Diastereoselection through chiral conformations.

Chiral conformations of flexible molecules may develop in a concerted manner if the molecule is crowded enough to assure sufficient level of through-the-space contacts. Higher number (> 4) of groups connected to the same atom, as in many coordination compounds, can be advantageous in this respect. The case study of R,S-[(sec-butoxycarbonyl)methyl]cobalt tricarbonyl triphenylphosphine is presented here. X-ray diffraction shows that the possible number of enantiomeric and diastereomeric conformations is reduced by 75% (from 8 to 2) by concerted development of the molecular conformations in crystalline phase.