反应详情

To a solution of 1-(2-nitrophenyl)-1-ethanone hydrazone (Preparation 137, 4.00 g, 22.3 mmol) in dioxan (50 ml) was added manganese (IV) oxide (4.27 g, 49.2 mmol) followed by a saturated ethanolic solution of potassium hydroxide (2.0 ml), and the reaction mixture was stirred at room temperature for 4 h. The suspension was filtered through Celite™ washing with dioxan (ca. 150 ml) to give a deep red solution. 1-Hexyl-1H-pyrrole-2,4-dione (Preparation 56, 4.05 g, 22.4 mmol) was added to the solution and the reaction mixture was stirred at room temperature overnight before heating under reflux for 24 h. The reaction mixture was cooled to room temperature, filtered through Celite™ and concentrated in vacuo a crude dark brown oil. This was purified by chromatography in two batches using a Biotage Flash 40M™ cartridge packed with silica gel (90 g) eluting with dichloromethane:hexane (2:1) to afford an 8:1 exo:endo mixture of diastereomers of the title compound as a pale brown oil (880 mg, 12%).

1. filtrationThe suspension was filtered through Celite™
2. washwashing with dioxan (ca. 150 ml)
3. customto give a deep red solution
4. stirringthe reaction mixture was stirred at room temperature overnight
5. temperaturebefore heating
6. temperatureunder reflux for 24 h
7. temperatureThe reaction mixture was cooled to room temperature
8. filtrationfiltered through Celite™
9. concentrationconcentrated in vacuo a crude dark brown oil
10. customThis was purified by chromatography in two batches
11. washeluting with dichloromethane:hexane (2:1)
12. customto afford an 8:1 exo