反应详情

To a solution of 4-[5-(3,5-dichloro-phenyl)-5-trifluoromethyl-4,5-dihydro-isoxazol-3-yl]-2-methyl-benzoic acid tert-butyl ester (preparation of similar compounds described in, for example, EP 1,731,512) (2.83 g) in tetrahydrofuran (25 ml) that was stirred at −78° C. for 5 minutes under argon, was slowly added lithium bis(trimethylsilyl)amide (“LiHMDS”) (1M in hexane) (6.9 ml). After 3 hours at −78° C., a cold (−20° C.) solution of 2-benzenesulfonyl-3-phenyl-oxaziridine (commercially available) (2.34 g) in tetrahydrofuran (10 ml) was added quickly. The temperature was kept below −65° C. for 4 hours and 30 minutes. The reaction was quenched by addition of aqueous ammonium chloride (saturated) at −78° C. tert-Butyl methyl ether (“TBME”) was added and the phases were separated. The organic layer was washed successively with ammonium chloride and brine, dried over magnesium sulfate and concentrated. The residue was purified by column chromatography on silica gel (eluent: heptane/TBME 9:1) to give 4-[5-(3,5-dichloro-phenyl)-4-hydroxy-5-trifluoromethyl-4,5-dihydro-isoxazol-3-yl]-2-methyl-benzoic acid tert-butyl ester (738 mg) as a white solid.

1. customwas stirred at −78° C. for 5 minutes under argon
2. waitThe temperature was kept below −65° C. for 4 hours and 30 minutes
3. customThe reaction was quenched by addition of aqueous ammonium chloride (saturated) at −78° C. tert-Butyl methyl ether (“TBME”)
4. additionwas added
5. customthe phases were separated
6. washThe organic layer was washed successively with ammonium chloride and brine
7. dry with materialdried over magnesium sulfate
8. concentrationconcentrated
9. customThe residue was purified by column chromatography on silica gel (eluent: heptane/TBME 9:1)