The Photosensitized Oxidation of Strained Olefins

The effect of strain in determining the rate, mode and direction of singlet oxygen attack is explored using small ring olefins as substrates. The data suggests that ¹O₂ is relatively insensitive to strain considerations present in either the starting material or the product. More important factors seem to be the ground state geometry of the olefin, the interatomic distance between the α‐olefinic carbon and the γ‐allylic hydrogen, and the ionization potential of the double bond. Strain does, however, play a crucial and fascinating role in the secondary rearrangements of the primary ¹O₂ products.