Reaction of chiral ester linked diynes with chlorotris(triphenylphosphine)cobalt(I) and sodium cyclopentadienide gave (η5-cyclopentadienyl)(triphenylphosphine) cobaltacyclopentadiene complexes as single chiral-at-metal diastereoisomers, including a non-racemic example synthesised in three steps from (S)-3-butyn-2-ol.
