Soluble polyisobutylene-supported reusable catalysts for olefin cyclopropanation |
| |
Authors: | David E Bergbreiter Jianhua Tian |
| |
Institution: | Department of Chemistry, Texas A&M University, PO Box 30012, College Station, TX 77842-3012, USA |
| |
Abstract: | Polyisobutylene oligomers (PIB) have been used as soluble supports for the immobilization of cyclopropanation catalysts. In addition to simple carboxylate ligands, chiral bisoxazolines have been successfully attached to these heptane-soluble polymers. Their use and recovery has been investigated using cyclopropanation of styrene as an example. An achiral PIB-bound Rh(II) catalyst showed good activity and could be easily recycled nine times using a liquid-liquid biphasic separation technique. PIB-supported bisoxazoline ligands for Cu(I) catalysts were also prepared. These chiral catalysts showed good catalytic activity and stereoselectivity. A chiral ligand prepared from phenylglycine provided the most effective stereocontrol and gave the trans- and cis-cyclopropanation products in 94% ee and 68% ee, respectively. All three PIB-bound chiral bisoxazoline-Cu(I) catalysts prepared could be reused five to six times. |
| |
Keywords: | Cyclopropanation Bisoxazoline Polyisobutylene Polymer supports |
本文献已被 ScienceDirect 等数据库收录! |