合成路线1

N-Benzyl-4-hydroxy-4-phenylpiperidine (II) was prepared by addition of phenyllithium to N-benzyl-4-piperidone (I). Carbinol (II) was then converted to acetamide (III) by acid-catalyzed Ritter reaction with acetonitrile. Replacement of the acetamido for an N-Boc group in (III) was effected by acidic hydrolysis of amide (III) to give (IV), followed by treatment with di-tert-butyl dicarbonate. The resultant 1-benzyl-4-(Boc-amino)-4-phenylpiperidine (V) was subjected to catalytic hydrogenolysis in the presence of Pd/C, and the N-debenzylated piperidine (VI) was reprotected as the N-trityl derivative (VII) by treatment with triphenylmethyl chloride and triethylamine. Reduction of the N-Boc group of (VII) by LiAlH4, yielded the N-methyl amine (VIII). After acylation of (VIII) with acetyl chloride to acetamide (IX), its N-trityl group was cleaved by treatment with hot aqueous formic acid to produce the intermediate piperidine (X).