REACTION OF O-1(2) WITH STRAINED OLEFINS .3. PHOTO-OXIDATION OF VINYLCYCLOPROPANES

The reaction of O2 with 1, 1-dicyclopropylpropene (13) and its 2-methyl analogue (12) yields two “ene” products corresponding to the abstraction of an allylic hydrogen from either the methyl or the cyclopropyl group. In the latter case an alkylidenecyclopropane is formed despite a resulting 11.4 kcal/mol increase in strain energy. This indicates that 402 is insensitive to any strain that might develop in the final product. In contradistinction, 2-cyclopropyl-3-methyl-2-butene (14) yields no alkylidenecyclopropane product, but this is explicable in terms of conformational analysis. 1, 1-Dicyclopropylethylene (15) yields only the corresponding ketone and polymer by what is most probably a free-radical process. Kinetic data indicate that the unperturbed vinylcyclopropane double bond is not particularly electron rich. The question of mechanism for the ene mode of O2 attack is discussed in light of this study. © 1979, American Chemical Society. All rights reserved.