3-acetyl-6-methylpyran-2,4-dione

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

Procedure: Magnesium methoxide (6% in MeOH, 530 mL) was added to a suspension of dehydroacetic acid (31 g) in methanol (600 mL) at room temperature. The reaction mixture was refluxed and stirred for 5 h. The solvent was removed and the residue dissolved in HCl 1M (1.5 L). The aqueous phase was extracted with EtOAc (2×750 mL) and then the solvent was evaporated under reduced pressure to give a yellow oil, which was filtered on a silica cartridge using dichloromethane as eluent. After the solvent removal, methyl 3,5-dioxohexanoate was obtained as a light yellow oil (19.9 g). The reaction mixture was refluxed The solvent was removed the residue dissolved in HCl 1M (1.5 L) The aqueous phase was extracted with EtOAc (2×750 mL) the solvent was evaporated under reduced pressure to give a yellow oil, which was filtered on a silica cartridge After the solvent removal

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

Procedure: A 1-liter, 3-neck, round-bottom flask is equipped with a mechanical stirrer, a thermometer, and a Soxhlet extractor topped with a water cooled condenser. The extractor is filled with 125 g of type 3A molecular sieves and the flask with 80.5 g (0.479 mole) dehydroacetic acid, 500 ml methyl alcohol, and 20 g of concentrated (96%) sulfuric acid. The stirred mixture in the flask is heated to the boiling point by means of an oil bath. The resulting vapor is condensed and allowed to flow through the molecular sieves and returned to the flask. This process is continued for 24 hours. The cooled mixture is then diluted with 250 ml of methylene chloride and neutralized with aqueous caustic. Water is added to the mixture and the methylene chloride layer is separated from the resulting two-phase system. The water layer is extracted twice more with 250 ml amounts of methylene chloride. The combined methylene chloride extracts are washed twice with water, dried over magnesium sulfate, filtered free of solids, and the solvent is removed on a rotary evaporator. The residue is then subjected to vacuum distillation through a 10 inch Vigreaux column yielding 48 g of methyl 2,6-dimethyl-4-oxopyran-3-carboxylate boiling between 130°-136° C. at 1.0 mm pressure. A 1-liter, 3-neck, round-bottom flask is equipped with a mechanical stirrer a thermometer, and a Soxhlet extractor topped with a water cooled condenser The stirred mixture in the flask is heated to the boiling point by means of an oil bath condensed the methylene chloride layer is separated from the resulting two-phase system The water layer is extracted twice more with 250 ml amounts of methylene chloride The combined methylene chloride extracts are washed twice with water dried over magnesium sulfate filtered free of solids the solvent is removed on a rotary evaporator The residue is then subjected to vacuum distillation through a 10 inch Vigreaux column

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

Procedure: A 1-liter, 3-neck, round-bottom flask is equipped with a mechanical stirrer, a thermometer, and a Soxhlet extractor topped with a water cooled condenser. The extractor is filled with 125 g of type 3A molecular sieves and the flask with 80.5 g (0.479 mole) dehydroacetic acid, 500 ml methyl alcohol, and 20 g of concentrated (96%) sulfuric acid. The stirred mixture in the flask is heated to the boiling point by means of an oil bath. The resulting vapor is condensed and allowed to flow through the molecular sieves and returned to the flask. This process is continued for 24 hours. The cooled mixture is then diluted with 250 ml of methylene chloride and neutralized with aqueous caustic. Water is added to the mixture and the methylene chloride layer is separated from the resulting two-phase system. The water layer is extracted twice more with 250 ml amounts of methylene chloride. The combined methylene chloride extracts are washed twice with water, dried over magnesium sulfate, filtered free of solids, and the solvent is removed on a rotary evaporator. The residue is then subjected to vacuum distillation through a 10 inch Vigreaux column yielding 48 g of methyl 2,6-dimethyl-4-oxopyran-3-carboxylate boiling between 130°-136° C. at 1.0 mm pressure. A 1-liter, 3-neck, round-bottom flask is equipped with a mechanical stirrer a thermometer, and a Soxhlet extractor topped with a water cooled condenser The stirred mixture in the flask is heated to the boiling point by means of an oil bath condensed the methylene chloride layer is separated from the resulting two-phase system The water layer is extracted twice more with 250 ml amounts of methylene chloride The combined methylene chloride extracts are washed twice with water dried over magnesium sulfate filtered free of solids the solvent is removed on a rotary evaporator The residue is then subjected to vacuum distillation through a 10 inch Vigreaux column

