Synthesizing process of 3-methyl-1 H-indazole

Abstract

The invention relates to a synthesizing process of 3-methyl-1 H-indazole. The synthesizing process comprises the following steps: acetophenone is dropped into a sulfuric acid and nitric acid mixture solution, then calcium metasilicate powder is added, the mixture is kept to be stirred at lower temperature and passes through the night, the mixture is added into ice water and filtered, and 2-nitroacetophenone is obtained; the 2-nitroacetophenone, iron powder and ammonium chloride are synthesized into white solid 2-aminoacetophenone; the 2-aminoacetophenone is added to hydrochloric acid, then an NaNO2 aqueous solution is added, the mixture is stirred, then a hydrochloric acid solution of SnCl2.H2O is added, the mixture is stirred, the mixture is added to ice water and filtered, and filtrate is adjusted to alkalescence, filtered and dried so that the 3-methyl-1 H-indazole is obtained. According to the synthesizing process of the 3-methyl-1 H-indazole, calcium silicate is taken as a catalyst, the yield of the 2-nitroacetophenone is increased remarkably, the raw material of calcium silicate is easy to obtain, the cost is low, the operation and the use are simple, later synthesis of 2-aminoacetophenone and the 3-methyl-1 H-indazole is further facilitated, and the synthesizing process is suitable for industrial large-scale synthesis of 3-methyl-1 H-indazole.

Description

technical field [0001] The invention relates to a synthesis process of indazole derivatives, in particular to a synthesis process of 3-methyl-1H-indazole. Background technique [0002] Indazole is an important intermediate in organic synthesis. Many indazole compounds have antidepressant, anti-inflammatory, analgesic and antipyretic, dopamine antagonism, anti-tumor, anti-HIV and contraceptive drug activities, and are also widely used in pesticides. Because of the important physiological activity and potential medicinal value of indazole derivatives, such as 3-methyl-1H-indazole, it is of great significance and application value to study their synthetic methods. [0003] CN102898374A (published on January 30, 2013) discloses a method for obtaining 3-methyl-1H-indazole without reflux heating reaction of hydrazine hydrate and without purification of the product through a column. The method includes The following steps: Step 1, 2-amino-5-R-acetophenone as a raw material or inte...

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Problems solved by technology

[0004] Although the above-mentioned prior art discloses a synthetic method of 3-methyl-1H-indazole, which can meet certain needs, but in the process of realizing the present invention, the inventor finds that there are still some defects in the above-mentioned prior art: for example The synthetic yield of 2-nitroacetophenone in the first step is only 80%, which is low and unfavorable for the large-scale synthetic production of 3-methyl-1H-indazole

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