Reaction of 1,2-Dimethoxybiphenylene with Dichlorocarbene. Chemical Detection of the Bond Fixation in Biphenylene Derivatives

Article abstract of DOI:10.1246/bcsj.53.2334

1,2-Dimethoxybiphenylene reacted with dichlorocarbene to give three chloro(methoxy)-6H-benzo<3,4>-cyclobuta<1,2>cyclohepten-6-one derivatives, two chloro(methoxy)fluorenones and two dimethoxyfluorenones.The reaction with dibromocarbene gave similar products.The formation of these products serves an unequivocal chemical evidence for bond fixation of 1,2-dimethoxybiphenylene.The chloro(methoxy)-6H-benzo<3,4>cyclobuta<1,2>cyclohepten-6-one was led to 9-chloro-5-hydroxy-6H-benzo<3,4>cyclobuta<1,2>cyclohepten-6-one, the first tropolone analogue of biphenylene.This compound was shown to exist in only one of the two possible tautomers in contrast with general monocyclic tropolones.