Application of P-stereogenic aminophosphine phosphinite ligands in asymmetric hydroformylation

New chiral aminophosphine phosphinite ligands with a stereogenic center at the aminophosphine phosphorus atom were prepared based on (R,S)-ephedrine as the chiral auxiliary and backbone. Substituents at the chiral aminophosphine as well as at the phosphinite phosphorus atom were varied. These new ligands were applied to the rhodium-catalyzed asymmetric hydroformylation of vinyl arenes. The enantiomeric excess reached up to 77%. 1H and 31P NMR studies of the Rh complexes under syngas pressure reveal that [HRh(CO)2(PP)] complexes with the NP* moiety in an axial position are responsible for enantioselectivity.     

Chiral Aminoalcohols and Squaric Acid Amides as Ligands for Asymmetric Borane Reduction of Ketones: Insight to In Situ Formed Catalytic System by DOSY and Multinuclear NMR Experiments

A series of squaric acid amides (synthesized in 66–99% isolated yields) and a set of chiral aminoalcohols were comparatively studied as ligands in a model reaction of reduction of α-chloroacetophenone with BH₃•SMe₂. In all cases, the aminoalcohols demonstrated better efficiency (up to 94% ee), while only poor asymmetric induction was achieved with the corresponding squaramides. A mechanistic insight on the in situ formation and stability at room temperature of intermediates generated from ligands and borane as possible precursors of the oxazaborolidine-based catalytic system has been obtained by ¹H DOSY and multinuclear 1D and 2D (¹H, ^10/11B, ¹³C, ¹⁵N) NMR spectroscopy of equimolar mixtures of borane and selected ligands. These results contribute to better understanding the complexity of the processes occurring in the reaction mixture prior to the possible oxazaborolidine formation, which play a crucial role on the degree of enantioselectivity achieved in the borane reduction of α-chloroacetophenone.     

Synthesis of New Ligand 1,2-Bis{di[（R,R）-1,3,2-oxzaphosphlidine]phosphino}ethane with C_2-symmetric Axis and Application in Rh-catalyzed Asymmetric Hydrogenation

New ligand 1,2-bis{di[（R,R）-1,3,2-oxzaphosphlidine]phosphino}ethane [（R,R）-BDOPPEs 1,2,3 and 4] with C2-symmetric axis and bearing nitrogen and oxygen were synthesized from readily available optically active amino alcohols.Rh complexes with these ligands were highly enantioselective catalysts for asymmetric hydrogenation of N-benzoyldehydroamino acid derivatives and α-functionalized ketones in 99%e.e.and 98%e.e.,respectively.This new class of（R,R）-BDOPPEs 1,2,3 and 4 gave much more effectivity and enantionselectivity than their corresponding non-C2-asymmetric aminophosphine phosphinite.     

Aminophosphine phosphinite (AMPP) and enantioselective hydrogenation of ketones: further developments

A new cyclohexyl-substituted aminophosphine phosphinite (AMPP) chiral auxiliary has been synthesised and evaluated along with other earlier described AMPP ligands in Ru-, Ir-, and Rh-based enantioselective hydrogenation of functionalised ketones. Enantioselectivities as high as 97% ee are obtained. To cite this article: V. Turcry et al., C. R. Chimie 6 (2003).     

Synthesis,characterization and first application of chiral C2‐symmetric bis(phosphinite)–Pd(II) complexes as catalysts in asymmetric intermolecular Heck reactions

A series of new chiral C₂‐symmetric bis(phosphinite) ligands and their palladium(II) complexes have been synthesized and for the first time used as catalysts in the palladium‐catalysed asymmetric intermolecular Heck coupling reactions of 2,3‐dihydrofuran with iodobenzene or aryl triflate. Under optimized conditions, products were obtained with high conversions and moderate to good enantioselectivities. The new C₂‐symmetric bis(phosphinite) ligands and their palladium(II) complexes were characterized using multinuclear NMR and Fourier transform infrared spectroscopies and elemental analysis. Copyright © 2015 John Wiley & Sons, Ltd.     

Synthesis and Characterization of Novel Aminophosphine Ligands Based on Ferrocenodecaline Backbones

 Novel aminophosphine ligands for enantioselective transition metal catalysts based on different ferroceno cis- and trans-decaline backbones were synthesized and structurally characterized. Their palladium dichloride complexes were tested in the asymmetric Grignard cross coupling reaction of vinyl bromide and phenylethyl magnesium chloride, but only very low enantioselectivities were obtained. Steric strain in the aminophosphine ligands causes a severe backbone deformation and in addition leads to a slowed rotation of the respective dimethylamino group as was detected by variable temperature NMR spectroscopy.     

