3-benzyl-1,3-oxazolidin-2-one

Conditions: temp:-40.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Alternately, combine (S)-benzyl-2-oxazolidinone (25 g, 140 mmol) and tetrahydrofuran (250 ml). Add triphenylmethane (30 mg) as an indicator. Cool to about −40° C. Add n-butyl lithium (about 56 ml, 1 M in hexane, 140 mmol) until an orange color persists. After 30 minutes, cool in a dry-ice/acetone bath the a solution of 3,4-dichlorophenylacetic acid trimethylacetyl ester as obtained in Preparation 3 and add by cannula the solution of lithio (S)-benzyl-2-oxazolidinone obtained above. When the addition is complete warm to ambient temperature. After 18 hours, partition the reaction mixture between diethyl ether and a saturated aqueous sodium bicarbonate solution. Separate the layers and dry the organic layer over MgSO4, filter, and evaporate in vacuo to give a residue. Chromatograph the residue on silica gel eluting sequentially is with 5% ethyl acetate/hexane and 10% ethyl acetate/hexane to give (S)-4-benzyl-3-(3,4-dichlorophenyl)acetyl-2-oxazolidinone. as obtained in Preparation 3 obtained above When the addition is complete warm to ambient temperature After 18 hours partition the reaction mixture between diethyl ether Separate the layers dry the organic layer over MgSO4 filter evaporate in vacuo to give a residue

Conditions: temp:-40.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Alternately, combine (S)-benzyl-2-oxazolidinone (25 g, 140 mmol) and tetrahydrofuran (250 ml). Add triphenylmethane (30 mg) as an indicator. Cool to about −40° C. Add n-butyl lithium (about 56 ml, 1 M in hexane, 140 mmol) until an orange color persists. After 30 minutes, cool in a dry-ice/acetone bath the a solution of 3,4-dichlorophenylacetic acid trimethylacetyl ester as obtained in Preparation 3 and add by cannula the solution of lithio (S)-benzyl-2-oxazolidinone obtained above. When the addition is complete warm to ambient temperature. After 18 hours, partition the reaction mixture between diethyl ether and a saturated aqueous sodium bicarbonate solution. Separate the layers and dry the organic layer over MgSO4, filter, and evaporate in vacuo to give a residue. Chromatograph the residue on silica gel eluting sequentially is with 5% ethyl acetate/hexane and 10% ethyl acetate/hexane to give (S)-4-benzyl-3-(3,4-dichlorophenyl)acetyl-2-oxazolidinone. as obtained in Preparation 3 obtained above When the addition is complete warm to ambient temperature After 18 hours partition the reaction mixture between diethyl ether Separate the layers dry the organic layer over MgSO4 filter evaporate in vacuo to give a residue

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

Procedure: A cold (ice-bath) suspension of sodium hydride (0.55 mole, hexane washed) in 100 mL of dry THF was stirred under a nitrogen atmosphere while a solution of 2-oxazolidinone in 500 mL of 10:1 THF:DMF was added dropwise. The resulting gray suspension was warmed to room temperature and stirred for 24 hour. Benzyl bromide (66 mL, 0.056 mole) was added to the resulting white suspension and stirred at ambient temperature 24 hour. The reaction was quenched by careful addition of 26 mL water and the resulting mixture was concentrated and poured into 500 mL of water. After extraction with methylene chloride, the combined extracts were washed with water and brine and dried over magnesium sulfate. Concentration in vacuo afforded 104 g of a yellow oil which was purified by Kugelrohr distillation (bp 100°/0.1 mm) to give 81 g (92% yield) of the product as a colorless liquid which solidified on standing at room temperature to a colorless solid, m.p. 76°-78°. stirred at ambient temperature 24 hour The reaction was quenched by careful addition of 26 mL water the resulting mixture was concentrated poured into 500 mL of water After extraction with methylene chloride the combined extracts were washed with water and brine dried over magnesium sulfate Concentration in vacuo

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

Procedure: 5-(4-Fluorophenyl)-5-oxopentanoic acid (10.08 g, 47.9 mmol) and triethylamine (6.8 mL, 4.94 g, 48.8 mmol) were dissolved in tetrahydrofuran (50 mL). The reaction was cooled to −5° C. (ice/brine bath), trimethylacetyl chloride (6.0 mL, 5.87 g, 48.7 mmol) was added quickly drop-wise and the mixture was warmed to room temperature and stirred for 1.5 h. The reaction was cooled to −5° C. (ice/brine bath) again for 30 min, filtered through Celite®, washed with cold 1:1 hexane-tetrahydrofuran (60 mL) and hexane (120 mL). The filtrate was concentrated, dissolved in N,N-dimethylformamide (16 mL) and to this mixture was added (S)-benzyl-2-oxazolidinone (8.47 g, 47.8 mmol) and 4-dimethylaminopyridine (8.57 g, 70.2 mmol) as solids. The reaction was stirred at room temperature for 20 h, poured into 1.0 N hydrochloric acid (400 mL) and extracted with ethyl acetate (2×300 mL). The organic layer was washed with water (400 mL), quarter saturated sodium bicarbonate solution (400 mL), brine (200 mL), dried over sodium sulfate, filtered, and concentrated. The residue was purified by crystallization from hot isopropyl alcohol (75 mL) with slow cooling to room temperature over 16 h. The crystals were filtered cold and washed with cold isopropyl alcohol (50 mL) to afford (4S)-4-benzyl-3-[5-(4-fluorophenyl)-5-oxopentanoyl]-1,3-oxazolidin-2-one (13.87 g, 78% yield) as a white crystalline solid; mp 114.5° C.; Rf 0.29 (1:2 ethyl acetate-hexane); 1H NMR (300 MHz, CDCl3) δ 8.03-7.98 (m, 2H), 7.37-7.19 (m, 5H), 7.14 (t, J=8.7 Hz, 2H), 4.72-4.64 (m, 1H), 4.25-4.15 (m, 2H), 3.32 (dd, J=13.3, 3.4 Hz, 1H), 3.12-3.01 (m, 4H), 2.78 (dd, J=13.3, 9.6 Hz, 1H), 2.15 (quint., J=7.2 Hz, 2H) ppm. was added quickly drop-wise filtered through Celite® washed with cold 1:1 hexane-tetrahydrofuran (60 mL) and hexane (120 mL) The filtrate was concentrated dissolved in N,N-dimethylformamide (16 mL) and to this mixture The reaction was stirred at room temperature for 20 h extracted with ethyl acetate (2×300 mL) The organic layer was washed with water (400 mL), quarter saturated sodium bicarbonate solution (400 mL), brine (200 mL) dried over sodium sulfate filtered concentrated The residue was purified by crystallization from hot isopropyl alcohol (75 mL) with slow cooling to room temperature over 16 h The crystals were filtered cold washed with cold isopropyl alcohol (50 mL)

