De Novo Synthesis of Highly Functionalized Benzimidazolones and Benzoxazolones through an Electrochemical Dehydrogenative Cyclization Cascade

Benzimidazolone and benzoxazolone moieties are important scaffolds in a variety of pharmaceutical molecules. These bicyclic heterocycles are usually prepared from a benzene derivative through the construction of an additional five‐membered heterocyclic ring. We report herein a method that enables the efficient synthesis of highly substituted benzimidazolone and benzoxazolone derivatives by building both the benzene and the heterocyclic rings through a dehydrogenative cyclization cascade. Readily available arylamine‐tethered 1,5‐enynes undergo a biscyclization/dehydrogenation cascade to afford functionalized benzanellated heterocycles in a single step with complete control of regioselectivity. These electricity‐powered oxidative transformations proceed with H2 evolution, thus obviating the need for transition‐metal‐based catalysts and oxidizing reagents. It's electrifying! An electricity‐powered synthesis of highly substituted benzimidazolone and benzoxazolone derivatives is reported, in which de novo construction of the benzene and the heterocyclic ring is achieved through a dehydrogenative cyclization cascade. The electrosynthesis method proceeds with H2 evolution, thus obviating the need for oxidizing reagents and proton acceptors.