CBC Seminar, Dr. Stavros Kariofillis - Visible Light in Catalysis: Exploring Cross-Coupling and Protein Modification

Chemistry & Biochemistry Seminar

Visible Light in Catalysis: Exploring Cross-Coupling and Protein Modification

Dr. Stavros Kariofillis

Abstract: Photoredox catalysis has emerged as a powerful strategy for activating small molecules to reactive intermediates under mild conditions. In these reactions, a transition metal complex or organic dye converts visible light into chemical energy by engaging in single-electron or energy transfer steps. This talk will describe the implementation of photoredox catalysis in a broad range of applications. First, methods that generate unstabilized radicals, with an emphasis on methyl radicals, will be described for the methylation of late-stage aryl halides. Critical to the success of these reactions is the photocatalytic generation of chlorine and bromine radicals to activate strong C(sp3)–H bonds, followed by bond scission processes merged with nickel-catalyzed cross-coupling. In one of these methods, a new data science-driven approach for generating diverse and representative substrate scopes using a conserved number of molecules is reported. Then, applications of photoredox catalysis towards protein labeling will be covered. These methods employ osmium catalysts to mediate the conversion of aryl(trifluoromethyl) diazo compounds to carbenes. The resulting carbenes rapidly tag proteins in a highly localized fashion using tissue-penetrable red light. This technology is translated to cell lysates and living cells, demonstrating that labeling proceeds within a very tight radius relative to a protein of interest.