Current Research Interests
The Bunt Lab
Our research is motivated by a desire to understand how catalytic process occur at the detailed molecular level. Catalysis of both traditional "organic" reactions and biological enzyme reactions form the basis for two project described below. Note that the distinction between organic and biological reactions and catalysis is entirely artificial and perhaps even misleading. A combination of organic synthesis, physical organic methods, NMR spectroscopy, and biochemical techniques will be used to study these reactions. However, both projects begin with considerable synthetic organic efforts to make the molecules that we wish to study. The first project investigates the mechanism of base-flipping by the DNA repair enzyme Uracil DNA Glycosylase (UDG). Modified nucleoside analogs that contain either one or two methyl groups at the 5’-position of the sugar ring will be synthesized and incorporated into short oligonucleotides. The enzyme kinetics, NMR dynamics, and NMR structure of these analogs will be studied. From this data, the role of the enzyme in generating the flipped base will be determined. This issue is of great interest as many DNA repair and recognition enzymes are postulated to function by a base-flipping mechanism.
The second project explores the functioning of chiral ligands in the palladium catalyzed allylic alkylation reaction. Chiral phosphinooxazoline ligands containing electron donating and withdrawing groups on the aryl backbone will be synthesized. The effects of these electronic perturbations will be determined by measuring the enantiomeric excess of the alkylation reaction products by chiral HPLC and by measuring the changes in the 13C NMR chemical shifts of the isolated pi-allylpalladium intermediate complexes on the department's 400 MHz NMR Spectrometer. The observed effects will be correlated to the electronic perturbations via Hammett analysis of the data.
Recent Publications
Paul B. Armstrong,# Lisa M. Bennett, Ryan N. Constantine,# Jessica L. Fields,# Jerry P. Jasinski, Richard J. Staples, Richard C. Bunt "Hammett 13C NMR and X-ray studies of allylpalladium phosphinooxazoline chiral ligand complexes", Tetrahedron Lett. 2005, 46, 1441-1445.
Sunhee Choi, Richard B. Cooley,# Amanda S. Hakemian, # Yuna C. Larrabee, Richard C. Bunt, Stéphane D. Maupas, James G. Muller, and Cynthia J. Burrows, "Mechanism of Two-Electron Oxidation of Deoxyguanosine 5'-Monophosphate by a Platinum(IV) Complex" J. Am. Chem. Soc. 2004, 126, 591.
Ryan N. Constantine,# Naomi Kim,# and Richard C. Bunt, "Hammett Studies of Enantiocontrol by PHOX Ligands in Pd-Catalyzed Allylic Substitution Reactions" Org. Lett. 2003, 5, 2279.
Recent Grants
2007 American Chemical Society-Petroleum Research Fund, "Hammett Studies of P,N-Chiral Ligands." 9/1/07- 8/31/10 ($55,000)
2007 National Science Foundation (NSF-RUI, CHE-0714541) "Hammett Studies of P,N-Chiral Ligands.", 8/15/07- 8/14/10 ($146,000)
2005 Vermont Genetics Network (NIH-BRIN), Equipment Grant for "A Solvent Purification System" Co-PI with Jeff Byers ($24,700)
2003 National Institutes of Health (NIH-AREA), "Mechanism of Base-Flipping by DNA Modifying Enzymes" ($137,971)
2003 Pfizer Summer Undergraduate Research Fellowship for Sarah S. Goodwin ($5,000)
2002 Vermont Genetics Network (NIH-BRIN), Partial Sabbatical Leave Support for "Altering the Rate of Base Flipping in DNA" ($20,000)
2001 American Chemical Society-Petroleum Research Fund, Type G, "Probing the Electronic Origins of Chiral Ligand Asymmetry in Palladium-Catalyzed Allylic-Alkylation Reactions" ($25,000)
2001 Cottrell College Science Award from Research Corporation, "Probing the electronic origins of chiral ligand asymmetry in palladium-catalyzed allylic-aklylation reactions" ($41,381)
2000 Pfizer Summer Undergraduate Research Fellowship for Agnes Makingwe ($5,000)
2000 VT EPSCoR Award, "Electronic Control of Chiral Ligand Asymmetry" ($5,500)
Recent Awards
2007 Perkins Award for Excellence in Teaching