• YAKHAK HOEJI
• /
• v.44 no.4
• /
• pp.325-333
• /
• 2000

The 1,3-dipolar cycloaddition reaction of the quinoxaline 4-oxides 2 with 2-chloroacrylonitrile gave the 2,3-dihydro-1H-1,2-diazepino[3,4-b]quinoxalines 3, which were converted into the 2,3,4,6-tetrahydro-1H-1,2-diazepino[3,4-b]quinoxalines 5-7. The reaction of compounds 3 with selenium dioxide in acetic acid/water resulted in ring transformation to give the 1,4-dihydro-4-oxopyridazino[3,4-b]quinoxalines 8.

• Journal of the Korean Chemical Society
• /
• v.49 no.2
• /
• pp.173-181
• /
• 2005

• Journal of the Korean Chemical Society
• /
• v.49 no.4
• /
• pp.389-398
• /
• 2005

• Journal of the Korean Chemical Society
• /
• v.49 no.4
• /
• pp.426-430
• /
• 2005

• Journal of the Korean Chemical Society
• /
• v.47 no.4
• /
• pp.345-353
• /
• 2003

The reaction of 6-chloro-3-methoxycarbonylmethylene-2-oxo-1,2,3,4-tetrahydroquinoxaline(5) or 3-methoxycarbonylmethylene-6-nitro-2-oxo-1,2,3,4-tetrahydroquinoxaline(6) with hydrazine hydrate gave 3-hydrazinocarbonylmethylene-2-oxo-1,2,3,4-tetrahydroquinoxalines(7, 8). The reaction of compound 7 or 8 with substituted benzaldehydes or heteroaromatic aldehydes afforded quinoxalines(9-14). Compounds showed the tautomerism between the enamine and methylene imine forms, and between the enamine, methylene imine and enaminol forms in dimethyl sulfoxide solution. The tautomer ratios were determined by the 1H NMR.

• Journal of the Korean Chemical Society
• /
• v.46 no.1
• /
• pp.37-45
• /
• 2002

The reaction of 3,6-dichloro-2-(3,5-dimethylpyrazol-1-yl)quinoxaline(8) or 6-chloro-3-hydrazino-2-(3,5-dimethylpyrazol-1-yl)quinoxaline(9) with substituted anilines, sulfa drugs and heteroacyl chlorides gave 2-(pyrazol-1-yl)quinoxalines(10-12). The reaction of compound 9 with alkyl (ethoxymeth-ylene) cyanoacetates resulted in the intramolecular cyclization to give 2,3-di(pyrazol-1-yl)quinoxalines(13).

• Journal of the Korean Chemical Society
• /
• v.49 no.4
• /
• pp.363-369
• /
• 2005

• Journal of the Korean Chemical Society
• /
• v.47 no.3
• /
• pp.241-249
• /
• 2003

The reaction of 3-(1-ethoxycarbonyl)ethyl-1,2-dihydro-2-oxoquinoxaline (8) with hydrazine hydrate gave 3-(1-hydrazinocarbonyl)ethyl-2-hydroxyquinoxaline (9). The reaction of compound 9 with substituted benzaldehydes and heteroaryl aldehydes afforded 2-hydroxyquinoxalines (10-12), respectively. The reaction of compound 9 with alkyl (ethoxymethylene)cyanoacetates and ethoxymethylenemalononitrile resulted in the intramolecular cyclization to give the 5-amino-1-[2-(3-hydroxyquinoxalin-2-yl)propanoyl]-pyrazoles (13), respectively. Compounds 10-13 showed the tautomerism between the lactam and lactim forms in dimethyl sulfoxide solution. The tautomer ratios were determined by the $^1H$ NMR. The herbicidal and fungicidal activities of the synthesized compounds were investigated.

• Journal of the Korean Chemical Society
• /
• v.48 no.4
• /
• pp.385-393
• /
• 2004

2-Ethoxycarbonyl-3-methylquinoxaline 1,4-dioxide (8) was synthesized from benzofuroxan and ethyl acetoacetate. The reaction of compound 8 with hydrazine hydrate or selenium dioxide gave 2-hydrazinocarbonyl-3-methylquinoxaline 1,4-dioxide (9) or 2-ethoxycarbonyl-3-formylquinoxaline 1,4-dioxide (10), respectively. The reaction of compound 9 with alkanoyl chlorides, benzoyl chlorides, heteroacyl chlorides, and benzenesulfonyl chlorides afforded 3-methyl-2-(substituted hydrazinocarbonyl)quinoxaline 1,4-dioxides (11-14), respectively. The reaction of compound 9 with sodium azide gave 2-azidocarbonyl-3-methylquinoxaline 1,4-dioxide (15), and then its refluxing in dioxane/alcohols resulted in the Curtius rearrangement to give N-(3-methyl-1,4-dioxoquinoxalin-2-yl)-alkyl carbamates (16). The reaction of compound 15 with substituted anilines afforded 2-(3-substituted phenylureido)-3-methylquinoxaline 1,4-dioxides (17). The reaction of compound 10 with benzoic hydrazide or substituted anilines provided quinoxaline 1,4-di-oxides (18, 19), respectively. The herbicidal and fungicidal activities of the synthesized compounds were investigated.