Etudes mécanistiques de la désoxygénation photocatalytique des liaisons N-O et S-O

The deoxygenation of N–O and S–O bonds is a chemical challenge. It represents an essential step in asymmetric synthesis of pharmaceutical interest, as well as an important strategy for mitigating greenhouse gases such as nitrous oxide (N₂O). These reactions currently rely on thermochemical methods that require high temperatures and/or sacrificial reducing agents used in stoichiometric amounts. In this thesis, we have developed new photocatalytic methods for the deoxygenation of N–O and S–O bonds under ambient conditions, using light and selective and efficient transition-metal-based catalysts. The mechanisms underlying these transformations were investigated through various spectroscopic techniques, including time-resolved photophysical analysis, which provide access to the initial stages of photocatalysis and to short-lived transient species. This work led to the design and characterization of robust photocatalysts capable of selectively activating N–O and S–O bonds under mild conditions, while offering depth insights into the reaction mechanisms involved. Altogether, these studies pave the way for more sustainable processes aligned with the principles of green chemistry.