Homogeneous decatungstate-catalyzed photooxygenation of tetrasubstituted alkenes: a deuterium kinetic isotope effect study

The decatungstate W10O32(4-) homogeneous photocatalyzed oxygenation of tetrasubstituted alkenes has been mechanistically studied. In all cases, allylic hydroperoxides are the major products. The primary inter- and intramolecular as well as the remote delta-secondary deuterium kinetic isotope effects for the photooxidation of the 2,3-dimethyl-2-butene and 1,1,1-trideuterio-7-methyl-2-(trideuteriomethyl)octa-2,6-diene along with product analysis suggest a hydrogen abstraction in the rate-determining step. For comparison, singlet oxygen photosensitized oxidations of the above substrates were also studied.