2-quinoxalinone

Chloro-l-methyl-2-quinoxalinone (215), which cannot anionize, reacts readUy with iV -methylaniline. 6-Bromo-as-triazine-3,5-dione (216) is largely anionized by dimethylamine but not by thiourea... 

Morpholino-2(l//)-quinoxalinone 3-Morpholino-2-quinoxalinone 4-oxide 2-(2-Morpholinovinyl)quinoxaline 1,4-dioxide... 

A -Acylation of l,2,3,4-tetrahydro-2-quinoxalinones anchored to Wang resin was achieved by the usual procedure to give 4-acyl derivatives (Equation 16) <1998JOC1172>. 

Substituted phenylglyoxals (6) are the starting cr-dicarbonyl compounds for the synthesis of 2-arylquinoxalines (7)," and the corresponding aryl a-ketoacids (8) yield 3-aryl-2-quinoxalinones (9)." 12... 

Ethyl-cr-chlorophenylacetate and o-phenylenediamine in the presence of triethylamine give 3-phenyl-1,2,3,4-tetrahydro-2-quinoxalinone (16), which is oxidized to 3-phenyl-2-quinoxalinone (17) with potassium... 

Halogenation of 2-quinoxalinone (60) in acetic acid gives the 7-sub-stituted product almost quantitatively bromine at 20° thus yields 95% of 7-bromo-2-quinoxalinone (61).72... 

Quinoxaline-2,3-dione is converted into 2,3-dichloroquinoxaline by phosphoryl chloride142 or phosphorus pentachloride.143 2,3-Dibromo-quinoxaline is similarly obtained using phosphoryl bromide in dimethyl-aniline.144 Quinoxalin-2-one undergoes ring contraction to 2-methyl-benzimidazole (134) with hydrazine145 however, quinoxaline-2,3-dione gives 3-hydrazino-2-quinoxalinone.145 Quinoxalin-2-one yields a 3-p-dimethylaminophenyl derivative with 7V,N-dimethylaniline (in AcOH, with NH4N03), and a 3-(indol-3-yl) derivative with indole.146... 

A similar reaction resulting in the formation of compound 185 is observed when 3-phenyl-2-quinoxalinone 4-oxide (184) is treated with... 

Quinoxaline 1-oxide (209) reacts with phenyl isocyanate to give 2-anilinoquinoxaline (210) together with 1,3-diphenyl-l-(2-quinoxalinyl)-urea (211) and cyclized oxidation product of the urea 212.215 2-Quinoxalinone 4-oxide (205) and its 1-methyl derivative undergo addition reactions, e.g., with phenyl isocyanate and benzyne to give compounds 214 and 216, respectively.216 These reactions are formulated as proceeding via the intermediate cycloadducts 213 and 215. Compound 216 has also been obtained by photolysis of 3-(o-hydroxy-phenyl)quinoxaline 1-oxide.51 1,3-Dipolar cycloaddition of quinoxaline... 

Reduction of 2-cyano-3-quinoxalinone 1-oxide with sodium dithionite, zinc and acetic acid, or by catalytic hydrogenation was accompanied by loss of the cyano group, and in each case 2-quinoxalinone was formed.194... 

Quinoxaline glycosides have been prepared from 2-quinoxalinone and its 3-methyl derivative and from 2-quinoxalinethione and its 3-methyl derivitive.233-232... 

Thus, when the silver salt of 2-quinoxalinone is condensed with tetra-O-acetyl-cr-D-glucopyranosyl bromide in xylene, the 2-glucosyl-quinoxaline (233 R = H R = Ac) is isolated. The latter compound is readily deacetylated to the glucoside (233 R = R = H). During the reaction only the 2-O-substituted derivative is formed (steric factors probably inhibit /V-glucosidation), and only the / -D-anomers are obtained.234... 

The preparation of a quinoxalinylthiophosphate (121) in biphasic systems from 2-quinoxalinone and ClPS(OEt)2 with TBAB-NaOH has been recently described by Gore et o/.187 the reaction was catalyzed with ammonium salts and with N-methylimidazole. 

When activating substituents are present in the benzenoid ring, substitution usually becomes more facile and occurs in accordance with predictions based on simple valence bond theory. When activating substituents are present in the heterocyclic ring the situation varies depending upon reaction conditions thus, nitration of 2(lfi )-quinoxalinone in acetic acid yields 7-nitro-2(l/f)-quinoxalinone (21) whereas nitration with mixed add yields the 6-nitro derivative (22). The difference in products probably reflects a difference in the species being nitrated neutral 2(l/2 )-quinoxalinone in acetic acid and the diprotonated species (23) in mixed acids. 

Keywords o-phenylendiamine, alloxane, cyclization, cascade reaction, solid-sol-id reaction, melt reaction, 2-quinoxalinone... 

When 2-quinoxalinone 4-oxide (205) is treated with cyanides of the type RCHjCN (R = COjEt or CN) in the presence of piperidine, an interesting rearrangement of the intermediate quinoxalinone takes place, via intramolecular nucleophilic attack of the JV-oxide oxygen on the cyanide group forming 206. ... 

Thus, when the silver salt of 2-quinoxalinone is condensed with tetra-... 

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