反应详情

Bromotrimethylsilane (0.31 g) in dichloromethane (3 ml) was added to a cooled (0°) stirred mixture of (R and S)-1-acetoxyethyl (6R,7R)-3-dimethoxyphosphorylcarbamoyloxymethyl-7-[Z-2-(fur-2-yl)-2-methoxyiminoacetamido]ceph-3-em-4-carboxylate (0.62 g) and trimethylsilylurethane (0.16 g) in dry dichloromethane (12 ml) in a nitrogen atmosphere. After 2.5 hours the reaction mixture was evaporated in vacuo to a foam. This foam was dissolved in ethyl acetate (30 ml) although a slight precipitate remained. The filtered organic solution was treated with saturated aqueous sodium bicarbonate solution (30 ml) and the aqueous solution was layered with butan-1-ol (20 ml) and acidified to pH 0.5 by addition of concentrated hydrochloric acid. The aqueous phase was extracted with butan-1-ol (2×15 ml) and the combined organic extracts were evaporated in vacuo to give a solid. Trituration of this solid with di-isopropyl ether afforded the title ester (0.396 g) as a solid; νmax (Nujol) 3270 (NH), 1788 (β-lactam), 1734 (CO2R) and 1684 and 1540 cm-1 (CONH); τ (DMSO-d6) 0.18 (d, J 8 Hz, NH), 2.9 to 3.4 (broad m, 2 superimposed q, CHCH3), 4.14 (m, 7-H, mixture of diastereoisomers), 4.76 (m, 6-H, mixture of diastereoisomers), 7.92 (s, OCOCH3) and 8.52 (d, J 5 Hz, CHCH3).

1. temperaturea cooled (0°)
2. customAfter 2.5 hours the reaction mixture was evaporated in vacuo to a foam
3. dissolutionThis foam was dissolved in ethyl acetate (30 ml) although a slight precipitate
4. additionThe filtered organic solution was treated with saturated aqueous sodium bicarbonate solution (30 ml)
5. additionacidified to pH 0.5 by addition of concentrated hydrochloric acid
6. extractionThe aqueous phase was extracted with butan-1-ol (2×15 ml)
7. customthe combined organic extracts were evaporated in vacuo
8. customto give a solid