Phosphine‐Catalyzed [4+3] Annulation Reaction of Indole Derivatives with MBH Carbonates: A Facile Access to Indole‐1,2‐fused 1,4‐Diazepinones and Azepines

Comprehensive Summary A phosphine‐catalyzed [4+3] annulation between dinucleophilic indole derivatives and Morita−Baylis−Hillman (MBH) carbonates was discovered by using the N1 and N4′/C4′ nucleophilicities of the indole precursors, in which indoles act as four atom synthons. This protocol provides an efficient and facile access to indole‐1,2‐fused 1,4‐diazepinones and azepines in good to high yields in one step, which illustrates potential synthetic utilities in drug discovery.