合成路线1

The cyclization of benzaldehyde (I) with methyl 4-nitrobutyrate (II) and ammonium acetate in refluxing acetic acid gives 5-nitro-6-phenylpiperidone (III), which is treated with ozone and t-BuOK in dichloromethane/methanol to yield 2-phenylpiperidine-3,6-dione (IV). The reduction of (IV) by means of LiAlH4 in THF affords 2-phenylpiperidin-3-ol (V) as a mixture of cis- and trans-isomers. The reaction of (V) with TsOH, followed by crystallization in methanol/ethyl acetate provides the corresponding tosylate (VI) as the (rac)(cis)-isomer. The neutralization of the tosylate (VI) with Na2CO3 in ethyl acetate/water gives 2-phenylpiperidin-3-ol (VII) as a racemic cis mixture, which is submitted to optical resolution with (+)-dibenzoyltartaric acid to yield (+)(cis)-(VIII). The reaction of (VIII) with Boc2O affords the N-protected compound (IX), which is alkylated with 3,5-bis(trifluoromethyl)benzyl bromide (X) and NaH to provide the benzyl ether (XI). Finally, this compound is N-deprotected by means of TFA to obtain the target piperidine.