Abstract: 1H-Cyclopropa [b] naphthalene (12) and 1H-cyclopropabenzene (2) are converted for the first time into the 1-alkylidene-1 H-cycloproparenes 17-22 and 27-30, respectively, via cycloproparenyl anion generation and subsequent Peterson olefination. To date the reaction sequence fails to provide parent hydrocarbons 5 and 6. The structure of (diphenyl- methy1ene) cyclopropabenzene 27 has been established by X-ray crystallographic ...