Visible Light Mediated Cycloaddition Reactions

This chapter reviews newly reported cycloaddition methods that use visible light. It realizes the impact of utilizing visible light to promote cycloadditions and annulations. The chapter discusses the [2+2] cycloaddition utilizing the oxidative quenching cycle. It examines [2+2] cycloaddition methodology that undergoes the energy transfer mechanism. The chapter then focuses on the advances made on [3+2] cycloadditions/annulations using visible light photoredox catalysis. It also examines the radical ion Diels-Alder cycloadditions using visible light and a ruthenium photocatalyst, to provide unique structures that Diels-Alder cycloadditions of the corresponding neutral species cannot generate. The chapter discusses the selected examples of visible light mediated cycloadditions and annulations for the construction of four-, five-, and six-membered rings. Five-membered rings, such as cyclopentanes and the heterocyclic analogs, are an important class of building blocks in organic synthesis.