Complexity-Building Photoinduced Cascade Involving C sp 2 -C sp 3 Coupling of Aromatic Amides via [2 + 2] Reactivity of ESIPT-Generated o- Azaxylylenes.

A new mode for complexity-building photochemical cascades which offers experimentally simple transition metal-free intramolecular C sp 2 -C sp 3 cross coupling of aromatic amides is attained via an unprecedented [2 + 2] reactivity of ESIPT-generated azaxylylenes. Coupled with short and straightforward postphotochemical modifications of the primary photoproducts, these cascades allow for a significant step-normalized growth of molecular complexity while accessing diverse and complex polyheterocyclic molecular architectures.