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Kaid Harper

Kaid Harper

Mon, Dec. 1, 2014, 3:15pm - 5:30pm
Frick Chemistry Laboratory, Taylor Auditorium
Host: Robert Knowles

3:15 p.m. – Public research seminar, Taylor Auditorium
4:30 p.m. – Research proposal, A81

Multidimensional Free Energy Relationships in Asymmetric Catalysis and Development of a General β-Selective Glycosylation Catalyst

The first part of my presentation will highlight the application of multidimensional free energy relationships to asymmetric catalyst design and optimization.  Through the use of steric and electronic parameters, substituent effects on enantioselectivity were quantified and predictive models were developed.  These models were used to predict catalyst performance de novo.  These models also provided mechanistic insight for the interrogated reactions.  The second part of my talk will focus on the design and development of a general catalyst for β-selective glycosylation.  An important challenge in oligosaccharide synthesis is controlling the stereochemistry at the anomeric center.  Many saccharides are inherently biased towards formation of the α-anomer due to the anomeric effect.  Chiral macrocyclic thioureas were rationally designed and are capable of overriding the inherent α-bias to provide high levels of β-selectivity.  The unique selectivity of these catalysts has been extended to a variety of challenging substrates including 2-deoxyglucose, mannose, glucose and galactose.  The scope of alcohol nucleophiles compatible with this reaction is also general, allowing the formation of many disaccharides with high levels of β-selectivity.