3- -2-quinoxalinecarboxylic

The substrates (79, R = CN or C02Me) also gave 3-imino-4-methyl-3,4,5,6,7,8-hexahydro-2-quinoxalinecarbonitrile (82, R = CN) or methyl 3-imino-4-methyl-3,4,5,6,7,8-hexahydro-2-quinoxalinecarboxylate (82, R = C02Me), rspectively, that appear to exist largely as such in solution but as the amino tautomers (83) in the solid state (MeNH2, MeOH—CHCI3, 20°C, 12 h 69% or... [Pg.14]

Benzenediamine (199) and C-(2-chloro-2-phenylacetyl)formamide (200) gave 3-phenyl-3,4-dihydro-2-quinoxalinecarboxamide (201), formulated as its 1,4-dihydro tautomer (EtOH, reflux, 6 h 56%) in contrast, the same substrate (199) with methyl C-(2-chloro-2-phenylacetyl)formate cyanohydrin (202) gave methyl 3-phenyl-2-quinoxalinecarboxylate (203), presumably by aerial oxidation of a dihydro precursor (MeCN, reflux, 12 h 7%). ... [Pg.29]

Benzenediamine (228) and diethyl dibromomalonate (229) gave ethyl 3-oxo-3,4-dihydro-2-quinoxalinecarboxylate (230) (MeOH, 20°C, 24 h 40%)." The same substrate (228) with ethyl a-bromoisobutyrate gave 3,3-dimethyl-3,4-dihydro-2(17i)-qumoxalinone (231) (Me2NCHO, NEtPr j, 110°C, 7 h 76%) or with methyl 2-bromo-2-phenylacetate gave 3-phenyl-3,4-dihydro-2(l//)-quinoxalinone (232) (KI, K2CO2, AcMe, reflux, 12 h then oily product, MeONa, PhH, reflux, 7 h 89%). ... [Pg.33]

Methyl 2,3-diamino-6-methylbenzoate gave methyl 6-methyl-2,3-dioxo-l,2,3,4-tetrahydro-5-quinoxalinecarboxylate (252) [(C02H)2,4M HCl, reflux, 90 min 69% note survival of the ester grouping]. 2,3-Diamino-5,6-dichlorotoluene gave 6,7-dichloro-5-methyl-2,3(l//,4//)-quinoxalinedione (253) [(C02H)2, 4M HCl, reflux, 6 h 66%], 2-Isopropylaminoaniline gave l-isopropyl-2,3(l//,4//)-quinoxalinedione (254)... [Pg.36]

Tetramethyl-l,2-cyclohexanedione (310) and methyl 2,3-diaminopropio-nate (311) (liberated in situ) gave methyl 5,5,8,8-tetramethyl-5,6,7,8,-tetra-hydro-2-quinoxalinecarboxylate (312) [MeOH, molecular sieve (3A), reflux, 5 h 45% note the spontaneous aerial ( ) oxidation]7 ... [Pg.43]

Ethoxycarbonylmethyl-3-(2-formylethyl)pyrazine (334) (freshly liberated from its acetal) gave a separable mixture of ethyl 6-hydroxy-5,6,7,8-tetrahydro-5-quinoxalinecarboxylate (335) its dehydration product, ethyl 7,8-dihydro-5-quinoxalinecarboxylate (336, R = Et), and the hydrolysis product, 7,8-dihy-dro-2-quinoxalinecarboxylic acid (336, R = H) [NaH, Et20, 0°C, 2 h 15%, 37%, and 37%, respectively when the aqueous workup was carried out at 0°C, product 335 predominated]. " ... [Pg.45]

This category is represented in the facile reaction of o-phenylenediamine (408) with 4-benzoyl-5-phenyl-2,3-dihydro-2,3-thiophenedione (409) (in toluene at 20°C for 30 min) to afford 3-(a-benzoyl-p-mercaptostyryl)-2(l//)-qumoxalinone (410) in 98% yield " also in the complicated reaction of 3-methyl-2,2,4-trinitro-2,5-dihydrothiophene 1,1-dioxide (411) with 2 equiv of ethyl 4-aminobenzoate (412) (in acetonitrile but no further details) to give ethyl 2-(p-ethoxycarbonylphenyl)-3-(l-methyl-2-nitrovinyl)-6-quinoxalinecarboxylate (413) in 51% yield.Several... [Pg.55]

DUiydroxy-2,3,4,5-tetrahydro-l//-benzodiazepine-2,4-dione (441) gave 2,3-(l//,47/)-quinoxalinedione (443) (xylene, reflux, 4 h 17% after purification) or 3-oxo-3,4-dihydro-2-quinoxalinecarboxylic acid (444) (2M HCl, reflux, 15 min 58%) both products appear to have come from the intermediate... [Pg.59]

