The simultaneous reduction of the carboxylic and azido groups of 3-azidobutyric acid derivative (I) first with ethoxalyl chloride and NaBH4 and then with H2 over Pd/C in gives the 4-aminobutanol derivative (II), which is protected at the amino group with tert-butoxycarbonyl anhydride providing carbamate (III). The reaction of the OH group of (III) first with methanesulfonyl chloride and then with sodium azide affords the primary azide (IV), which is reduced with H2 over Pd/C to the primary amine (V). The acylation of (V) with 2-(4-methoxybutoxy)benzoic acid (VI) by means of BOP-Cl gives the benzamide (VII), which is condensed at the lactone group with 2-(1-acetylpiperidin-4-yl)ethylamine (VIII) by heating at 80 C to afford intermediate (IX) with a new amide group. Finally, the carbamate protecting group of (IX) is hydrolyzed with HCl in dioxane.

The simultaneous reduction of the carboxylic and azido groups of 3-azidobutyric acid derivative (I) first with ethoxalyl chloride and NaBH4 and then with H2 over Pd/C in gives the 4-aminobutanol derivative (II), which is protected at the amino group with tert-butoxycarbonyl anhydride providing carbamate (III). The reaction of the OH group of (III) first with methanesulfonyl chloride and then with sodium azide affords the primary azide (IV), which is reduced with H2 over Pd/C to the primary amine (V). The acylation of (V) with 2-(4-methoxybutoxy)benzoic acid (VI) by means of BOP-Cl gives the benzamide (VII), which is condensed at the lactone group with 2-(1-acetylpiperidin-4-yl)ethylamine (VIII) by heating at 80 C to afford intermediate (IX) with a new amide group. Finally, the carbamate protecting group of (IX) is hydrolyzed with HCl in dioxane.