Chiral 1,2-bis(phosphanes) 13, devoid of individual chiral centers, have been prepared in three steps from chiral sulfoxide 10. Their corresponding rhodium complexes were used as catalysts for asymmetric hydrogenation, giving high ee values (⩽ 95%) in the reduction of itaconic acid or its ester. A cationic rhodium complex involving coordination of two molecules of 13b and one molecule of oxygen has been isolated and its crystal structure established.
Argouarch, G., Samuel, O., Riant, O., Daran, J.-C., & Kagan, H. B. (2000). A New Class of Ferrocene-Based 1,2-Bis(phosphanes) Possessing only Planar Chirality. European Journal of Organic Chemistry, 2893. https://doi.org/10.1002/1099-0690(200008)2000:16<2893::AID-EJOC2893>3.0.CO;2-D (Original work published 2000)