Guest speaker: Dr. Jeffrey Lipshultz

Title:

Synthetic Methods Enabled by the Rational Design of Photoactive Catalyst-Substrate Complexes

Abstract:

Photocatalysis typically employs a discrete, photoactive species which can repeatedly access a photoexcited state and then transfer its chemical potential energy (via electron or energy transfer) to a substrate of interest. In our work, we instead rationally design catalysts to engage productively with substrates to generate photoactive catalyst-substrate complexes, whereby excitation and substrate activation occurs simultaneously, engendering new types of selectivity and catalyst control.

Within this conceptual framework, we have developed a platform for biomimetic organocatalysis inspired by the enzymatic chemistry of Vitamin B6 for the decarboxylative functionalization of amino acids. Separately, we have adapted a synthetically underappreciated Vit B6 reactivity paradigm for amino acid homologation. In a disparate research thrust, we have employed a variety of discrete complexes of Ti(IV) as catalysts via ligand-to-metal charge-transfer (LMCT) excitation for the generation, exploitation, and control of heteroatom-centered radicals, whereby catalyst structure and electronics are tuned to optimize and dictate reaction outcomes.