Diaza-Crown Ether-Bridged Chiral Diphosphoramidite Ligands: Synthesis and Applications in Asymmetric Catalysis

J Org Chem. 2020 Jun 19;85(12):8176-8184. doi: 10.1021/acs.joc.0c00223. Epub 2020 May 29.

Abstract

A small library of diaza-crown ether-bridged chiral diphosphoramidite ligands was prepared. In the rhodium-catalyzed asymmetric hydrogenation and hydroformylation reactions, these ligands exhibited distinct properties in catalytic activity and/or enantioselectivity. Hydrogenated products with opposite absolute configurations could be obtained in high yields with excellent ee values by utilizing (S,S)-L1 and (S,S)-L3, respectively. Meanwhile, the addition of alkali metal cations caused variations in catalytic outcomes, showing the supramolecular tunability of these Rh/diphosphoramidite catalytic systems.