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

Procedure: A 1-liter, 3-neck, round-bottom flask was equipped with a mechanical stirrer, thermometer, and a Dean-Stark water trap topped with a water cooled condenser. The flask was charged with a mixture of 80.5 g (0.479 mol) dehydroacetic acid, 75.0 g (0.479 mol) 4-amino-2,2,6,6-tetramethylpiperidine, and 600 ml toluene. The stirred mixture in the flask was heated to the boiling point by means of an oil bath and the water formed during the reaction was collected in the trap. After 6 hours of reflux a total of 7.0 ml water had been collected and the flask and its contents cooled to room temperature. The mixture deposited crystals on standing which were collected by vacuum filtration. Reduction of volume of toluene in the filtrate caused a deposit of a second crop of crystals. The combined crystals were recrystallized from a 65/35 mixture of hexane/benzene to give 111 g (75.6%) of a white to colorless crystalline solid (M.P. 174° C.). The chemical structure and purity of these crystals were verified by mass spectroscopy, nuclear magnetic resonance spectroscopy; and by elemental analysis. A 1-liter, 3-neck, round-bottom flask was equipped with a mechanical stirrer The stirred mixture in the flask was heated to the boiling point by means of an oil bath was collected in the trap After 6 hours of reflux a total of 7.0 ml water had been collected were collected by vacuum filtration The combined crystals were recrystallized from a 65/35 mixture of hexane/benzene

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

Procedure: Five separate batches of dehydroacetic acid (1.5 g, 8.92 mmol) are each suspended in conc. ammonia (4 mL) and irradiated at 120° C. for 20 minutes (150 W, Discover® System microwave reactor by CEM Corporation, Matthews, N.C., USA) in the microwave. Once cooled, the solutions are combined and evaporated to dryness to afford the title compound. irradiated at 120° C. for 20 minutes (150 W, Discover® System microwave reactor by CEM Corporation, Matthews, N.C., USA) in the microwave Once cooled evaporated to dryness

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

Procedure: Five separate batches of dehydroacetic acid (1.5 g, 8.92 mmol) are each suspended in conc. ammonia (4 mL) and irradiated at 120° C. for 20 minutes (150 W, Discover® System microwave reactor by CEM Corporation, Matthews, N.C., USA) in the microwave. Once cooled, the solutions are combined and evaporated to dryness to afford the title compound. irradiated at 120° C. for 20 minutes (150 W, Discover® System microwave reactor by CEM Corporation, Matthews, N.C., USA) in the microwave Once cooled evaporated to dryness

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

Procedure: Into a 500 ml reaction flask equipped with a stirrer, a thermometer and a condenser, 200 ml of dimethylformamide, 13.8 g (0.1 mol) of potassium carbonate, 39.6 g (0.2 mol) of phenylguanidine nitrate and 33.6 g (0.2 mol) of dehydroacetic acid were charged, and the reaction was conducted at 140° C. for 3 hours. After completion of the reaction, the reaction solution was cooled and put into ice water. Then, the reaction solution was extracted with toluene and washed with water. Then, 21 g (0.2 mol) of concentrated hydrochloric acid was dropwise added thereto. Precipitated crystals were collected by filtration, washed with toluene, then neutralized with an aqueous sodium carbonate solution and again extracted with toluene. This toluene layer was washed with water and concentrated to obtain 24.1 g of 2-anilino-4-methyl-6-acetonyl-pyrimidine having a melting point of from 77° to 80° C. The yield was 50%. Into a 500 ml reaction flask equipped with a stirrer After completion of the reaction the reaction solution was cooled Then, the reaction solution was extracted with toluene washed with water Precipitated crystals were collected by filtration washed with toluene again extracted with toluene This toluene layer was washed with water concentrated

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

Procedure: 4-Nitrobenzaldehyde (4.5 g, 29.7 mmol) and then a number of drops of piperidine were added to a benzene (40 ml) solution of dehydroacetic acid (5.00 g, 29.7 mmol) at room temperature, after which refluxing was performed for 6 hours while eliminating water by azeotropy. The majority of the benzene was distilled of directly, and then the distillation taken to dryness under reduced pressure. Following which, when recrystallization was performed from ethanol, 4-hydroxy-6-methyl-3-(4-nitrophenyl)acryloyl-2-pyrone (7.3 g, 82%) was obtained as orange crystals. after which refluxing The majority of the benzene was distilled of directly, and then the distillation which, when recrystallization

