The central goal of research in the Yoon Group is to develop strategies for the controlled synthesis of complex organic molecules. We are particularly interested in photochemical synthesis because of the distinctive reactivity available from excited-state compounds. Controlling the stereoselectivity, chemoselectivity, and regioselectivity of complex photoreactions requires the development of new catalytic principles for modulating the reactivity of high-energy reactive intermediates. The resulting methods have applications in total synthesis and pharmaceutical chemistry.