The C-2-symmetric bis(1,6-enynes) threo-1,10-diphenyl-5,6-divinyl-1,9-decadiyn and threo-9,1 0-divinyl-5,13-octadecadiyne undergo the intramolecular Pauson-Khand reaction regio- and stereoselectively to give C(2)symmetric bis(enones) with two bicyclo[3.3.0]octyl moieties joined at the C6 position. Experiments aimed at converting the bis(enones) into chiral, diastereopure ansa-bridged group 4 metallocene complexes are described. (C) 1999 Elsevier Science Ltd. All rights reserved.