A series of Me substituted 1, 2-diphenylcyclobutenes was subjected to dye-sensitized photooxidanon in the presence ofmethylene blue. In the case of the 3, 3-dimcthyl-, 3, 3, 4- tnmethyl-and 3, 3, 4, 4tetramcthyl, 2-diphcnylcyclobutencs, the sensitized oxidations arc accompanied by ring-contraction with concomitant ortho hydroxylation of one aromatic nucleus. When electron transfer induced photooxidation techniques utilizing 9, 10- ...
[Ishii, Akihiko; Ding, Meng-Xin; Maeda, Kiyoto; Nakayama, Juzo; Hoshino, Masamatsu Bulletin of the Chemical Society of Japan, 1992 , vol. 65, # 12 p. 3343 - 3349]