Green method for preparing heterocyclic compounds from nitriles

Abstract

The invention provides a green method for preparing heterocyclic compounds from nitriles. The method is characterized in that nitriles and compounds such as o-aminophenol, aminothiophenol, beta-amino alcohol, beta-amino thioalcohol and the like are catalyzed by a non-transition metal catalyst to synthesize the heterocyclic compounds such as benzoxazole, benzothiazole, oxazoline, thiazoline and the like by one step. The method has the beneficial effects that the non-transition metal catalyst with low price, water solubility and low toxicity is used, inert gas shielding is not needed, and the reaction can be directly carried out in the air to obtain the target heterocyclic compounds; the reaction conditions are simple and mild, the reaction is easy to operate, and the problems of transitional hydrolysis of nitriles and generation of byproducts are avoided, so that the products are simple and easy to separate and purify and have high recovery rates; and the method has lower requirements for the reaction conditions, wide range of application and good research and industrial application prospects.

Description

technical field [0001] The invention belongs to the field of chemical synthesis, and specifically relates to the synthesis of benzoxazole, benzothiazole, oxazoline and thiazoline by reacting nitrile with o-aminophenol, o-aminothiophenol, β-aminoalcohol and β-aminothiol and other compounds A green approach to heterocyclic compounds. Background technique [0002] Substituted benzoxazole, benzothiazole compounds and their derivatives have heterocyclic structures with drug activity and biochemical activity such as oxazole and thiazole, and many derivatives can be used to treat diabetes, Alzheimer's disease, or have antitumor Therefore, these heterocyclic structures play an important role in many fields such as drug synthesis and biopharmaceuticals, and are very important intermediates in drug synthesis. Benzoxazole, benzothiazole compounds and their derivatives can generally be prepared by dehydration condensation of o-aminophenol, o-aminothiophenol and acid, or oxidative conde...

AI Technical Summary

Problems solved by technology

Benzoxazole, benzothiazole compounds and their derivatives can generally be prepared by dehydration condensation of o-aminophenol, o-aminothiophenol and acid, or oxidative condensation reaction with aldehyde, but these methods have obvious disadvantages. If a strong dehydrating reagent is required , high temperature harsh conditions, or require the participation of a large amount of oxidants, resulting in a lot of by-products

In recent years, metal-catalyzed coupling reactions have also been used to synthesize benzoxazole and benzothiazole compounds, but transition metal catalysts, ligands, a large amount of bases, and ortho-halogenated compounds that are difficult to prepare are required

In addition, the condensation reaction of o-aminophenol, o-aminothiophenol and widely available nitrile compounds is also a desirable method, but there are few known synthetic methods at present, and there are still many disadvantages

For example, using ZnCl 2 The method as a catalyst needs to be heated and refluxed in chlorobenzene as a solvent; the method using Cu catalyst requires a large amount of alkali and heating conditions; while the method of heating and microwave promotion is limited to active substrates, and is greatly limited by microwave conditions

In addition, transition metal-catalyzed methods still have problems such as metal residues and toxicity.

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