L. Næsborg

Over the last century UV‐light mediated processes gave access to synthetically valuable products. Some of the disadvantages encountered when performing such UV‐light triggered synthetic reactions are the necessity for special glassware (quartz), the environmentally unfriendly irradiation sources and the need for oxygen removal, often via time consuming freeze‐pump‐thaw cycles. In addition, the penetration of UV‐light into the reaction mixture is a challenge due to absorption effects and scattering. A solution to these disadvantages could be triplet‐triplet annihilation upconversion performed under micellar reaction conditions. Hereby, UV‐light can be generated in the reaction mixture using visible light irradiation. In addition, the aqueous micellar medium can allow for the process to occur without the need for oxygen removal. This concept has been sporadically demonstrated and holds a great promise for the development of UV‐light promoted photochemical reactions under milder and more benign reaction conditions that may eventually allow for the development of scale up protocols.