(1) Photoredox catalysis: Photoredox catalysis is one of the emerging areas of organic synthesis, drawing the attention of many scientists across the globe. In these approaches, visible light energy transforms into chemical energy in the presence of organic dyes and metal complexes. These photocatalysts or dyes get excited selectively in the presence of visible light irradiation and at a wavelength where normal organic molecules do not absorb. These excited photocatalysts or dyes can either undergo oxidation or reduction thereby providing a reaction environment that is unique in organic chemistry.