Abstract: The scope and limitations of the reaction between cyclopropylcarbene-chromium complexes and alkynes have been examined. A variety of cyclopropylcarbene complexes and alkynes have been employed in these studies. The reaction appears to be general for most simple alkynes, producing cyclopentenones. A mechanism has ken proposed involving metallacyclobutene formation, electrocyclic ring opening, electrocyclic ring closure, CO ...