The reaction of δ-halo-γ-oxide ylide, prepared from methylenetriphenylphosphorane and epichlorohydrin, with aldehydes afforded alkylidenecyclobutanols in moderate yields. The reactioninitially proceeded through internal nucleophilic attack on δ-carbon of this ylide. Another novelapproach toward the synthesis of 4-methylenetetrahydrofurans was achieved by the reaction ofγ-oxide ylides with paraformaldehyde.
