合成路线1

The cyclopropanation of (-)-2,3-(cyclohexylidenedioxy)-4-cyclopentenone (I) with (ethoxycarbonylmethyl)dimethylsulfonium bromide (II) by means of DBU in chloroform gives the bicyclo[3.1.0]hexane derivative (II), which is treated with chloroform and LiHMDS in THF yielding the trichloromethyl derivative (IV). The reaction of (IV) with sodium azide, DBU and 18-crown-6 in methanol affords the azido-dicarboxylate derivative (V), which is hydrogenated with H2 over Pd/C in ethyl acetate to give the amino-dicarboxylic ester (VI). The acylation of (VI) with acetyl chloride and TEA in dichloromethane yields the corresponding acetamide (VII), which is treated with TFA to afford the bicyclic diol (VIII). The esterification of (VIII) with triethyl orthoformate provides the cyclic orthoester (IX), which is decomposed thermically at 170-90 C giving the unsaturated bicyclic compound (X). The hydrogenation of (X) with H2 over Pd/C in ethyl acetate affords the saturated compound (XI), which is finally deacetylated and hydrolyzed by a treatment with refluxing 1H aqueous HCl.