Mechanistic Studies of Organic Reactivity

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Professor Jeehiun Katherine Lee of the Department of Chemistry at Rutgers University is utilizing funding provided by the Chemical Structure, Dynamic & Mechanism B Program of the Chemistry Division to explore mechanisms of catalysis. The specific focus will be reactions catalyzed by N-heterocyclic carbenes (NHCs). NHCs are novel organic substances which have been shown to act as catalysts for a broad collection of important chemical reactions. Mechanisms for these reactions are poorly understood. Reactions are studied both computationally and experimentally, in the absence of solvent, using a mass spectrometer. The absence of solvent allows for intrinsic reactivity to be revealed. These fundamental mechanistic studies provide educational opportunities for undergraduate and graduate scientists. The project also provides mentoring and training for groups underrepresented in science. Mass spectrometric and theoretical computations are used to examine the properties and reactivities of N-heterocyclic carbenes (NHCs) NHCs are a versatile species that provide ligands for transition metal catalysts as well as being catalysts in their own right. NHCs catalyze "Umpolung" reactions, triggering polarity reversal; the focus of this proposal is on polarity reversal at a carbonyl carbon. Such reactions are of great synthetic utility, but the mechanism is poorly understood. Both computations and experiments are being used to probe the mechanisms by which the polarity reversal is incurred, with the plan of designing a strategy that would greatly enhance the overall utility of this reaction. The gas phase is uniquely suited to this study because the role of solvent can be ascertained. Mechanistic understanding of these NHC-catalyzed transformations leads to the development of improved catalysts.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.