3-Methyl-2 -quinoxalinone alkylation

Alkylation of pyrazinones and quinoxalinones may be carried out under a variety of conditions and it is usually observed that while O-alkylation may occur under conditions of kinetic control, to yield the corresponding alkoxypyrazines or alkoxyquinoxalines, under thermodynamic control the A-alkylated products are formed. Alkylation using trialkyl-oxonium fluoroborate results in exclusive O-alkylation, and silylation under a variety of conditions (75MI21400) yields specifically the O-silylated products. Alkylation with methyl iodide or dimethyl sulfate invariably leads to A-methylation. 

N-oxides of this type are accessible from o-nitroaniline-based syntheses (see earlier section). l,2-Dihydro-2-oxoquinoxaline 4-oxide (64) and its N-methyl derivative (65) condense with compoimds containing an active methylene group in the presence of piperidine, yielding 3-alkylated quinoxalinones (66). The oxide 64, when warmed with aqueous potassium cyanide, affords 3-cyano-l,2-dihydro-2-oxoquinoxaline, whereas oxide 65 gives l,2-dihydro-3-hydroxy-2-oxo-l-methylquinoxaline. ... 

The following fluorescent alkylating agents have been introduced as pre-chromatographic reagents 9-bromo-methylacridine [480], 3-bromomethyl-6,7-dimethoxy-l-methyl-2(lH)-quinoxalinone [481], naphthacyl bromide (2-bromoacetonaphthone) [482, 483], p-(anthroyloxy)-phenacyl bromide (panacyl bromide) [484], 1-bromo-acetylpyrene [485], 9-chloromethy[anthracene [486], and 9-anthryldiazomethane [487, 488]. 

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