Dicobalt hexacarbonyl complexes of enynes serve as Co-2(CO)(8) surrogates for the intramolecular Pauson-Khand cycloaddition. Enynes with polar functional groups allow for easy separation of the catalyst cyclopentenone byproduct (acid or base wash, silica gel plug column) from the desired cyclopentenone. (C) 1999 Elsevier Science Ltd. All rights reserved.