反应详情

N-(tert-Butoxycarbonyl)-D-proline (1.505 g, 6.99 mmol), DCC (1.443 g, 6.99 mmol), HOBt (1.071 g, 6.99 mmol), and Hunig's base (2.78 mL, 15.89 mmol) in DCM (31.8 mL) were stirred at room temperature for 1 h. N,O-Dimethylhydroxylamine hydrochloride (0.62 g, 6.36 mmol) and DMAP (0.078 g, 0.636 mmol) were added and the solution stirred at room temperature for 4 h. The mixture was concentrated in vacuo. The residue was purified by column chromatography on silica gel (10%→100% ethyl acetate in hexanes). Obtained (R)-tert-butyl 2-(methoxy(methyl)carbamoyl)pyrrolidine-1-carboxylate (794 mg, 3.07 mmol, 48.4% yield) as a colorless oil. Rotomers (a and b) seen in NMR: 1H NMR (500 MHz, CDCl3) δ 4.52-4.76 (m, 1H), 3.77 (s, 1.5 Ha), 3.71 (s, 1.5 Hb), 3.51-3.64 (m, 1H), 3.33-3.51 (m, 1H), 3.18 (s, 3H), 2.08-2.27 (m, 1H), 1.74-2.04 (m, 3H), 1.45 (s, 4.5 Ha), 1.40 (s, 4.5 Hb); LRMS (ESI) m/e 158.76.

1. concentrationThe mixture was concentrated in vacuo
2. customThe residue was purified by column chromatography on silica gel (10%→100% ethyl acetate in hexanes)