Electrochemical C3 acyloxylation reactions of 2-indazoles with carboxylic acids C(sp)-O coupling

A green and practical electrooxidation protocol for C3 acyloxylation of 2 H -indazoles with carboxylic acids in the presence of potassium carbonate has been developed by intermolecular cross-dehydrogenative C(sp 2 )-O coupling. It is sustainable without the use of transition-metal catalysts, stoichiometric oxidants, and even extra supporting electrolytes. Potassium carbonate plays a key role in the reaction, and reacts with carboxylic acids to form carboxylates. Mechanistic studies by cyclic voltammetry and control experiments reveal that the reaction proceeds via an ECE mechanism. In addition, various carboxylic acids and 2 H -indazoles are suitable in this system and provide a series of novel desired products at room temperature in an undivided cell. The electrochemical C3 acyloxylation reactions of 2 H -indazoles with carboxylic acids in the presence of K 2 CO 3 were successfully developed, which were green and sustainable without transition-metal catalysts and stoichiometric oxidants.