Photo-Induced Unsymmetrical Dearomative Self-Fusion of N-Heteroarenes

Naturally occurring dimeric products have attracted considerable attention from both chemists and biologists. The construction of pseudo-dimers often requires elaborate synthetic effort with low efficiency. Dearomatization reactions represent an ideal method to transform planar aromatics into three-dimensional skeletons, which has attracted increasing interest in medicinal chemistry and total synthesis. Herein, we present a self-fusion of N-heteroarenes via an energy transfer-induced dearomatization under photocatalysis. With aromatic compounds as coupling partners, this reaction enables the straightforward construction of pseudo-dimers of N-heteroarenes. This protocol features a broad substrate scope, atomic economy, and metal-free catalysis. Mechanistic studies revealed the intertwined EnT/SET nature in this process and offered guidelines for synthesizing novel bridged polycycles. In addition, this strategy provides an effective approach for constructing functional polymers with high atomic economy and environmental benefits by metal-free one-pot polymerization. Furthermore, the synthetic transformations provide a supplement for the synthesis of formal cross products that were previously inaccessible.