反应详情

CDI (511.3 mg, 3.1 mmol) was added to a solution of crude (2S,5R)-6-(benzyloxy)-2-(5-(piperidin-4-yl)-1,3,4-oxadiazol-2-yl)-1,6-diazabicyclo[3.2.1]octan-7-one (726 mg, 2.6 mmol) in DMF (15 mL). The mixture was stirred at rt for 1 h, then, (E)-tert-butyl 4-(N′-hydroxycarbamimidoyl)piperidine-1-carboxylate (631.8 mg, 2.6 mmol) was added at rt. The mixture was stirred at rt for 2 hrs, and then stirred at 50° C. for another 6 hrs. The mixture was diluted with EtOAc (150 mL) and washed with 1 M HCl (2×), water (2×), and saturated sodium chloride (2×), dried over Na2SO4, and concentrated. The residue was purified by silica gel column chromatography (1:5 to 1:1 EtOAc/hexanes) to give tert-butyl 4-(5-((2S,5R)-6-(benzyloxy)-7-oxo-1,6-diaza-bicyclo[3.2.1]octan-2-yl)-1,2,4-oxadiazol-3-yl)piperidine-1-carboxylate (968 mg, 76%) as a white solid. ESI-MS (EI+, m/z): 506.2 [M+Na]+. 1H-NMR (400 MHz, CDCl3): δ 7.47-7.36 (m, 5H), 4.99-4.94 (m, 2H), 4.73 (d, J=6.0 Hz, 1H), 3.93 (d, J=9.6 Hz, 1H), 3.72 (s, 1H), 3.08-2.90 (m, 4H), 2.72 (d, J=9.6 Hz, 1H), 2.15 (dd, J=12.0, 5.2 Hz, 1H), 2.09-1.93 (m, 5H), 1.85-1.79 (m, 1H), 1.59-1.50 (m, 2H), 1.40 (s, 9H).

1. stirringThe mixture was stirred at rt for 2 hrs
2. stirringstirred at 50° C. for another 6 hrs
3. washwashed with 1 M HCl (2×), water (2×), and saturated sodium chloride (2×)
4. dry with materialdried over Na2SO4
5. concentrationconcentrated
6. customThe residue was purified by silica gel column chromatography (1:5 to 1:1 EtOAc/hexanes)