反应详情

To a solution of benzyl 2-[3-phenoxyacetamido-4-(2,2,2-trichloroethoxycarbonylthio)-2-oxo-1-azetidinyl]-2-isocyanoacetate (2.20 g.) in N,N-dimethylformamide (15 ml.) was added zinc powder (3.30 mg.) at 0° C., and the mixture was stirred at the same temperature for 10 minutes. Thereto was added dropwise acetic acid (2.0 ml.) over a period of 3 minutes and the mixture was stirred at 0° C. for 25 minutes. The reaction mixture was diluted with ethyl acetate (50 ml.) and filtered through a pad of Celite. To the filtrate was added ethyl acetate (50 ml.) and washed with a mixture of 5 to 6% aqueous solution of sodium bicarbonate (60 ml.) and a saturated aqueous solution of sodium chloride (30 ml.), a dilute aqueous solution of sodium chloride (30 ml.×2), a saturated aqueous solution of sodium chloride (30 ml.), water (50 ml.) and a saturated aqueous solution of sodium chloride successively. Drying and removal of the solvent left an amorphous solid (1.51 g.). Chromatography on silica gel (15 g.) with a mixed solvent of methylene chloride and ethyl acetate (5:1 by volume) as an eluent and crystallization from diethyl ether gave benzyl 7-phenoxyacetamido-8-oxo-5-thia-1,3-diazabicyclo[4,2,0]oct-3-ene-2-carboxylate (750 mg.), mp 141.5°-143.0° C.

1. stirringthe mixture was stirred at 0° C. for 25 minutes
2. filtrationfiltered through a pad of Celite
3. additionTo the filtrate was added ethyl acetate (50 ml.)
4. washwashed with a mixture of 5 to 6% aqueous solution of sodium bicarbonate (60 ml.)
5. customDrying
6. customremoval of the solvent
7. waitleft an amorphous solid (1.51 g.)
8. customChromatography on silica gel (15 g.) with a mixed solvent of methylene chloride and ethyl acetate (5:1 by volume) as an eluent and crystallization from diethyl ether