Direct Dearomatization of Quinoline/Isoquinoline Ammonium Halides to Construct N-Substituted Tetrahydroquinolines and Tetrahydroisoquinolines

Dearomatization of quinoline/isoquinoline quaternary ammonium salts to synthesize valuable tetrahydroquinolines was firstly reported. Under this method, we used phenylsilane as a reducing agent to prepare a series of tetrahydroquinoline and tetrahydroisoquinoline derivatives conveniently and quickly in moderate to good yields. This method showed good functional group tolerance, wide substrate range, mild reaction conditions and simple operation. We have developed an efficient, convenient new method for the synthesis of tetrahydroquinoline derivatives via PhSiH3-mediated dearomatization of quinoline quaternary ammonium salts in moderate to good yields for the first time. This process has successfully constructed various substituted tetrahydroquinoline/isoquinoline derivatives, and has the advantages of mild reaction conditions and simple operation.image