Stable semiquinone radicals serve as novel molecular platforms on which a Norrish-type-II photoreaction can be initiated. A detailed reaction scheme involving a 1,5-hydrogen transfer followed by a cyclization step that finally leads to a new C—C bond formation could be verified. Transient absorption spectroscopy and DFT calculations trace convincingly the intermediates and transition states along the reaction path (see scheme).

This work was carried out under the guidance of Dr. Shi-Xia Liu (in the group of Prof. Silvio Decurtins).

References:

• J. Grilj, T. K. Todorova, C. Yi, S.-X. Liu, E. Vauthey, S. Decurtins;
  "A Spectroscopic and Computational Study of a Photoinduced Cross-Dehydrogenative Coupling Reaction of a Stable Semiquinone Radical"
  Chem. Eur. J., 18, 13605-13608, (2012); doi:10.1002/chem.201201463.