Visible-light Induced Decarboxylative C2-alkylation Of Benzothiazoles With Carboxylic Acids Under Metal-free Conditions

Thiazoles are widely found in various products such as agriculture,pharmaceuticals,and materials science.The ability to selectively functionalize benzothiazole can greatly enhance their use in these fields.In recent years,the organic synthesis reaction induced by visible light under metal-free conditions is simple and efficient,and the reaction is generally carried out at room temperature,which has attracted the attention of chemists.Conventional C2-alkylation of benzothiazoles reaction often requires transition metal catalysts,strong oxidants,high temperature and other harsh reaction conditions,while the visible-light induced C2-alkylation of benzothiazoles under metal-free conditions avoids the disadvantages of traditional methods.It has its unique advantages:the reaction conditions are simple and gentle,efficient,without the need for additional ligands or additives.In this paper,we mainly focus on the study of visible-light induced decarboxylative C2-alkylation of benzothiazoles with carboxylic acids under metal-free conditions,and the related research work was carried out as following:A highly efficient visible light induced decarboxylation C2-alkylation of benzothiazole with a carboxylic acid under metal free conditions has been developed.The reaction proceeds under the irradiation of 1.5 W blue LED?410-415 nm?in air for 36 h with of 9-mesityl-10-methylacridinium perchlorate?[Acr⁺-Mes]ClO₄?as the photocatalyst,Na₂HPO₄·12H₂O as the base and CH₃CN/H₂O?1:1?as the solvent,providing the desired products with good yields and the reaction mechanism through energy transfer and electron transfer pathway was proposed.