Chiral cyclopentadiene-mediated approach to enantioselective heterobimetallic Pauson–Khand reactions

When the dicobalt(hexacarbonyl) complex of N-(2-butynoyl)-4,4-dimethyloxazolidinone (1) is treated with chiral cyclopentadienyl (tricarbonyl)molybdenum anions, pairs of diastereomeric heterobimetallic (Co–Mo) complexes are obtained. In one instance, the two diastereomers have been separated by chromatography and they have been reacted with norbornadiene; each diastereomer leads with virtually complete stereocontrol to a single enantiomer of the endo Pauson–Khand cycloadduct 5.