| Summary: | 碩士 === 國立臺灣大學 === 化學研究所 === 93 === 2,2''-di(phenylethynyl)-biphenyls undergo thermal cyclization reaction at high temperature (260℃) to yield compound 6. To probe the reaction mechanism, a series of 2,2''-di (phenylethynyl)-4,4''-disubstitued-biphenyl were synthesized and then were subjected to the reeaction conditions . In order to differentiate the diradical or benzocyclobutadiene mechanism, we added tetraphenylcyclo- pentadienone to trap the intermediate. Cyclooctatetraene derivatives, which were derived from addition reaction of tetraphenylcyclopentadienone and benzocyclobutadiene intermediate, were finally isolated. As a result, we concluded that the cyclization proceeds through the benzocyclobutadiene process. However the possibility of the diradical pathway couldn’t be completely excluded. We also explored the effects of the 4,4’-disubstitued functional groups on the thermal cyclization reaction.
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