Sodium Bicarbonate → (S)-4-benzyl-3-(3,4-dichlorophenyl)acetyl-2-oxazolidinone

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Reaction Steps

Combine (S)-4-benzyl-2-oxazolidinone (2.6 g, 34 mmol) and tetrahydrofuran (80 mL). Cool in a dry-ice/acetone bath. Add dropwise a solution of n-butyl lithium (13.5 mL, 2.5 M, 27 mmol). After 15 minutes, slowly add a solution of 3,4-dichlorophenylacetyl chloride (9.4 g, 44 mmol) in tetrahydrofuran (20 mL). After 20 minutes, warm to ambient temperature. After 2 hours, dilute the reaction mixture with diethyl ether and add a saturated aqueous sodium bicarbonate solution. Separate the layers and extract the organic layer with a saturated ammonium chloride solution and then water. Dry over MgSO4, filter, and evaporate in vacuo to give a residue. Chromatograph the residue on silica gel eluting sequentially with 5% ethyl acetate/hexane, 10% ethyl acetate/hexane, and 15% ethyl acetate/hexane. Combine the product containing fraction to give a residue. Rechromatograph the residue on silica gel eluting sequentially with 5% ethyl is acetate/hexane, 10% ethyl acetate/hexane, 15% ethyl acetate/hexane, and 20% ethyl acetate/hexane to give a residue. Recrytallize from diethyl ether/hexane to give (S)-4-benzyl-3-(3,4-dichlorophenyl)acetyl-2-oxazolidinone: mp; 70.5-71.5° C. Rf=0.75 (silica gel, 50% ethyl acetate/hexane).

Provenance & Evidence