Photosensitized Oxygenation of Carbonyl Stabilized Sulfur and Pyridinium Ylids, and Related Diazo Compounds. Carbon‐sulfur and Nitrogen Bond Cleavages

The dye sensitized photooxygenation of sulfur and pyridinium ylids proceeds by way of singlet oxygen under the reaction conditions studied. The most remarkable results were that dimethyl sulfoxide and pyridine were obtained in the photooxygenations of oxosulfonium and pyridinium methy‐lids, respectively. as the major cleavage products. These results suggested that the 1,2‐dioxetane like intermediates were not significant ones in these reactions. The oxygenation reactions in the presence of diphenyl sulfide which was known as the most unreactive one to singlet oxygen afforded diphenyl sulfoxide efficiently. A new type of intermediate instead of 1,2‐dioxetane. that can monooxygenate the substrate may be formed. Photosensitized oxygenations of corresponding diazo compounds were also studied.