反应详情

To a solution of (2S,3S)-3-(tert-butoxycarbonyl)-4-(2,2-difluorobenzo[d][1,3]dioxol-5-yl)-2-hydroxybutyl acetate (1050 mg, 2603 μmol) in 5 mL of DMF was added 2-methoxypropene (872 μl, 9111 μmol) and CSA (181 mg, 781 μmol). The mixture was stirred at rt overnight, and 91 mg of CSA and 0.872 mL of 2-methoxypropene were added. The reaction was stirred for 2 hours, then poured into ice-cold aqueous saturated sodium bicarbonate (150 mL) and extracted with ethyl acetate (3×50 mL). The combined organic layers were washed with water, brine, and dried over sodium sulfate. The derived yellow oil was taken up in 10 mL of methanol cooled to 0° C. and treated with potassium carbonate (1079 mg, 7809 μmol). After warming to rt over the course of 1 hour the reaction was diluted with ethyl acetate (25 mL) and poured in saturated ammonium chloride (50 mL). The aqueous layer was extracted with ethyl acetate (3×50 mL) and the combined organic layers were washed with water and then brine and dried over Na2SO4. Concentration of the solvents under reduced pressure and purification by silica gel provided (4S,5S)-tert-butyl 4-((2,2-difluorobenzo[d][1,3]dioxol-5-yl)methyl)-5-(hydroxymethyl)-2,2-dimethyloxazolidine-3-carboxylate as a colorless oil.

1. stirringThe reaction was stirred for 2 hours
2. extractionextracted with ethyl acetate (3×50 mL)
3. washThe combined organic layers were washed with water, brine
4. dry with materialdried over sodium sulfate
5. temperaturecooled to 0° C.
6. temperatureAfter warming to rt over the course of 1 hour the reaction
7. extractionThe aqueous layer was extracted with ethyl acetate (3×50 mL)
8. washthe combined organic layers were washed with water
9. dry with materialbrine and dried over Na2SO4
10. customConcentration of the solvents under reduced pressure and purification by silica gel