AbstractSubstituted methylidenecyclopropanes12a–d, being easily available from 1,1‐dibromo‐2‐(phenylthio)‐cyclopropane (9a), are attractive precursors of triafulvene (2‐methylidene‐1‐cyclopropene;1). Both the sulfoxide12band the sulfone12creact with an excess of alkoxides (t‐BuOK and NaOMe) to give12eand12f, respectively, while the sulfinyl group of12bmay be replaced by the PhCH2S substituent in the presence of PhCH2SH/t‐BuOK. These reactions (Scheme 4) may be explained by assuming1as a reactive intermediate, although an alternative sequence including carbene20(Scheme 6) is not completely ruled out.D‐labelling experiments (Scheme 5) do not give conclusive evidence due to D scrambling, but deprotonation/methylation sequences show that HC(2) of12a–cis the most acidic proton. Final evidence for1results from the reaction of12dwith cyclopentadienide(Scheme 7):the reaction of1with cyclopentadiene produces the expected [4 + 2]‐cycloaddition product23, while some mechanistic insight results