REMOTE PARTICIPATION DURING PHOTOOXIDATION AT SULFUR - EVIDENCE FOR SULFURANE INTERMEDIATES

The photooxidations of geminally substituted gamma-hydroxy sulfides results in formation of unusual oxidative elimination products. Detailed spectral data and the independent synthesis of a close analogue provide compelling evidence for the structures of these olefins. The formation of the olefins is attributed to decomposition of sulfurane intermediates. This conclusion is supported by a detailed kinetic study which separated the chemical, k(r), and physical, k(q), components to the overall deactivation of singlet oxygen. Those sulfides with the best geometry for sulfide-hydroxyl interaction are also the substrates which react most rapidly with singlet oxygen to give oxidation products. In addition, sulfone yields are in excess of 50% for the hydroxy-substituted sulfides but less than 5% for their hydrocarbon analogues. Several mechanisms that provide explanations for these unusually high sulfone yields are presented.