175358-02-8

Add 4 (1.5 g, 8.3 mmol) to a 50 mL round-bottom flask, add 30 mL of phosphorus oxychloride and 2 drops of N,N-dimethylaniline, react at 107°C for 1 h, monitor the reaction for completeness by TLC, cool, evaporate the solvent to dryness, redissolve the obtained solid in dichloromethane, adjust the pH to 7 with saturated sodium bicarbonate aqueous solution, filter to remove insoluble solids, separate the dichloromethane layer and the aqueous layer, extract the aqueous layer twice with dichloromethane, combine the dichloromethane layers, and dry with anhydrous sodium sulfate. Column chromatography yields 1.1 g of white solid, yield 65%.