@sbuxs Pohl me some sugar please #coffeeaddict #carbs #gradlife
Alison Vickman received a B.S. degree in Chemistry from St. Norbert College (De Pere, WI) in 2013. During her undergraduate career, she worked with Dr. Jonathon Russel on the selective functionalization of indolines and interned with Kimberly-Clark for two years in formulation development and materials science. She is currently pursuing a Ph.D. in Organic Chemistry with a Chemical Biology minor at Indiana University¬–Bloomington under the supervision of Dr. Nicola Pohl. Her doctoral research is focused on using computational methods to investigate the conformational preference of carbohydrate derivatives, with the goal of formulating straightforward rules to govern carbohydrate reactivity and drive quicker, more efficient chemical syntheses. Upon completion of her graduate studies, she would like to pursue a career in cosmetic formulation.
Towards Rules for Carbohydrate Synthesis: A Computational Study of the Effects
of Varying the 6-Position Oxidation State of Hexopyranoses
Department of Chemistry, Indiana University, Bloomington, IN 47405; Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Korea; Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon 305-701, Korea
Knowledge of multi-dimensional carbohydrate structure is essential when delineating structure-function relationships in the development of analytical techniques such as ion mobility mass spectrometry and of carbohydrate-therapeutics, as well as in rationally modifying the chemical and physical properties of drugs and materials based on sugars. This work comprises the first systematic computational study of all the possible glucose stereoisomers that probes the electronic and steric implications of oxidizing or reducing the hydroxymethyl substituent at the 6-position (C-6) to the carboxylic acid or methyl group. The conformational space of all eight glucose stereoisomers, as well as the corresponding 6-deoxyhexose and uronic acid derivatives, was evaluated using density functional theory (M05-2X/cc-pVTZ(-f)) to determine the conformational and anomeric preference for each sugar in the gas phase. All 6-deoxyhexose and hexopyranose isomers were found to favor the 4C1 conformation, while an increase of the oxidation state at C-6 was shown to shift the equilibrium in favor of the alternate 1C4 chair for B-alluronic acid, B-guluronic acid, and B-iduronic acid. Oxidation and reduction at the C-6 position also showed a significant effect on the anomeric stability of select isomers, where anomeric preference was found to be dependent on both the stereochemistry and identity of exocyclic substituents distant from the anomeric center. Several isomers were observed to shift preference to the alternate anomer upon oxidation or reduction. Using computational methods to quickly uncover specific structure-reactivity relationships will provide a more structured and focused approach to experimental design and will hopefully lead to the development of synthetic rules that can be used to drive more efficient carbohydrate syntheses. These intriguing findings also point to many future experimental possibilities to test the predictive role of such ground state structures in determining glycosylation reaction outcomes.