Diiluoro-2,l,3-benzoxadiazole 1-oxide and ethyl acetoacetate gave ethyl 6,7-difluoro-3-methyl-2-quinoxalinecarboxylate 1,4-dioxide (486) (neat... [Pg.65]

One interesting example of this type of synthesis has been reported. 6-Phenyl-5//-5,7(6F/)-pyrrolo[3,4-/>]pyrazine (515) underwent electrolytic reduction in the presence of chlorotrimethylsilane to give the (unisolated ) substrate (516) that reacted with methyl acrylate (minimal detail) to afford a mixture of methyl 8-anilino-5-oxo-l,5-dihydro-6-quinoxalinecarboxylate (517) and methyl 5-ani-lino-8-oxo-4,8-dihydro-6-quinoxalinecarboxylate (517a) (17% and 21%, respectively, after separation). [Pg.69]

The unsymmetric 6-nitro-2,3-dihydro-l,4-ethanoquinoxaline (549, R = N02) and ethyl chloroformate naturally gave a mixture of ethyl 4-(2-chloro-ethyl)-7-nitro- (551) and ethyl 4-(2-chloroethyl)-6-nitro-1,2,3,4-tetrahydro-1-quinoxalinecarboxylate (552) (CHCI3, 20°C, 1 h 30% each, after... [Pg.75]

Photolysis of several 2-azidophenazines has been shown to afford quinoxahnes. Thus irradiation of 2-azidophenazine (576, R = H) in cyclohexane or acetonitrile gave, among other products, 3-(2-cyanovinyl)-2-quinoxalmecarbaldehyde (577) in <17% yield and irradiation of 2-azido-l-methoxyphenazine in degassed benzene or acetonitrile gave, among other products, a separable mixture of cis- and frawi-isomers of methyl 3-(2-cyanovinyl)-2-quinoxalinecarboxylate (578), each in low yield. 3 ... [Pg.79]

Phenyl-l//-pyrrolo[3,4-h]quinoxaline-l,3(2//)-dione (589) gave 3-(A(-phenyl-carbamoyl)-2-quinoxalinecarboxylic acid (590, R = H) initially as the crude ammonium salt (590, R = NH4) (NH3, H2O, reflux, 4 h ... [Pg.81]

Dimethylquinoxaline gave 2-quinoxalinecarboxylic acid (186, R = H) [excess SeOa, xylene, reflux, 8h 40% clearly involving monodecarboxyla-... [Pg.125]

Ethyl 6,7-dimethyl-3-oxo-3,4-dihydro-2-quinoxalinecarboxylate gave ethyl 3-chloro-6,7-dimethyl-2-quinoxalinecarboxylate (9) (POCI3, 110°C, 10 min 75% note survival of the ester grouping). ... [Pg.135]

Methyl 6-methyl-7-nitro-2,3-dioxo-1,2,3,4-tetrahydro-5-quinoxalinecarboxylate gave methyl 2,3-dichloro-6-methyl-7-nitro-5-quinoxalinecarboxylate (27)... [Pg.139]

Ethyl 3-chloro-2-quinoxalinecarboxylate gave ethyl 3-p-fluorobenzylamino-2-quinoxalinecarboxylate (109) [H2NCH2C6H4F-P (1 equiv), EtOH, reflux, 13 h 73% analogs likewise]or ethyl 3-morpholino-2-quinoxalinecarboxylate (110) [0[CH2CH2)NH (1 equiv), MeOH, reflux, 2h 34%]. ... [Pg.154]

Methyl 3-chloro-5-methoxy-6,7-dimethyl-2-quinoxalinecarboxylate (111) gave 5-methoxy-6,7,A-trimethyl-3-methylamino-7-quinoxalinecarboxamide (112) (excess MeNH2, MeOH, 150°C, sealed, 7h 85%). " ... [Pg.154]

Methyl 3-chloro-2-quinoxalinecarboxylate (113) gave a separable mixture of A,A -bis(3-methoxycarbonylqumoxalin-2-yl)hydrazine (114) and methyl 3-hydrazino-2-quinoxalinecarboxylate (115) [substrate, H2N1SIH2 H20 ( 1 equiv), EtOH, 20°C 70°C, short time 25% of each product after separation] or 3-hydrazino-2-qumoxalinecarbohydrazide (116) [H2N1SIH2 H20 ( 2.5 equiv), EtOH, 70°C, substrate during 30 min 95%]. °... [Pg.154]

