Study On The Copper-Catalyzed Imino-Diels-Alder Reaction

Diels-Alder reaction has been proved to be a useful tool for construction of C-C bond and six-membered ring skeleton. Aza-Diels-Alder reaction is of particular interest because of its wide applications in biology, pharmaceutical and organic synthesis such as total synthesis of natural products and preparation of polymers. On the other hand, some Aza-Diels-Alder reactions have been used in industry successfully. Therefore, the development of convenient and efficient Aza-Diels-Alder reaction is still strongly desirable.In this paper, a new type of copper-catalyzed Imino-Diels-Alder reaction is described. That is. Cu2O catalyzed intramolecular Imino-Diels-Alder reaction of imines, which were generated in situ from the condensation of2-(prop-2-yn-l-yloxy)benzaldehydes and anilines. When chloranil was used as an additive,7-Cl-6H-chromeno[4,3-b]quinolines were obtained in moderate yields. The results showed that this reaction has good functional group tolerance. Products3a-3h,3I-3o, and4m-4o were unknown, and their structures were confirmed by1H NMR,13C NMR, IR, and HRMS.