1-cyclopentylethanone

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

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: (R)-1-Phenylethanamine (1.36 ml, 1.2 mmol) and triethylamine (7.46 ml, 53.5 mmol) were dissolved in DCM (30 ml) and cooled to 0° C. Titanium tetrachloride (0.49 ml, 4.46 mmol) was added, followed by the solution of 1-cyclopentyl-ethanone (1 g, 8.92 mmol) in DCM (5 ml). The reaction mixture was stirred 3 h at reflux temperature. After cooling to rt diethylether was added (130 ml) and the reaction mixture was filtered. The filtrate was collected and the solvents were evaporated at reduced pressure to give the product as yellow, viscous oil (2.04 g, crude quantitative). [1H-NMR (DMSO-d6, 600 MHz) δ 7.35 (d, 2H), 7.28 (t, 2H), 7.17 (t, 1H), 4.61 (q, 1H), 2.67-2.62 (m, 1H), 1.81 (s, 3H), 1.71-1.50 (m, 8H), 1.27 (d, 3H); LCMS RtL=2.706 min; [M+H]+=216.2] at reflux temperature was added (130 ml) the reaction mixture was filtered The filtrate was collected the solvents were evaporated at reduced pressure to give the product as yellow, viscous oil (2.04 g [1H-NMR (DMSO-d6, 600 MHz) δ 7.35 (d, 2H), 7.28 (t, 2H), 7.17 (t, 1H), 4.61 (q, 1H), 2.67-2.62 (m, 1H), 1.81 (s, 3H), 1.71-1.50 (m, 8H), 1.27 (d, 3H); LCMS RtL=2.706 min; [M+H]+=216.2]

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

Procedure: To a solution of 16.1 g (0.143 mol) of acetylcyclopentane in 175 ml of methanol cooled in an ice bath was added 7.7 ml (0.15 mol) of bromine during 5 min. The reaction mixture was then allowed to warm to 10°-15° and held there by occasional application of the ice bath for 45 min until the reaction mixture became colorless. Then 100 ml of water was added and it was allowed to stir at room temperature for 0.5 hr. It was partially neutralized by the cautious addition of 10 g (72 mmol) of solid potassium carbonate, diluted with 200 ml of water and extracted with 4×150 ml of ether. The combined organic extracts were washed with 2×100 ml of saturated sodium bicarbonate solution and with 3×100 ml of water, dried over magnesium sulfate and concentrated in vacuo at room temperature to leave 30 g (110%) of bromoacetylcyclopentane as an oil whose nmr spectrum indicated that it was mainly the desired product. to warm to 10°-15° extracted with 4×150 ml of ether The combined organic extracts were washed with 2×100 ml of saturated sodium bicarbonate solution and with 3×100 ml of water dried over magnesium sulfate concentrated in vacuo at room temperature

Conditions: temp:-30.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A mixture of 12.3 g of cyclopentylmethyl ketone and 18.5 g of tert.-butyl dichloroacetate was cooled to -30° C with stirring under an inert atmosphere and a solution of 12.2 g of potassium tert.-butylate in 60 ml of tetrahydrofuran was added thereto at the said temperature. After returning to room temperature, hexane and water were added and the organic phase was separated, washed with water and dried over magnesium sulfate. The solvents were evaporated off to leave an oily residue of tert.-butyl 2-chloro-3-cyclopentyl-2,3-epoxy-butanoate. 26.5 g of the latter product was added to a solution of 3 g of lithium carbonate and 20 g of lithium bromide in 100 ml of hexamethylphosphorotriamide and after stirring for 1 hour at room temperature, petroleum ether and water were added thereto. The organic phase was washed with water, dried over magnesium sulfate and filtered. The solvent was evaporated to obtain an oily residue which was tert.-butyl 3-cyclopentyl-2-oxo-3-butenoate which was used as is for the next step. After returning to room temperature the organic phase was separated washed with water dried over magnesium sulfate The solvents were evaporated off

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

Procedure: Sodium pellets (3.1 g, 135 mmol) were dissolved in ethanol (100 ml) under nitrogen at room temperature and a solution of diethyloxalate (18.4 ml, 135 mmol) and 1-cyclopentylethanone (16.7 g, 149 mmol) was added dropwise at room temperature over 30 minutes. The reaction was diluted with ethanol (100 ml), heated to 60° C. and stirred at this temperature for 2 hours. After cooling to room temperature the reaction was poured onto ice-cold 2N HCl (200 ml) and extracted with diethylether (300 ml) and ethyl acetate (300 ml). The combined organic extracts were dried over MgSO4, concentrated under reduced pressure and the residue was purified by flash column chromatography on silica gel eluting with pentane:ethyl acetate (6:1, by volume) to give 3-cyclopentyl-3-oxo-propionc acid ethyl ester (23.8 g) as an orange oil. 1H NMR (400 MHz, CDCl3): δ=14.38-14.65 (1H, brs), 6.83 (1H, s), 4.30-4.39 (2H, quart), 2.82-2.92 (1H, quin), 1.83-1.96 (2H, m), 1.57-1.83 (6H, 2×m), 1.33-1.40 (3H, t) ppm. LRMS (electrospray): m/z [M−H]+ 211. After cooling to room temperature the reaction was poured onto ice-cold 2N HCl (200 ml) extracted with diethylether (300 ml) and ethyl acetate (300 ml) The combined organic extracts were dried over MgSO4 concentrated under reduced pressure the residue was purified by flash column chromatography on silica gel eluting with pentane:ethyl acetate (6:1, by volume) to give 3-cyclopentyl-3-oxo-propionc acid ethyl ester (23.8 g) as an orange oil

