反应详情

A solution of 1.47 g (5.45 mmol) of potassium persulphate in 25 ml of water is added dropwise within 30 minutes to a suspension, heated to 80°, of 0.964 g (3 mmol) of (S)-1-(2,4-dimethoxybenzyl)-4-[(R)-2,2-dimethyl-1,3-dioxolan-4-yl]-2-azetidinone in a mixture of 10 ml of water and 10 ml of acetonitrile, whereby the pH of the reaction mixture is held at 5 by the addition of saturated sodium hydrogen carbonate solution. The reaction mixture is stirred for a further 1 hour at pH 5, then cooled and extracted three times with 50 ml of methylene chloride each time. The organic phases are washed with 20 ml of saturated sodium chloride solution, dried over sodium sulphate and evaporated. The residue is chromatographed on silica gel with ethyl acetate/hexane (3:1 by volume) as the eluent. By crystallization of the resulting material from ethyl acetate/hexane there is obtained (S)-4-[(R)-2,2-dimethyl-1,3-dioxolan-4-yl] -2-azetidinone as white crystals of melting point 91°-92°; [α]D20 =+13.6° (c=1, ethyl acetate).

1. temperaturecooled
2. extractionextracted three times with 50 ml of methylene chloride each time
3. washThe organic phases are washed with 20 ml of saturated sodium chloride solution
4. dry with materialdried over sodium sulphate
5. customevaporated
6. customThe residue is chromatographed on silica gel with ethyl acetate/hexane (3:1 by volume) as the eluent
7. customBy crystallization of the resulting material from ethyl acetate/hexane there