Advances of chiral metal complexes as standalone photocatalyst for asymmetric organic transformations

Many enantiopure chiral organic molecules are very important unit for drug discovery. Ready access to a wide range of enantiopure organic compounds, attached with one or more chiral centres significantly enhance the quality and diversity of chemical libraries for screening of drug discovery. The ability to control the stereochemistry of many organic reactions remains an area of interest in organic synthesis to allow the development of novel, structurally diverse 3D molecules. Asymmetric catalysis has been extensively studied for controlling the stereochemistry in modern synthetic organic chemistry. Recently, the use of light as the energy source with a chiral photocatalysts for photocatalytic asymmetric organic reactions has drawn much attentions but limited in numbers. The short lifetime of excited chiral photocatalysts and very fast reactions make the stereocontrol difficult in many reactions. However, by making a chiral photoactive metal complex with a suitable metal and ligands, this problem could be solved. As these chiral metal complexes are stable under light irradiation, versatile, having easy tuneable properties, these can provide more chiral inductions in many asymmetric organic reactions. So, in this review, we have focused on the recent development on chiral metal complexes as the standalone chiral photocatalysts for asymmetric organic reactions. We hope this review will help to understand the scopes and limitations to the research community in the field of asymmetric synthesis.