Phototransformation of the drug trazodone in aqueous solution

Irradiation of trazodone at 310 nm in water has been investigated. In addition to the OH-substitution in the chlorobenzene ring a peculiar dimerization of the dihydropyridine moiety leading to a cage-like product was involved in the photo-induced modification of the drug. The photoproducts, isolated by chromatographic techniques, have been identified by spectroscopic means. Further support of the structure of the cage-like product was sought by a comparison between the experimental chemical shifts and the values computed at the DFT level.