合成路线1

2) The silylation of the hydroxyketal (XXXI) with TBDMS-Tf in dichloromethane gives the corresponding silyl ether (XXXII), which is treated sequentially with borane in THF, with H2O2 and tetrapropylammonium perruthenate catalyst to afford ketone (XXXIII). The reaction of (XXXIII) with KHMDS and TFNP in anhydrous THF yields the enol triflate (XXXIV), which by addition of CO catalyzed by triphenylphosphine and Pd(OAc)2 in methanol is converted to the methyl ester (XXXV). The reduction of (XXXV) with DIBAL in hexane gives the alcohol derivative (XXXVI), which by OsO4 oxidation in acetone/water gives the triol (XXXVII). The dehydration of (XXXVII) by previous silylation with TMS-Cl and reaction with trifluoromethanesulfonic anhydride in dichloromethane affords the oxetane derivative (XXXVIII), which is submitted to deketalization with CLTS to yield the ketone (XXXIX). The dehydrogenation of (XXXIX) by reaction with lithium diisopropylamide TMS-Cl and Pd(OAc)2 in THF gives the enone (XL), which is silylated with TBDMS-Cl in DMF to the fully silylated enone (XLI). The enolization of (XLI) with butyllithium and TMS-Cl followed by ozonolysis with O3 in dichloromethane yields the dialdehyde (XLII), which is submitted to a selective ketalization of the less hindered aldehyde group, affording the monoketal (XLIII). The addition of the lithium dithiane derivative (XLIV) to (XLIII) followed by a Swern oxidation of the intermediate alcohol gives the ketone (XLV), which is deketalized in acidic medium to yield the keto aldehyde (XLVI). The addition of the vinyllithium compound (XLVII) to (XLVI) gives the Diels-Alder precursor (XLVIII), which is submitted to cyclization by heating to afford the polycyclic compound (II) with the basic skeleton of paclitaxel.