Ethyl 4-(1-benzyloxycarbonyl-4-piperidyl)-2-chlorobutyrate → 4-Piperidinebutanoic acid, ethyl ester

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Reaction Steps

A solution of ethyl 4-(1-benzyloxycarbonyl-4-piperidyl)-2-chlorobutyrate (10.5 g) in ethanol (20 ml) is catalytically hydrogenated over 10% Palladium-carbon (5 g, 50% wet) as a catalyst at ordinary temperature under atmospheric pressure. After the absorption of hydrogen ceases, the catalyst is removed by filtration and the filtrate is concentrated in vacuo to yield ethyl 4-(4-piperidyl)butyrate, which is dissolved in a mixture of ethyl acetate (200 ml) and water (100 ml). To the solution is added sodium bicarbonate (6 g), and the resulting mixture is stirred at room temperature. Benzyloxycarbonyl chloride (6 ml) is added dropwise to the stirred mixture, and the stirring is continued for 1.5 hours at room temperature. The ethyl acetate layer is separated, dried over anhydrous magnesium sulfate and concentrated in vacuo. The residue is purified by silica gel column chromatography using hexane:ethyl acetate (3:1) as an eluent to yield ethyl 4-(1-benzyloxycarbonyl-4-piperidyl)butyrate (5.3 g) as a colorless oil.

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