A novel pH‐responsive molecular shuttle based on a [2]rotaxane with a phosphine ligand has been designed and synthesized. In the rhodium‐catalyzed hydrogenation of α,β‐dehydroamino acid esters and aryl enamides, ON/OFF‐switchable catalysis was accomplished with high ON/OFF ratios by adjusting the movements of the rotaxane wheels located at the catalyst terminals with acid/base. Mechanistic studies using NMR spectroscopy and quasi in situ X‐ray photoelectron spectroscopy revealed that RhIII‐hydride species are possibly formed in a H2 atmosphere when the catalyst is in the OFF state. During the reaction, a heterolytic activation of dihydrogen occurs by the interlocked rotaxane dibenzylamine and RhI catalytic center acting as a frustrated Lewis pair. Subsequent homolytic splitting of dihydrogen with the newly formed RhI‐hydride species generates RhIII‐hydride species. These findings show that a substrate‐selective hydrogenation can be achieved by using the OFF‐state catalyst.

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.