4-Bromo-1-chloro-2-fluorobenzene → (R)-N-((S)-(4-chloro-3-fluorophenyl)(1-methyl-1H-pyrazol-4-yl)methyl)-2-methylpropane-2-sulfinamide

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Reaction Steps

To a mixture of 4-bromo-1-chloro-2-fluorobenzene (11.7 g, 56.0 mmol) and magnesium turnings (2.1 g, 84 mmol) in THF (150 mL) at RT was added a few drops of 1,2-dibromoethane (1.1 g, 5.6 mmol). The mixture was stirred at RT for 1.5 h. After cooling to −78° C., (R,E)-2-methyl-N-((1-methyl-1H-pyrazol-4-yl)methylene)propane-2-sulfinamide (4.00 g, 18.7 mmol) was added and stirred at −78° C. for 6 h. The reaction was quenched with aq. NH4Cl solution and extracted with EtOAc. The combined organic layers were dried (MgSO4), filtered, and concentrated. The crude product was purified by SiO2 chromatography eluting with DCM/MeOH (150:1) to afford the 2.9 g (45%) of (R)—N—((S)-(4-chloro-3-fluorophenyl)(1-methyl-1H-pyrazol-4-yl)methyl)-2-methylpropane-2-sulfinamide (48). LCMS (ESI) m/z: 344.1 [M+H]+.

Provenance & Evidence