NEW CHEMISTRY OF ZWITTERIONIC PEROXIDES ARISING BY PHOTOOXYGENATION OF ENOL ETHERS

Article abstract of DOI:10.1016/S0040-4020(01)96578-0

The rose bengal-sensitized photooxygenation of 2-methoxynorborn-2-ene (1) in acetaldehyde gave cis-1-carboxaldehyde-3-carbomethoxycyclopentane (31percent) and the cis and trans-Me derivatives of the cis-fused exo-1,2,4-trioxanes arising by addition of a molecule of oxygen and acetaldehyde to 1 at C3 and C2 respectively (13percent).Similar photooxygenation of 2-(methoxymetylidene)adamantane in the presence of acetaldehyde, propionaldehyde and pivalaldehyde gave adamantanone (31-42percent), and the cis and trans tricyclo<3.3.1.1^3.7>decane-2-spiro-6'-<3-alkyl-5-methoxy-1,2,4-trioxanes> in yields of 32-53percent.Trioxane formation under similar conditions was experienced for 1,1-di-t-butyl-2-methoxyethene and 2-(methylmercaptomethylidene)adamantane.The results are discussed in terms of an intermediate zwitterionic peroxide which can either close directly to a 1,2-dioxetane or, if aldehyde is present, condense across the CO function giving the 1,2,4-trioxane.