Design and synthesis of novel chiral dihydroimidazolium cyclophanes as N-heterocyclic carbene precatalysts

A series of novel diphenyl ethylenediamine (DPEN) derived C-2 symmetric dihydroimidazolium cyclophanes were designed and synthesized as organo NHC precatalysts. The resultant organo NHC-catalyzed reactions with superior enantioselectivity than traditional C-2 dihydroimidazolidine NHCs as exemplified by NHC-catalyzed asymmetric intramolecular Stetter reactions. (C) 2012 Elsevier Ltd. All rights reserved.