Covalent intermediates in flavin-sensitized photodehydrogenation and photodecarboxylation.

The photoreactions of the flavin triplet with unsaturated hydrocarbons, aldehydes, sulphur compounds, and carbonic acids are reported. These reactions proceed by attack at the allylic C-H-, the RCO-H-, or the α-C-H-bond, respectively; in the case of carbonic acids decarboxylation occurs. In all the reported reactions covalent adducts are formed, whose structure and mode of decay is characterized.