Synthesis of o‐Bis(3‐indolyl)arenes under Brønsted Acid Catalysis: Carbonyl Compounds as Sources of Aryl Groups

Abstract

AbstractA method of synthesizing o‐bis(3‐indolyl)arenes was developed by reacting indoles with 7‐oxabicyclo[2.2.1]hept‐5‐en‐2‐one and derivatives thereof having no aromatic ring. All 23 unknown o‐bis(3‐indolyl)arenes could be obtained using this method. Palladium catalysis is useful for enlarging the π‐conjugated area of o‐bis(3‐indolyl)arenes, delivering aryl‐, alkynyl‐, and alkenyl‐unit‐installed o‐bis(3‐indolyl)arenes, and benzo[c]indolo[2,3‐a]carbazoles, the derivatization to which is effective for raising fluorescence quantum yield. A possible reaction mechanism is proposed based on several mechanistic studies.magnified image