3-Aminoquinoxalin-2-one

Treatment of an alkaline solution of quinoxalin-2-one or quinoxa-line-2,3-dione with an alkyl iodide or sulfate results in A-methylation. Thus methylation of 3-aminoquinoxalin-2-one (74) with methyl sulfate and alkali gives 3-amino-l-methylquinoxalin-2-one (75) and not as previously reported the isomeric 0-methyl derivative. ... 

There have been several reports of the hydrolysis of 2-aminoquinoxalines to quinoxalinones. For example, 2,3-diamino-quinoxaline is very readily hydrolyzed (2.5 M HCI, 100°, 5 min) to 3-aminoquinoxalin-2-one, and treatment of 2-amino-3-phenylquinoxaline with nitrous acid furnishes 3-phenylquinoxalin-2-one in excellent yield. ... 

Although the 1,3-diphenyl 2-oxo compound 63 is stable to acid hydrolysis, imidazo[4,5-h]quinoxaline itself undergoes very ready hydrolytic ring opening. Hot dilute hydrochloric acid gives 3-aminoquinoxalin-2-one (74), and hot alkali affords 2,3-diaminoquinoxaline (57). Similarly acid treatment of the 2-methyl N-oxides 72 and 73 provides the quinox-aline N-oxides 75 and 76, respectively. ... 

Condensation of ethyl ethoxyiminoacetate with benzene-1,2-diamine in refluxing ethanol gives 3-aminoquinoxalin-2(l//)-one in essentially quantitative yield.With 4-methylbenzene-1,2-diamine a mixture of two possible isomers is formed, but 4-nitrobenzene-l,2-diamine reacts with ethyl ethoxyiminoacetate to yield only a single product. 

Hydrolysis of 3-methylquinoxalin-2-amine with dilute sodium hydroxide on heating at 100 C affords 3-methylquinoxalin-2(l/f)-one, and of quinoxaline-2,3-diamine in dilute hydrochloric acid yields 3-aminoquinoxalin-2(l f)-one. ... 

Relatively few reactions of quinoxaline derivatives occur with change of ring size. Isolated examples are noted in the following text. For example, ring contraction to benzimidazole derivatives occurs when 2,3-diphenylquinoxaline (Chapter XV) or 2-halogenoquinoxalines (Chapter X) are treated with potassium amide in liquid ammonia and quinoxalin-2-one is treated with hydrazine (Chapter VX It is also found that oxidation of l-aminoquinoxalin-2-ones with lead tetraacetate give benzo-1,2,4-triazines (Scheme 6) (Chapter V). 

There is evidence that in the acid hydrolysis of the 2,3-dicycloalkyl-aminoquinoxalines to the corresponding substituted quinoxalinones, the ease of hydrolysis is in the order morpholino>piperidino>pyrrolidinyl. Thus 2-morpholino-3-pyrrolidinylquinoxaline (10) can be selectively hydrolyzed to 3-pyrrolidinylquinoxalin-2-one (11). The hydrolysis of 2,3-dicycloaminoquinoxalines proceeds much more readily than is the case with the corresponding 2,4-disubstituted quinazolines, presumably because of the steric hindrance in the quinoxaline derivatives. ... 

Finally the preformed 2-formyl-3-aminoquinoxaline (448) gave the pyrido[2,3-f ]quin-oxalin-2-one (449) with activated esters/sodium alkoxide (79ZC422). 

Aminoquinoxalin-3-one Pyrid-2-one-3-carboxylic acid Benzo-1,2,4-thiodiazin-3-one-l, 1-dioxide Pyrimido[5,4-dlpyrimidine-2,4,6,8-... 

Bromoquinoxaline has been prepared by heating quinoxalin-2-one with phosphoryl bromide at 120°, and a series of 2-bromo-3-alkyl-quinoxalines have been prepared in analogous fashion. 2-lodoquinoxaline is prepared by the action of sodium iodide and hydriodic acid on 2-chloroquinoxaline and 2-fluoroquinoxaline by application of the Balz-Schiemann reaction to 2-aminoquinoxaline. ... 

A novel synthesis of 2-aminoquinoxalin-3-one 1-oxide has been effected by the hydrogenation of o-nitro-l-cyanoformanilide in ethanol in the presence of Adam s catalyst.- ... 

Scheme 2.72 The synthesis of ethyl 7-aminoquinoxalin-l(2W)-one-3-carboxylate 402 and 6,7-diamino-2-quinoxalinols 403...

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