A rhodium carbonyl complex,[RhCl (CO) 2] 2, serves as a catalyst of the intra-and inter- molecular Pauson–Khand reaction. By the use of the rhodium catalyst, cyclopentenone derivatives are prepared from various 1, 6-and 1, 7-enynes under 1 atm of CO. Furthermore, this rhodium-catalyzed reaction is accelerated by reducing partial pressure of CO to less than 1 atm.
