合成路线1

The enzymatic resolution of the tricyclic carboxylate (XXIX) with chiralzyme L-2 and vinyl acetate gives the monoacetate (XXX) and the dihydroxy compound (XXXI) that are easily separated. The hydrolysis of the acetate (XXX) with K2CO3 in methanol yields the diol (XLIII), which silylated with TBDMS-Cl and imidazole at the less hindered OH affording the silyl ether (XLIV). The acetylation of (XLIV) with acetyl chloride, TEA and DMAP gives the acetate (XLV), which is desilylated with TBAF in THF yielding the alcohol (XLVI). The oxidation of (XLVI) with ammonium formate and PdCl2(PPh3)2 in refluxing acetonitrile affords the ketone (XLVII), which is epoxidized with H2O2 and Triton B in THF providing the ketoepoxide (XLVIII). The thermolysis of (XLVIII) at 300 C in diphenyl ether gives the epoxycyclohexenone (II), which is reduced with NaBH4 and CeCl3 in methanol yielding a mixture of the two diastereomeric alcohols (L) and (LI) that are separated by column chromatography. The desired alcohol (LI) is treated with refluxing 80% AcOH to afford the methyl ester (XLII) of the target compound. Finally, this compound is hydrolyzed with KOH in THF. The undesired diastereomeric alcohol (L) is recycled to epoxyketone (II) by oxidation with tetrapropylammonium perruthenate (TPAP) and NMMO.