Annulation of 3-methylcyclopentenone onto a cyclopentenol double bond by intramolecular Pauson–Khand reaction

A procedure for regio- and diastereocontrolled annulation of a 3-methylcyclopentenone moiety on a cyclopentenol double bond has been developed by employing the Pauson–Khand reaction in the presence of a promoter having reductive potential. During the examination, a novel substrate specific 3-hydroxycyclopentanone formation reaction was also discovered.