CYCLIC PEROXIDE SERIES .88. REACTION OF 7-SUBSTITUTED CYCLOHEPTATRIENES WITH SINGLET OXYGEN AND "4-PHENYL-1,2,4-TRIAZOLINE-3,5-DIONE

A series of 7-substituted cycloheptatrienes 1, including the CN, CO2CH3, CHO, OCH3, and C6H5groups, has been submitted to photosensitized singlet oxygenation and reaction with 4-phenyl-1,2,4-triazoline-3,5-dione. The yields of the nor-caradiene-type and tropilidene-type adducts 2 (1O2) and 3 (PTAD) were determined to probe the effect of the π-acceptor and π-donor properties of these substituents on the cycloheptatriene valence tautomerization equilibrium. From the yields of exo and endo products, the steric effect of the 7-substituent on the ring inversion equilibrium was examined. The novel endo-peroxides 2 of the 7-substituted cycloheptatrienes were'characterized by diimide reduction to their saturated cyclic peroxides 4, thermal isomerization to their bisepoxides 5, and deoxygenation with triphenylphosphine to their epoxy olefins 6. © 1979, American Chemical Society. All rights reserved.