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

Participants

Reaction Conditions

Reaction Steps

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.

Provenance & Evidence