Light-Driven Intramolecular C-N Cross-Coupling via a Long-Lived Photoactive Photoisomer Complex.

Reported herein is a visible-light-driven intramolecular C-N cross-coupling reaction under mild reaction conditions (metal- and photocatalyst-free, at room temperature) via a long-lived photoactive photoisomer complex. This strategy was used to rapidly prepare the N-substituted polycyclic quinazolinone derivatives with a broad substrate scope (>50 examples) and further exploited to synthesize the natural products tryptanthrin, rutaecarpine, and their analogues. The success of gram-scale synthesis and solar-driven transformation, as well as promising tumor-suppressing biological activity, proves the potential of this strategy for practical applications. Mechanistic investigations, including control experiments, DFT calculations, UV-vis spectroscopy, EPR, and X-ray single-crystal structure of the key intermediate, provides insight into the mechanism.