Ethyl 2- -6-quinoxalinecarboxylate

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]

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]

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]

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]

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]

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]

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]

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]

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

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]

Ethyl 3-p-methoxybenzylamino-2-quinoxalinecarboxylate (3, R = Et) gave h-p-methoxybenzylamino-2-quinoxalinecarboxylic acid (3, R = H) (NaOH, H2O, EtOH, reflux, 1 h 95% several analogs likewise). ... [Pg.318]

Ethyl 3-benzoyl-2-quinoxalinecarboxylate 1,4-dioxide (5) gave 2-quinoxaline-carboxylic acid 1,4-dioxide (6) (KOH, EtOH, 20°C, rapidly 58% note additional debenzoylation). " ... [Pg.319]

Ethyl 3-methyl-2-quinoxalinecarboxylate 1,4-dioxide (61, R = Et) gave methyl 3-methyl-2-quinoxalinecarboxylate 1,4-dioxide (61, R = Me) (Et3N, CaCl2, MeOH, 50°C, 2 h 80%).2 ... [Pg.328]

Ethyl 3-methyl-2-quinoxalinecarboxylate gave 7/-(2-dimethylaminoethyl)-3-methyl-2-quinoxalinecarboxamide (74) (neat H2NCH2CH2NEt2, reflux, 1 h ... [Pg.330]

Ethyl 3-morpholino-2-quinoxalinecarboxylate (78, R = OEt) gave 3-morpho-lino-2-quinoxalinecarbohydrazide (78, R = NHNH2) (H2NNH2 H2O, MeOH, reflux, 8 h 73%). ... [Pg.331]

Ethyl 3-bromomethyl-6,7-difluoro-2-quinoxalinecarboxylate 1,4-dioxide (84) gave 6-fluoro-2-methyl-7-methylamino-2,3-dihydro-17/-pyrrolo[3,4-h]quinoxalm-l-one 4,9-dioxide (85) (MeCN, MeNH2i, 15°C, 90 min 87% note additional replacement of one fluoro substituent) analogs likewise. ° ... [Pg.333]

Ethyl 3-formyl-2-quinoxalinecarboxylate 1,4-dioxide (86) gave 2-phenylpyrida-zino[4,5-h]quinoxaline-l(277)-one (87) (excess PhNHNH2, EtOH, reflux, 2h ... [Pg.333]

Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...