Abstract
Photocycloaddition reaction is one of the most useful reactions to afford the unique structures, such as cyclobutanes, which are difficult to construct by a thermal reaction. Nevertheless, there are a few reports of the enantioselective photocyclization because of the difficulty of controlling racemic background reactions that occur by just excitation of substrates. This review focuses on two reports about the enantioselective catalytic intermolecular [2+2] photocycloaddition using visible light to afford chiral functionalized cyclobutenes and cyclobutanes.
