Novel photoredox and photoinduced approaches for synthetic applications

The use of light as activation mode for organic molecules is surely one of the oldest concepts in the universe. In fact, organic photochemistry is almost as old as organic chemistry itself. However, for long time the field remained mostly unexplored, and the applications limited. Only now, with depauperate reserves of fossil fuels, a quest for more sustainable energy sources to feed our processes started. Light, omnipresent on our planet and in the universe, makes the perfect candidate as source of green energy. After more than a hundred years humanity is eventually answering the hopes of Giacomo Ciamician, that envisioned a light-driven world already in 1912. Within the context of this steadily expanding field, the aim of the present thesis was to expand the synthetic toolbox of light driven transformation available to an organic chemist. The Introduction to this thesis will deliver to the readers less acquianted with modern photochemical processes the necessary background and theoretical context for the treated arguments. Within Chapters 2-4, each project is discussed in details after a shorter state-of-the art introduction. Chapter 2 presents the results of the recent merger between isocyanide-based multicomponent reactions and visible light activation. The development of a more selective, facile and effective protocol for performing ketene multicomponent reactions is discussed. The products achieved from the multicomponent transformation were then used for the stereoselective synthesis of simplified analogues of bioactive natural compounds, discussed in the second part of the chapter. A study aimed to the radical functionalization of olefins exploiting light induced protocols is presented in Chapter 3. Several approaches to achieve the desired functionalization are discussed, and the presented results, although yet not conclusive, represent a good leap forward towards the mild functionalization of olefin substrates. In the light of the recent Nobel prize awarded for the development of organocatalysis, I had the pleasure of working on the topic of enantioselective photoorganocatalysed processes towards the functionalization of enals. The results of my efforts are reported in Chapter 4.