Preparation method for indole-4-formaldehyde

Abstract

The invention discloses a preparation method for indole-4-formaldehyde. The preparation method comprises the following steps of: (1) adding 5-amino isoquinoline and acetonitrile into a reaction device and stirring; adding methyl iodide; raising temperature to 70-100 DEG C to react for 0.5-2 hours; and performing post-treatment to obtain 5-amino-2-methyl isoquinoline iodate after complete reaction; and (2) adding the 5-amino-2-methyl isoquinoline iodate, a catalyst and a mixed solvent into a high-pressure reaction device and sealing, reacting under internal pressure of 0.3-2 MPa and at the temperature of 100-140 DEG C for 10-40 hours; and performing post-treatment to obtain the indole-4-formaldehyde after complete reaction. The method has the advantages of simple process, high yield, short production period, less catalyst, less solvent and low production cost.

Description

Technical field [0001] The invention belongs to the field of fine chemicals, and specifically relates to a preparation method of indole-4-carbaldehyde. Background technique [0002] Indole-4-carbaldehyde is an important pharmaceutical and organic chemical intermediate. It can synthesize many compounds with physiological and pharmacological activities, such as being used to treat Parkinson’s disease (or called paralysis tremens) and prevent promoting The released ergoline of lactotrophin. [0003] Chinese patent document CN101245045 discloses a method for synthesizing indole-4-carboxaldehyde, which uses methyl 2-methyl-3-nitrobenzoate as a raw material, and firstly undergoes sodium borohydride reduction to obtain 2-methyl-3 -Nitrobenzyl alcohol, then catalytic oxidation to obtain 2-methyl-3-nitrobenzaldehyde, and then protect the aldehyde group with ethylene glycol, then conduct condensation, and finally reductive cyclization and hydrolysis to obtain indole-4-carbaldehyde . The d...

AI Technical Summary

Problems solved by technology

The disadvantage of this method is that it requires five steps of reaction, and the yield of the last step is only 25.8%. Some reaction intermediates must be separated and purified by column chromatography, resulting in cumbersome process routes and low yields, which are not suitable for large-scale production.

The disadvantages of this method are: the amount of inorganic salt catalyst used in the ring-opening condensation is too large (20 times the equivalent of sodium bisulfite, 10 times the equivalent of sodium sulfite), the reaction time is long (need 192h), and the amount of solvent is large (the weight and volume of raw materials and solvent ratio as high as 1g / 300mL), which leads to a long production cycle, high production costs, and a large amount of waste residue and wastewater discharge, which is not suitable for large-scale industrial production