Quinoxalinecarboxylic acids

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]

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]

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]

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 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]

Methoxy-6,7,Al-trimethyl-3-methylamino-2-quinoxalinecarboxamide(16)gave 5-methoxy-6,7-dimethyl-3-methylamino-2-quinoxalinecarboxylic acid (17) (NaOH, H2O, MeOH, reflux, 3 h 89%). ... [Pg.320]

Quinoxalinecarbaldehyde 1-oxide (25) gave initially mainly 2-quinoxaline-carboxylic acid 1-oxide (26) (AcOH, 30% H2O2, 20°C, 24 h %) but subsequently 2-quinoxalinecarboxylic acid 1,4-dioxide (27) (same condi-... [Pg.321]

Phenoxy-2-quinoxalinecarboxylic acid (28, R=OPh) gave 2-phenoxyqui-noxaline (29, R = OPh) [polyphosphoric acid (from P2O5 + 85% H3PO4), xylene, 90°C, 5 h 72%]. " °... [Pg.322]

Azido formyl-2-quinoxalinecarboxylic acid (34) underwent a Curtius reacrtion to afford the cyclic anhydride of 3-carboxyamino-2-quinoxalinecarboxylic acid, 4//-[l,3]oxazino[4,5-fc]quinoxaline-2,4(17/)-dione (35) (for details, see original). ... [Pg.323]

Oxo-3,4-dihydro-2-quinoxalinecarboxylic acid (36, R = OH) gave 3-oxo-3,4-dihydro-2-quinoxalinecarbonyl chloride (36, R = Cl) (neat SOCI2, reflux, 1 h 6,7-dimethoxy -methyl-3-oxo-3,4-dihydro-2-quinoxalinecarboxylic acid (37, R = OH) gave 6,7-dmieihoxy-4-methyl-3-oxo-3,4-dihydro-2-quinoxalinecarbonyl chloride (37, R = C1) (likewise >91%). ... [Pg.323]

Quinoxalinecarboxylic acid (43) gave -nitrophenyl 2-quinoxalinecarboxylate (44) (F3CO2C6H4NO2-P, pyridine, 25°C, 3.5 h 91% or PhS02Cl, pyridine,... [Pg.325]

Quinoxalinedicarboxylic anhydride (47) and 2-amino-4,5,6,7-tetrahydroben-zo[Z ]thiophene-2-carboxylic acid (48) gave 3-[iV-(3-carboxy-4,5,6,7-tetrahy-drobenzo[/7]thien-2-yl)carbamoyl]-2-quinoxalinecarboxylic acid (49) (EtOH, reflux, 30 min 80% analogs likewise). [Pg.325]

Formation constants and thermodynamic parameters have been measured for the Fe(II) chelates of 3-chloro-2-quinoxalinecarboxylic acid and 3-oxo-3,4-dihy-dro-2-quinoxalinecarboxylic acid. ... [Pg.327]

Note Quinoxalinecarboxamides may be converted into quinoxalinecarbohydra-zides and vice versa (albeit indirectly). 3-Carbamoyl-2-quinoxalinecarboxylic acids and 2,3-quinoxalinedicarboxamides can give cyclic quinoxalinedicar-boximides. [Pg.336]

Ethyl 2-quinoxalinecarboximidate 1-oxide Ethyl 2-quinoxalinecarboxylate Ethyl 5-quinoxalinecarboxylate Ethyl 6-quinoxalinecarboxylate Ethyl 2-quinoxalinecarboxylate 4-oxide 3-Ethyl-2-quinoxalinecarboxylic acid 2-Ethylquinoxaline 1,4-dioxide 2-Ethylquinoxaline 1-oxide 2-Ethylquinoxaline 4-oxide... [Pg.407]

Big Chemical Encyclopedia

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