Construction of Tricyclic Nitrogen Heterocycles by a Gold(I)‐Catalyzed Cascade Cyclization of Allenynes and Application to Polycyclic π‐Electron Systems
Hiroki Komatsu, Takaya Ikeuchi, Hitomi Tsuno, Norihito Arichi, Kosuke Yasui, Shinya Oishi, Shinsuke Inuki, Aiko Fukazawa, Hiroaki Ohno
Abstract
Abstract A novel 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 a catalytic amount of BrettPhosAuNTf 2 in the presence of i PrOH to produce 1,2‐dihydrobenzo[ cd ]indole derivatives in good yields. When 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 π‐electron systems. A newly obtained hexacyclic indolium salt showed characteristic concentration‐dependent absorption and emission properties.