Boron complex dissociation method for preparing azithromycin
A technology of azithromycin and boron complex, which is applied in the field of pharmaceutical chemical synthesis, can solve the problems of low yield, many side reactions, harsh reaction conditions of azithromycin, etc., and achieve the effect of high reaction yield and mild acidity
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Embodiment 1
[0016] Embodiment 1. Preparation of azithromycin borate
[0017] Erythromycin A6, 9-imine ether (30.12 g, 41 mmol) was added to water (180 ml), cooled to 0-5°C under stirring, and 20% sulfuric acid (18.83 g, 38 mmol) was added dropwise to adjust PH5, after 5 minutes, add 20% sulfuric acid (0.80 g, 1.6 mmol) to adjust PH2, a large amount of foam is generated on the liquid surface, add 10% sodium hydroxide (1.47 g, 3.6 mmol) dropwise to adjust PH5, add dropwise after 5 minutes Potassium borohydride (2.22 g, 41 mmol) in water (25 ml) was added dropwise in about 1 hour. A large amount of foams are produced in the process of adding potassium borohydride dropwise, add an appropriate amount of methanol to defoam, react to pH8 after 1.5 hours, add dropwise 20% sulfuric acid (8.18 grams, 17 mmol) to adjust pH5, add dropwise potassium borohydride (2.22 grams) after 5 minutes , 41 mmol) water (25 milliliters) solution, dripped in about 1 hour, and the pH rose to 8 after 1.5 hours of rea...
Embodiment 2
[0018] Embodiment 2. Preparation of Azithromycin
[0019] Azithromycin borate (392 mg, 0.50 mmol) was dissolved in methanol (150 ml), heated to reflux for 10 hours, and then the azeotropic mixture was slowly evaporated with a water separator, and methanol was added appropriately until the steam boiling point reached 64.7°C and kept for 1 After 1 hour, the product was evaporated to dryness under reduced pressure, and azithromycin (67 mg, 0.085 mmol) was obtained by column chromatography with a yield of 17%.
[0020] Developing agent ratio (volume ratio): ethyl acetate: n-hexane: diethylamine = 100: 175: 40
[0021] Azithromycin Rf=0.78
Embodiment 3
[0022] Example 3. Preparation of Azithromycin
[0023] Azithromycin borate (392 mg, 0.50 mmol) was dissolved in methanol (150 ml), and 1N methanolic sulfuric acid solution (1 ml, 0.5 mmol) was added dropwise, heated to reflux for 10 hours and then slowly evaporated with a water trap The mixture was appropriately supplemented with methanol until the boiling point of the steam reached 64.7° C. and kept for 1 hour. After treatment, it was evaporated to dryness under reduced pressure, and azithromycin (86 mg, 0.11 mmol) was obtained by column chromatography with a yield of 22%.
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