反应详情

To a solution of 3-acetoxy-7beta-phenylacetylaminocepham-4-carboxylic acid diphenylmethyl ester (3a) in dichloromethane (13 parts) under nitrogen are added at -5° to 0° C. pyridine (2 equivalents) and at -25° to -20° C. phosphorus pentachloride. After stirring at -15° to -10° C. for 4 hours, the mixture is diluted with a mixture of methanol (20 parts) and dichloromethane (5 parts) cooled at -40° to -30° C., and stirred at -30° to -25° C. for 3.5 hours. To the mixture keeping at -25° to -20° C. is dropwise added triethylamine (10.9 equivalents). After keeping at 0° to 5° C. overnight, the mixture is diluted with ice-water (20 parts) and stirred for 20 minutes. The formed organic layer is taken, washed with hydrochloric acid, water, aqueous sodium hydrogen carbonate, and water, dried, and concentrated. The residue is crystallized from ethyl acetate to give 7betaamino-3-cephem-4-carboxylic acid diphenylmethyl ester (5). Yield: 60.2%.

1. customat -25° to -20° C.
2. temperaturecooled at -40° to -30° C.
3. stirringstirred at -30° to -25° C. for 3.5 hours
4. customkeeping at -25° to -20° C.
5. waitAfter keeping at 0° to 5° C. overnight
6. stirringstirred for 20 minutes
7. washwashed with hydrochloric acid, water, aqueous sodium hydrogen carbonate, and water
8. customdried
9. concentrationconcentrated
10. customThe residue is crystallized from ethyl acetate