合成路线1

Hydrogenation of (XXI) with H2 over Pd/C in ethanol gives the triol (XXII), which is treated with benzaldehyde dimethyl acetal and camphorsulfonic acid (CSA) in dichloromethane yielding the cyclic ketal (XXIII). The cyclopropanation of (XXIII) with chloro(iodo)methane and Et2Zn in toluene affords compound (XXIV), which is oxidized with Dess-Martin periodinane (DMPI) in dichloromethane providing the ketonic compound (XXV). The deproctection of (XXV) with H2 over Pd(OH)2 in ethanol in order to remove the benzylidene ketal group, followed by reaction with triphosgene in order to form a cyclic carbonate and finally selective desilylation of the cyclic silyl ether with TBAF, furnishes diol (XXVI). The protection of the diol moiety of (XXVI) with benzaldehyde dimethylacetal, followed by cleavage of the cyclic carbonate with K2CO3 in methanol provides the diol (XXVII), which is submitted to cyclopropane ring-opening with SmI2 and TBAF in THF giving the enol (XXVIII). Enol-keto isomerization of (XXVIII) by treatment with NaOMe in methanol yields ketone (XXIX), which is treated with phenylboronic acid and pyridine to afford the cyclic phenylboronic ester (XXX). Silylation of the remaining hydroxy group of (XXX) with TBDMS-OTf gives the silyl ether (XXXI), which is then treated with H2O2 and NaHCO3 in water/ethyl acetate to remove the boron-protecting group and yielding diol (XXXII). The selective oxidation of diol (XXXII) with Dess-Martin periodinane in dichloromethane, followed by protection of the remaining OH group as a 2-methoxy-2-propyl (MOP) ether by reaction with 2-methoxypropene (XXXIII) and PPTS in THF gives diketone (XXXIV), which is enolized with PhNTf2 and KHMDS in THF yielding the enol triflate (XXXV).