BINAP Ligand Research Articles

Applications of 3,3′-Disubstituted BINAP Derivatives in Inter- and Intramolecular Heck/Mizoroki Reactions

A series of 3,3'-disubstituted BINAP ligands are used in asymmetric inter- and intramolecular Heck/Mizoroki reactions and their enantioselectivity compared to BINAP.

Efficient dynamic kinetic resolution of secondary alcohols with a novel tetrafluorosuccinato ruthenium complex

Dynamic kinetic resolution (DKR) of a series of secondary alcohols has been conducted with a novel dinuclear ruthenium complex, bearing tetrafluorosuccinate and ( rac)-BINAP ligands as the racemization catalyst. Novozym 435 has been used as the enzyme, and isopropyl butyrate as the acyl donor. Five substrates underwent DKR successfully: an aliphatic and an aromatic secondary alcohol, an aromatic alcohol with an electron-withdrawing substituent on the phenyl ring, an aromatic alcohol bearing an electron-donating substituent on the ring and a heteroaromatic secondary alcohol. The catalyst performed optimally at 70 °C. Typically the reaction reached complete conversion within 1 day with 0.1 mol % of racemization catalyst relative to the substrate. The addition of the ketone corresponding to the substrate stabilizes the active Ru complex and, therefore, increases the rate of the reaction.

Synthesis and Luminescence of New Cu(I) Complexes Containing a Binap Ligand and a Diimine Ligand

Abstract A series of novel Cu(I) complexes with an s-binap ligand and a diimine ligand, [Cu(s-binap)(bpy)]PF6, [Cu(s-binap)(phen)]PF6, and [Cu(s-binap)(dmp)]PF6, were synthesized, where bpy = 2,2′-bipyridine, phen = 1,10-phenanthroline, dmp = 2,9-dimethyl-1,10-phenanthroline, and s-binap = (S)-2,2′-bis(diphenylphosphino)-1,1′-binaphthyl. All three complexes show intense photoluminescence in the solid state, whereas [Cu(s-binap)(dmp)]PF6 is a comparatively good emitter in CH2Cl2 solutions. These luminescence bands have been assigned to the emission from 3MLCT states. The complexes [Cu(s-binap)(bpy)]PF6 and [Cu(s-binap)(dmp)]PF6 were characterized by X-ray structure analyses. Although the distorted tetrahedral structures around the central metals of the two complexes are similar, the photophysical properties of the dmp complex differ from those of the other complexes in solution. The structures and the photophysical properties of the three complexes have been discussed.

Catalytic Ability of a Cationic Ru(II) Monochloro Complex for the Asymmetric Hydrogenation of Dimethyl Itaconate and Enamides

The synthesis of two Ru chloro complexes, Ru(III)Cl(3)(bpea), 1, and cis-fac-Delta-[Ru(II)Cl{(R)-(bpea)}{(S)-(BINAP)}](BF(4)), cis-fac-Delta-(R)-(S)-2, (bpea = N,N-bis(2-pyridylmethyl)ethylamine; (S)-BINAP = 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl), is described. Complex 2 is characterized in solution through UV-vis, cyclic voltammetry (CV), and 1D and 2D NMR spectroscopy. X-ray diffraction analysis indicates that in the solid state it possesses the same structure as in solution, as expected for a low-spin d(6) Ru(II)-type complex. The molecular structure of cis-fac-Delta-(R)-(S)-2, consists of a nonsymmetric complex, where the Ru metal center has a significantly distorted octahedral-type coordination because of the bulkiness of the (S)-BINAP ligand. cis-fac-Delta-(R)-(S)-2 has a remarkable catalytic performance at P = 6.8 atm of H2 and T = 70 degrees C toward the hydrogenation of prochiral double bonds both from efficiency and from stereoselectivity viewpoints. As an example, prochiral olefins of technological interest such as dimethyl itaconate, methyl 2-acetamidoacrylate or methyl 2-acetamidocinnamate are catalytically hydrogenated by cis-fac-Delta-(R)-(S)-2, with conversions higher than 99.9% and ee > 99. Furthermore, cis-fac-Delta-(R)-(S)-2, also catalyzes the selective hydrogenation of beta-keto esters, although the reaction rates are lower than those found with the former substrates.

