Dearomatization-Rearomatization Reaction of Metal-Polarized Aza-ortho-Quinone Methides

Metal-polarized aza-ortho-quinone methides (aza-o-QMs) are a unique and efficient handle for azaheterocycle synthesis. Despite great achievements, the potential of these reactive intermediates has not yet been fully exploited, especially the new reaction modes. Herein, we disclosed an unprecedented dearomatization process of metal-polarized aza-o-QMs, affording transient dearomatized spiroaziridine intermediates. Based on this serendipity, we accomplished three sequential dearomatization-rearomatization reactions of benzimidazolines with aza-sulfur ylides, enabling the divergent synthesis of bis-nitrogen heterocycles with high efficiency and flexibility. Moreover, experimental and theoretical studies were performed to explain the proposed mechanisms and observed selectivity. Further cellular evaluation of the dibenzodiazepine products identified a hit compound for new antitumor drugs.

Automated summary

Metal-polarized aza-ortho-quinone methides (aza-o-QMs) have been effectively utilized in azaheterocycle synthesis, and a new reaction mode involving transient dearomatized spiroaziridine intermediates has been discovered. This has led to the efficient and flexible divergent synthesis of bis-nitrogen heterocycles through sequential dearomatization-rearomatization reactions. Experimental, theoretical, and cellular evaluations have been conducted to explain the mechanisms, selectivity, and potential medicinal applications of the synthesized compounds.