UC San Diego

Cyclic compounds are ubiquitous in natural products and FDA approved drug molecules. A sustainable, efficient, and readily accessible method for direct access to cyclic compounds under mild reaction conditions is highly desired in modern synthetic chemistry. The emerging visible-light-driven photocatalysis, which shows complementary reactivity to the conventional method, has been developed as a powerful tool for making valuable cyclic compounds. Among this catalytic category, heterogeneous photocatalysis showcases significant advantages, such as low cost, high photostability and facile regeneration of photocatalysts as well as unique photochemical selectivity and reactivity relative to those of homogeneous photocatalysis. Our group has shown that lead-halide perovskite nanocrystals (LHP NCs), a material with demonstrated excellent photophysical properties in photovoltaics, can be a promising heterogeneous visible-light photocatalyst for organic transformations. Because an efficient photocatalytic reaction can also essentially benefit from the LHP NCs’ intensive visible light absorption, long charge carrier lifetime, long charge carrier diffusion length and high charge carrier mobility. These critical photophysical properties of LHP NCs along with the basic principles of visible-light-driven photocatalysis and an overview of other typical heterogeneous photocatalysts for ring-forming reactions have been discussed in Chapter 1. This dissertation further advances the application of the LHP NCs as visible-light photocatalysts towards some synthetically challenging, biorelevant cyclic compounds syntheses. Specifically, the photocatalytic synthesis of pharmaceutically important N-heterocycles (pyrroles and pyrazoles) is detailed in Chapter 2. The photocatalytic highly regio- and diastereoselective synthesis of cyclobutanes, a class of scaffolds that are widely present in natural compounds, is detailed in Chapter 3. Lastly, the photocatalytic synthesis of medicinally relevant vinylcyclopentanes is detailed in Chapter 4. The works described in this dissertation may lay the foundation for the design and development of highly valuable photocatalytic ring-forming reactions that directly benefit from the unique photophysical and photochemical properties of heterogeneous lead-halide perovskite nanocrystals photocatalysts.