3,3′‐Disubstituted BINAP Ligands: Synthesis, Resolution, and Applications in Asymmetric Hydrogenation.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Regioselectivity in the Palladium/(S)-BINAP(S)-Catalyzed Asymmetric Allylic Amination: Reaction Scope, Kinetics, and Stereodynamics

Studies defining the scope of the reaction and understanding the factors controlling the unusual regioselectivity observed in the Pd/{BINAP(S)}-catalyzed allylic amination reaction are presented. Most of the unsymmetrically substituted allylic substrates tested show regioselectivity that is the reverse of that which would normally be expected in Pd-catalyzed systems. Several cationic η 3 -allylic complexes containing a Pd{BINAP(S)} fragment have been synthesized in an attempt to correlate this behavior with structural features of the ligand and the solution structure of the allylpalladium complex. Notably, allylic amines with an α-quaternary carbon center may be prepared with high regioselectivity with this system. Spin-saturation transfer studies (SST) were performed on two (κ 2 -P,S)Pd-π-allyl complexes in order to determine relative rates for Pd-η 3 -η 1 -η 3 -allyl interconversions and the hemilabile behavior of the BINAP(S) ligand.

3,3‘-Disubstituted BINAP Ligands: Synthesis, Resolution, and Applications in Asymmetric Hydrogenation

A novel family of BINAP ligands were prepared with alkoxy- and acetoxy-derived substituents in the 3,3'-positions. They were prepared through a convergent synthesis starting from readily available 4-bromo-2-naphthol. These ligands afforded excellent enantioselectivities in the asymmetric hydrogenation of substituted olefins. The presence of the 3,3'-substituents was shown to be beneficial by a direct comparison with the parent unsubstituted BINAP. [reaction: see text]

Palladium/BINAP(S)‐Catalyzed Asymmetric Allylic Amination.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Palladium/BINAP(S)-Catalyzed Asymmetric Allylic Amination

The enantioselective allylic amination of acyclic allylic carbonates catalyzed by a palladium/(S)-BINAP(S) system was investigated. Amination of several substrates proceeded with high ee. Crotyl carbonates show an unusually high regioselectivity for the branched isomer. The use of (S)-TolBINAP(S) and (S)-3,5-xylyl-BINAP(S) as ligands was found to increase the enantioselectivity of the aminations. A P,S binding mode of the BINAP(S) ligand was found in an X-ray crystallographic study. [reaction: see text]

ジホスフィンロジウムおよびルテニウム錯体を用いるデヒドロアミノ酸類の触媒的不斉水素化の機構研究の新展開

The Rh-catalyzed enantioselective hydrogenation of N-acylated dehydroamino acids or their esters, initiated by Kagan, constitutes now a standard tool for the synthesis of natural and unnatural amino acids of high enantiomeric purity. The reaction proceeds via the unsaturate-dihydride mechanism in which the oxidative addition of hydrogen to Rh-enamide complex is the rate-limiting and stereodifferentiating step. In addition to this standard pathway, alternative dihydrideunsaturate mechanisms have also been reported. The formation of a RhH2 may precede the olefin-Rh interaction, depending on the chiral ligands and reaction conditions. Reactions using BINAP-Ru (II) complexes (BINAP = 2, 2'-bis (diphenylphosphino) -1, 1'-binaphthyl), find a wider synthetic scope, allowing asymmetric hydrogenation of a range of functionalized olefins and ketones. Interestingly, the Rh and Ru complexes with the same BINAP ligand exhibit an opposite sense of asymmetric induction in hydrogenation of dehydroamino acid derivatives. This review summarizes some mechanistic studies in this hydrogenation catalyzed by diphosphine-Rh and-Ru complexes.

