diethyl 2-oxopropanedioate

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A solution of N-methylpropionohydrazide (18.78 g, 183.9 mmol) and diethyl ketomalonate (56.1 mL, 368 mmol) in toluene (136 mL) was refluxed with a Dean-Stark trap for 4 hours. The reaction mixture was concentrated under reduced pressure to give the crude material that was purified by silica gel flash column chromatography (100% hexanes to 5 to 10% EtOAc in hexanes) to afford 23 g (49%) of the desired product. The reaction mixture was concentrated under reduced pressure to give the crude material that was purified by silica gel flash column chromatography (100% hexanes to 5 to 10% EtOAc in hexanes)

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A solution of N-methylpropionohydrazide (18.78 g, 183.9 mmol) and diethyl ketomalonate (56.1 mL, 368 mmol) in toluene (136 mL) was refluxed with a Dean-Stark trap for 4 hours. The reaction mixture was concentrated under reduced pressure to give the crude material that was purified by silica gel flash column chromatography (100% hexanes to 5 to 10% EtOAc in hexanes) to afford 23 g (49%) of the desired product. The reaction mixture was concentrated under reduced pressure to give the crude material that was purified by silica gel flash column chromatography (100% hexanes to 5 to 10% EtOAc in hexanes)

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: In ethanol (20 ml), 4-pyridinecarboxyamidrazone (1.48 g) was dissolved. To the resulting solution, diethyl ketomalonate (1.65 ml) was added dropwise at room temperature, followed by stirring for 13 hours. After heating under reflux for 4 hours, the reaction mixture was cooled. Yellow crystals thus precipitated were collected by filtration and dried, whereby the title compound (1.50 g, 56%) was obtained. After heating under reflux for 4 hours the reaction mixture was cooled Yellow crystals thus precipitated were collected by filtration dried

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A suspension of diethyl ketomalonate (1.11 mL, 7.3 mmol) and 1,2-diamino-4,5-difluorobenzene (1.0 g, 6.9 mmol) in anhydrous ethanol (20 mL) was heated at reflux under nitrogen for 3 h. The solvent was removed under reduced pressure and the residue was purified by flash column chromatography on silica gel, eluting with ethyl acetate/methylene chloride (1:2), to provide ethyl 6,7-difluoro-3-hydroxyquinoxaline-2-carboxylate as a light yellow solid: was heated at reflux under nitrogen for 3 h The solvent was removed under reduced pressure the residue was purified by flash column chromatography on silica gel eluting with ethyl acetate/methylene chloride (1:2)

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 19.8 g (0.1 mol) of N-(6-methylpyridine-2-yl)benzene-1,2-diamine was dissolved in toluene (100 ml), and 19.0 g (0.11 mol) of diethyl ketomalonate and 57.1 g of 4 A molecular sieve were added thereto. The solution was heated to reflux for 3 hours while removing water using a Dean-Stark apparatus. Reaction mixture was filtered, and the filtrate was concentrated under reduced pressure to obtain 27.2 g (yield: 89%) of ethyl 1-(6-methylpyridine-2-yl)-2-oxo-1,2-dihydroquinoxaline-3-carboxylate. The solution was heated to reflux for 3 hours while removing water using a Dean-Stark apparatus Reaction mixture was filtered the filtrate was concentrated under reduced pressure

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 5.0 g (21 mmol) of N-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)benzene-1,2-diamine and 3.9 g (22 mmol) of diethyl ketomalonate were dissolved in toluene (60 ml), and the solution was heated to reflux for 12 hours while removing water using a Dean-Stark apparatus. The reaction solution was washed with water, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure. The residue thus obtained was purified by silica gel chromatography (developing solvent: ethyl acetate:hexane=2:3) to obtain 4.6 g (yield: 63%) of ethyl 1-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)-2-oxo-1,2-dihydroquinoxaline-3-carboxylate as a milky yellow powder. the solution was heated to reflux for 12 hours while removing water using a Dean-Stark apparatus The reaction solution was washed with water dried over anhydrous magnesium sulfate concentrated under reduced pressure The residue thus obtained was purified by silica gel chromatography (developing solvent: ethyl acetate:hexane=2:3)

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 10.5 g (73.6 mmol) of 3-chloro-1,2-phenylenediamine and 12.8 g (73.5 mmol) of diethyl ketomalonate were dissolved in ethanol, and the solution was heated to reflux for 3 hours. While heating to reflux, ethanol was added thereto until precipitated crystals dissolved. The reaction mixture was cooled to room temperature, and then precipitated crystals were separated by filtration. The filter cake was washed with cold ethanol, and then dried, to obtain 10.5 g (yield: 51%) of ethyl 5-chloro-2-oxo-1,2-dihydroquinoxaline-3-carboxylate as pale yellow acicular crystals. the solution was heated to reflux for 3 hours While heating to reflux until precipitated crystals dissolved precipitated crystals were separated by filtration The filter cake was washed with cold ethanol dried

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 9.2 g (62.9 mmol) of N-(2-propynyl) 1,2-phenylenediamine and 12.1 g (69.2 mmol) of diethyl ketomalonate were dissolved in toluene (100 mL), and the solution was refluxed for 3 hours. After confirming the completion of the reaction, the reaction solution was concentrated under reduced pressure, and the solid matter thus obtained was washed with diisopropyl ether, to obtain 15.0 g (yield: 93%) of ethyl 2-oxo-1-(2-propynyl)-1,2-dihydroquinoxaline-3-carboxylate as a white powder. the solution was refluxed for 3 hours the completion of the reaction the reaction solution was concentrated under reduced pressure the solid matter thus obtained was washed with diisopropyl ether