反应详情

3-Hydroxy-3,6-dihydro-2H-pyridine-1-carboxylic acid tert-butyl ester (3.1 g, 17.3 mmol) was dissolved in dichloromethane (30 mL) under an argon atmosphere. Pyridinium chlorochromate (5 g, 23 mmol) was added in portions over 1 hour. The dichloromethane solution was filtered through silica gel (100 g), eluting with dichloromethane. The crude brown solid (2.84 g) was purified by MPLC (Companion) on a silica cartridge (40 g), eluting with 100% heptane followed by a gradient of ethyl acetate/heptane (0 to 60%). The product containing fractions were combined, concentrated, and dried under high vacuum for 1 hour at room temperature to provide 3-oxo-3,6-dihydro-2H-pyridine-1-carboxylic acid tert-butyl ester (2.1 g, 61% yield) as a clear oil that solidified on standing at low temperature. 1H NMR (300 MHz, CDCl3/TMS): δ=6.95 (m, 1H), 6.08 (d, 1H, J=10.5 Hz), 4.15 (m, 2H), 4.02 (br s, 2H), 1.39 (s, 9H). 13C NMR (75 MHz, CDCl3/TMS): δ=193.11, 154.02, 147.17, 127.40, 80.89, 51.97, 42.69, 28.41.

1. filtrationThe dichloromethane solution was filtered through silica gel (100 g)
2. washeluting with dichloromethane
3. customThe crude brown solid (2.84 g) was purified by MPLC (Companion) on a silica cartridge (40 g)
4. washeluting with 100% heptane
5. additionThe product containing fractions
6. concentrationconcentrated
7. customdried under high vacuum for 1 hour at room temperature