合成路线1

The partial hydrogenation of (VIII) with H2 over Pd/(CaCO3) in methanol gives the allyl ether (IX), which is epoxidized with MCPBA in dichloromethane yielding epoxide (X). Epoxide cleavage with the lithium salt of 1-methyltetrazole-5-thiol (XI) in THF affords the isopropanol derivative (XII), which is oxidized with CrO3/H2SO4 in acetone giving the ketone (XIII). The ozonolysis of the isopropylidene group of (XIII) with O3 in dichloromethane affords the alpha ketoester (XIV), which is reduced with Zn/AcOH to the alpha hydroxyester (XV). The reaction of (XV) with SOCl2 and pyridine affords the alpha chloroester (XVI), which by reaction with triphenylphosphine in refluxing dichloromethane gives the alpha triphenylphosphoranylidene acetate (XVII). Thermal cyclization of (XVII) in refluxing dioxane affords the oxacephem derivative (XVIII), which is deacylated by reaction with PCl5 and pyridine providing the 7-beta-amino oxacephem derivative (XIX).