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).
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
Lewis Acid Catalyzed Formation of Tetrahydroquinolines via an Intramolecular Redox Process
作者:Sandip Murarka、Chen Zhang、Marlena D. Konieczynska、Daniel Seidel
DOI:10.1021/ol802519r
日期:2009.1.1
Polycyclic tetrahydroquinolines were prepared by an efficient Lewis acid catalyzed 1,5-hydride shift, ring closure sequence. Gadolinium triflate was Identified as a catalyst that Is superior to scandium triflate as well as other Lewis acids. An approach toward a catalytic enantioselective variant Is also described.