Conditions: temp:50.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a solution of 65.0 g (0.39 mole) of dehydroacetic acid and 47.0 g (0.42 mole) of thiophene-2-aldehyde in 370 ml of benzene was added dropwise 6.8 g of piperidine with cooling in an ice-water bath. After termination of the dropwise addition, the mixture was stirred at 50° C. for 7 hours. After the reaction, the solvent was concentrated under a reduced pressure. The precipitated crystal was collected by filtration and recrystallized from toluene to obtain 58.5 g (yield: 58%) of 3-(2-thienylacryloyl)-6-methyl-2H-pyran-2,4(3H)-dione in the form of a light crystal, m.p. 162°-164° C. with cooling in an ice-water bath After termination of the dropwise addition After the reaction the solvent was concentrated under a reduced pressure The precipitated crystal was collected by filtration recrystallized from toluene

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

Procedure: In 270 ml of tetrahydrofuran was dissolved 32.0 g of 3-(2-furylacryloyl)-6-methyl-2H-pyran-2,4(3H)-dione which had been obtained by condensation between dehydroacetic acid and furfural. To the solution, 1.6 g of 5% palladium on carbon was added as the hydrogenation catalyst. Hydrogenation was carried out at room temperature under a pressure of 5 kg/cm2 for 10 hours. The catalyst was removed by filtration and the solvent was evaporated under a reduced pressure. The light-yellow oily product thus obtained was purified by silica gel chromatography to obtain a 21.0 g (yield: 65%) of 3-(3-(2-tetrahydrofuryl)propionyl)-6-methyltetrahydropyran-2,4-dione in the form of the light-yellow crystal, m.p. 43°-45° C.

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

Procedure: To a solution of 30.2 g (0.18 mole) of dehydroacetic acid and 30.0 g (0.19 mole) of decyl aldehyde in 300 ml of chloroform was added dropwise 4.8 g of piperidine at room temperature. The mixture was refluxed for 7 hours, while removing the water formed on the reaction with the aid of a Soxhlet extractor charged with anhydrous sodium sulfate. After the reaction, the reaction mixture was extracted with 600 ml of chloroform. The organic layer was separated, washed with 2N HCl and then with water, and dried over anhydrous sodium sulfate. The extract was concentrated under a reduced pressure and 60 ml of ether/hexane (1/2) was added to the residue. The mixture was allowed to stand overnight. The precipitated crystal was recovered by filtration and recrystallized from tetrahydrofuran to obtain 9.5 g (yield: 17%) of 3-(2-dodecenoyl)-6-methyl-2H-pyran-2,4(3H)-dione in the form of a white crystal, m.p. 112°-113° C. The mixture was refluxed for 7 hours while removing the water formed on the reaction with the aid of a Soxhlet extractor After the reaction the reaction mixture was extracted with 600 ml of chloroform The organic layer was separated washed with 2N HCl with water, and dried over anhydrous sodium sulfate The extract was concentrated under a reduced pressure and 60 ml of ether/hexane (1/2) was added to the residue The precipitated crystal was recovered by filtration recrystallized from tetrahydrofuran

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

Procedure: Magnesium methoxide (6% in MeOH, 530 mL) was added to a suspension of dehydroacetic acid (31 g) in methanol (600 mL) at room temperature. The reaction mixture was refluxed and stirred for 5 h. The solvent was removed and the residue dissolved in HCl 1M (1.5 L). The aqueous phase was extracted with EtOAc (2×750 mL) and then the solvent was evaporated under reduced pressure to give a yellow oil, which was filtered on a silica cartridge using dichloromethane as eluent. After the solvent removal, methyl 3,5-dioxohexanoate was obtained as a light yellow oil (19.9 g). The reaction mixture was refluxed The solvent was removed the residue dissolved in HCl 1M (1.5 L) The aqueous phase was extracted with EtOAc (2×750 mL) the solvent was evaporated under reduced pressure to give a yellow oil, which was filtered on a silica cartridge After the solvent removal