[C:1]([O:5][C:6]([NH:8][CH:9]1[C:12](=[O:13])[N:11](CC2C=CC(OC)=CC=2OC)[CH:10]1[C:25]([O:27][CH3:28])=[O:26])=[O:7])([CH3:4])([CH3:3])[CH3:2].S(OOS([O-])(=O)=O)([O-])(=O)=O.[K+].[K+].P([O-])([O-])(O)=O.[Na+].[Na+]>C(#N)C.O>[C:1]([O:5][C:6]([NH:8][C@H:9]1[C:12](=[O:13])[NH:11][C@H:10]1[C:25]([O:27][CH3:28])=[O:26])=[O:7])([CH3:4])([CH3:3])[CH3:2]
A solution of 10.5 g (26.7 mmole) of methyl 3-t-butoxycarbonylamino-1-(2,4-dimethoxybenzyl)-4-oxoazetidine-2-carboxylate in 500 ml of acetonitrile is degassed with argon and warmed to 80°. A degassed solution of 15 g (55.5 mmole) of potassium persulfate and 7.5 g (28 mmole) of sodium monohydrogen phosphate in 150 ml of water is added in five portions over 1 hr. The reaction is stirred at 80°-85° under argon for 2-3 hrs until all starting material is consumed (tlc). The reaction mixture is cooled, concentrated in vacuum, shaken with ethyl acetate-water. The organic phase is washed with dilute HCl, NaHCO3 solution and brine; dried over magnesium sulfate and evaporated to dryness. The residue is chromatographed over silica gel with 1:1 benzene-ethyl acetate to afford pure product which crystallized from ethyl acetate-hexane to yield 2.0 g (31%) of the title compound. A less pure fraction from the column, is crystallized from ethyl acetate-hexane to give an additional 0.5 g of product, overall yield, 38%.
読み込み中…
