1-cyclopropylbutane-1,3-dione

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: 10 g (51 mmol) of phenylguanidine hydrogen carbonate and 9.7 g (77 mmol) of 1-cyclopropyl-1,3-butanedione are heated at 110° C. for 6 hours with stirring, the evolution of carbon dioxide which occurs subsiding as the reaction progresses. After the dark brown emulsion has been cooled to room temperature, 50 ml of diethyl ether are added and the mixture is washed twice with 20 ml of water each time, dried over sodium sulfate and filtered, and the solvent is evaporated. The dark brown oil which remains (=13.1 g) is purified by column chromatography over silica gel (diethyl ether/toluene: 5/3). After the eluant mixture has been evaporated off, the brown oil is made to crystallise and recrystallised from diethyl ether/petroleum ether at 30°-50° C. Light-brown crystals are obtained. Melting point: 67°-69° C.; yield: 8.55 g (38 mmol) (=74.5% of the theoretical yield). as the reaction progresses the mixture is washed twice with 20 ml of water each time dried over sodium sulfate filtered the solvent is evaporated is purified by column chromatography over silica gel (diethyl ether/toluene: 5/3) After the eluant mixture has been evaporated off to crystallise recrystallised from diethyl ether/petroleum ether at 30°-50° C Light-brown crystals are obtained yield: 8.55 g (38 mmol) (=74.5% of the theoretical yield)

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

Procedure: A mixture of 1-cyclopropylbutan-1,3-dione (65.3 g), hydroxylamine hydrochloride (36.6 g) and anhydrous potassium carbonate (71.8 g) in ethanol (375 ml) was stirred and heated at reflux for 2 hours. The mixture was cooled and filtered and the filtrate was evaporated to dryness. The residue was distilled under reduced pressure to give 5-cyclopropyl-3-methyl isoxazole containing approximately 20% 3-cyclopropyl-5-methylisoxazole (51.85 g) as a clear oil, b.p. 74° C./12 mm.Hg. heated at reflux for 2 hours The mixture was cooled filtered the filtrate was evaporated to dryness The residue was distilled under reduced pressure

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

Procedure: A mixture of 1-cyclopropylbutan-1,3-dione (65.3 g), hydroxylamine hydrochloride (36.6 g) and anhydrous potassium carbonate (71.8 g) in ethanol (375 ml) was stirred and heated at reflux for 2 hours. The mixture was cooled and filtered and the filtrate was evaporated to dryness. The residue was distilled under reduced pressure to give 5-cyclopropyl-3-methyl isoxazole containing approximately 20% 3-cyclopropyl-5-methylisoxazole (51.85 g) as a clear oil, b.p. 74° C./12 mm.Hg. heated at reflux for 2 hours The mixture was cooled filtered the filtrate was evaporated to dryness The residue was distilled under reduced pressure

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

Procedure: A mixture of 1-cyclopropylbutan-1,3-dione (65.3 g), hydroxylamine hydrochloride (36.6 g) and anhydrous potassium carbonate (71.8 g) in ethanol (375 ml) was stirred and heated at reflux for 2 hours. The mixture was cooled and filtered and the filtrate was evaporated to dryness. The residue was distilled under reduced pressure to give 5-cyclopropyl-3-methyl isoxazole containing approximately 20% 3-cyclopropyl-5-methylisoxazole (51.85 g) as a clear oil, b.p. 74° C./12 mm.Hg. heated at reflux for 2 hours The mixture was cooled filtered the filtrate was evaporated to dryness The residue was distilled under reduced pressure

