Multicomponent Cross-Coupling Enables Modular Construction of Biaryls and 1-Azahelicenes

The selective assembly of azahelical structures is not trivial and constitutes a pivotal challenge in material science and organic synthesis. Described herein is a facile and modular approach to construct diverse functionalized 1-azahelicenes through the combination of a Pd/NBE-catalyzed three-component cross-coupling reaction with an alkyne benzannulation process. The appealing features of this method include readily accessible starting materials, step economy, good functional-group tolerance, and a scale-up potential. In particular, application of this method has been demonstrated in postproduct functionalization of many natural products and drug molecules. Photophysical studies disclose that the optical properties can be tuned through the introduction of different substituents into azahelical backbones.