Modification of diphenylamine-linked bis(oxazoline) ligands: Tuning of electronic effect and rigidity of ligand skeleton  

作　　者：LIU Han LI Wei DU DaMing 

机构地区：[1]Beijing National Laboratory for Molecular Sciences(BNLMS),and Key Laboratory of Bioorganic Chemistry and Molecular Engineering,College of Chemistry and Molecular Engineering,Peking University,Beijing 100871,China [2]School of Chemical Engineering and Environment,Beijing Institute of Technology,Beijing 100081,China

出　　处：《Science China Chemistry》2009年第9期1321-1330,共10页中国科学（化学英文版）

基　　金：Supported by the National Natural Science Foundation of China (Grant No. 20772006);the Program for New Century Excellent Talents in University (Grant No. NCET-07-0011);the Development Program for Distinguished Mid-Youth Teachers of Beijing Institute of Technology

摘　　要：The electronic effect of diphenylamine-linked bis(oxazoline) ligands was tuned through introduction of electron-withdrawing bromo and nitro substituents onto the 4 and 4′ position. The variation of the NH bond acidity was determined by the different chemical shifts of NH. The catalytic activity and enantioselectivity of the modified ligands were tested in the asymmetric Friedel-Crafts alkylation of indole with β-nitrostyrene. The effect of ligand skeleton rigidity was also investigated through the synthesis of iminodibenzyl-linked bis(oxazoline) ligands and evaluation of their catalytic activity in Friedel-Crafts alkylation.The electronic effect of diphenylamine-linked bis(oxazoline) ligands was tuned through introduction of electron-withdrawing bromo and nitro substituents onto the 4 and 4′ position. The variation of the NH bond acidity was determined by the different chemical shifts of NH. The catalytic activity and enantioselectivity of the modified ligands were tested in the asymmetric Friedel-Crafts alkylation of indole with β-nitrostyrene. The effect of ligand skeleton rigidity was also investigated through the synthesis of iminodibenzyl-linked bis(oxazoline) ligands and evaluation of their catalytic activity in Friedel-Crafts alkylation.

关 键 词：asymmetric catalysis electronic effect bis(oxazoline) FRIEDEL-CRAFTS ALKYLATION 

分 类 号：O621.1[理学—有机化学]