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

Procedure: Magnesium turnings (3.04 g, 125 mmol), suspended in methanol (145 ml), were heated to reflux under nitrogen for 1 hour, then cooled to room temperature and the β-keto acid from Preparation 2 (25.5 g, 250 mmol) dissolved in methanol (25 ml) was added dropwise, with ice-cooling. The reaction mixture was stirred for 1 hour, at room temperature, and then the solvent was removed under reduced pressure to give the magnesium salt of the acid. Meanwhile, cyclopropane-carboxylic acid (9.91 ml, 125 mmol) was dissolved in dimethylformamide (200 ml). Carbonyldiimidazole (22.4 g, 138 mmol) was then added portionwise, under nitrogen, at 0° C. This reaction mixture was stirred for 1.5 hours, and then the magnesium salt from above was added as a solution in N,N-dimethylformamide (100 ml) at 0° C. The reaction mixture was allowed to stir at room temperature for 92 hours, and then it was poured into 2M aqueous hydrochloric acid (85 ml), followed by dilution with water (170 ml). The mixture was extracted with diethyl ether (6×200 ml), and the combined organic extracts were then washed with brine (3×200 ml), dried over magnesium sulphate and concentrated under reduced pressure. The residual orange oil was purified by flash chromatography on silica gel eluting with pentane:diethyl ether (100:0 then 90:10 then 80:20, by volume) to provide the title compound (7.39 g, 24%) as a yellow oil. 1H NMR (400 MHz, CDCl3): δ=0.83-0.95 (m, 2H), 1.06-1.10 (m, 2H), 1.54-1.63 (m, 1H), 2.00 (s, 3H); LRMS (electrospray): m/z 149 [MNa+]. to stir at room temperature for 92 hours The mixture was extracted with diethyl ether (6×200 ml) the combined organic extracts were then washed with brine (3×200 ml) dried over magnesium sulphate concentrated under reduced pressure The residual orange oil was purified by flash chromatography on silica gel eluting with pentane:diethyl ether (100:0

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

Procedure: To a stirred solution of 8.4 g (0.1 mol) of cyclopropyl methyl ketone in 100 mL of ethyl acetate under nitrogen was added dropwise 39 mL (0.1 mol) of a 21 wt % solution of sodium ethoxide in absolute ethanol. The flask was fitted with a condenser and Dean-Stark trap and was heated. The ethanol was removed by azeotropic distillation. Additional ethyl acetate was added to the flask as needed. After three hours the temperature of the distillate had reached 75° C. and the reaction was allowed to cool and stand overnight. The white solid which precipitated out was collected by filtration and the filtrate was set aside. The solid was dissolved in water and this solution was acidified at 0° C. with 10% aqueous hydrochloric acid. This solution was extracted three times with ethyl ether. The ethyl acetate filtrate was washed with water three times, acidified with 10% aqueous hydrochloric acid, and extracted with ethyl ether. The ether extracts from both extractions were combined, dried over magnesium sulfate, and filtered. Removal of solvents gave 3.5 g of 1-cyclopropyl-1,3-butanedione as an oil. Analysis by GC showed 75% purity. This intermediate was used without further purification. The flask was fitted with a condenser Dean-Stark trap and was heated The ethanol was removed by azeotropic distillation Additional ethyl acetate was added to the flask to cool stand overnight The white solid which precipitated out was collected by filtration The solid was dissolved in water was acidified at 0° C. with 10% aqueous hydrochloric acid This solution was extracted three times with ethyl ether The ethyl acetate filtrate was washed with water three times extracted with ethyl ether The ether extracts from both extractions dried over magnesium sulfate filtered Removal of solvents

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

Procedure: To a stirred solution of 8.4 g (0.1 mol) of cyclopropyl methyl ketone in 100 mL of ethyl acetate under nitrogen was added dropwise 39 mL (0.1 mol) of a 21 wt % solution of sodium ethoxide in absolute ethanol. The flask was fitted with a condenser and Dean-Stark trap and was heated. The ethanol was removed by azeotropic distillation. Additional ethyl acetate was added to the flask as needed. After three hours the temperature of the distillate had reached 75° C. and the reaction was allowed to cool and stand overnight. The white solid which precipitated out was collected by filtration and the filtrate was set aside. The solid was dissolved in water and this solution was acidified at 0° C. with 10% aqueous hydrochloric acid. This solution was extracted three times with ethyl ether. The ethyl acetate filtrate was washed with water three times, acidified with 10% aqueous hydrochloric acid, and extracted with ethyl ether. The ether extracts from both extractions were combined, dried over magnesium sulfate, and filtered. Removal of solvents gave 3.5 g of 1-cyclopropyl-1,3-butanedione as an oil. Analysis by GC showed 75% purity. This intermediate was used without further purification. The flask was fitted with a condenser Dean-Stark trap and was heated The ethanol was removed by azeotropic distillation Additional ethyl acetate was added to the flask to cool stand overnight The white solid which precipitated out was collected by filtration The solid was dissolved in water was acidified at 0° C. with 10% aqueous hydrochloric acid This solution was extracted three times with ethyl ether The ethyl acetate filtrate was washed with water three times extracted with ethyl ether The ether extracts from both extractions dried over magnesium sulfate filtered Removal of solvents

