The Pauson-Khand reaction is formal [2+2+1] cycloaddition reaction involving an alkyne, an alkene and carbon monooxide mediated by a hexacarbonyldicobalt komplex to yield cyclopentanones in a single step. Since its discovery many of asymmetric Pauson-Khand reactions have been developed.
Also the chiral pool approach to the asymetric Pauson-Khand reactions has been very popular methodology used up to now.