-fluorenes was achieved by using Dewarbenzenes as important intermediates. The corresponding Dewarbenzenes were prepared by reactions of tetraalkylcyclobutadiene–AlCl3 complexes with methyl phenylpropynoate. Their subsequent hydrolysis followed by photochemical rearrangement provided substituted biphenylcarboxylic acids. Treatment of the prepared acids with thionyl chloride gave rise to the fluorenones