合成路线1

The condensation of benzaldehyde (I) with malonic ester (II) by means of piperidine and acetic acid in benzene gives the unsaturated malonate (III), which by a selective ester cleavage and a Curtius rearrangement by means of N3-PO(OPh)2 and Et3N in toluene yields the unsaturated aminoester (IV). The reduction of (IV) with a chiral rhodium catalyst affords the chiral protected aminoester (V), which is cyclized to the bridged lactone (VI) by means of BF3 ethearate in dichloromethane. Reductive cleavage of the benzyloxycarbonyl benzyl ether groups of (VI) with H2 over Pd/C affords the free aminophenol (VII). The condensation of (VII) with aldehyde (VIII) (obtained by reduction of ester (IX) with DIBAL in dichloromethane) by means of KCN and AcOH, and after allylation of the aromatic OH group with allyl bromide, the intermediate (X) is obtained. The reduction of the lactone group of (X) with DIBAL, followed by desilylation with KF and cyclization with CH3SO3H affords the polycyclic compound (XI).