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

Procedure: A solution of 2,4-dimethoxybenzaldehyde (10.27 g, 45 mmol) and methyl cyclopentyl ketone (6.06 g, 54 mmol) in anhydrous ethanol (81 mL) was treated with 5 M NaOH (aq) (18 mL, 90 mmol) and the mixture stirred at room temperature for 18 h. The volatiles were removed in vacuo. The residue was extracted with ether (100 mL) and the extract washed with water (3×60 mL), then with brine. The ethereal solution was dried over MgSO4, filtered, and concentrated in vacuo, affording the intermediate chalcone in a crude yield of 14.63 g. The crude intermediate (14.52 g) was dissolved in 110 mL ethyl acetate, treated with platinum oxide (5 mole %) and stirred over 1 atm of H2 at room temperature overnight. The Pt was filtered through a fine fritted funnel and the black residue washed with ethyl acetate. The filtrate was concentrated in vacuo to give a yellowish resin. The resin was chromatographed using silica gel and 6:1 hexanes/ethyl acetate, yielding 6.02 g (41%) of the ketone as a colorless oil. 1H NMR (CDCl3): δ 1.48–1.81 (m, 8H), 2.67 (m, 2H), 2.80 (m, 3H), 3.76 (s, 3H), 3.75 (s, 3H), 6.37 (dd, J=8.1, 2.1 Hz, 1H), 6.41 (d, J=2.1 Hz, 1H), 7.00 (d, J=8.1 Hz, 1H). MS(APCI) calcd for C16H22O3: 262.2; found (M+H+): 263.1. The volatiles were removed in vacuo The residue was extracted with ether (100 mL) the extract washed with water (3×60 mL) The ethereal solution was dried over MgSO4 filtered concentrated in vacuo

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

Procedure: A solution of 2,4-dimethoxybenzaldehyde (10.27 g, 45 mmol) and methyl cyclopentyl ketone (6.06 g, 54 mmol) in anhydrous ethanol (81 mL) was treated with 5 M NaOH (aq) (18 mL, 90 mmol) and the mixture stirred at room temperature for 18 h. The volatiles were removed in vacuo. The residue was extracted with ether (100 mL) and the extract washed with water (3×60 mL), then with brine. The ethereal solution was dried over MgSO4, filtered, and concentrated in vacuo, affording the intermediate chalcone in a crude yield of 14.63 g. The crude intermediate (14.52 g) was dissolved in 110 mL ethyl acetate, treated with platinum oxide (5 mole %) and stirred over 1 atm of H2 at room temperature overnight. The Pt was filtered through a fine fritted funnel and the black residue washed with ethyl acetate. The filtrate was concentrated in vacuo to give a yellowish resin. The resin was chromatographed using silica gel and 6:1 hexanes/ethyl acetate, yielding 6.02 g (41%) of the ketone as a colorless oil. The volatiles were removed in vacuo The residue was extracted with ether (100 mL) the extract washed with water (3×60 mL) The ethereal solution was dried over MgSO4 filtered concentrated in vacuo

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: (R)-1-Phenylethanamine (1.36 ml, 1.2 mmol) and triethylamine (7.46 ml, 53.5 mmol) were dissolved in DCM (30 ml) and cooled to 0° C. Titanium tetrachloride (0.49 ml, 4.46 mmol) was added, followed by the solution of 1-cyclopentyl-ethanone (1 g, 8.92 mmol) in DCM (5 ml). The reaction mixture was stirred 3 h at reflux temperature. After cooling to rt diethylether was added (130 ml) and the reaction mixture was filtered. The filtrate was collected and the solvents were evaporated at reduced pressure to give the product as yellow, viscous oil (2.04 g, crude quantitative). [1H-NMR (DMSO-d6, 600 MHz) δ 7.35 (d, 2H), 7.28 (t, 2H), 7.17 (t, 1H), 4.61 (q, 1H), 2.67-2.62 (m, 1H), 1.81 (s, 3H), 1.71-1.50 (m, 8H), 1.27 (d, 3H); LCMS RtL=2.706 min; [M+H]+=216.2] at reflux temperature was added (130 ml) the reaction mixture was filtered The filtrate was collected the solvents were evaporated at reduced pressure to give the product as yellow, viscous oil (2.04 g [1H-NMR (DMSO-d6, 600 MHz) δ 7.35 (d, 2H), 7.28 (t, 2H), 7.17 (t, 1H), 4.61 (q, 1H), 2.67-2.62 (m, 1H), 1.81 (s, 3H), 1.71-1.50 (m, 8H), 1.27 (d, 3H); LCMS RtL=2.706 min; [M+H]+=216.2]

