Designing systems for one-way trans to cisphotoisomerization for solar reactions

We have examined triplet photosensitized isomerization of sterically crowded derivatives of stilbene, diene, triene and styrene. Under selective triplet sensitization, several such compounds proceeded in the synthetically desirable manner of complete one-way trans to cis conversion or in a highly stereoselective manner. In the process, we have identified several systems suitable for solar irradiation as a “green” procedure for preparation of hindered olefinic isomers. A simple procedure for determining the relative efficiency of a solar reaction has also been introduced.