Direct observation for the cyclization of a diarylcarbonyl oxide

Trapping and laser flash spectroscopic experiments showed that the cyclization of diphenylcarbonyl oxide is turned into a very facile process by introducing p-methoxyl substituent, the lifetime of which is as short as 10−8 s. The trapping with diphenylsulfide and -sulfoxide suggested the intervention of a dioxirane intermediate.