Maria C. Milletti, PhD, Eastern Michigan University
During this second year of the grant we have explored the role of the following variables in determining stereoselectivity:
For each of the substrates described below, we map the energy profile for the key steps of the reaction, including coordination of the acid catalyst to the oxazolidine starting material to produce the iminium cation intermediate, a series of C-C bond rotations that lead to the other possible stereoconformers and can interconvert among them, and the rate-determining aza-Cope rearrangement for each of the stereoisomers. A comparison of the activation barriers for these key steps will shed light on the factors that determine the observed stereochemical product ratios and enable us to suggest ways to improve it.
Results obtained to date are described below:
During the third year of the grant we will focus on three areas of inquiry:
1) exploration of the aza-Prins-pinacol mechanism as an alternative to the aza-Cope – Mannich mechanism;
2) continue to investigate whether the use of chiral catalysts can improve product stereoselectivity;
3) the effect of substituents at various positions of the oxazolidine starting material, including an electronegative protecting group at the iminium position and a series of aryl substituents at the carbon adjacent to the nitrogen of the oxazolidine ring.
This project is in collaboration with one of my colleagues at Eastern Michigan University, Prof. Harriet Lindsay, who is carrying out the experimental work. The grant has allowed me to make significant progress on the project by giving me the opportunity to hire student researchers. Prof. Lindsay and I plan to submit a grant proposal to NSF by the end of the year to secure continued funding for this joint project.
In addition, financial support from this grant provided my students with the opportunity to present their results at the ACS Central Regional meeting in May of this year and at the ACS Fall National Meeting in September. Participation at both events gave them confidence in their abilities to do research at a professional level and an opportunity to hear about areas of chemistry other than our own computational field.
The increased activity in my lab has also been an excellent recruiting tool and two new students joined our research group in January. I am sure that this academic year will be a very productive one.
[1] Vedejs, E. Shapland, P.; J. Org. Chem. 2006, 71, 6666-6669.
[2] Lindsay, H.A. and Pendleton, I., unpublished data, Eastern Michigan University, 2012.
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