Photooxidation of several mesoionic compounds gave ring cleavage products, some of which were apparently formed via the endoperoxides of the mesoionicrings. Photooxidation of a Δ2-oxazolin-4-one and a Δ2-thiazolin-4-one gave the corresponding 4,4′-bisoxa- and bisthiazolinone in dichloromethane, whereas the former gave benzamide in dimethylformamide.
Photochemical and Thermal Reactions of Heterocycles. IV. Phooto-oxidation Reactions of Mesoionic Dithioliumolate, Thiazoliumolate, and Related Heterocycles. Solvent Effects of the Course of the Photo-oxidation