Author ORCID Identifier

https://orcid.org/0009-0003-3475-9306

Semester

Summer

Date of Graduation

2024

Document Type

Dissertation

Degree Type

PhD

College

Eberly College of Arts and Sciences

Department

Chemistry

Committee Chair

Brian Popp

Committee Co-Chair

Gregory Dudley

Committee Member

Gregory Dudley

Committee Member

Margaret Hilton

Committee Member

Carsten Milsmann

Committee Member

Werner Geldenhuys

Abstract

As a major greenhouse gas, carbon dioxide (CO2) is an abundant and renewable C1 feedstock, and developing methods for fixing CO2 into high-value products is a major interest for the movement of greener chemistry. The boracarboxylation of alkenes provides access to difunctionalized products containing pharmaceutically relevant motifs, including carboxylic acids and boron-containing moieties. Significant work has been done to improve the versatility and efficiency of this methodology, with the recent expansion into a wide variety of terminal alkenes. The use of different phosphine and alkene additives have demonstrated positive effects on reaction rates and productivity, indicating the need for further understanding of the additive effects on the different aspects of the boracarboxylation mechanism.

Extensive mechanistic investigations have been performed to experimentally probe the effects of various additives on the system. A series of IPrCu(β-borylalkyl) complexes were synthesized to examine the insertion of the alkene substrate into the copper-boryl bond. These studies revealed an unexpected regioselective alkene insertion that was unique to the stoichiometric methodology and fully depended on the presence of the additive, Xantphos, which would selectively promote the 2,1-alkene insertion observed catalytically. Effects of Xantphos on the rates of carboxylation of the IPrCu(β-borylalkyl) complexes were also explored, but Xantphos did not prove influential in rate of carboxylation.

The 1,2-alkene insertion of the alkene into the copper-boryl bond was explored further. It was found that these copper-alkyl intermediate could be effectively carboyxlated, leading the development of the novel 1,2-boracarboxylation of alkenes, which was achieved through stoichiometric rather than catalytic conditions. A variety of alkenes were amenable to this methodology, including cyclic alkenes, which were not accessible through catalytic boracarboxylation. Interestingly, α-substituted olefins that were inaccessibly catalytically exhibited exclusively 2,1-boracarboxylation, similar to previously observed vinyl arenes. Stoichiometric boracarboxylation provides access a new class of difunctionalized, pharmaceutically relevant molecules, opening new avenues for this methodology.

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