反应详情

温度

0 °C

The product of step A (13.7 g, 61.02 mmol) and tert-butyl 4-oxopiperidine-1-carboxylate (13.37 g, 67.12 mmol) in acetic acid (36 mL) and concentrated sulfuric acid (4 mL) were heated to 110° C. for 2 h. After concentrating in vacuo the reaction mixture was diluted with dichloromethane (100 mL) and water (200 mL), basified with saturated aqueous potassium carbonate solution at 0° C. and extracted with dichloromethane. The organic extracts were dried over sodium sulfate, filtered and concentrated in vacuo. The residue was dissolved in 2-propanol (102 mL) and water (120 mL) before addition of potassium carbonate (9.5 g, 68.95 mmol) and di-tert-butyl dicarbonate (15 g, 68.9 mmol). The reaction mixture was stirred at 0° C. for 2 h then diluted with water (200 mL) and extracted three times with dichloromethane. The organic extracts were dried over sodium sulfate, filtered and concentrated in vacuo. The residue was purified by flash column chromatography (SiO2, 90:10 hexane/ethyl acetate) to give tert-butyl 8-bromo-3,4-dihydrobenzofuro[3,2-c]pyridine-2(1H)-carboxylate (8.7 g, 40%) as a light-pink solid: 1H NMR (CDCl3, 300 MHz) δ 7.53 (d, J=1.2 Hz, 1H), 7.36-7.25 (m, 2H), 4.51 (s, 2H), 3.82 (t, J=5.4 Hz, 2H), 2.84 (t, J=5.4 Hz, 2H), 1.50 (s, 9H).

1. concentrationAfter concentrating in vacuo the reaction mixture
2. additionwas diluted with dichloromethane (100 mL) and water (200 mL)
3. custombasified with saturated aqueous potassium carbonate solution at 0° C.
4. extractionextracted with dichloromethane
5. dry with materialThe organic extracts were dried over sodium sulfate
6. filtrationfiltered
7. concentrationconcentrated in vacuo
8. dissolutionThe residue was dissolved in 2-propanol (102 mL)
9. extractionextracted three times with dichloromethane
10. dry with materialThe organic extracts were dried over sodium sulfate
11. filtrationfiltered
12. concentrationconcentrated in vacuo
13. customThe residue was purified by flash column chromatography (SiO2, 90:10 hexane/ethyl acetate)