Design of cyclic reaction driven by two-color two-photon excitation

We propose a new cyclic reaction based on the concept of two-color two-photon excitation. N-Methylphtalimide (MePI)-linked 4-methoxybenzophenone (MeOBP) was synthesized. The excited benzophenone ketyl radical formed by the two-color two-photon excitation reduces the MePI moiety to form the diphenylmethanol cation and the MePI radical anion (MePI center dot-). The cation quickly deprotonates to regenerate MeOBP. In the presence of an appropriate electron acceptor, MePI center dot- reduces the acceptors to regenerate the initial state. As a result, the circular reaction is completed. The proposed cyclic reaction produces one reducing reagent (radical anion) and one proton from two photons (UV and vis light) and a hydrogen donor.