Our research interests bridge the traditional disciplines of organic and inorganic chemistry.  Catalysis and transition metal-mediated organic synthesis constitute the principal themes of our research program.  We are developing the synthesis and reactivity of early and late transition metal complexes that are of interest for applications in organic synthesis, polymer chemistry, modeling of catalytic reactions, and as catalyst precursors.  The development of environmentally benign chemical processes is another key objective of our research.  Current projects include:

• Ruthenium-Based Hydrogenation and Hydrogenolysis Catalysts

Promising carbohydrate biomass-derived carbon resources, such as sugars, furan derivatives, and polyalcohols, are generally characterized by an abundance of reactive oxygen functional groups. Hence efficient technologies need to be developed for selectively deoxygenating molecules derived from biomass resources so that they can be integrated into the existing energy and petrochemical production streams. We are developing the synthetic potential of electrophilic Ru(II) complexes and exploring strategies for the development of efficient catalysts for selective hydrogenation and deoxygenation (via hydrogenolysis) of furan derivatives. Currently, we are developing ruthenium catalysts, which act by well-understood mechanism(s) and display both high activity and product selectivity, for the selective deoxygenation of furfural and 5-hydroxymethylfuran to 2-methylfuran and 2,5-dimethylfuran, respectively. 

    
• Heterogeneous Olefin Epoxidation Catalysts from Tripodal Titanium Silsesquioxane Complexes (collaboration with Dr. Mark Crocker, University of Kentucky Center for Applied Energy Research)

Tripodal Ti silsesquioxane complexes appear to be among the most active and selective of all known catalysts for epoxidation reactions using alkyl hydroperoxides.  We are probing whether the advantageous catalytic properties of homogeneous Ti silsequioxane catalysts can be retained upon immobilization, particularly with regard to the epoxidation of demanding substrates, such as alkenes that are electronically and/or sterically “deactivated” with respect to epoxidation, such as allylic alcohols and alpha, beta-unsaturated carbonyl compounds.  We are investigating the development of heterogeneous titanium silsesquioxane-based catalysts suitable for alkene epoxidation reactions using H 2 O 2 or H 2 /O2 gas mixture as the oxidant.


• Well-defined titanium(II) reductants

Better understanding of the synthesis, structure, and reactivity of low-valent titanium complexes is required in order to achieve better mechanistic understanding and greater control over regio-, diastereo-, and chemo-selectivity in titanium-mediated carbon-carbon bond forming reactions.  We are investigating the development of well-characterized Ti(II) reductants which operate via well-understood mechanisms.  As an approach to achieving this goal, we are probing ancillary ligand effects in titanium chemistry.  Emphasis is placed on discovery and use of supporting ligands that afford well-characterized Ti(II) complexes or synthetic equivalents.   We are interrogating the reactivity of these well-defined compounds with particular emphasis on their reactions with unsaturated organic substrates, such as alkynes, alkenes, imines, aldehydes, and ketones.  Our mechanistic investigations are helping to elucidate parameters key to designing selective titanium reductants.  

Acknowledgments

We are grateful to all of our collaborators for their insight and contributions. We are also grateful to the Kentucky Science and Engineering Foundation (KSEF) and the National Science Foundation (NSF) for support of our research program.

Additional Information

• Our Research Group

• Selected Publications

Postdoctoral Fellowship Opportunities

Lyman T. Johnson Postdoctoral Fellowship

Postdoctoral Fellowship for Women in Under-Represented Areas