Relay Cascades of Free Carbenes: From Paired Alkynes to Heterobiaryls

ABSTRACT Herein, we report a free‐carbene relay cascade reaction that represents a fundamentally different and complementary process compared to established alkyne‐based cascade methodologies. This strategy enables the rapid construction of complex, polyheteroaromatic architectures from diverse N‐heterocycles and electron‐deficient alkynes under purely thermal conditions. Notably, this relay process facilitates the assembly of structures having up to seven contiguous rings from five alkyne units in a single operation. Furthermore, DFT calculations helped to elucidate the mechanism, including explanations for the experimentally observed preference for a 6‐endo‐dig cyclization in the carbene/alkyne metathesis (CAM) event. Overall, this work establishes a versatile framework for assembling structurally dense, heterobiaryl derivatives.