ethyl 2-(5-bromo-2-fluorophenyl)-2-oxoacetate

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:70.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A solution of (S)-(−)-2-methyl-2-propanesulfinamide (2.35 g, 19.4 mmol) and (5-bromo-2-fluoro-phenyl)-oxo-acetic acid ethyl ester (5.33 g, 19.4 mmol) in tetrahydrofuran (80 ml) was treated at room temperature with titanium(IV) ethoxide (8.04 ml, 38.8 mmol). The light brown solution was stirred at 70° C. for 3.5 hours. For the workup, the cooled reaction mixture was poured into ice water, diluted with ethyl acetate, and filtered through a pad of Dicalite. The organic layer was separated, washed with brine, dried over sodium sulfate, and finally evaporated at reduced pressure. The crude product (6.7 g) was purified by chromatography on silica gel using a gradient of cyclohexane and dichloromethane=100/0 to 0/100 as the eluent. (S)-(5-bromo-2-fluoro-phenyl)-[(Z)-2-methyl-propane-2-sulfinylimino]-acetic acid ethyl ester was obtained as a yellow oil (4.9 g, 66% of theory). Mass (calculated) C14H17BrFNO3S [378.260]; (found) [M+H]+=378, [M+2-H]+=380. For the workup, the cooled reaction mixture filtered through a pad of Dicalite The organic layer was separated washed with brine dried over sodium sulfate finally evaporated at reduced pressure The crude product (6.7 g) was purified by chromatography on silica gel using a gradient of cyclohexane and dichloromethane=100/0 to 0/100 as the eluent