Event Title

Photoredox-Mediated Alkylation of Imines with Potassium Organotrifluoroborates in the Presence of an Organic Photocatalyst

Session Title

STEM and Biomedical Research

Document Type

Oral Presentation

Faculty Mentor

James M. Hanna Jr., Ph.D.

College

College of Arts and Sciences

Department

Department of Chemistry, Physics, and Geology

Description

Recently, the use of visible light combined with a suitable photocatalyst to promote key bond-forming steps in organic synthesis has emerged as a viable strategy to achieve a number of important synthetic transformations. The photocatalyst involved is often a ruthenium or iridium polypyridyl complex, which absorbs light in the visible range to give a relatively long-lived excited state, which may engage organic substrates in a series of single-electron-transfer (SET) events. The organic radicals thus generated participate in downstream reactions leading to the final product(s). During previous research, this strategy for the alkylation of aldimines with potassium organotrifluoroborates using transition-metal photocatalysts was deployed. However, because of the much lower cost of organic photocatalysts (approximately $50/mmol for acridinium-based catalysts versus $1,000/mmol for Ir-based catalysts), it was desired to explore the use of organic photocatalysts in this transformation. Optimization studies using the reaction of potassium isopropyltrifluoroborate with benzalaniline revealed that the photocatalyst 9-mesityl-10-methylacridinium tetrafluoroborate (Mes-Acr-Me) in dichloromethane gave the best yields of alkylation product, N-(2-methyl-1-phenylpropyl)aniline. In this presentation, the results of current efforts to expand the scope of the protocol to other imines and potassium organotrifluoroborates will be described.

Previously Presented/Performed?

Southeast Regional Meeting of the American Chemical Society (SERMACS), Savannah, Georgia, October 2019; NC Photochem, Boone, North Carolina, October 2019; Sixth Annual Showcase of Undergraduate Research and Creative Endeavors (SOURCE), Winthrop University, April 2020

Grant Support?

Supported by the Donors of the American Chemical Society Petroleum Research Fund, and by an SC INBRE grant from the National Institute for General Medical Sciences (NIH-NIGMS)

Awards Won

Second Place, Best Undergraduate Poster, NC Photochem, October 2019

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Apr 24th, 12:00 AM

Photoredox-Mediated Alkylation of Imines with Potassium Organotrifluoroborates in the Presence of an Organic Photocatalyst

Recently, the use of visible light combined with a suitable photocatalyst to promote key bond-forming steps in organic synthesis has emerged as a viable strategy to achieve a number of important synthetic transformations. The photocatalyst involved is often a ruthenium or iridium polypyridyl complex, which absorbs light in the visible range to give a relatively long-lived excited state, which may engage organic substrates in a series of single-electron-transfer (SET) events. The organic radicals thus generated participate in downstream reactions leading to the final product(s). During previous research, this strategy for the alkylation of aldimines with potassium organotrifluoroborates using transition-metal photocatalysts was deployed. However, because of the much lower cost of organic photocatalysts (approximately $50/mmol for acridinium-based catalysts versus $1,000/mmol for Ir-based catalysts), it was desired to explore the use of organic photocatalysts in this transformation. Optimization studies using the reaction of potassium isopropyltrifluoroborate with benzalaniline revealed that the photocatalyst 9-mesityl-10-methylacridinium tetrafluoroborate (Mes-Acr-Me) in dichloromethane gave the best yields of alkylation product, N-(2-methyl-1-phenylpropyl)aniline. In this presentation, the results of current efforts to expand the scope of the protocol to other imines and potassium organotrifluoroborates will be described.