Phenyl-cyclo-propene

Klett and Johnson have demonstrated the interrelationship between the photoreactions of allenes (93) and cyclopropenes. Their results indicate that irradiation of (93) leads to the carbenes (94) and (95) such carbenes have been proposed as the key intermediates in the photoreactions of cyclopropenes. Thus the irradiation of (93a) yields the indene (96) as the primary photo-pnoduct via the carbene (94) produced by phenyl migration. With aUene (93b) irradiation affords the carbene (95), by hydrogen migration, which then reacts to form photoproducts (97)—(99). For comparison, the irradiation of cyclo-propene (100) was carried out it yielded the allene (93b) and the two indenes (97) and (99). 

In a similar manner 1,3-di-ferf-butyl-2-phenylcyclopropenc (4) gave both di- ert-buty 1- and tert-butyl(phenyl)acetylenes, as well as an enone derived from the normal epoxidation of the cyclo-propene double bond. The mechanism by which the alkynes are formed is not clear, although radical scavengers did not significantly affect the reaction and addition of acetate did not lead to this being incorporated. 

Analog erhalt man aus 1-Phenyl-propen J-Phenyl-propan6 bzw. aus 4-Methyl-cyclo-hexen 4-Methyl-cyclohexan6. 

---