Preparation method of eltrombopag
A benzyl compound technology, applied in the field of preparation of Eltrombopag, can solve the problems of no practical industrialization value, high production cost, and many reaction steps
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Embodiment 1
[0129] Embodiment 1: Preparation of tetrafluoroboric acid-3-formic acid methyl benzene diazo
[0130] 3-Aminobenzoic acid methyl ester hydrochloride (191.0mmol) was dissolved in 120mL of water, then concentrated hydrochloric acid (398.0mmol) was added, cooled and stirred at low temperature to about -8°C, and the temperature was controlled at about -8°C. Sodium nitrate aqueous solution (191.0mmol sodium nitrite, 24mL water), temperature control about -8°C, stirring reaction for about 2h, temperature control about -3°C, slowly add sodium tetrafluoroborate aqueous solution (3.0eq. sodium tetrafluoroborate, 600mL water ), about 20 minutes after the dropwise addition was completed, the temperature was controlled at -3°C and the reaction was stirred for about 30 minutes. Filtered, the filter cake was washed once with 100mL ice water to obtain a white solid, namely 44.0g of methyl tetrafluoroborate-3-carboxylate diazobenzene, collected The rate is 91.7%.
Embodiment 2
[0131] Embodiment 2: the preparation of chloro-3-formic acid methyl benzene diazo
[0132] Dissolve 3-aminobenzoic acid methyl ester hydrochloride (16.0mmol) in 15mL of methanol, add concentrated hydrochloric acid (32.0mmol), cool and stir at low temperature to about -8°C, and slowly add dropwise to the above solution under temperature control of about -8°C Sodium nitrite aqueous solution (16.0mmol sodium nitrite, 2.0mL water), temperature control at about -8°C, stirring reaction for about 2h, filtering to obtain the filtrate, which is methyl chloride-3-carboxylate diazobenzyl alcohol solution, which can be used directly react in the next step.
Embodiment 3
[0133] Embodiment 3: the preparation of hydrosulfate-3-formic acid methyl benzene diazo
[0134] To a solution of methyl 3-aminobenzoate (19.87 mmol) in concentrated sulfuric acid (10 mL) was slowly added dropwise 1.56M nitrosylsulfuric acid at 0-5°C, and the addition was completed in about one hour. After dropping, keep warm at 0-5°C until the reaction of the raw materials is complete, and then the hydrosulfate-3-formic acid methyl diazobenzene solution is obtained, which can be directly used in the next reaction step.
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