反应详情

温度

-27 °C

A 500 mL 3-neck flask was charged with 3,5-dimethylphenoxybutanoic acid (17) (25 g, 120 mmol) and CH2Cl2 (100 mL). This solution was cooled to −27° C. with mechanical stirring then chlorosulfonic acid (42 g, 360 mmol) was added dropwise over 30 min (temperature reached a max. of −20° C.). The material was stirred for an additional 1 hr at −25° C. then NaHCO3 (20 g, 238 mmol) was added to the reaction mixture. The reaction mixture was then added to 150 g of ice. The reaction mixture was then extracted into EtOAc (750 mL), dried over Na2SO4 (10 g), filtered and then concentrated in vacuo. Two triturations of the crude product with MTBE at 5° C. (50 mL then 25 mL) gave 20.0 g 18 (54% yield).

1. customof −20° C.
2. stirringThe material was stirred for an additional 1 hr at −25° C.
3. extractionThe reaction mixture was then extracted into EtOAc (750 mL)
4. dry with materialdried over Na2SO4 (10 g)
5. filtrationfiltered
6. concentrationconcentrated in vacuo