Boron trifluoride etherate → (R)-N-(2-(5-Bromo-2-fluorophenyl)-1-((2-cyanopropan-2-yl)sulfonyl)-3-fluoropropan-2-yl)-2-methylpropane-2-sulfinamide

Participants

Reaction Conditions

Reaction Steps

To a solution of 2-methyl-2-(methylsulfonyl)propanenitrile (1.654 g, 11.24 mmol) in THF (14 mL) at −78° C. was added a 2.5 M solution of n-butyllithium in hexanes (4.49 mL, 11.24 mmol) dropwise via syringe. After 30 minutes at −78° C., a 0° C. solution of (R,Z)—N-(1-(5-bromo-2-fluorophenyl)-2-fluoroethylidene)-2-methylpropane-2-sulfinamide (1.9 g, 5.62 mmol) in THF (14.00 mL), which had been pretreated with boron trifluoride diethyl etherate (0.693 mL, 5.62 mmol) at 0° C. for 15 minutes, was added dropwise via cannula. The reaction was stirred for 2 hours at −78° C., and then quenched with saturated aqueous ammonium chloride at −78° C. and diluted with water and ethyl acetate. The layers were separated and the aqueous layer was extracted with EtOAc. The combined organic extracts were washed with water and saturated aqueous sodium chloride, and dried over sodium sulfate. The solution was filtered, concentrated, and purified by silica-gel chromatography, eluting with 25% ethyl acetate in hexanes followed by 40% ethyl acetate hexane to provide the title compound. The product was isolated as a 2:1 mixture of diastereomers. LC/MS (ESI+) m/z=485, 487 (M+H; 2 bromine isotopes).

Provenance & Evidence