Asymmetric hydrogenation of dehydroamino acid derivatives catalyzed by a new aminophosphine phosphinite ligand derived from ketopinic acid

A new chiral aminophosphine phosphinite N,O-bis(diphenylphosphino)-(1S,2R)-1-(N-methylamino) methyl-2-hydroxyl-7,7-dimethylbicyclo[2.2.1]heptane was synthesized from ketopinic acid and its application to the asymmetric hydrogenation of dehydroamino acid derivatives examined.     

Synthesis and Characterization of Novel Aminophosphine Ligands Based on Ferrocenodecaline Backbones

Summary.  Novel aminophosphine ligands for enantioselective transition metal catalysts based on different ferroceno cis- and trans-decaline backbones were synthesized and structurally characterized. Their palladium dichloride complexes were tested in the asymmetric Grignard cross coupling reaction of vinyl bromide and phenylethyl magnesium chloride, but only very low enantioselectivities were obtained. Steric strain in the aminophosphine ligands causes a severe backbone deformation and in addition leads to a slowed rotation of the respective dimethylamino group as was detected by variable temperature NMR spectroscopy. Received January 4, 2002. Accepted January 16, 2002     

Synthesis of novel chiral N, P-containing multidentate ligands and their applications in asymmetric transfer hydrogenation

Novel chiral PN₄-type multidentate aminophosphine ligands have been successfully synthesized by Schiff-base condensation of bis（o-formylphenyl）phenylphosphane and various chiral amino-sulfonamides.Their structures were fully characterized by IR,EI-MS and NMR.The catalytic systems,prepared in situ from the multidentate ligands and iridium（I） complexes,showed high activity in asymmetric transfer hydrogenation of propiophenone in 2-propanol solution,leading to corresponding optical alcohol with up to 75%ee.     

具有C2对称的氮磷-氧磷配体双噁唑啉磷乙烷的合成及在不对称催化加氢中的应用

利用易得的光学纯N-甲基氨基醇与1,2-双(二氯磷)乙烷缩合合成了一类新的具有C₂对称轴的氮磷-氧磷配体(R,R)-双噁唑啉磷乙烷(BOAPE) 1～4. 该类配体不仅具有C₂对称结构和刚性五元环, 还具有富电子特性, 利用500 MHz进行了¹H NMR, ³¹P NMR, ¹³C NMR表征. 与这些配体配位形成的Rh配合物用于N-苯甲酰基脱氢丙氨酸衍生物和α-功能化酮不对称加氢, 分别可以得到99%和98%的ee. 这类配体比它们相对应的非C₂对称的氮磷-氧磷化合物(AMPP)配体具有更高的对映选择性. 在这四个新的配体中配体(R,R)-Ph-BOAPE (2)的催化性能最优. 催化剂[Rh(COD)(R,R)-Ph-BOAPE]BF₄的半反应周期t_1/2和周转频率(TOF)在N-苯甲酰基肉桂酸甲酯的不对称加氢反应中分别为12 min和6.5 min^－1.     

The application of tunable tridendate P‐based ligands for the Ru(II)‐catalysed transfer hydrogenation of various ketones

Two novel versatile tridendate aminophosphine–phosphinite and phosphinite ligands were prepared and their trinuclear neutral ruthenium(II) dichloro complexes were found to be effective catalysts for the transfer hydrogenation of various ketones in excellent conversions up to 99% in the presence of 2‐propanol/NaOH in 0.1 M isopropanol solution. Particularly, [Ru₃(PPh₂OC₂H₄)₂ N–PPh₂(η⁶‐p‐cymene)₃Cl₆] acts as an excellent catalyst giving the corresponding alcohols in excellent conversion up to 99% (turnover frequency ≤ 1176 h^?1). A comparison of the catalytic properties of the complexes is also discussed briefly. Furthermore, the structures of these ligands and their corresponding complexes have also been clarified using a combination of multinuclear NMR spectroscopy, infrared spectroscopy and elemental analysis. ¹H–¹³C HETCOR or ¹H–¹H COSY correlation experiments were used to confirm the spectral assignments. Copyright © 2014 John Wiley & Sons, Ltd.     

Palladium-catalyzed asymmetric allylic alkylation using (R)-2-(methoxymethyl)pyrrolidine-derived aminophosphine ligands

Palladium-catalyzed asymmetric allylic alkylation of 1,3-diphenyl-2-propenyl acetate 7a using a dimethyl malonate–BSA–LiOAc system has been successfully carried out in the presence of new chiral aminophosphine ligands such as 4 in good yields with good enantioselectivities (up to 96% e.e.).     

Palladium-catalyzed asymmetric allylic alkylation using chiral aminophosphine ligands

Palladium-catalyzed asymmetric allylic alkylation of 1,3-diphenyl-2-propenyl acetate 18 with a dimethyl malonate–BSA–LiOAc system has been successfully carried out in the presence of new chiral aminophosphine ligands 1–5 in good yields with good enantioselectivities (up to 85% e.e.).     

