Construction of Tricyclic Nitrogen Heterocycles by a Gold(I)‐Catalyzed Cascade Cyclization of Allenynes and Application to Polycyclic π‐Electron Systems

Abstract

An ovel approach to the direct construction of tricyclic nitrogen heterocycles based on gold-catalyzed cascade cyclization of aminoallenynes is described. The expected biscyclization reaction of hydroxyisobutyryl-protected aminoallenynes was efficiently promoted by ac atalytic amount of BrettPhosAuNTf 2 in the presence of iPrOH to produce 1,2dihydrobenzo[cd]indole derivatives in good yields.W hen the reaction was combined with Friedel-Crafts acylation or palladium-catalyzed N-arylation, the resulting tricyclic products were efficiently converted into nitrogen-containing polycyclic aromatic compounds (N-PACs) with highly conjugated p-electron systems.Anewly obtained hexacyclic indolium salt showed characteristic concentration-dependent absorption and emission properties. Scheme 1. Gold(I)-catalyzed reactions of diynes and related compounds proceedingvia vinyl cation intermediates.