反应详情

To a suspension of 5-chloromethyl-4-methyl-2-(4-trifluoromethyl-phenyl)-oxazole (0.30 g, 1.8 mmol) and Cs2CO3 in 8 mL acetonitrile is added (4-Mercapto-2-methyl-phenoxy)-acetic acid ethyl ester (0.25 g, 1.1 mmol). The solution is stirred for 6 hrs and poured into water (50 mL) and extracted with ethyl acetate (3×25 mL). The combined organics are washed with water (10 mL) and brine (30 mL), dried (Na2SO4), filtered and concentrated in vacuo. The crude product is purified using flash column chromatography (10%-20% ethyl acetate/hexanes) to afford 0.40 g (79%) of {2-Methyl-4-[4-methyl-2-(4-trifluoromethyl-phenyl)-oxazol-5-ylmethylsulfanyl]-phenoxy}-acetic acid ethyl ester. To a stirred solution of this ester (0.21 g, 0.44 mmol) is added m-CPBA (50%) (0.31 g, 0.89 mmol) at 0° C. After 10 min. the solution is poured into water (50 mL) and extracted with methylene chloride (3×20 mL). The combine methylene chloride layers are washed with 1 N NaOH (25 mL), water (25 mL) and brine (25 mL), dried (Na2SO4), filtered and concentrated in Vacuo. The crude sulphone is purified using flash column chromatography (10%-25% ethyl acetate hexanes) to give 0.15 g (68%) of {2-Methyl-4-[4-methyl-2-(4-trifluoromethyl-phenyl)-oxazol-5-ylmethanesulfonyl]-phenoxy}-acetic acid ethyl ester. Hydrolysis of this sulphone (0.15 g, 0.30 mmol) occurred under the usual conditions (3 eq. of a 1N solution of LiOH in 1 mL of a 3:2:1 solution of THF:MeOH:H2O) to provide the title compound 0.11 g (78%) after workup with aq. NH4Cl and ethyl acetate.

1. extractionextracted with ethyl acetate (3×25 mL)
2. washThe combined organics are washed with water (10 mL) and brine (30 mL)
3. dry with materialdried (Na2SO4)
4. filtrationfiltered
5. concentrationconcentrated in vacuo
6. customThe crude product is purified