反应详情

温度

-20 °C

Tert-Butyletherification: To a solution of (2S,4R)-4-hydroxy-1-(naphthalene-2-sulfonyl)-pyrrolidine-2-carboxylic acid benzyl ester (14.8 g) in dichloromethane (140 ml) were added boron trifluoride ethyl etherate (3 ml) and isobutylene (cooled and liquefied at −30° C., 170 ml) at −30° C. The turbid reaction mixture was stirred at −20° C. for 2 h, poured onto a saturated sodium bicarbonate solution, and extracted with dichloromethane. The organic phases were washed with water, dried over magnesium sulphate and concentrated. The residue was chromatographed on silica gel using EtOAc/hexane 1:4 and 1:2 as eluents to obtain (2S,4R)-4-tert-butoxy-1-(naphthalene-2-sulfonyl)-pyrrolidine-2-carboxylic acid benzyl ester (16.4 g) as a glassy syrup, MS: 467 (M).

1. customThe turbid reaction mixture
2. extractionextracted with dichloromethane
3. washThe organic phases were washed with water
4. dry with materialdried over magnesium sulphate
5. concentrationconcentrated
6. customThe residue was chromatographed on silica gel