반응 #607441
ord-0b8659006e4145b09ee1d587f3ff8831
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용매
반응 조건
후처리
- 1온도cooled to −27° C. to −25° C.
- 2온도The reaction was maintained at this temperature for 17 h
- 3기타to reach room temperature
- 4기타The solvent was then removed in vacuo
- 5기타the resulting residue was partitioned between water (10 mL) and TBME (tert-butyl-methyl ether) (20 mL)
- 6추출The aqueous phase was extracted again with TBME (20 mL)
- 7세척The organic layer was washed with an aqueous 2 N NaOH solution (20 mL), brine (20 mL)
- 8건조dried over anhydrous Na2SO4
- 9여과filtered
- 10기타The solvent was removed in vacuo
- 11기타to give a residue, which
- 12기타was purified by two subsequent column chromatographic steps
실험 절차
To a stirred solution of (−)-DIP-Cl ((−)-diisopinocampheylboron chloride) (2.67 g, 8.33 mmol, 1.3 eq) in THF (20 mL) kept under inert atmosphere (Ar) and cooled to −27° C. to −25° C., 3′,5′-difluoroacetophenone (1.00 g, 6.40 mmol) was added drop wise over 2 min. The reaction was maintained at this temperature for 17 h. The reaction mixture was then treated with acetaldehyde (0.44 mL, 7.69 mmol, 1.2 eq). Thereafter, the temperature was allowed to reach room temperature and the reaction mixture was stirred at for 7 h. The solvent was then removed in vacuo and the resulting residue was partitioned between water (10 mL) and TBME (tert-butyl-methyl ether) (20 mL). The aqueous phase was extracted again with TBME (20 mL). The organic layer was washed with an aqueous 2 N NaOH solution (20 mL), brine (20 mL), dried over anhydrous Na2SO4 and filtered. The solvent was removed in vacuo to give a residue, which was purified by two subsequent column chromatographic steps: First by normal phase chromatography (silica gel, heptane/ethyl acetate, v/v=1/0-9/1) followed by a reversed phase chromatography (90 C18-silica gel, acetonitrile for the second one). This gave the title compound (0.40 g, 40%) as a colorless oil with a specific rotation of [α]25D=−26.66 (c=1.054 g/100 mL, CH2Cl2, 589 nm).