Preparation method of entecavir intermediate
A technology of entecavir and intermediates, applied in the field of medicinal chemistry, can solve the problems of low product yield and difficult post-processing, and achieve the effects of simple post-processing, overcoming the difficulty of post-processing, and short reaction time
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Embodiment 1
[0031] The preparation of the compound shown in formula IV
[0032]
[0033] Add 187.3g (0.5mol) of the compound shown in formula V, 94.9g (1.2mol) of pyridine, 120g (1.1mol) of trimethylchlorosilane and 500ml of anhydrous THF into a 1000ml flask, stir and react at room temperature for 4 hours, monitor To the end of the reaction, add 400ml of saturated ammonium chloride solution, extract with ethyl acetate, wash with saturated brine three times, dry over anhydrous sodium sulfate, concentrate under reduced pressure, and flash column chromatography to obtain 218g of the compound represented by formula E, with a yield of 97.7% .
Embodiment 2
[0035] The preparation of the compound shown in formula III
[0036]
[0037]Add 44.6g (100mmol) of the compound shown in formula IV, 11.3g (120mmol) of 1,2-ethanedithiol and 7.1g (50mmol) of boron trifluoride etherate complex into the reaction vessel, dichloromethane After reacting at room temperature for 2 hours, the reaction was completed. The reaction solution was washed with saturated sodium bicarbonate, extracted with dichloromethane, washed with water, dried over anhydrous sodium sulfate, and concentrated under reduced pressure to obtain 51.6 g of the compound represented by formula III with a yield of 98.7%.
Embodiment 3
[0039] The preparation of the compound shown in formula III
[0040] 44.6g (100mmol) of the compound shown in formula IV, 13.2g (140mmol) of 1,2-ethanedithiol and 4.3g (30mmol) of boron trifluoride etherate complex were added to the reaction vessel, dichloromethane After reacting at room temperature for 1 hour, the reaction was completed. The reaction solution was washed with saturated sodium bicarbonate, extracted with dichloromethane, washed with water, dried over anhydrous sodium sulfate, and concentrated under reduced pressure to obtain 51.8 g of the compound represented by formula III with a yield of 99.0%.
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