Conditions: temp:75.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a stirred solution of ethanol (5 mL) were added 1-cyclopropyl-1,3-butanedione (505 mg, 3.00 mmol) and cyanoacetamide (252 mg, 3.00 mmol), and the heterogenous contents heated until homogenous (ca. 75° C.). Piperidine was added (0.395 mL, 4.00 mmol) and the mixture was heated at reflux for 30 min. The reaction mixture was allowed to cool to room temperature, wherein precipitation ensued. The solid precipitate was filtered and set aside. The filtrate was concentrated in vacuo and the oily residue treated with minimal EtOAc and then 10 mL hexanes to afford a second crop of solid. The solid product crops were combined, suspended in water (7 mL), vigorously stirred, and vacuum filtered to afford 6-cyclopropyl-4-methyl-2-oxo-1,2-dihydro-3-pyridinecarbonitrile as a nearly white solid (380 mg, 73%). LCMS E-S (M+H)=175.1. 1H NMR (400 MHz, CDCl3) δ ppm 1.01-1.09 (m, 2 H), 1.28 (dd, J=8.59, 2.27 Hz, 2 H), 1.95-2.01 (m, 1H), 2.43 (s, 3H), 5.82 (s, 1 H). the mixture was heated at reflux for 30 min to cool to room temperature wherein precipitation The solid precipitate was filtered The filtrate was concentrated in vacuo the oily residue treated with minimal EtOAc 10 mL hexanes to afford a second crop of solid vacuum filtered

Conditions: temp:60.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a stirring solution of THF (100 mL) was added potassium tert-butoxide (5.60 g, 49.5 mmol), followed by a mixture of cyclopropyl methyl ketone (3.27 mL, 33 mmol) and ethyl acetate (9.69 mL, 99 mmol) in 30 mL THF at 35° C., via addition funnel over a 25 min period. The contents were heated and stirred at 60° C. After 3 h, the contents were removed from heating, and allowed to cool to room temperature. The reaction mixture was carefully diluted with 30 mL 2 N HCl and stirred for 10 min. The mixture was extracted with diethyl ether (3×50 mL), and the combined organic layers washed with brine (1×50 mL). The organic layer was dried over MgSO4, filtered, and concentrated in vacuo. Purification by chromatography on silica gel (eluent: 0 to 15% EtOAc in hexanes) with good separation afforded 1-cyclopropyl-1,3-butanedione as a light yellow colored oil, 3.9 g in ˜75% purity (residual solvent), for an overall yield of 70%. 1H NMR (400 MHz, CDCl3) δ ppm 0.89-0.96 (m, 2 H), 1.09-1.15 (m, 2 H), 1.59-1.69 (m, 1H), 2.04 (s, 3H), 5.63 (s, 1 H), 15.5-16.0 (br s, 1H). The contents were heated the contents were removed from heating to cool to room temperature The reaction mixture was carefully diluted with 30 mL 2 N HCl stirred for 10 min The mixture was extracted with diethyl ether (3×50 mL) the combined organic layers washed with brine (1×50 mL) The organic layer was dried over MgSO4 filtered concentrated in vacuo Purification by chromatography on silica gel (eluent: 0 to 15% EtOAc in hexanes) with good separation