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.