反应详情

A 100-mL single-neck round-bottomed flask equipped with a magnetic stirrer and a reflux condenser was charged with 1,4-dioxane (8 mL), cesium carbonate (221 mg, 0.68 mmol), 324a (80 mg, 0.34 mmol), and 4-bromo-6-chloro-2-methylpyridazin-3(2H)-one (80 mg, 0.36 mmol). After bubbling nitrogen through the suspension for 5 minutes, Xantphos (40 mg, 0.068 mmol) and tris(dibenzylideneacetone)dipalladium(0) (24 mg, 0.034 mmol) were added. The system was subjected to three cycles of vacuum/nitrogen flush and heated at reflux for 2.5 h. It was then cooled to room temperature and filtered. The solid was washed with dichloromethane (3×10 mL). The combined filtrate was concentrated under reduced pressure. The residue was purified by silica-gel column chromatography eluting with petroleum ether/ethyl acetate (2/1 to 100% ethyl acetate) to afford 324b (40 mg, 31%) as a yellow solid. MS-ESI: [M+H]+ 378.3

1. customA 100-mL single-neck round-bottomed flask equipped with a magnetic stirrer and a reflux condenser
2. customAfter bubbling nitrogen through the suspension for 5 minutes
3. customflush
4. temperatureheated
5. temperatureat reflux for 2.5 h
6. filtrationfiltered
7. washThe solid was washed with dichloromethane (3×10 mL)
8. concentrationThe combined filtrate was concentrated under reduced pressure
9. customThe residue was purified by silica-gel column chromatography
10. washeluting with petroleum ether/ethyl acetate (2/1 to 100% ethyl acetate)