title: Asymmetric synthesis of tetrahydroquinolines with quaternary stereocenters through the Povarov reaction.
abstract: The asymmetric Povarov reaction with α-alkyl styrenes as dienophiles was catalyzed by an N,N'-dioxide L4-Sc(OTf)(3) complex. Enantiopure tetrahydroquinoline derivatives with a quaternary stereocenter at the C4 position were synthesized for the first time. A wide variety of α-alkyl styrenes and N-aryl aldimines were tolerated in the reaction, to give excellent diastereo- (up to 99:1 d.r.) and enantioselectivities (92 to >99% ee). In addition, the reaction could be performed on the gram scale without any loss of yield, diastereoselectivity, or enantioselectivity. An intermolecular hydrogen-shift reaction was found to be a side reaction, which offered a method to synthesize the corresponding quinoline derivatives with chiral quaternary sterocenters.
authors.affiliation: Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, P. R. China.
authors.forename: Mingsheng
authors.initials: M
authors.lastname: Xie
authors.forename: Xiaohua
authors.initials: X
authors.lastname: Liu
authors.forename: Yin
authors.initials: Y
authors.lastname: Zhu
authors.forename: Xiaohu
authors.initials: X
authors.lastname: Zhao
authors.forename: Yong
authors.initials: Y
authors.lastname: Xia
authors.forename: Lili
authors.initials: L
authors.lastname: Lin
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Feng