A chiral catalyst prepared from N,N′-dioxide and Co(BF4)2·6H2O was applied in the asymmetric hydride transfer initiated cyclization reaction, giving optically active tetrahydroquinolines in good yields with high enantioselectivities under mild reaction conditions. Meanwhile, in light of the absolute configuration of the product, a possible working model was proposed to explain the origin of the activation
Theoretical Studies of the Asymmetric Binary‐Acid‐Catalyzed
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‐Aminocyclization Reaction: Origins of the CH Activation and Stereoselectivity
作者:Long Zhang、Liujuan Chen、Jian Lv、Jin‐Pei Cheng、Sanzhong Luo
DOI:10.1002/asia.201200674
日期:2012.11
energy of CN bond rotation. The intrinsic feature of this Lewisacid activation was found to be the activation of the LUMO, as well as an intermediate‐stabilization effect. The catalytically active species was believed to be a 1:1 complex of phosphoric acid and MgCl2, which was stabilized by a H⋅⋅⋅Cl hydrogen bond. The chiral catalytic complex selectively recognizes and activates one of the two helical
Catalytic Enantioselective tert-Aminocyclization by Asymmetric Binary Acid Catalysis (ABC): Stereospecific 1,5-Hydrogen Transfer
作者:Liujuan Chen、Long Zhang、Jian Lv、Jin-Pei Cheng、Sanzhong Luo
DOI:10.1002/chem.201201532
日期:2012.7.16
Selective H transfer by ABC: A new asymmetric binary acid catalyst was developed to promote 1,5‐H transfer specifically and stereoselectively in tert‐aminocyclization reactions with excellent activity, high enantioselectivity, and broad substrate scope. The H atom (in red) was proven to transfer through a stereospecific suprafacial pathway (see scheme).