1,n-Radical ions. Photosensitized (electron transfer) and electrochemical oxidation of 1,1,2,2-tetraphenylcyclopropane

The photosensitized (electron transfer) and the electrochemical oxidation of 1,1,2,2-tetraphenylcyclopropane (1) have been studied. The products obtained from the photosensitized (electron transfer) study are 1,1,3,3-tetraphenylpropene (2), 1,3,3-triphenylindene (3), tetraphenylallene (4), and 3-methoxy-1,1,3,3-tetraphenylpropene (8). The product ratios are dramatically dependent upon the reaction conditions, particularly sensitizer (aromatic nitriles, tetracyanoethylene, chloranil, and 2,3-dichloro-5,6-dicyanobenzoquinone were used), and solvent. The variations in product ratios are attributed to variations in the redox behaviour of the sensitizer radical anion and upon the basicity and nucleophilicity of the medium. The products in the electrochemical study are 3, 4, and 8. Common intermediates have been identified and a mechanism for the formation of products is proposed.