合成路线1

The Grignard reaction of aldehyde (XVII) with allylmagnesium bromide in presence of ZnCl2, followed by protection of the resulting alcohol with benzyloxymethyl chloride (Bom-Cl) gives the intermediate (XVIII), which by desilylation of NH4F; cleavage of the cyclic carbonate with Ph-Li and acylation of the OH group with Ac2O yields the benzoate ester (XIX). The transposition of the acetoxyketone grouping, catalyzed by the cyclic guanidine (XX) provides (XXI) with the correct stereochemistry of taxol. The ozonolysis of the terminal double bond of (XXI) gives aldehyde (XXII), which is cyclized by means of DMAP in dichloromethane yielding the tricyclic alcohol (XXIII). The protection of the OH group of (XXIII) with 2,2,2-trichloroethyl chloroformate (Troc-Cl) affords the expected carbonate (XXIV), which is treated with NaI and HCl in order to eliminate the Bom protecting group to give the secondary alcohol (XXV). The reaction of (XXV) with Ms-Cl yields the mesylate (XXVI), which by reaction with LiBr is converted into the bromide (XXVII). The oxidation of (XXVII) with OsO4, followed by a treatment with triphosgene affords the glycol (XXVIII), which is cyclized with means of KCN and DIEA and acetylated with Ac2O providing (XXIX) with the oxetane ring of taxol.