反应详情

To a solution of 1.45 g of methyl α-(3ξ-carboxy-2-phenylacetyl-7-oxo-4-oxa-2,6-diazabicyclo[3.2.0]heptan-6-yl)-α-isopropylideneacetate in 7 ml of methylene chloride is added 1.2 ml of thionyl chloride, and the mixture refluxed under heating for 2 hours and concentrated under reduced pressure. The resulting residue [methyl α-(3ξ-chlorocarbonyl-2-phenylacetyl-7-oxo-4-oxa-2,6-diazabicyclo[3.2.0]heptan-6-yl)-α-isopropylideneacetate] is dissolved in 20 ml of tetrahydrofuran and mixed with 15 ml of ether solution of diazomethane which has been prepared from 1.5 g of nitrosomethylurea, and the mixture is kept at room temperature for 30 minutes. Into the resulting solution of methyl α-(3ξ-diazoacetyl-2-phenylacetyl-7-oxo-4-oxa-2,6-diazabicyclo[3.2.0]heptan-6-yl)-α-isopropylideneacetate is introduced hydrogen chloride gas under ice-cooling until the spot of diazo ketone disappears. The mixture is concentrated under reduced pressure, and the residue is purified by chromatography on 17 g of silica gel containing 10% water and eluted with benzene containing 10% ethyl acetate to yield 1.19 g of methyl α-(3ξ-chloroacetyl-2-phenylacetyl-7-oxo-4-oxa-2,6-diazabicyclo[3.2.0]heptan-6-yl)-α-isopropylideneacetate in 75.3% yield.

1. temperaturethe mixture refluxed
2. temperatureunder heating for 2 hours
3. concentrationconcentrated under reduced pressure
4. dissolutionThe resulting residue [methyl α-(3ξ-chlorocarbonyl-2-phenylacetyl-7-oxo-4-oxa-2,6-diazabicyclo[3.2.0]heptan-6-yl)-α-isopropylideneacetate] is dissolved in 20 ml of tetrahydrofuran
5. additionmixed with 15 ml of ether solution of diazomethane which
6. customhas been prepared from 1.5 g of nitrosomethylurea
7. concentrationThe mixture is concentrated under reduced pressure
8. customthe residue is purified by chromatography on 17 g of silica gel containing 10% water
9. washeluted with benzene containing 10% ethyl acetate