Ruthenium catalyst TpRuPPh3(CH3CN)2Cl isfound to effect the cyclization of epoxyalkynes to furans inthe presence of Et3N. The reactions worked well for variousepoxyalkynes with suitable oxygen and nitrogen functionalities with low loading of catalyst. It failed with disubstituted epoxyalkynes. The mechanism was elucidated by adeuterium labeling experiment that suggested that themechanism involved a ruthenium−vinylidenium intermediate.
