75% 2-methyl-5,6-pyrazine-dicarboxylic acid. The further oxidation of 2-methylquinoxaline to... [Pg.216]

Peracetic acid oxidation of l-methylquinoxalin-2-one (42) at 55°C gives l-methylquinoxaline-2,3-dione (43) in moderate yield, and similar treatment of l,3-dimethylquinoxalin-2-one (44) yields a small quantity of the 4-oxide, An improved yield of (43) is obtained by... [Pg.216]

Oxidation of 4-methylquinoxalin-3-one 2-carboxy-fV -methylamlide (45) with hydrogen peroxide and acetic acid furnishes the 1-oxide but, on removal of either or both of the fV-raethyl groups (giving 46, 47, or 48), oxidation with hydrogen peroxide or with peracetic or perbenzoic acid results in the removal of the carboxyamide groups and the formation of a quinoxaline-2,3-dione. ... [Pg.217]

Chloro-3-methylquinoxaline (166) gave 2-methyl-3-phenylsulfonylquinoxa-line (167) (PhS02Na, Et3N+CH2Ph Cl, MeCN, reflux, 10 h 81% identified with that produced by oxidation of 2-methyl-3-phenylthioquinoxaline see Section 5.2.2) 996 likewise 2-phenylsulfonyl-3-styrylquinoxaline (80%) and... [Pg.164]

Oxidation, by nitric acid, 48 of aldehyde to carboxyl group, 49 of hydroxyl to carboxyl group, 49 of 2-methylquinoxaline to 2-methyl-pyrazine-5,6-dicarboxylic acid, 89 of quinoxaline to 2,3-pyrazinedicar-boxylic acid, 87... [Pg.58]

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... [Pg.414]

Peracetic acid or monoperoxysulfuric acid oxidation of 2,4-dimethyl-l,5-benzodiazepine also gives 2-acetyl-3-methylquinoxaline in 28 and 12% yield, respectively. ... [Pg.216]

Substituted quinoxalines afford mono-A-oxides, presumably the 1-oxides, and are resistant to further oxidation, though 5-methoxyquin-oxaline is exceptional in forming a 1,4-dioxide. In the case of 6-substituted quinoxalines, as the substituent becomes more electron attracting, the yields of 1,4-dioxide decrease but more of the corresponding 2,3-dioxo compound (41) is formed.50 55 Peracetic acid oxidation of l-methylquinoxalin-2-one (42) at 55°C gives l-methylquinoxaline-2,3-dione (43) in moderate yield, and similar treatment of l,3-dimethylquinoxalin-2-one (44) yields a small quantity of the 4-oxide.56 An improved yield of (43) is obtained by... [Pg.216]

Reaction of 2-methylquinoxaline 1-oxide with acetic anhydride gives... [Pg.46]

Peracetic acid oxidation of 2,4-dimethyl-1,5-benzodiazepine (4) gives some 2-acetyl-3-methylquinoxaline (5). The latter compound is also formed on treatment of the diazepine with a mixture of concentrated nitric and sulfuric acids, together with benzotriazole (6) and 4-nitro-N,N -diacetyl-o-phenylenediamine (7). ... [Pg.131]

Chromic acid oxidation of hydroxyiminomalon-bis-AT -methylanilide (93) gives 4-methylquinoxalin-3-one-2-carboxy-A -methylanilide 1-oxide (94) by a process involving AT -oxidation and dehydrative ring closure. ... [Pg.235]

Azido-3-methylquinoxaline 1,4-dioxide (293) underwent thermolytic ring contraction with loss of N2 to give a separable mixture of 2-methyl-3//-benzimidazole-2-carbonitrile 1,3-dioxide (294) and its rearrangement product, 3-methyl-3//-2,l,4-benzoxadiazine-3-carbonitrile 4-oxide (295) (PhH, reflux, 10 min 46% and 41%, respectively) the latter product (295) was also obtained from the benzimidazole (294) (PhH, reflux, 30 min 76%) or from the quinoxaline (293) (PhMe, 90°C, 30 min 94%). ... [Pg.313]

Quinoxaline has been prepared by the reaction of glyoxal with o-phenylenediamine, and 2-methylquinoxaline by the reaction of pyruvic aldehyde or isonitrosoacetone with < -phenylenedi-amine. 2,3-Pyrazinedicarboxylic acid has been prepared only by the permanganate oxidation of quinoxaline. 2-Methyl-5,6-pyrazinedicarboxylic acid has been prepared from 2-methyl-quinoxaline in the same way. - ... [Pg.105]

Methylquinoxaline and some of its 6,7-substituted derivatives give 4-methylquinoxalin-ium methosulfates and perchlorates. The reactions must be carried out under an inert atmosphere to avoid oxidative dimerization. 2,3-Dimethylquinoxaline is quatcrnizcd with dimethyl sulfate to give 1,2,3-trimethyl quinoxalinium methosulfate. ... [Pg.224]

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