反应详情

To a 0° C. solution of ethyl 2-(benzyloxycarbonylamino)-1-hydroxycyclopropanecarboxylate (6b, 12.5 g, 44.7 mmol) in THF (100 mL) was added K2CO3 (24.7 g, 179.0 mmol) as a solution in H2O (300 mL). The reaction was allowed to warm to room temperature and stirred for 4 h and then additional H2O (200 mL) was added. After stifling an additional 18 h at room temperature the reaction was concentrated to remove most of the THF. The remaining aqueous solution was washed with Et2O (2×500 mL), acidified with 2 N HCl to pH 2, and then extracted with EtOAc (5×200 mL). The combined EtOAc layers were washed with brine (500 mL), dried (Na2SO4), filtered and concentrated in vacuo to afford the title compounds (7.75 g, 69%) as a mixture of diastereomers. The mixture was triturated with Et2O to afford a white solid as mostly the major diastereomers. The supernatant was concentrated and then triturated with Et2O to afford a clean mixture of both diastereomers. Major Diastereomer: 1H NMR (300 MHz, MeOD) δ 7.50-7.14 (m, 5H), 5.22-4.96 (m, 2H), 3.23-3.10 (m, 1H), 1.60 (dd, J=8.9, 6.3 Hz, 1H), 1.10 (t, J=6.2 Hz, 1H); Multimode (APCI+ESI) MS m/z 250 [M−H]−. Mixture of Diastereomers: 1H NMR (300 MHz, MeOD) δ 7.45-7.14 (m, 5H), 5.24-5.01 (m, 2H), 3.25-3.15 (m, 0.46H), 3.14-3.01 (m, 0.54H), 1.71-1.53 (m, 1H), 1.42 (dd, J=9.1, 6.4 Hz, 0.54H), 1.12 (t, J=6.2 Hz, 0.46H); Multimode (APCI+ESI) MS m/z 250 [M−H]−.

1. waitAfter stifling an additional 18 h at room temperature
2. concentrationthe reaction was concentrated
3. customto remove most of the THF
4. washThe remaining aqueous solution was washed with Et2O (2×500 mL)
5. extractionextracted with EtOAc (5×200 mL)
6. washThe combined EtOAc layers were washed with brine (500 mL)
7. dry with materialdried (Na2SO4)
8. filtrationfiltered
9. concentrationconcentrated in vacuo