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 H 2 evolution, thus obviating the need for transition‐metal‐based catalysts and oxidizing reagents.