This paper describes carbonylative cycloaddition reations catalyzed by Ru-3(CO)(12), Ru3(CO)(12) was found tocatalyze an intramolecular Pauson-Khand -type reaction. Carbonylative cycloaddition reactions involving a carbonyl group in aldehydes, ketones, and esters as a two-atom assembling unit were also achieved in the presence if Ru-3(CO)(12) as the catalyst. The reaction of 5-hexyn-1-al and 6-heptyn-1-al derivatives with CO in the presence of Ru-3(CO)(12) resulted in cyclocarbonylation from which bicyclic alpha,beta-unsaturated lactones were obtained. Intramolecular [2 + 2 +1] catalyst to give saturated gamma-lactone derivatives. Simple Ketones were not applicable, but ketones having at C=O or C=N group at the alpha-position served as a good Substrate. These reactions could be extended to carbonylative cycloaddition of the corresponding imines leading to gamma-bucyrolactam derivatives. The [4 + 1] carbonylative addition of alpha,beta-unsaturated imines leading to unsaturated gamma-lactams was achieved with Ru-3(CO)(12). (C) 2008 The Japan Chemical Journal Forum and Wiley Periodicals, Inc.