Building molecular complexity through visible light photocatalysis: Spotlight on undergraduate research

In this work, we explore the utility of visible light photocatalysis in both carbon-nitrogen (C-N) and carbon-carbon (C-C) bond-forming reactions, targeting aziridine and cyclobutane ring systems, respectively. These motifs can be found in both natural and unnatural small molecules and can both be prepared through cycloadditions promoted by ultraviolet (UV) light. However, UV light sources are expensive, hazardous to use, and often lead to unwanted reactivity. To mitigate these challenges, our methods focus on transforming and tuning photocycloaddition protocols to use lower-energy visible light (blue LEDs). Harnessing this energy with iridium bypyridyl transition metal complexes, we synthesize aziridines from electrophilic amine and alkene starting materials and cyclobutanes from vinylogous esters and enones. Central to the undergraduate research experience in our lab, is experimental design and analysis of results to improve our understanding of the mechanistic nuances of photocatalytic reactions.