Tert-butyl 4-(4-ethoxy-4-oxobutyl)piperidine-1-carboxylate → 4-Piperidinebutanoic acid, ethyl ester

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Reaction Steps

tert-Butyl 4-(3-ethoxycarbonylpropyl)piperidine-1-carboxylate (1.2 g, 4.0 mmol, Production example 43-1) was dissolved in trifluoroacetic acid (30 ml), and the reaction mixture was stirred at room temperature for 20 minutes. This was concentrated under reduced pressure, and was further azeotropically distilled with toluene. The obtained residue was partitioned between ethyl acetate and a saturated aqueous solution of sodium hydrogencarbonate. The organic layer was dried over anhydrous magnesium sulfate. In addition, the aqueous layer was concentrated under reduced pressure to dryness; the obtained solid was suspended in tetrahydrofuran; insoluble portion were filtered off, and this solution was added to the previously obtained organic layer. This was purified by silica gel column chromatography (Fuji Silysia NH, hexane-ethyl acetate-methanol system) to yield the title compound (1.15 g, quantitative) as a yellow oil.

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