Preparation method of 6-chloro-2-methyl-2H-indazole-5-amine

Abstract

The invention discloses a preparation method of 6-chloro-2-methyl-2H-indazole-5-amine, which sequentially comprises the following steps of: nitrifying 4-chloro-2-fluorobenzaldehyde to obtain 4-chloro-2-fluoro-5-nitrobenzaldehyde, adding potassium nitrate, sulfuric acid and the like in the reaction process, reacting, and filtering to obtain the 6-chloro-2-methyl-2H-indazole-5-amine. The method comprises the following steps: in the presence of hydrazine hydrate, generating 6-chloro-5-nitro-1H-indazole from 4-chloro-2-fluoro-5-nitrobenzaldehyde, then methylating the 6-chloro-5-nitro-1H-indazole by using trimethyloxy onium tetrafluoroboric acid to obtain 6-chloro-2-methyl-5-nitro-2H-indazole, and reducing the 6-chloro-2-methyl-2H-indazole-5-amine to obtain 6-chloro-2-methyl-2H-indazole-5-amine; according to the preparation method disclosed by the invention, toxic reagents and potential explosion risks are reduced, and the operation convenience is improved.

Description

Technical field [0001] The invention belongs to the technical field of pharmaceutical production, and specifically relates to a preparation method of 6-chloro-2-methyl-2H-indazole-5-amine. Background technique [0002] The molecular formula of 6-chloro-2-methyl-2H-indazole-5-amine is Its synthesis is not easy, and the following routes have been reported in relevant literature: [0003] [0004] This route starts from compound A, through ring closure with sodium nitrite, then methylation, and then through reduction to obtain the target compound. [0005] The first step of the reaction in this route has a low yield and requires column chromatography; the second step of the reaction in this route requires the use of methyl iodide, which is toxic; and the mixture of NaH and DMF is potentially explosive and the reaction risk is high; and the reaction The yield is very low, requires column chromatography, and is expensive. Contents of the invention [0006] The object of ...

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Problems solved by technology

[0005] The yield of the first step of the route reaction is low, and column chromatography is required; the second step of the route reaction needs to use methyl iodide, which is toxic; and NaH is mixed with DMF, which is potentially explosive, and the reaction risk is high; and the reaction Very low yield, requires column chromatography, expensive

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