Date of Graduation

12-2021

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Chemistry (PhD)

Degree Level

Graduate

Department

Chemistry & Biochemistry

Advisor/Mentor

Matt McIntosh

Committee Member

Nan Zheng

Second Committee Member

Joshua Sakon

Third Committee Member

Wesley Stites

Keywords

homolysis reactions, low temperature homolysis

Abstract

Thermal homolysis is one of the most fundamental reactions in organic chemistry. Free radical reactions are generally initiated by light or a radical initiator to generate the first radical, which can then propagate or terminate the reaction. Direct thermal homolysis requires no chemical initiators, just an increase in temperature depending on the homolysis energy.There are few studies of direct radical homolysis in complex systems or under mild conditions. The reactions involving C-N homolysis under mild conditions are reported in Chapter 1. Though the authors do not all propose a radical mechanism, we believe they can all be explained by a radical mechanism similar to our own chemistry reported in the later chapters. These all involve an electron rich alkene intermediate, which we believe to be especially prone to homolysis based on DFT calculations and our own research presented in this work.

We have uncovered multiple C-N homolysis reactions from electron rich alkenes. The first, is a Breslow intermediate that undergoes facile rearrangement from the enolate when a benzyl group is installed on the azolium nitrogen atom. This reaction leads to products consistent with a radical mechanism, and those previously reported by our group. Second, is a reaction that generates 2-alkyl pyridines from an electron rich enamine. This C-N homolysis requires heat, but the products are also consistent with a radical mechanism. Currently efforts are underway to expand the scope of this chemistry to include heterocycles with fused rings.

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