反应详情

温度

0 °C

Iodomethyl pivalate (2.66 g.) is added to a suspension of the potassium salt of 2-carboxy-3-[(2-methyl-1,3,4-thiadiazol-5-yl)-thiomethyl]-8-oxo-7-[(1,3-dithiol-2-on-4-yl)-acetamido]-5-thia-1-aza-bicyclo-[4.2.0]oct-2-ene (5.18 g.) in dimethyl formamide (100 cc.) cooled to 0° C. The reaction mixture is stirred for 10 minutes at 5° C.; it becomes limpid and is poured into a decanting funnel containing ethyl acetate (100 cc.) and water (200 cc.). The organic phase is washed with a saturated sodium bicarbonate solution (100 cc.) and then with a saturated sodium chloride solution (100 cc.). The organic phase is dried over sodium sulphate, treated with decolourising charcoal, filtered and concentrated to dryness under reduced pressure (20 mm Hg). The residue (5 g.) is chromatographed on silica (80 g.). A product (4.5 g.) is eluted with a 70-30 by volume mixture of ethyl acetate and cyclohexane, and is crystallised from a mixture of ethyl acetate and cyclohexane (50-50 by volume) (60 cc.). 3-[(2-Methyl-1,3,4-thiadiazol-5-yl)-thiomethyl]-8-oxo-7-[(1,3-dithiol-2-on-4-yl)-acetamido]-2-pivaloyloxymethoxycarbonyl-5-thia-1-aza-bicyclo[4.2.0]oct-2-ene (3 g.) is thus obtained as white crystals m.p. approximately 110° C.

1. additionis poured into a decanting funnel
2. washThe organic phase is washed with a saturated sodium bicarbonate solution (100 cc.)
3. dry with materialThe organic phase is dried over sodium sulphate
4. additiontreated with decolourising charcoal
5. filtrationfiltered
6. concentrationconcentrated to dryness under reduced pressure (20 mm Hg)
7. customThe residue (5 g.) is chromatographed on silica (80 g.)
8. washA product (4.5 g.) is eluted with a 70-30 by volume mixture of ethyl acetate and cyclohexane
9. customis crystallised from a mixture of ethyl acetate and cyclohexane (50-50 by volume) (60 cc.)