Acetic Acid → (2S,5R)-tert-butyl 5-(benzyloxyamino)piperidine-2-carboxylate

Participants

Reaction Steps

Water (9.2 mL) was added to a solution of 6.91 g (17.17 mmol) of (2S,5R)-tert-butyl 5-(benzyloxyamino)-1-(2,2,2-trifluoroacetyl)piperidine-2-carboxylate in 1,4-dioxane (34 mL), and, under ice cooling, 2.5M NaOH (13.7 mL) was added dropwise, followed by allowing to react at the same temperature for 0.5 hours. Acetic acid (ca. 1 mL) was added to the reaction mixture, followed by concentration under reduced pressure, and subsequently the resulting concentrated residue was extracted with ethyl acetate (58 mL, 29 mL). After the organic layers were washed respectively with 50% aqueous potassium carbonate solution, they were combined, followed by drying with anhydrous sodium sulfate, and the solvent was distilled off under reduced pressure. The resulting residue was applied to silica gel column chromatography (hexane/ethyl acetate=4/1→0/1→ethyl acetate/methanol=19/1) to afford 4.74 g of the title compound as a colorless oil (yield 90%). Enantiomeric excess: 98.9% ee (CHIRALPAK AD-H, 4.6×150 mm, UV 210 nm, diethylamine/hexane/ethanol=0.1/80/20, flow rate 1 mL/min., retention time 5.5 min.).

Provenance & Evidence