Author ORCID Identifier

https://orcid.org/0000-0002-0508-2573

Semester

Spring

Date of Graduation

2024

Document Type

Thesis

Degree Type

MS

College

Eberly College of Arts and Sciences

Department

Chemistry

Committee Chair

Margaret Hilton

Committee Member

Brian Popp

Committee Member

Hacer Karatas Bristow

Abstract

Hydroxy (-OH) groups are one of the most abundant functional groups found in natural products and pharmaceuticals with many of these compounds containing multiple alcohol classes. The ability to selectively functionalize a specific α-OH C–H bond in the presence of other competitive sites would provide straightforward access to new, potentially bioactive compounds. In recent literature, photoredox catalysis has been implemented to perform site and stereoselective α-OH C–H functionalization of cis-diol containing substrates. Incorporating an organoboron cocatalyst into these systems have proven to be crucial in decreasing the bond dissociation energy (BDE) and increasing hydricity of the α-OH C–H bond for abstraction by an HAT catalyst. Although a mechanistic investigation has been performed on the alkylation of cis-diols, the relative behavior of other alcohol classes under these conditions has yet to be observed.

The successful α-OH C–H alkylation of primary alcohol, 3-phenyl-1-propanol, led to the optimization and working scope for mono-alcohols. Preliminary results observed a greater dependence on the presence of the boronic acid cocatalyst for the primary alcohol compared to the cis-diol. Similarly, an increase in reaction efficiency is observed in the presence of an electron-poor aryl boronic acid cocatalyst. When investigating initial reaction rates between these two substrates, initial alkylation rates of the primary alcohol are slower. Competition experiments demonstrated that there is preferential reactivity towards the cis-diol, while there was no detection of alkylated primary alcohol. Stoichiometric NMR experiments with the primary alcohol did provide insight into the formation of various boron-containing species under a dynamic equilibrium. The boron complex that undergoes HAT is still unknown, thus future work will focus on characterizing the most reasonable activated boron species undergoing HAT and designing a chiral-boron catalyst for site and stereoselective α-OH C–H alkylation.

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