Electrochemical catalytic synthesis method of 2-N-substituted benzoxazole compounds

Abstract

The invention relates to an electrochemical preparation method of 2-N-substituted benzoxazole compounds. The 2-N-substituted benzoxazole compounds are obtained by constant current electrolysis in a single-chamber electrolytic cell by utilizing benzoxazole compounds and amine as raw materials and utilizing a halide as an electrocatalyst, wherein the dosage of the catalyst is 5-20% (mol), an organic solvent serves as electrolyte, glacial acetic acid serves as an additive, the reaction temperature is 0-40 DEG C and the current density is 2-10mA/cm<2>. According to the method provided by the invention, an indirect electrolytic method is used for the first time to synthesize the 2-N-substituted benzoxazole compounds, thereby avoiding the use of excessive organic hypervalent iodine reagent with high price and potential explosiveness or other co-oxidants and avoiding the generation of reduction wastes resulting from the use of the excessive oxidant or co-oxidant as well. According to the method provided by the invention, common industrial reagents and conventional production conditions, instead of supporting electrolyte, are used, and the reaction conditions are mild, so that the method is more suitable for industrial production.

Description

technical field [0001] The invention relates to an electrochemical catalytic synthesis method of 2-N-substituted benzoxazole compounds. Background technique [0002] 2-N-substituted benzoxazole compounds have a variety of biological activities, such as serotonin antagonists (Bioorg.Med.Chem.Lett.2009,19,1115) are effective in the treatment of Alzheimer's disease and schizophrenia Potential targeted drugs, the synthesis of such compounds has become the focus of attention. [0003] The synthesis of 2-N-substituted benzoxazoles can be achieved by direct oxidative coupling of benzoxazole derivatives with amines. According to different oxidation conditions, there are two different oxidant systems: excess oxidant system or catalytic oxidation system composed of catalytic amount of oxidant and co-oxidant. Under the action of excess oxidant, Chang et al. (Chem.Eur.J.,2011,17,8294-8298) reported the synthesis of 2-N-substituted benzoxazole compounds with excess iodobenzene diacetat...

AI Technical Summary

Problems solved by technology

[0005] (1) High cost

When using an excess oxidant system to synthesize 2-N-substituted benzoxazole compounds, because the oxidant needs to be used in large quantities, the price is expensive, and there is a potential explosion hazard in organic hypervalent iodine oxidants such as iodobenzene diacetate, in most solvents Disadvantages such as low solubility; when using a catalytic oxidation system composed of an oxidant and a co-oxidant, although the oxidant is a catalytic amount, it is necessary to put in a stoichiometric or excessive co-oxidant, which also causes a waste of the co-oxidant

[0006] (2) Complicated operation

The removal of excess oxidant or co-oxidant used in the reaction process and the separation of the reduction products produced after the reduction of the oxidant bring difficulties to the post-treatment of the reaction.

[0007] (3) Cause environmental pollution

The use of excess oxidant or co-oxidant and the reduction products produced after the oxidant is reduced have caused serious environmental problems

[0008] At present, the method of preparing 2-N-substituted benzoxazole compounds by constant current electrolysis method has not been reported in the literature at home and abroad.

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