CHAPTER 6: Colored Compounds for Eco-sustainable Visible-light Promoted Syntheses

In the frame of eco-sustainable synthesis, photochemistry has acquired a predominant role in recent years. This implies the use of photons as the real green reagents to promote chemical reactions, with no waste to remove at the end of the process. However, the adoption of UV-photons involves a high electricity cost not suitable for industrial applications. Different strategies have been devised to use cheap visible light sources, but these require the presence of an additive or a photocatalyst to make photoreactive colorless organic compounds. However, it is important to stress that there are classes of colored compounds that can be very useful for the construction of molecular scaffolds present in bioactive compounds. The aim of this chapter is to collect selected photochemical reactions occurring on colored compounds and their application in synthesis.