反应详情

To a cooled solution of silver salt at the mercapto group of benzyl 2-azido-2-(3-phenoxyacetamido-4-mercapto-2-oxo-1-azetidinyl)acetate (3.08 g.) in hexamethylphosphoramide (12 ml.) was added 2,2,2-trichloroethyl chloroformate (1.15 ml.) over a period of 3 minutes, and the resultant mixture was stirred at room temperature. After stirring for 22 hours, the mixture was diluted with benzene (15 ml.) and filtered through a pad of Celite. The filtrate was poured into cold water and extracted with ethyl acetate (100 ml.). The extract was washed with water, a dilute aqueous solution of sodium bicarbonate, water and then an aqueous solution of sodium chloride successevely. Drying and removal of the solvent left an oil (3.40 g.), which was chromatographed on silica gel (60 g.) with a mixed solvent of methylene chloride and ethyl acetate (20:1 by volume) as an eluent to give benzyl 2-azido-2-[3-phenoxyacetamido-4-(2,2,2-trichloroethoxycarbonylthio)-2-oxo-1-azetidinyl]acetate (2.20 g.). Further, the same product (160 mg.) was recovered from the other fractions.

1. filtrationfiltered through a pad of Celite
2. additionThe filtrate was poured into cold water
3. extractionextracted with ethyl acetate (100 ml.)
4. washThe extract was washed with water
5. customDrying
6. customremoval of the solvent
7. waitleft an oil (3.40 g.), which
8. customwas chromatographed on silica gel (60 g.) with a mixed solvent of methylene chloride and ethyl acetate (20:1 by volume) as an eluent