N-Arylimine 1,4-Cycloaddition Reaction. Preparation of Substituted Hexahydrofuro[3,2c] Quinolines from Shiff Bases and 2,3-Dihydrofuran

The synthesis of nitrogen heterocycles through cycloaddition reaction of imines has stimulated much preparative and mechanistic work. ^1,2The reaction of Shiff bases with electro-rich olefins has been utilized for the systhesis of quinoline derivatives. ³This paper introduces Lewis acid catalyzed cycloaddition reactions of N-arylideneaniline(Ⅰ) with 2,3-dihydrofuran(Ⅱ), which gives a pair of epimers dl-2,3,3a,4,5,9b-hexahydro-4-arylfuro3,2-c]quinolines (Ⅲ and Ⅲ') and a few of their corresponding aromatized compounds.(Ⅳ)