A chiral multidentate salan-supported heterobimetallic catalyst for asymmetric Friedel-Crafts reaction

• Published in: Inorganic chemistry communications 2017-10, Vol.84, p.24-27
• Main Authors: Xiong, Hangxing, Li, Li, Liu, E, Cheng, Jessica, Zhang, Guoqi
• Format: Article
• Language: English
• Subjects: Asymmetric catalysis; Copper/zinc complex; Friedel-Crafts reaction; Salan
• ISSN: 1387-7003; 1879-0259
• DOI: 10.1016/j.inoche.2017.07.016

A new hydroxymethyl-pendant salan (3) containing a chiral backbone and an extra O4 cavity has been prepared through a facile one-pot procedure. The ligand has been characterized by ESI-MS, elemental analysis and 2D NMR techniques. To continue our previous work on the catalytically asymmetric F-C reactions using multimetallic complexes involving salan-type ligands, we investigated the applicability of 3 for both asymmetric Henry and F-C reactions, in comparison with previously reported results using salans 1 and 2. It was revealed that although 3 was not a suitable ligand for homometallic copper-catalyzed Henry reaction, it was effective for the hetereobimetallic Cu/Zn-catalyzed asymmetric F-C reaction, affording desired alkylated product with good yield and moderate enantiomeric excess (ee), after screening of various catalyst combinations. [Display omitted] •A new salan ligand containing extra O4 cavity was synthesized and characterized.•The catalytic Henry reaction and Friedel-Crafts alkylation were studied.•The combination of hetereobimetallic Cu/Zn with new salan ligand gave the best results.•The catalytic activity and enantioselectivity were compared with different salan-type ligands.