GRADUATE STUDENT ASSOCIATION

 

Colloquium Schedule: Spring 2012

March 16th

Dr. Hien Nguyen, Assistant Professor of Chemistry at University of Iowa; Iowa city, IA

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Title: "Catalytic Transformations of Imidates and Epoxides: Application to the Synthesis of 1,2-Cis-2-Aminosugars, Allylic Fluorides and Allylic Amines"

 

 

Abstract:

One facet of our research program is to develop a new and innovative strategy for the effective synthesis of 1,2-cis-2-aminosugars via nickel-catalyzed alpha-selective glycosylation. These aminosugars make up one of the most important classes of naturally occurring oligosaccharides and glycoconjugates. Obtaining an adequate supply of these aminosugars from natural sources is exceedingly challenging. We have recently developed the novel method of the nickel-catalyzed glycosylation with C(2)-substituted-benzylidene glycosyl imidates for the preparation of 1,2-cis-2-aminosugars. This nickel method is applied to the synthesis of heparin oligosaccharides, mycothiol, GPI anchors, and mucin O-glycans.

Our second program is to develop a novel methodology for the regio- and enantioselective synthesis of branched allylic fluorides and amines via transition metal catalysis. The past decade has seen an explosion in the use of fluorinated molecules for application in pharmaceutical drug candidates and medical imaging. We have recently developed a rapid allylic fluorination method utilizing trichloroacetimidates in conjunction with an iridium catalyst. The reaction is conducted at room temperature under ambient air and relies on Et3N.3HF reagent to provide branched allylic fluorides with complete regioselectivity and good enantioselecitivty. Use of [18F]-KF.Kryptofix has allowed [18F]-fluoride incorporation in 10 min. The second project involves rhodium-catalyzed dynamic kinetic asymmetric transformations of racemic tertiary allylic trichloroacetimidates with unactivated anilines.

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Updated 03/13/2012