Effect of the Dihedral Angle of Biaryl-Bridged Bisphosphite Ligands on Enantioselectivity and Regioselectivity of Asymmetric Hydroformylation

Christopher J. Cobley,† Robert D. J. Froese, Jerzy Klosin,* Cheng Qin, and Gregory T. Whiteker*‡
Corporate R&D, The Dow Chemical Company, 1776 Building, Midland, Michigan 48674
Khalil A. Abboud
Department of Chemistry, University of Florida, Gainesville, Florida 32611
Organometallics, 2007, 26 (12), pp 2986–2999
DOI: 10.1021/om061065z
Publication Date (Web): May 2, 2007
Copyright © 2007 American Chemical Society
†

 Dowpharma, Chirotech Technology Limited, a subsidiary of The Dow Chemical Company, 162 Cambridge Science Park, Cambridge CB4 0GH, UK.

,
*

 Corresponding authors:  E-mail:  jklosin@dow.com; whitekgt2@dow.com.

,
‡

 Current address:  Dow Agrosciences, 9330 Zionsville Rd., Indianapolis, Indiana 46268.

Abstract

Abstract Image

Eight new biaryl-bridged bisphosphite ligands have been synthesized and applied in rhodium-catalyzed asymmetric hydroformylation of styrene, allyl cyanide, and vinyl acetate. X-ray crystallographic studies of square planar LRh(acac) complexes of four of these bisphosphite ligands revealed that the dihedral angle of the bridging biaryl moiety depends on its identity and lies between 59.8° and 80.0°. A correlation between the dihedral angle in these Rh complexes and hydroformylation enantioselectivity and regioselectivity for both allyl cyanide and vinyl acetate is reported. Smaller dihedral angles were found to lead to increased regio- and enantioselectivity. Density functional theory calculations of a five-coordinate model complex (LRh(CO)2H) show that decreased dihedral angles lead to smaller P−Rh−P bite angles. Although large bite angles have previously been correlated with increased hydroformylation regioselectivity, these results provide the first demonstration of a bite angle effect on enantioselectivity in asymmetric hydroformylation.

View: Full Text HTML | Hi-Res PDF

Tools

History

  • Published In Issue June 04, 2007
  • Received November 20, 2006

Recommend & Share

Related Content

Other ACS content by these authors: