反应详情

3-Dimethoxymethyl-1-oxa-2-aza-spiro[4.5]dec-2-ene (1.06 g, 4.97 mmol, as prepared in the previous step) was placed in a 50 mL round-bottom flask equipped with a stir bar. Acetone (20 mL), water (0.3 mL), and Amberlyst-15 resin (200 mg) were added. The mixture was stirred at rt for 24 h. The solids were removed by filtration and rinsed with acetone (20 mL), and the solvent was removed under reduced pressure. The residue was purified by column chromatography using a 40-g SiO2 pre-packed column eluting with EtOAc/heptane, 0:1 to 3:2, v/v over 30 min, yielding 451 mg (54%) of the desired compound. 1H-NMR (400 MHz, CDCl3) δ: 9.90 (s, 1H), 2.81 (s, 2H), 1.72-1.87 (m, 4H), 1.58-1.69 (m, 2H), 1.40-1.53 (m, 4H).

1. customwas placed in a 50 mL round-bottom flask
2. customequipped with a stir bar
3. customThe solids were removed by filtration
4. washrinsed with acetone (20 mL)
5. customthe solvent was removed under reduced pressure
6. customThe residue was purified by column chromatography
7. washeluting with EtOAc/heptane, 0:1 to 3:2, v/v over 30 min