Electrochemical Cross-Dehydrogenative Coupling between Phenols and β-Dicarbonyl Compounds: Facile Construction of Benzofurans

Preparative electrochemical synthesis is an ideal method for establishing green, sustainable processes. The major benefits of an electro-organic strategy over that of conventional chemical synthesis are the avoidance of reagent waste and mild reaction conditions. Here, an intermolecular cross-dehydrogenative coupling between phenols and β-dicarbonyl compounds has been developed to build various benzofurans under undivided electrolytic conditions. Neither transition metals nor external chemical oxidants are required to facilitate the dehydrogenation and dehydration processes. The key factor in success was the use of nBu₄ NBF₄ as the electrolyte and hexafluoroisopropanol as the solvent, which play key roles in the cyclocondensation step. This electrolysis is scalable and can be used as a key step in drug synthesis. On the basis of several experimental results, the mechanism, particularly of the remarkable anodic oxidation and cyclization process, was illustrated.

Oxo-Thiolation of Cationically Polymerizable Alkenes Using Flow Microreactors

The present study describes the cationic oxo-thiolation of polymerizable alkenes by using highly reactive cationic species generated by anodic oxidation. These highly reactive cations were able to activate alkenes before their polymerization. Fast mixing in flow microreactors effectively controlled chemoselectivity, enabling higher reaction temperatures.