Bisphosphinite, Bisphosphonite, and Bisphosphite Ligands

Some excellent bisphosphonite ligands have also been developed. For example, Re-etzfs binaphthol-derived ferrocene-based bisphosphonite hgand L12 has demonstrated to have excellent reactivity and enantioselectivity in the rhodium-catalyzed hydrogenation of itaconates and a-dehydroamino acid derivatives [76]. Zanotti-Gerosa s bisphosphonite ligand L13 has also been successfully apphed to the asymmetric hydrogenation of a-dehydroamino acid derivatives with up to 99% ee [77]. 

A few efficient bisphosphite ligands have been used for asymmetric hydrogenation of itaconates or a-dehydroamino acid derivatives. Reetz has developed a series of C2-symmetric bisphosphite ligands such as L14, which are based on the structure of 1,4 3,6-dianhydro-D-mannite [78]. The ligands exhibit excellent reactivity and enantioselectivity for the asymmetric hydrogenation of itaconates. 

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