合成路线1

The methylation of the homoallyl alcohol (I) with methyl iodide and NaH in DMF gives the methyl ether (II), which is oxidized with O3, yielding the aldehyde (III). The diastereoselective allylation of (III) with the chiral borane (IV) in ethyl ether affords the homoallyl alcohol (V), which is epoxidized to the epoxide (VI). The cleavage of the epoxide (VI) with trichloromethyl carbonate provides the cyclic carbonate (VII), which is protected with Troc-Cl and pyridine and then oxidized with NaIO4, furnishing the aldehyde (VIII). The asymetric allylation of (VIII) with the chiral boronate (IX) gives the new homoallyl alcohol (X), which is treated with dimethyldioxirane (XI) to yield the epoxide (XII). Elimination of the Troc- group of (XII) with Zn/HOAc, followed by selective silylation with Tbdps-Cl and imidazole, affords the cyclized tetrahydropyran derivative (XIII), which is cyclized with P2O5 and formaldehyde, and oxidized with CrO3 and sulfuric acid to provide the bicyclic carboxylic acid (XIV).