合成路线1

Treatment of 2,2-diphenylacetic acid (I) with diphenyl phosphoryl azide (DPPA) yielded acyl azide (II). Then, Curtius rearrangement of (II) in boiling toluene produced the intermediate isocyanate (III), which was coupled with 1-benzyl-4-piperidinol (IV) to afford the corresponding carbamate (V). Subsequent N-debenzylation of (V) was achieved by reaction with 1-chloroethyl chloroformate in refluxing 1,2-dichloroethane, followed by methanolysis to give (VI). Reductive alkylation of (VI) with aldehyde (VII) in the presence of sodium triacetoxyborohydride furnished the substituted benzyl piperidine (VIII). The N-Boc protecting group of (VIII) was finally removed with ethanolic HCl to provide the title compound.