Connect via Zoom here!
Development and Application of Low-Energy Photoredox Catalysis Methodologies
Presented By: Katherine Beck
Abstract:
The development and application of photoredox methodologies in organic synthesis is a powerful paradigm in the synthesis of value-added products. While conventional methods of photoredox catalysis employ ultraviolet (UV) or blue light, the associated high energies can lead to deleterious off-cycle pathways and the formation of undesired byproducts. Transitioning to a low-energy (i.e. red/orange) light manifold can mitigate some of these challenges and promote batch-scale reactivity. We first show standardized syntheses and photophysical/electrochemical characterizations of a library of OsII polypyridyl complexes activatable by red light and demonstrate their application in metallaphotoredox-assisted aryl etherification. Thereafter, we leverage the advantages of spin-forbidden excitation (SFE) in the activation of novel IrIII photocatalysts, showing the first known examples of C(sp2)–C(sp3) bond formation with low-energy light. We further utilize the low triplet energy and high redox versatility of an orange light photocatalyst to enable unified oxidative/reductive pathways in decarboxylative arylation, the first such photoredox system to effect dual catalytic manifolds in this reaction paradigm with broadly similar reaction conditions, and additionally show an example of cross-electrophile coupling enabled by orange light and a feedstock amine as an XAT reagent.
