Organische Photochemie, XIV. Photoreaktionen sulfinylsubstituierter Carbonsäure‐, Thiocarbonsäure‐ und Selenocarbonsäurederivate in Lösung; lichtinduzierte Säurespaltungen, Heterocyclenbildungen und Photosubstitutionen

Deoxygenation and Other Photochemical Reactions of Aromatic Selenoxides1

“…Direct photolysis of dibenzothiophene- S -oxide (DBTO) has been suggested as a source of atomic oxygen O( 3 P) in solution. − This assertion is based on the observation that it produces dibenzothiophene (DBT) and solvent oxidation products consistent with expectations for O( 3 P) along with experiments that demonstrate the reaction is unimolecular in sulfoxide and has a low activation barrier. While deoxygenation is a relatively common process in the photochemistry of aromatic sulfoxides, in most cases the sulfide is only a minor component of the product mixture. − However, with DBTO and some related thiophene derivatives, the oxidation products and DBT can be obtained in high chemical yield. − ,− Substantial evidence points toward a unimolecular mechanism for sulfoxide deoxygenation, but establishment of O( 3 P) as the principal reactive intermediate has not been definitively achieved, due largely to the lack of direct detection. This paper concerns the extension of this chemistry to the selenium analogue, describing the greatly enhanced photochemical efficiency of the process and evidence for a reaction pathway parallel to that of the sulfoxide.…”