m-Chlorostyrene → (R)-(+)-3-Chlorostyrene oxide

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A round-bottom flask equipped with a overhead stirrer was charged with 3-chlorostyrene (1.00 g, 7.22×10−3 mol), CH2Cl2 (78 mL), (R,R)-4 (0.349 g, 3.61×10−4 mol), and NMO (4.22 g, 3.62×10−2 mol). The solution was cooled to −78° C. before solid m-CPBA (2.51 g, 1.46×10−2 mol) was added in portions over 1.5 minutes. The reaction was monitored by GC. Upon completion (3 h), the reaction was quenched by the addition of a solution of dimethyl sulfide (6 mL) in CH2Cl2 (25 mL) precooled to −78° C. The solution was stirred for an additional 10 minutes at −78° C. before removal of the cold bath and addition of 2N NaOH (20 mL) and CH2Cl2 (20 mL). The phases were separated and the aqueous layer was washed with CH2Cl2 (2×50 mL). The combined organic layers were dried over Na2SO4, filtered and concentrated in vacuo. Removal of the catalyst was effected by elution through a pad of SiO2 (10 g) using pentane and CH2Cl2 (1:1). The eluent was concentrated in vacuo, and subsequent bulb-to-bulb distillation from CaH2 afforded (R)-3-chlorostyrene oxide (0.963 g, 86%) as a colorless liquid in 81% ee.

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