Iodine → 4-(3-Bromo-phenyl)-4-(4-difluoromethoxy-3-methyl-phenyl)-oxazolidin-2-one

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Reaction Steps

A solution of iodine (5.5 g, 1.1 eq.) in ethyl acetate (60 ml) was added dropwise to a suspension of silver isocyanate (3.3 g, 1.2 eq) and 4-[1-(3-bromo-phenyl)-vinyl]-1-difluoromethoxy-2-methyl-benzene (CAS 1180015-79-9) (6.7 g, 1 eq.) in acetonitrile (80 ml) and ethyl acetate (20 ml). During the addition the suspension was cooled in an ice-bath. The resulting brown suspension was stirred for 1 hour at room temperature. After an TLC sample indicated complete conversion of the starting material, the reaction mixture was filtrated and concentrated in vacuo. The crude was dissolved in tert-butanol (100 ml) and triethylamine (2.76 ml, 1 eq.) was added. The mixture was stirred at 100° C. overnight. For the workup the mixture was allowed to cool to room temperature, then the solvent was removed at reduced pressure and the residue taken up in ethyl acetate. The solution was washed with water (3×20 ml), dried over sodium sulphate and concentrated at reduced pressure. The residue was purified by chromatography on silica gel using a 9:1-mixture of cyclohexane and ethyl acetate as the eluent. There were obtained 5.1 g (67% of theory) of the (RS)-4-(3-bromo-phenyl)-4-(4-difluoromethoxy-3-methyl-phenyl)-oxazolidin-2-one as a white solid. MS (ISP): m/z=398 [M+H]+.

Provenance & Evidence