Sodium Chloride → (1S)-[(2R)-(2,4-difluorophenyl)-2-oxiranyl]ethanol

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To a solution of diethyl L(+)-tartrate (2.43 g, 0.0118 mole) in 470 ml of dry CH2Cl2 were added activated 3A° molecular sieve powder (6 g) and cooled the mixture to -5° C. Added a solution of titanium (IV) isopropoxide (7.2 g, 0.0253 mole) in 38 ml of CH2Cl2 followed by t-butyl hydroperoxide (11.2 g, 0.124 mole) in 75 ml of CH2Cl2 and continue to stir at -5° C. for 25 minutes. To this mixture, a solution of compound 6a, (2S)-3-(2,4-Difluorophenyl)-3-buten-2-ol, (7.5 g, 0.041 mole) in 38 ml of CH2Cl2 was added and stirred for 12 hours at 5° C. Cooled the reaction mixture to -40° C., added 20 ml of 30% aq. NaOH solution saturated with NaCl and the mixture was allowed to warm to 10° C. 20 g of MgSO4, 6 g of celite was added to the mixture and continued to stir at 10° C. for 30 minutes. The mixture was suction-filtered over celite. To the filtrate 280 ml of toluene, 225 ml of ether were added and insoluble material removed by filtration. The filtrate was evaporated in vacuo, the residue was dissolved in 200 ml of ether and suction filtered to remove the insoluble material. The filtrate was passed through a bed of silica gel and washed the pad of silica gel with 20 ml of ether. The filtrate was concentrated under reduced pressure to give yellow oil, which was chromatographed on silica gel. Elution with CHCl3 gave title compound 7a as an oil (3.5 g, 43%).

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