53348-05-3

216312-73-1

General procedure for the synthesis of 3,6-dibromo-9,10-phenanthrenequinone from 3,6-dibromo-9H-fluoren-9-one: 60.0 g (1.0 mol) of potassium hydroxide was dissolved in 400 ml of water, followed by the addition of 13.0 g (35.0 mmol) of 3,6-dibromoquinolinone obtained from step 1 to a 1000 ml three-necked flask. The reaction mixture was heated to 100 °C and kept at this temperature for 3 hours. During the reaction, 30.0 g (200.0 mmol) of potassium permanganate was added in batches and the reaction was continued for 10 hours after addition. Upon completion of the reaction, the mixture was cooled to room temperature. Subsequently, solid sodium thiosulfate powder was added to the reaction solution and the pH was adjusted to neutral, at which point a black solid precipitated. The precipitate was collected by filtration and the filter cake was wrapped in filter paper and placed in a Soxhlet extractor and extracted with dichloromethane for 3 consecutive days. After the extraction was completed, the dichloromethane solution was rotary evaporated to dryness to give 4.8 g of a light yellow solid, i.e., the intermediate 3,6-dibromo-9H-fluoren-9-one, in 40% yield.