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: (R)-1-Phenylethanamine (1.36 ml, 1.2 mmol) and triethylamine (7.46 ml, 53.5 mmol) were dissolved in DCM (30 ml) and cooled to 0° C. Titanium tetrachloride (0.49 ml, 4.46 mmol) was added, followed by the solution of 1-cyclopentyl-ethanone (1 g, 8.92 mmol) in DCM (5 ml). The reaction mixture was stirred 3 h at reflux temperature. After cooling to rt diethylether was added (130 ml) and the reaction mixture was filtered. The filtrate was collected and the solvents were evaporated at reduced pressure to give the product as yellow, viscous oil (2.04 g, crude quantitative). [1H-NMR (DMSO-d6, 600 MHz) δ 7.35 (d, 2H), 7.28 (t, 2H), 7.17 (t, 1H), 4.61 (q, 1H), 2.67-2.62 (m, 1H), 1.81 (s, 3H), 1.71-1.50 (m, 8H), 1.27 (d, 3H); LCMS RtL=2.706 min; [M+H]+=216.2] at reflux temperature was added (130 ml) the reaction mixture was filtered The filtrate was collected the solvents were evaporated at reduced pressure to give the product as yellow, viscous oil (2.04 g [1H-NMR (DMSO-d6, 600 MHz) δ 7.35 (d, 2H), 7.28 (t, 2H), 7.17 (t, 1H), 4.61 (q, 1H), 2.67-2.62 (m, 1H), 1.81 (s, 3H), 1.71-1.50 (m, 8H), 1.27 (d, 3H); LCMS RtL=2.706 min; [M+H]+=216.2]

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

Procedure: To a solution of 16.1 g (0.143 mol) of acetylcyclopentane in 175 ml of methanol cooled in an ice bath was added 7.7 ml (0.15 mol) of bromine during 5 min. The reaction mixture was then allowed to warm to 10°-15° and held there by occasional application of the ice bath for 45 min until the reaction mixture became colorless. Then 100 ml of water was added and it was allowed to stir at room temperature for 0.5 hr. It was partially neutralized by the cautious addition of 10 g (72 mmol) of solid potassium carbonate, diluted with 200 ml of water and extracted with 4×150 ml of ether. The combined organic extracts were washed with 2×100 ml of saturated sodium bicarbonate solution and with 3×100 ml of water, dried over magnesium sulfate and concentrated in vacuo at room temperature to leave 30 g (110%) of bromoacetylcyclopentane as an oil whose nmr spectrum indicated that it was mainly the desired product. to warm to 10°-15° extracted with 4×150 ml of ether The combined organic extracts were washed with 2×100 ml of saturated sodium bicarbonate solution and with 3×100 ml of water dried over magnesium sulfate concentrated in vacuo at room temperature

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

Procedure: To a solution of 16.1 g (0.143 mol) of acetylcyclopentane in 175 ml of methanol cooled in an ice bath was added 7.7 ml (0.15 mol) of bromine during 5 min. The reaction mixture was then allowed to warm to 10°-15° and held there by occasional application of the ice bath for 45 min until the reaction mixture became colorless. Then 100 ml of water was added and it was allowed to stir at room temperature for 0.5 hr. It was partially neutralized by the cautious addition of 10 g (72 mmol) of solid potassium carbonate, diluted with 200 ml of water and extracted with 4×150 ml of ether. The combined organic extracts were washed with 2×100 ml of saturated sodium bicarbonate solution and with 3×100 ml of water, dried over magnesium sulfate and concentrated in vacuo at room temperature to leave 30 g (110%) of bromoacetylcyclopentane as an oil whose nmr spectrum indicated that it was mainly the desired product. to warm to 10°-15° extracted with 4×150 ml of ether The combined organic extracts were washed with 2×100 ml of saturated sodium bicarbonate solution and with 3×100 ml of water dried over magnesium sulfate concentrated in vacuo at room temperature

Conditions: temp:-30.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A mixture of 12.3 g of cyclopentylmethyl ketone and 18.5 g of tert.-butyl dichloroacetate was cooled to -30° C with stirring under an inert atmosphere and a solution of 12.2 g of potassium tert.-butylate in 60 ml of tetrahydrofuran was added thereto at the said temperature. After returning to room temperature, hexane and water were added and the organic phase was separated, washed with water and dried over magnesium sulfate. The solvents were evaporated off to leave an oily residue of tert.-butyl 2-chloro-3-cyclopentyl-2,3-epoxy-butanoate. 26.5 g of the latter product was added to a solution of 3 g of lithium carbonate and 20 g of lithium bromide in 100 ml of hexamethylphosphorotriamide and after stirring for 1 hour at room temperature, petroleum ether and water were added thereto. The organic phase was washed with water, dried over magnesium sulfate and filtered. The solvent was evaporated to obtain an oily residue which was tert.-butyl 3-cyclopentyl-2-oxo-3-butenoate which was used as is for the next step. After returning to room temperature the organic phase was separated washed with water dried over magnesium sulfate The solvents were evaporated off