Methyl 2,3-dichloro- (140, R = C1) gave methyl 2,3-dimethoxy-6-methyl-7-nitro-5-quinoxalinecarboxylate (140, R = OMe) (MeONa, MeOH, 20°C substrate), slowly (exothermic), 15 min 87% note the very gentle conditions... [Pg.159]

Ethyl 3-bromomethyl- (270, R = Br) gave ethyl 2-acetoxymethyl-6,7-difluoro-2-quinoxalinecarboxylate 1,4-dioxide (270, R = OAc) (AcOH-AcMe, 20°C, Et3N dropwise, 15 min then substratej, slowly, 20°C, 2h 80%). ° ... [Pg.182]

Ethyl 3-dichloromethyl-2-quinoxalinecarboxylate 1,4-dioxide (292) gave pyri-dazino[4,5-/7]quinoxalin-l(2/i)-one (293) (H2NNH2-H20, EtOH, 0°C 20°C, 24 h 60% note the concomitant removal of the A(-oxide entities). ... [Pg.186]

Dimethoxy-3-oxo-3,4-dfliydro-2-quinoxalinecarboxylic acid (61, R = H) gave methyl 6,7-dimethoxy-4-methyl-3-oxo-3,4-dihydro-2-quinoxalinecarboxylate... [Pg.198]

Ethyl 6-hydroxy-5,6,7,8-tetrahydro-5-quinoxalinecarboxylate (94) gave a separable mixture of ethyl 5,6,7,8-tetrahydro-5-quinoxahnecarboxylate (95) and 5-hydroxymethyl-5,6,7,8-tetrahydroquinoxaline (96) pSfaBEU (1 mol), Et20, 20°C, 4 h 11% and 69%, respectively when an excess of NaBH4 was used, only product 96 was isolated]. ... [Pg.203]

Ethyl 3-methyl-2-quinoxalinecarboxylate 1-oxide (249) from the corresponding 1,4-dioxide (250) [(MeO)3P, PrOH, reflux, 2.5 h 81% this selective 4-deoxygenation was not obtained with PCI3 or Na2S204]. ° ... [Pg.230]

Benzoylquinoxaline from its 1,4-dioxide (253, R = H) (substrate, HCl, MeOH, warm then Na2S204-H20 dropwise, until color persisted 74%) also ethyl 3-benzoyl-2-quinoxalinecarboxylate from its 1,4-dioxide (253, R = C02Et)... [Pg.231]

Methyl 3-methyl-2-quinoxalinecarboxylate 1,4-dioxide (259) gave a 5 2 3 mixture of methyl 3-methyl-2-quinoxalinecarboxylate 1-oxide (260), the isomeric 4-oxide, and methyl 3-methyl-2-quinoxalmecarboxylate itself only the 1-oxide (260) could be isolated therefrom [PCI3, CHCI3, 20°C, 12 h 85% (mixture) affording 260 in 20% yield]. ... [Pg.233]

Ethyl 3-methyl-2-quinoxalinecarboxylate from its 1,4-dioxide (261) (P2I4,... [Pg.233]

Methyl 3-(2-phenylsulfonylethyl)-2-quinoxalinecarboxylate 1,4-dioxide (66) and diethylamine gave only methyl 3-(2-diethylaminoethyl)-2-quinoxalme-carboxylate 1,4-dioxide (67) (Et2NH, MeCN, 20°C, 2 h 40%) ° when ammonia or a primary amine was used similarly, the analogous (unisolated) product (68, R = H or alkyl) underwent spontaneous cyclization to afford, for... [Pg.251]

Methyl 6-methyl-2,3-dioxo-l,2,3,4-tetrahydro-5-quinoxalinecarboxylate (18, R = H) gave its 7-nitro derivative (18, R = NO2) (KNO3, 95% H2SO4,... [Pg.258]

Methyl 3-amino-2-quinoxalinecarboxylate (157) gave methyl 3-(A -methyl-ureido)-2-quinoxalinecarboxylate (158) (excess neat MeNCO, 20°C, dark. [Pg.288]

Ethyl 7-amino-2,3-dimethyl-6-quinoxalinecarboxylate (196) and urea gave 7,8-dimethylpyrazino[2,3-g]quinazoIine-2,4(l//, 3/7)-dione (197) (neat reactants, 198°C, 20 min 92%) analogs Ukewise. " ... [Pg.295]

Ethyl l-(o-aminobenzoyl)-3-oxo-l,2,3,4-tetrahydro-2-quinoxalinecarboxylate (204) underwent thermal cyclization with loss of EtOH to give 6a,7-dfliydroquinoxalino[2,1 -c] [ 1,4]benzodiazepine-6,7,13(5//, 8//)-trione (205) (neat substrates, 200°C, vacuum, 30 min 60%). " ... [Pg.296]

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