Lithium diisopropylamide, 2.0M solution in tetrahydrofuran/heptane/ethylbenzene (1.474 ml, 2.95 mmol) was added dropwise via syringe to a solution of (E)-1,1-dimethyl-2-(1,1,1-trifluoropropan-2-ylidene)hydrazine (0.454 g, 2.95 mmol) in THF 4.0 mL at −78° C. After stirring at −78° C. for 1 h, the solution was added dropwise via cannula to a solution of (R,E)-N-(1-(5-bromo-2-fluoropyridin-3-yl)-2-fluoroethylidene)-2-methylpropane-2-sulfinamide (0.500 g, 1.474 mmol) in toluene 4 mL cooled to −78° C. The reaction was stirred 3 h at −78° C. before being quenched with saturated aqueous ammonium chloride at −78° C. The mixture was warmed up to room temperature and diluted with water and EtOAc. The layers were separated and the aqueous layer was extracted with EtOAc three times. The combined organic layers were washed with brine, dried on sodium sulfate, filtered and concentrated. The crude material was purified by column chromatography using a gradient of 10-50% EtOAC/Hexane to give 0.50 g of (R)-N-((S,Z)-2-(5-bromo-2-fluoropyridin-3-yl)-4-(2,2-dimethylhydrazono)-1,5,5,5-tetrafluoropentan-2-yl)-2-methylpropane-2-sulfinamide (0.50 g, 1.014 mmol, 68.8% yield). MS m/z=494.9 [M+H]+. Calculated for C16H22BrF5N4OS: 493.3.
