Abstract

Tunable Asymmetric Photochemical Induction in Flow

Amanda Evans, Assistant Professor, California State University Fullerton

This talk will focus on the use of circularly polarized (cp), or “chiral”, light as a supramolecular enantioinductive field for the generation of asymmetric building blocks as a continuous photochemical process. Enantioselective chiral photolysis of small molecules has already been achieved under batch, solid-phase conditions: using synchrotron-sourced cp light, asymmetric photolytic selectivities of up to 4.2% enantiomeric excess (e.e.) have been reported. To determine the optimal wavelengths to use for irradiation with cp light for any given molecular building block, CD and anisotropy spectra for each building block of interest have been generated in two different solvents (water, hexafluoroisopropanol) across a range of wavelengths (130-400 nm). These spectra have been used to optimize conditions for a series of continuous photochemical processing experiments performed using synchrotron-sourced cp light as the sole source of enantioinduction for a family of small molecules. A mechanism for this enantioinduction and methods for enhancing the initial selectivities observed will be discussed, and predictive approaches for describing the behavior of similar small molecules will also be presented.