α-Ferrocenylvinylacetylenes

Thermolysis of 3-isopropyl- and 3-cyclobutyl-3-ferrocenylcyclopropenes results in the formation of 3-alkylidene-3-ferrocenylpropynes and (Z,E)-1-alkyl-1-ferrocenylpropenes; 2,2-dibromo-1-methyl-, 2,2-dibromo-1-isopropyl- and 2,2-dibromo-1-cyclobutylferrocenylcyclopropanes are converted into ferrocenylvinylacetylenes on treatment with Bu^tOK in THF.