Sulfonamido−Phosphoramidite Ligands in Cooperative Dinuclear Hydrogenation Catalysis

Abstract

Sulfonamido-phosphoramidite ligands lead to the formation of Rh-Rh dinuclear complexes through the anionic P-N(-) bridging character. The resulting "boat-shaped" dinuclear catalysts activate molecular H(2) through a cooperative dinuclear endocyclic mechanism, resulting in one bridging and one classical hydride on the dinuclear complex. These new complexes are very active hydrogenation catalysts that operate via a new cooperative hydrogenation activation mechanism, as calculated with density functional theory, and they display unequaled high selectivities in the hydrogenation of hindered cyclic acetamidoalkenes.

Ureaphosphanes as Hybrid, Anionic or Supramolecular Bidentate Ligands for Asymmetric Hydrogenation Reactions

“…S1 and S2 are frequently used benchmark substrates in the asymmetric hydrogenation reaction, however, S3 is a relatively difficult substrate to hydrogenate and only few systems are reported that provide high enantioselectivity for this substrate. [18] The reaction mixtures were prepared in situ by addition of solvent (CH 2 Cl 2 ) to a mixture of the appropriate amounts of metal precursor, ligand and substrate. Next, the reaction mixtures were put under an atmosphere of dihydrogen.…”

Neutral Tridentate PNP Ligands and Their Hybrid Analogues: Versatile Non‐Innocent Scaffolds for Homogeneous Catalysis

“…It remains to be seen if the amino linker of ligand 20, like its CH 2 analogues, will be available for cooperative catalysis (as observed for the METAMORPhos type sulfonamidophosphoramidites [7,8] ). This reaction would, in principle, offer new possibilities for this versatile subclass of tridentate PNP ligands.…”

“…[7,8] These developments in turn allow a wider range of activity than that traditionally provided by metal-based catalysis alone.…”

Neutrale dreizähnige PNP‐Liganden und deren Hybrid‐Analoga: vielseitige Liganden für die kooperative homogene Katalyse

“…[7,8] Diese Entwicklungen könn-ten die Möglichkeiten üblicher metallkatalysierter Reaktionen erweitern.…”

“…Es bleibt abzuwarten, ob die Aminogruppe, die im Ligand 20 als Brücke vorliegt, wie die CH 2 -Gruppen in analogen Liganden für die kooperative Katalyse zur Verfügung steht (wie bei Sulfonamido-Phosphoramiditen vom MetamorphosTyp [7,8] ). Somit würden sich neue Möglichkeiten für diese vielseitige Klasse dreizähniger PNP-Liganden ergeben.…”