合成路线1

The Wittig condensation of protected bicyclic aldehyde (I) with methyl triphenyl phosphonium bromide and potassium tert-butoxide in THF gives the diene (II), which by hydroboration with disiamyl borane followed by oxidative hydrolysis with NaOH and H2O2 is converted into the alcohol (III). Oxidation of (III) with Collins' reagent followed by treatment with acetic anhydride yields the dienol acetate (IV), which is submitted to a 1,4-catalytic hydrogenation with naphthalene Cr(CO)3-H2 in THF and hydrolysis with K2CO3 to afford the allyl alcohol (V). The condensation of (V) with tert-butyl bromoacetate (VI) by means of tetrabutylammonium bisulfate, followed by partial deprotection with tetrabutylammonium fluoride gives the alcohol (VII), which is oxidized with the SO3-pyridine complex to the aldehyde (VIII). The condensation of (VIII) with 1,1-dibromo-3-methyl-5-octyn-2-one (IX) by means of Zn, diethylaluminum chloride and CuBr in THF yields the B-bromoenone (X), which is reduced stereoselectively with (S)-(-)-2,2'-dihydroxy-1,1'-binaphthyl and LiAlH4 in THF to afford the a bromodienol (XI). Finally, this compound is dehydrominated and saponified with tetrabutylammonium bisulfate and NaOH in ether toluene-water.