Aminoquinoxalines alkylation

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. ... 

Note The alkylation of nuclear or extranuclear aminoquinoxalines is an unattractive process, and examples are limited. Initial acylation of an aminoquinoxaline is sometimes used to assist subsequent alkylation, and the acyl group can be removed later with ease. 

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. ... 

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