p-Toluenesulfonic acid → 3-((S)-1-cyclopentyloxycarbonyl-3-methyl-butylamino)-piperidine-1-carboxylic acid tert-butyl ester

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Reaction Steps

To a solution of 3-oxo-piperidine-1-carboxylic acid tert-butyl ester (0.458 g, 2.3 mmol) in dichloroethane (18 mL) was added the tosic acid salt of (S)-2-amino-4-methyl-pentanoic acid cyclopentyl ester (0.496 g, 2.53 mmol) and sodium triacetoxyborohydride (0.975 g, 4.6 mmol). The solution was stirred at room temperature for 18 hours. An aqueous solution of sodium hydrogen carbonate (20 mL) was added and the mixture stirred for 20 minutes. The desired product was extracted into ethyl acetate (3 times 15 mL). The organic layers were combined, dried (MgSO4) and concentrated to give the desired product (0.840 g, 95% yield) which was used without further purification. LC/MS: m/z 383 [M+H]+

Provenance & Evidence