CCB Young Investigator Seminar Series presentation by Dr. Sukwon Hong, University of Florida.
Sponsored in part by Organic Syntheses, Inc.
Host: Dr. Lawrence Williams
Talk Title: "Exploring New Ligand Designs for Asymmetric Catalysis"
Abstract: Novel chiral Co-salen catalysts capable of self-assembly through hydrogen bonding have been developed. First, a self-assembled dinuclear Co(II)-Salen catalyst featuring the pyridone/aminopyridine H-bonding pair results in significant rate acceleration (48 times faster rate) as well as excellent enantioselectivity (96% ee vs 55% ee) in nitro-aldol reaction, compared to the corresponding monomeric catalyst.  Second, bis-urea functionalized salen-Co(III) complexes have been designed to form self assembled structures in solution through self-complementary urea-urea hydrogen bonding interactions. Bis-urea functionalized salen-Co catalysts result in rate acceleration (up to 14 times) in hydrolytic kinetic resolution of terminal epoxides, compared to the corresponding monomeric catalyst.  Detailed kinetic and mechanistic study results will be discussed.
X-ray structure of SA-Salen-Ni Complex
 Park, J.; Lang, K.; Abboud, K. A.; Hong, S. Self-Assembled Dinuclear Cobalt(II)-Salen Catalyst Through Hydrogen-Bonding and Its Application to Enantioselective Nitro-Aldol (Henry) Reaction. J. Am. Chem. Soc. 2008, 130, 16484-16485.
 Park, J.; Lang, K.; Abboud, K. A.; Hong, S. Self-Assembly Approach toward Chiral Bimetallic Catalyst: Bis-Urea Functionalized (Salen)Cobalt Complexes for the Hydrolytic Kinetic Resolution of Epoxides. Chem.-Eur. J. Early View (DOI: 10.1002/chem.201002600).