Palladium‐Catalyzed Enantioselective Synthesis of 2‐Aryl Cyclohex‐2‐enone Atropisomers: Platform Molecules for the Divergent Synthesis of Axially Chiral Biaryl Compounds

The palladium‐catalyzed asymmetric synthesis of enone‐based atropisomers from 2‐iodo‐3‐methylcyclohex‐2‐enones and aryl boronic acid is reported. BoPhoz‐type phosphine–aminophosphine ligands showed superior enantioselectivity over other ligands. These cyclohexenone‐based atropisomers are useful compounds for further elaboration. The divergent synthesis of biaryl atropisomers with different ortho substituents was demonstrated.     

Enantioselektive Synthese von α-Phosphinoketonen. Vorläufige Mitteilung

Enantioselective Synthesis of α-Phosphinoketones The first asymmetric (C? P)-connective synthesis of α-phosphinoketones in high enantiomeric purity (e.e.91–97%) is described. Key step is the highly diastereoselective phosphinylation of SAMP-hydrazones (S)- 2 to produce α-phosphinohydrazones (S,R)- 3 , isolated as the more stable borane adducts. Subsequent ozonolysis afforded the title compounds (R)- 4 , potential ligands for enantioselective homogeneous catalysis.     

Steric hindrance versus asymmetric induction: new PN-ligands for carbon–carbon coupling reactions

Two new aminophosphine ligands 4 and 5 with increased steric interaction in proximity to the N-coordination site have been prepared. Their asymmetric induction in five model reactions was tested and compared to results obtained with the parent ligand 2. This resulted in improved enantioselectivity in only one case, from 5 to 68% e.e., while in all the other cases the more crowded ligands exhibited significantly lower reactivity accompanied by decreased enantioselectivity.     

Recent development of aminophosphine chalcogenides and boranes as ligands in s-block metal chemistry

The coordination chemistry of the aminophosphine chalcogenide ligands [Ph₂P(O)NHR], [Ph₂P(S)NHR], and [Ph₂P(Se)NHR] (R = 2,6-Me₂C₆H₃,^tBu, CHPh₂, CPh₃) or corresponding borane derivative [Ph₂P(BH₃)NHR] toward group 1 and 2 metals is reviewed. The structural characterization of a huge number of mono- and bis-aminophosphine chalcogenide/borane complexes with group 1 and 2 metals—in most cases lithium, sodium, potassium, magnesium, calcium, strontium, and barium complexes—reveals a poly-metallacyclic motif in each case. The coordination takes place from adjacent chalcogen/borane and nitrogen as donor atom or group of the ligand confirming the direct bond between metal and chalcogen/borane to develop homoleptic and heteroleptic complexes. The heteroleptic group 2 metal complexes were used as pre-catalysts in hydrophosphination and hydroamination reactions. Similarly, aminophosphine chalcogenide alkaline earth metal complexes were used in the catalytic ring-opening polymerization (ROP) study of ?-caprolactone.     

Enantioselective borane reduction of aromatic ketones using chiral BINOL derivatives as ligands in an aluminum catalyst

Chiral aluminum complex-catalyzed asymmetric borane reduction of aromatic ketones has been successfully carried out in the presence of (R)-BINOL derivatives as ligands. Secondary alcohols were obtained in high yields with good enantioselectivities (up to 90% e.e.).     

Synthesis of Aminophosphine Ligands with Binaphthyl Backbones for Silver(I)-catalyzed Enantioselective Allylation of Benzaldehyde

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Asymmetric synthesis of P-stereogenic o-hydroxyaryl-phosphine (borane) and phosphine-phosphinite ligands

The first asymmetric synthesis of P-stereogenic 2-hydroxyarylphosphine ligands is described, using borane complexation methodology. This synthesis is based on the highly stereoselective preparation of bromoarylphosphinite boranes, leading to the 2-hydroxyarylphosphine derivatives, by an intramolecular ortho Fries-like rearrangement mediated in basic conditions. The o-anisyl-2-hydroxynaphthylphenylphosphine borane has been decomplexed in EtOH, affording the P(III)-stereogenic hydroxyarylphosphine ligand with 84% yield. The interest of the hydroxyarylphosphine borane is also demonstrated by the preparation of a new class of phosphine-phosphinite ligands, by trapping the rearrangement products first with chlorodiphenylphosphine, Ph₂PCl, then with borane. The corresponding phosphine-phosphinites are obtained and purified as diborane complexes, with the decomplexation of these borane complexes being achieved by heating with dabco, to afford the free hybrid ligands with retention of the configuration at the P-atom (isolated yield up to 53%).