Cation Radical Imino Diels-AlderReaction: A New Approach for the Synthesis of Tetrahydroquinolines - Jia, Xiaodong; Lin, Hechun; Huo, Congde; Zhang, Wei; Lü, Jianming; Yang, Li; Zhao, Guangyu; Liu, Zhong-Li (Synlett, 2003)