反应详情

N,N-Dimethylacetamide (1.5 ml) was added to a solution of phosphorus pentachloride (750 mg, 3.6 mmole) in anhydrous dichloromethane (15 ml) cooled to -10°. After 10 minutes, 2-(fur-2-yl)-2-methoxyiminoacetic acid (syn isomer) (612 mg, 3.6 mmole) was added to the resulting suspension, which soon became a clear solution and was stirred at -10° for 15 minutes. Ice (3 g) was added and after 10 minutes the layers were allowed to separate in a dropping funnel. The organic phase was slowly (over 5 minutes) run into a cooled (-10°) solution of (6R,7R)-7-amino-3-chloroacetylcarbamoyloxymethylceph-3-em-4-carboxylic acid (1.05 g, 3 mmole) in dichloromethane (15 ml) containing triethylamine (0.9 ml, 6.5 mmole). Methanol (1 ml) was added after 40 minutes, and 5 minutes later the reaction mixture was extracted twice with 3% w/v aqueous sodium bicarbonate solution (150 ml). The aqueous extract was washed with ethyl acetate (25 ml) and left at 20° for 4 hours. The solution was washed twice with ethyl acetate, acidified with 2N-hydrochloric acid, and extracted 3 times with ethyl acetate. The combined organic layers were dried over magnesium sulphate, decolourised with activated charcoal, and evaporated in vacuo to give a pale-yellow solid (1.15 g, 87%). This was washed with diethyl ether and filtered off to give the title compound (0.91 g, 71%); λmaxpH6 274 nm (ε 17,300). The IR and NMR spectra of the product agreed with those of an authentic sample.

1. temperaturecooled to -10°
2. customto separate in a dropping funnel
3. custom(over 5 minutes)
4. extraction5 minutes later the reaction mixture was extracted twice with 3% w/v aqueous sodium bicarbonate solution (150 ml)
5. extractionThe aqueous extract
6. washwas washed with ethyl acetate (25 ml)
7. waitleft at 20° for 4 hours
8. washThe solution was washed twice with ethyl acetate
9. extractionextracted 3 times with ethyl acetate
10. dry with materialThe combined organic layers were dried over magnesium sulphate
11. customevaporated in vacuo