Methanamine, N-methoxy-, hydrochloride (1:1) → (R)-tert-butyl 3-(N-methoxy-N-methylcarbamoyl)piperidine-1-carboxylate

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Reaction Steps

(R)-1-(tert-Butoxycarbonyl)piperidine-3-carboxylic acid (25 g, 0.1 mol, 1.0 equiv), N,O-dimethylhydroxylamine hydrochloride, (10.5 g, 0.14 mol, 1.25 equiv), EDC.HCl (26.3 g, 0.14 mol, 1.25 equiv), and diisopropylethylamine (48 mL, 0.28 mol, 2.5 equiv) were dissolved in CH2Cl2 (400 mL) and stirred overnight at rt. The reaction mixture was diluted with EtOAc, washed with 5% aq HCl (2×150 mL), satd aq NaHCO3 (150 mL), and brine (100 mL) and dried over Na2SO4. Concentration afforded (R)-tert-butyl 3-(N-methoxy-N-methylcarbamoyl)-piperidine-1-carboxylate (24.42 g, 82%) as a clear oil. LC-MS (3 min) tR=1.41 min, m/z 295 (M+Na). 1H NMR (CDCl3) δ 4.19-4.00 (m, 2H), 3.77 (m, 3H), 3.12 (s, 3H), 2.79 (m, 2H), 2.64 (m, 1H), 1.89 (m, 1H), 1.71-1.52 (m, 2H), 1.51-1.33 (m, 10H). Chiral HPLC indicated 100% purity. The crude product was used for next step without further purification.

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