Diastereoselection through chiral conformations

Chiral conformations of flexible molecules may develop in a concerted manne r if the molecule is crowded enough to assure sufficient level of through-t he-space contacts. Higher number (>4) of groups connected to the same atom, as in many coordination compounds, can be advantageous in this resp ect. T he case study of R,S-[(sec-butoxycarbonyl)methyl]cobalt tricarbonyl triphen ylphosphine is presented here. X-ray diffraction shows that the possible nu mber of enantiomeric and diastereomeric conformations is reduced by 75% (fr om 8 to 2) by concerted development of the molecular conformations in cryst alline phase.