4-bromo-1-fluoro-2-(1-iodo-2-isocyanatopropan-2-yl)benzene

Conditions: temp:80.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A solution of the crude (RS)-4-bromo-1-fluoro-2-(2-iodo-1-isocyanato-1-methyl-ethyl)-benzene (10.01 g, 26 mmol) in N,N-dimethyl-formamide (90 ml) was treated at room temperature with silver tetrafluoroborate (5.58 g, 29 mmol) and tert-butanol (3.86 g, 52 mmol). The yellow suspension was stirred at 80° C. overnight. For the workup, the reaction mixture was evaporated at reduced pressure, the residue triturated in ethyl acetate then filtered. The solution was concentrated at reduced pressure and the crude product purified by chromatography on silica gel using a gradient of dichloromethane/methanol=100/0 to 40/60 as the eluent. The (RS)-4-(5-bromo-2-fluoro-phenyl)-4-methyl-oxazolidin-2-one was obtained as a white solid (4.33 g, 61% of theory). MS (ISP): m/z=274.2 [M+H]+, 276.2 [M+2+H]+. For the workup, the reaction mixture was evaporated at reduced pressure the residue triturated in ethyl acetate then filtered The solution was concentrated at reduced pressure the crude product purified by chromatography on silica gel using a gradient of dichloromethane/methanol=100/0 to 40/60 as the eluent

Conditions: temp:80.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A solution of the crude (RS)-4-bromo-1-fluoro-2-(2-iodo-1-isocyanato-1-methyl-ethyl)-benzene (20.0 g, 52 mmol) in N,N-dimethylformamide (180 ml) and tert-butanol (7.7 ml, 104 mmol) was treated with silver tetrafluoroborate (11.15 g, 57 mmol). The yellow suspension was heated at 80° C. for 16 hours. For the workup, the reaction mixture was evaporated at reduced pressure. After chromatography on silica gel using a using a gradient of heptane and ethyl acetate=100/0 to 40/60 as the eluent, the (RS)-4-(5-bromo-2-fluoro-phenyl) -4-methyl-oxazolidin-2-one (intermediate C4A) was obtained as a white solid (28.49 g, 53.5% of theory). For the workup, the reaction mixture was evaporated at reduced pressure