Abstract: Selectivity has always been a major goal in any chemical processes, and particularly in organic synthesis. It is thus not surprising that more and more selective reagents have been developed in the last few decades. In photochemical reactions, the light can be considered as one of the reactants. Among the parameters characterizing the light, the wavelength is undoubtedly the most easily tunable one. This project aims at developing a set of functional groups that can be selectively activated by monochromatic light at various wavelengths, either to form bonds (eg. photoacylation) or to break bonds (eg. photodeprotection).