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Reaction of 3-methoxybenzyl alcohol (XXIX) with TBDMS-Cl and imidazole in dichloromethane gives the silyl ether (XXX), which is condensed with allyl bromide (XXXI) by means of BuLi in hexane to yield the 2-allyl derivative (XXXII). Deprotection of (XXXII) by means of TBAF in THF affords the benzyl alcohol (XXXIII), which is oxidized with oxalyl chloride and TEA in DMSO/dichloromethane to provide 2-allyl-3-methoxybenzaldehyde (XXXIV). Condensation of compound (XXXIV) with the chiral 1-decyne (XXXV) by means of ethylmagnesium bromide in THF gives the secondary alcohol (XXXVI), which is oxidized with pyridinium chlorochromate (PCC) in dichloromethane yielding ketone (XXXVII). The enantioselective reduction of ketone (XXXVII) by means of trimethylboroxine (TMBO), BH3/Me2S and (R)-(2-pyrrolidinyl)diphenylmethanol in toluene affords the chiral secondary alcohol (XXXVIII) as a single diastereomer. Silylation of alcohol (XXXVIII) with TBDMS-Cl and imidazole yields the corresponding ether (XXXIX), which is submitted to cyclization catalyzed by Co2(CO)8 in refluxing acetonitrile affording the tricyclic ketone (XL). Hydrogenation of the conjugated double bond of (XL) with H2 over Pd/C in ethanol provides the saturated ketone (XLI), which is reduced with NaBH4 in ethanol to give the tricyclic alcohol (XLII). Elimination of the tetrahydropyranyl-protecting group of (XLII) with p-toluensulfonic acid in methanol provides diol (XXV) already described.

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合成路线3