Chromatic orthogonality in organic synthesis

A major challenge in organic synthesis is the selective reaction of a functional group in the presence of others. This can be achieved by using an appropriate reagent, tuned to react exclusively at the desired center. An alternate approach would be to use a single reagent, and to transmit from the outside the information as to where it should react. This account describes the use of light as a controlling element; indeed, in addition to the intensity, changing the wavelength gives an additional handle to direct the chemoselectivity.