Upon treatment with organolithium compds., 2-alkyl-4,5-dihydrofurans underwent ring opening through b-elimination to give the corresponding 3,4-dien-1-ol. 3-Chloro-2-methyl-4,5-dihydrofuran gave 3-chloro-3,4-dien-1-ol as a reaction intermediate, but it could not be isolated. Its formation was slow compared to subsequent replacement of halogen by the org. moiety of the alkyllithium reagent. Under certain reaction conditions, the 3,4-pentadien-1-ol which formed isomerized to terminal acetylenes, which, as well as their allene precursors, could be converted with Na-NH3 into 4-penten-1-ol or 3-penten-1-ol derivs. [on SciFinder (R)]