Cationic Rh-bisphosphine-diolefin complexes as precatalysts for enantioselective catalysis––what information do single crystal structures contain regarding product chirality?

Drexler, Hans‐Joachim; Zhang, Songlin; Sun, Ai-Ling; Spannenberg, Anke; Arrieta, Antonio F.; Preetz, Angelika; Heller, Detlef

doi:10.1016/j.tetasy.2004.06.036

Cited by 78 publications

(26 citation statements)

References 58 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The reasons behind these differences are unclear, although when examining the published X-ray structures it would seem that the generally less active COD complexes all have a larger tetrahedral distortion from the expected square-planar structure than the structures of the corresponding NBD complexes [19]. For COD, the analogue difference approximately amounts to three orders of magnitude.…”

Section: Induction Period Caused By Slow Hydrogenation Of Cod or Nbdmentioning

confidence: 99%

Catalyst Inhibition and Deactivation in Homogeneous Hydrogenation

Heller¹,

Vries²,

Vries³

2006

The Handbook of Homogeneous Hydrogenation

Self Cite

View full text Add to dashboard Cite

Section: Induction Period Caused By Slow Hydrogenation Of Cod or Nbdmentioning

confidence: 99%

Catalyst Inhibition and Deactivation in Homogeneous Hydrogenation

Heller¹,

Vries²,

Vries³

2006

The Handbook of Homogeneous Hydrogenation

Self Cite

View full text Add to dashboard Cite

“…Simple computer modeling (PC-Model) [63] performed for the model compound Rh(AMPP 4b)Cl 2 (in the gas phase) has confirmed that this "quasi"-boat structure is more stable than the "quasi"-chair one (by about 10 kJ mol -1 ). Although the origin of the catalytic asymmetric induction needs to be carefully explained with the aid of crystal structures, [37,42,54,64] the observation of the same boat conformation regardless of the metal and other ligands (Cl or Cp) used suggests a remarkable stability of this geometry during the catalytic process. Consequently, it may reasonably be assumed that this boat conformation was also retained during the dihydride stereodetermination step.…”

Section: Model For the Catalyzed Asymmetric Hydrogenationmentioning

confidence: 99%

Modular P‐Chirogenic Aminophosphane‐Phosphinite Ligands for Rh‐Catalyzed Asymmetric Hydrogenation: A New Model for Prediction of Enantioselectivity

Darcel

Moulin²,

Henry³

et al. 2007

Eur J Org Chem

View full text Add to dashboard Cite

An original series of P-chirogenic aminophosphane-phosphinite (AMPP) ligands has been synthesized from (+)-or (-)-ephedrine in 23 to 61 % overall yields by a versatile threestep methodology. The AMPP ligands, bearing either one or two P-chirogenic centers, were used in the form of rhodium complexes for the catalyzed hydrogenation of α-acetamidocinnamate as a test reaction. Notably, even with AMPP ligands all derived from (+)-ephedrine, variation of the substituent on a P-center allowed the phenylalanine derivatives to be obtained in either (S) or (R) absolute configurations, with ee values ranging from 99 % (S) to 88% (R). The asymmetric induction was analyzed with the aid of X-ray structures of AMPP complexes, and a new model for the enantioselectivity, taking into consideration the boat conformation and the steric and electronic dissymmetries at the dihydride

show abstract

“…The C 2 -symmetrical ligand was considered as R L R S P(X)PR S R L with the bulky R L ligands disposed to equatorial positions in the chelate ring and R S to axial positions. Formulation of this Rule in specific cases is aided by a thorough analysis of the X-ray structures of the "precatalyst" diolefin complex, with respect to the bite angle and coordination geometry of the dialkene [43]. The rule was incomplete in its predictive power in its original form, however, and needed correction.…”

Section: Mnemonics For the Sense Of Enantioselective Hydrogenationmentioning

confidence: 99%

Mechanism of Enantioselective Hydrogenation

Brown¹

2006

The Handbook of Homogeneous Hydrogenation

View full text Add to dashboard Cite

John M. Brown IntroductionThe discovery of the first practical catalyst for homogeneous hydrogenation by Wilkinson, Osborn, Jardine and Young in 1965 [1] occurred at around the same time that others, especially Mislow and Horner [2], were demonstrating that chiral trivalent phosphorus compounds were capable of existing as stable, noninterconverting enantiomers. With suitable adaptation of Wilkinson's catalyst, a prostereogenic alkene could be hydrogenated with preferential formation of one enantiomer of the reduced product. The possibility of such enantioselective hydrogenation was recognized by both Horner [3] and Knowles [4], but it was Knowles who won the race to demonstrate the first example in 1968. This led rapidly to a period of seminal discoveries: the application of chelate biphosphine ligands came from Kagan [5], and the development of a full-scale enantioselective hydrogenation of a dehydroamino acid to provide a rhodium-complex-based catalytic synthesis of l-Dopa by Knowles' team at Monsanto [6]. For many years this provided a substantial part of the supply of the main drug active in the control of Parkinson's disease. Kagan was also the first to demonstrate, in his synthesis and application of DIOP (derived very simply from RR-or SS-tartaric acid), that the difficult synthesis of enantiomerically pure phosphines was unnecessary for effective enantioselective hydrogenation, since a suitable chelate backbone could provide the necessary level of stereochemical control. For many years the development of enantioselective hydrogenation converged on the preparation of enantiomerically pure chelate diphosphines and the application of their rhodium complexes to the hydrogenation of dehydroamino acids, enamides and closely related reactants [7]. Although both ruthenium [8] and iridium catalysts [9] for homogeneous hydrogenation were known at an early stage, the development of effective enantioselective hydrogenation in these two spheres occurred much later. For ruthenium enantioselective hydrogenation, the spectacular efficiency of BINAP catalysts [10] developed by Noyori's group was first demonstrated for alkenes, and then in rather greater depth for ketones [11]. The high efficiency of iridium complexes in hydrogenation had been demonstrated 1073The Handbook of Homogeneous Hydrogenation. Edited by J. G. de Vries and C. J. Elsevier

show abstract

Cationic Rh-bisphosphine-diolefin complexes as precatalysts for enantioselective catalysis––what information do single crystal structures contain regarding product chirality?

Cited by 78 publications

References 58 publications

Catalyst Inhibition and Deactivation in Homogeneous Hydrogenation

Catalyst Inhibition and Deactivation in Homogeneous Hydrogenation

Modular P‐Chirogenic Aminophosphane‐Phosphinite Ligands for Rh‐Catalyzed Asymmetric Hydrogenation: A New Model for Prediction of Enantioselectivity

Mechanism of Enantioselective Hydrogenation

Contact Info

Product

Resources

About