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

Procedure: 5-(4-Fluorophenyl)-5-oxopentanoic acid (10.08 g, 47.9 mmol) and triethylamine (6.8 mL, 4.94 g, 48.8 mmol) were dissolved in tetrahydrofuran (50 mL). The reaction was cooled to −5° C. (ice/brine bath), trimethylacetyl chloride (6.0 mL, 5.87 g, 48.7 mmol) was added quickly drop-wise and the mixture was warmed to room temperature and stirred for 1.5 h. The reaction was cooled to −5° C. (ice/brine bath) again for 30 min, filtered through Celite®, washed with cold 1:1 hexane-tetrahydrofuran (60 mL) and hexane (120 mL). The filtrate was concentrated, dissolved in N,N-dimethylformamide (16 mL) and to this mixture was added (S)-benzyl-2-oxazolidinone (8.47 g, 47.8 mmol) and 4-dimethylaminopyridine (8.57 g, 70.2 mmol) as solids. The reaction was stirred at room temperature for 20 h, poured into 1.0 N hydrochloric acid (400 mL) and extracted with ethyl acetate (2×300 mL). The organic layer was washed with water (400 mL), quarter saturated sodium bicarbonate solution (400 mL), brine (200 mL), dried over sodium sulfate, filtered, and concentrated. The residue was purified by crystallization from hot isopropyl alcohol (75 mL) with slow cooling to room temperature over 16 h. The crystals were filtered cold and washed with cold isopropyl alcohol (50 mL) to afford (4S)-4-benzyl-3-[5-(4-fluorophenyl)-5-oxopentanoyl]-1,3-oxazolidin-2-one (13.87 g, 78% yield) as a white crystalline solid; mp 114.5° C.; Rf 0.29 (1:2 ethyl acetate-hexane); 1H NMR (300 MHz, CDCl3) δ 8.03-7.98 (m, 2H), 7.37-7.19 (m, 5H), 7.14 (t, J=8.7 Hz, 2H), 4.72-4.64 (m, 1H), 4.25-4.15 (m, 2H), 3.32 (dd, J=13.3, 3.4 Hz, 1H), 3.12-3.01 (m, 4H), 2.78 (dd, J=13.3, 9.6 Hz, 1H), 2.15 (quint., J=7.2 Hz, 2H) ppm. was added quickly drop-wise filtered through Celite® washed with cold 1:1 hexane-tetrahydrofuran (60 mL) and hexane (120 mL) The filtrate was concentrated dissolved in N,N-dimethylformamide (16 mL) and to this mixture The reaction was stirred at room temperature for 20 h extracted with ethyl acetate (2×300 mL) The organic layer was washed with water (400 mL), quarter saturated sodium bicarbonate solution (400 mL), brine (200 mL) dried over sodium sulfate filtered concentrated The residue was purified by crystallization from hot isopropyl alcohol (75 mL) with slow cooling to room temperature over 16 h The crystals were filtered cold washed with cold isopropyl alcohol (50 mL)

Conditions: temp:-40.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Alternately, combine (S)-benzyl-2-oxazolidinone (25 g, 140 mmol) and tetrahydrofuran (250 ml). Add triphenylmethane (30 mg) as an indicator. Cool to about −40° C. Add n-butyl lithium (about 56 ml, 1 M in hexane, 140 mmol) until an orange color persists. After 30 minutes, cool in a dry-ice/acetone bath the a solution of 3,4-dichlorophenylacetic acid trimethylacetyl ester as obtained in Preparation 3 and add by cannula the solution of lithio (S)-benzyl-2-oxazolidinone obtained above. When the addition is complete warm to ambient temperature. After 18 hours, partition the reaction mixture between diethyl ether and a saturated aqueous sodium bicarbonate solution. Separate the layers and dry the organic layer over MgSO4, filter, and evaporate in vacuo to give a residue. Chromatograph the residue on silica gel eluting sequentially is with 5% ethyl acetate/hexane and 10% ethyl acetate/hexane to give (S)-4-benzyl-3-(3,4-dichlorophenyl)acetyl-2-oxazolidinone. as obtained in Preparation 3 obtained above When the addition is complete warm to ambient temperature After 18 hours partition the reaction mixture between diethyl ether Separate the layers dry the organic layer over MgSO4 filter evaporate in vacuo to give a residue