Using 17α-cyanomethyl-17β-hydroxy-estra-5(10)-en-3-one (142 g, 0.45 mol) as raw material, it was dissolved in 850 ml of pyridine, stirred and cooled to 20-25 °C to form a homogeneous solution. Subsequently, a solution of tribrominated pyridine (150 g, 0.47 mol) in 640 ml of pyridine was slowly added and the reaction temperature was controlled to gradually increase to 50 °C. The reaction mixture was stirred continuously at this temperature for 1 hour. After completion of the reaction, the mixture was slowly poured into a stirred mixture consisting of 320 ml of concentrated sulfuric acid and 5600 ml of water to quench the reaction. The precipitated crystals were separated by filtration and dried under vacuum at below 60°C. The crude product was purified by recrystallization from acetone to give 116 g (83% yield) of the final target compound 2-((8S,13S,14S,17R)-17-hydroxy-13-methyl-3-oxo-2,3,6,7,8,11,12,13,14,15,16,17-dodecahydro-1H-cyclopenta[a]phenanthren-17-yl)acetonitrile. The product was analyzed by HPLC showing no less than 97% active ingredient content and no more than 1% impurity of 4-bromo-dienoglucose. The compound has a melting point of 210-213°C and a specific optical rotation [α]20D of -318° (c=1%, dichloromethane).
