The reaction of 5-acetylsalicylamide (I) with benzyl chloride (II) by means of sodium methoxide in hot DMF gives 4-benzyloxy-3-carbamoylacetophenone (III), which by bromination with Br2 in refluxing CHCl3 is converted into 4-benzyloxy-3-carbamoylphenacyl bromide (IV). The condensation of (IV) with N-(4-phenyl-2-butyl)benzylamine (V) (prepared from benzylamine (VI) and 4-phenyl-2-butanone (VII), p-toluenesulfonic acid and NaBH4 in benzene -methanol) by means of K2CO3 in DMF yields 2-benzyloxy-5-[N-benzyl-N-(1-methyl-3-phenylpropyl)glycyl]benzamide (VIII), which is reduced with NaBH4 in ethanol to afford 2-benzyloxy-5-[1-hydroxy-2-[(4-phenyl-2-butyl)-N-benzylamino]ethyl]benzamide (IX). Finally, this compound is debenzylated by hydrogenolysis with H2 over Pd/C in ethanol. The separation into its optical isomers is performed by conventional methods.

The reaction of 5-acetylsalicylamide (I) with benzyl chloride (II) by means of sodium methoxide in hot DMF gives 4-benzyloxy-3-carbamoylacetophenone (III), which by bromination with Br2 in refluxing CHCl3 is converted into 4-benzyloxy-3-carbamoylphenacyl bromide (IV). The condensation of (IV) with N-(4-phenyl-2-butyl)benzylamine (V) (prepared from benzylamine (VI) and 4-phenyl-2-butanone (VII), p-toluenesulfonic acid and NaBH4 in benzene -methanol) by means of K2CO3 in DMF yields 2-benzyloxy-5-[N-benzyl-N-(1-methyl-3-phenylpropyl)glycyl]benzamide (VIII), which is reduced with NaBH4 in ethanol to afford 2-benzyloxy-5-[1-hydroxy-2-[(4-phenyl-2-butyl)-N-benzylamino]ethyl]benzamide (IX). Finally, this compound is debenzylated by hydrogenolysis with H2 over Pd/C in ethanol. The separation into its optical isomers is performed by conventional methods.

The reaction of 5-acetylsalicylamide (I) with benzyl chloride (II) by means of sodium methoxide in hot DMF gives 4-benzyloxy-3-carbamoylacetophenone (III), which by bromination with Br2 in refluxing CHCl3 is converted into 4-benzyloxy-3-carbamoylphenacyl bromide (IV). The condensation of (IV) with N-(4-phenyl-2-butyl)benzylamine (V) (prepared from benzylamine (VI) and 4-phenyl-2-butanone (VII), p-toluenesulfonic acid and NaBH4 in benzene -methanol) by means of K2CO3 in DMF yields 2-benzyloxy-5-[N-benzyl-N-(1-methyl-3-phenylpropyl)glycyl]benzamide (VIII), which is reduced with NaBH4 in ethanol to afford 2-benzyloxy-5-[1-hydroxy-2-[(4-phenyl-2-butyl)-N-benzylamino]ethyl]benzamide (IX). Finally, this compound is debenzylated by hydrogenolysis with H2 over Pd/C in ethanol. The separation into its optical isomers is performed by conventional methods.