Base‐Catalyzed Dehalogenation of 2,6‐Di‐ tert ‐butyl‐4‐iodophenol Formation and Structure of a New Oxocyclohexadienylidene Bisphenol

2,6‐Di‐ tert ‐butyl‐4‐iodophenol ( 1 ) does not react to the keto carbene 4 under strongly basic conditions and exclusion of oxygen, in contrast to a report in the literature. In the presence of oxygen, however, oxidation takes place. Reaction times and product pattern strongly depend on the concentration of O 2 . Besides biphenyl 2 , diphenoquinone 3 , and quinone 5 , a new (oxocyclohexadienylidene)bisphenol 6 was isolated, and its molecular structure was determined by X‐ray crystallography. A radical mechanism is suggested for the formation of the above products from 1 . The bisphenol 6 was also synthesized by thermolysis of the quinone diazide 11 in the presence of 3 .