反应详情

温度

4 °C

To a 3-neck, 5 L, round bottom flask fitted with a mechanical stirrer and a Teflon-coated temperature probe was added (5a) (2.79 mol) followed by acetonitrile (2 L). The suspension was cooled in an ice bath to 4° C., followed by the addition of 50% aqueous hydroxylamine (180 mL, 2.93 mol) over 1 h. The starting material gradually dissolved during the addition and the reaction mixture was warmed to 20° C. and stirred for 1 h. The reaction mixture was concentrated in vacuo, diluted with EtOAc (1 L) and washed with 1 N HCl (2×1 L). The organic phase was separated and concentrated in vacuo to afford a viscous red syrup. The syrup was then heated for two hours in toluene (2.5 L) at 100° C. with azeotropic removal of water. The syrup gradually dissolved and then the product crystallized. After cooling to room temperature the solid was collected by filtration, washed with 10% acetone in hexane (2×1 L) and dried in a vacuum oven to afford the title compound (5b) (862 g, 2.43 mol, 87%) as a white solid. 1H NMR (CDCl3, 400 MHz): δ 5.85 (s, 2H), 7.45 (app. t, 4H), 7.65 (app t, 2H), 8.05 (m, 4H).

1. customTo a 3-neck, 5 L, round bottom flask fitted with a mechanical stirrer
2. dissolutionThe starting material gradually dissolved during the addition
3. temperaturethe reaction mixture was warmed to 20° C.
4. concentrationThe reaction mixture was concentrated in vacuo
5. additiondiluted with EtOAc (1 L)
6. washwashed with 1 N HCl (2×1 L)
7. customThe organic phase was separated
8. concentrationconcentrated in vacuo
9. customto afford a viscous red syrup
10. dissolutionThe syrup gradually dissolved
11. customthe product crystallized
12. temperatureAfter cooling to room temperature the solid
13. filtrationwas collected by filtration
14. washwashed with 10% acetone in hexane (2×1 L)
15. customdried in a vacuum oven