Regioselectivity in the ene-reaction of singlet oxygen with cyclic alkenes: photooxygenation of methyl-substituted 1,4-cyclohexadiene derivatives


Yardimci S. D. , Kaya N., Balci M.

TETRAHEDRON, vol.62, no.46, pp.10633-10638, 2006 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 62 Issue: 46
  • Publication Date: 2006
  • Doi Number: 10.1016/j.tet.2006.07.103
  • Title of Journal : TETRAHEDRON
  • Page Numbers: pp.10633-10638
  • Keywords: singlet oxygen, endoperoxide, hydroperoxide, photooxygenation, ene-reaction, hydrocarbons, SYNTHETIC APPLICATIONS, PROTO-QUERCITOL, CARBA-SUGARS, CONDURITOLS, MECHANISM, OLEFINS, INTERMEDIATE, STREPTOMYCES, PREFERENCE, CHEMISTRY

Abstract

The photooxygenation of the 1-methyl-, 2,3-dimethyl-, and 1,4-dimethylcyclohexa-1,4-dienes, which are readily available through Birch reduction, yielded the corresponding ene-products. The formed endocyclic dienes were trapped by the addition of singlet oxygen to give the corresponding bicyclic endoperoxy hydroperoxides. In the case of 1-methylcyclohexa-1,4-diene and 1,4-dimethylcyclohexa-1,4,-diene, the cis-effect determined the product distribution. Photooxygenation of 2,3-dimethylcyclohexa-1,4-dienes gave mainly exocyclic olefin, which was attributed to the lowered rotational barrier of the methyl group and increased reactivity of the methyl groups. (c) 2006 Elsevier Ltd. All rights reserved.