反应详情

To a solution of 6-methoxy-4-chromanone (35 g) in ethyl ether (1.6 liters) at 5°-10° C. was added dropwise over 30 minutes 10.6 ml of bromine. The mixture was stirred at 5°-10° C. for 30 minutes and then allowed to warm to room temperature. After 2 hours tlc (CH2Cl2) indicated formation of less polar products and only a trace of starting material remaining. The reaction mixture was washed with water (1 liter), saturated NaHCO3 (500 ml), and brine (500 ml), dried over MgSO4, and concentrated in vacuo to a yellow solid. The crude product was purified by silica gel flash column chromatography on 2.4 Kg fine silica gel, eluting with a gradient system consisting of 3:1 hexanes/dichloromethane followed by 2:1 hexanes/dichloromethane and finally 30% hexanes/dichloromethane. This afforded title product as a yellow solid in 80% yield.

1. washThe reaction mixture was washed with water (1 liter), saturated NaHCO3 (500 ml), and brine (500 ml)
2. dry with materialdried over MgSO4
3. concentrationconcentrated in vacuo to a yellow solid
4. customThe crude product was purified by silica gel flash column chromatography on 2.4 Kg fine silica gel
5. washeluting with a gradient system