ABSTRACT
In addition to avoiding the use of undesirable reagents, the method has a number of other advantages. It is atom e¤cient in the usual sense that all of the atoms in the reactant molecules end up in the product. e nature of the reaction allows molecules such as cycloalkanes and cyclic ethers, which are not functionalized in the normal sense and are most commonly encountered as solvents, to participate as H-donors. It also opens up diœerent reaction pathways for molecules, such as in the case of a secondary alcohol, which reacts through its methine hydrogen rather than in the usual way through its hydroxyl group. In many cases, the photomediator is eœective in signi£cantly substoichiometric quantities [5,6] relative to the amount of the unsaturated reactant and so its involvement does not materially aœect the atom e¤ciency of the process. An interesting property of the reaction system is that it can be driven by solar radiation [7], as two of the most widely used photomediators, benzophenone [8] and the polyoxometallate tetrabutylammonium decatungstate (TBADT) [9], absorb at approximately 350 nm, a wavelength that is available in the sunlight reaching the surface of the earth.
