合成路线1

Treatment of 5-(1-naphthyl)cyclohexane-1,3-dione (I) with 2,2-dimethoxypropane and MeOH in the presence of p-toluenesulfonic acid provided enol ether (II). Condensation of (II) with n-octylmagnesium bromide in cold THF, followed by acidic treatment of intermediate (III) yielded enone (IV). The subsequent oxidative cleavage of (IV) with NaIO4 and a catalytic amount of ruthenium oxide gave ketoacid (V), which was converted into the oxime (VI) on treatment with hydroxylamine. Reduction of oxime (VI) with NaBH4 in AcOH gave the hydroxylamine (VII). Then, cyclization to the piperidone acid in the presence of silica gel in refluxing benzene, followed by chromatographic separation of the cis isomer, provided the target compound.