Asymmetric Photochemical Transformations Using a Chiral Hydrogen Bond Donor

Hydrogen bond (H-bond) has long been identified as the dominant element responsible for molecular recognition and enzymatic catalytic activity in biological systems. And it has also been developed into a sophisticated and important tool in asymmetric chemical transformations. Photoreactions, notably those based on photoredox catalysis, featuring an eco-friendly and sustainable approach in synthetic chemistry, have attracted more and more attention. The merger of H-bond with photo/photoredox transformations has and certainly will orient the advance of asymmetric photoreactions. This chapter is to provide an overview of the ways in which H-bond has been applied to deal with asymmetric photocatalysis, especially focusing on contemporary developments in small molecule-weight catalysts. Particularly, mechanistically distinct modes of H-bond activation in asymmetric photochemical transformations are discussed based on published examples.