Dichloromethane → 3-Bromo-6-methoxychroman-4-one

Participants

Reaction Conditions

Reaction Steps

To a solution of 6-methoxy-4-chromanone (35 g) in ethyl ether (1.6 liters) at 5-101 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.

Provenance & Evidence