Enantioselective Tandem Michael Addition/H2-Hydrogenation Catalyzed by Ruthenium Hydride Borohydride Complexes Containing β-aminophosphine Ligands

A variety of ruthenium(II) catalyst precursors containing beta-aminophosphine ligands and a borohydride ligand were found to be active for a one-pot, tandem asymmetric Michael addition/H2-hydrogenation reaction to give the chiral alcohol in excellent diastereomeric excess. The most effective catalyst is 4b, containing the (S)-binap ligand and (R,R)-Pnor ligand, derived from (1S,2R)-norephedrine.

Preparation of an Amphiphilic Resin‐Supported BINAP Ligand and Its Use for Rhodium‐Catalyzed Asymmetric 1,4‐Addition of Phenylboronic Acid in Water.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Dendronized Poly(Ru‐BINAP) Complexes: Highly Effective and Easily Recyclable Catalysts For Asymmetric Hydrogenation

AbstractA new kind of dendronized polymeric chiral BINAP ligands has been synthesized and applied to the Ru‐catalyzed asymmetric hydrogenation of simple aryl ketones and 2‐arylacrylic acids. These dendronized poly(Ru‐BINAP) catalysts exhibited high catalytic activity and enantioselectivity, very similar to those obtained with the corresponding parent Ru(BINAP) and the Ru(BINAP)‐cored dendrimers. It was found that the pendant dendrons had a major impact on the solubility and the catalytic properties of the polymeric ligands. These polymeric catalysts could be easily recovered from the reaction solution by using solvent precipitation, and the reused catalyst showed no loss of activity or enantioselectivity.

Design and study of Bi[1,8]naphthyridine ligands as potential photooxidation mediators in Ru(II) polypyridyl aquo complexes.

A series of 3,3'-polymethylene-bridged bi[1,8]naphthyridine (binap) ligands, 3a-c, are complexed with Ru(II) to afford [Ru(tpy)(3a-c)(H(2)O)](2+) where an uncomplexed nitrogen on 3a-c is situated so it can form a H-bond with the coordinated water. An additional complex involving [Ru(4'-NMe(2)tpy)(3b)(H(2)O)](2+) is also prepared. X-ray analyses of the [Ru(tpy)(3a,c)(H(2)O)](2+) complexes indicate well-organized H-bonds even when the binap is nonplanar. In an attempt to realize photooxidation, the effects of light, varying potential, and pH were examined. A Pourbaix diagram indicated that the oxidation potential decreased by approximately 0.5 V in the pH range of 1.9-11.6. The lowest-energy electronic absorption for the binap complexes involves the metal-to-ligand charge transfer to the binap ligand and is sensitive to ligand planarity. The absorbance shifted to a lower energy as the auxiliary ligand became a better donor (4'-NMe(2)tpy) or as the water was deprotonated. Acetonitrile was found to displace water most easily for the complex of 3c, where the ligand is the least planar. Despite promising features, photooxidation of the bound water was not observed.

Improved synthesis of 5,5‐diamino BINAP and application to asymmetric hydrogenation

Abstract5,5‐Diamino BINAP has been synthesized via three steps using BINAPO as starting material with high reaction yield. Present method needed only a stoichiometric quantity of nitric acid in the step of nitration of BINAPO, giving almost quantitative reaction yield. Based on 5,5‐diamino BINAP, other three new BINAP derivatives have been synthesized. These modified BINAP ligands showed better catalytic properties as compared to BINAP itself in the asymmetric hydrogenation of 2–(6‐methoxyl‐2′‐naphthyl)acrylic acid.

Preparation of an amphiphilic resin-supported BINAP ligand and its use for rhodium-catalyzed asymmetric 1,4-addition of phenylboronic acid in water.

[reaction: see text] The axially chiral bisphosphine ligand, 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl (binap), was supported on a polystyrene-poly(ethylene glycol) copolymer (PS-PEG) resin and was used successfully for the rhodium-catalyzed asymmetric 1,4-addition of phenylboronic acid to alpha,beta-unsaturated ketones in water.

Ruthenium-catalysed asymmetric hydrogenation with fluoroalkylated BINAP ligands in supercritical CO2

Fluoroalkylated BINAP ligands have been evaluated in the ruthenium-catalysed asymmetric hydrogenation of dimethyl itaconate in supercritical CO 2 as well as MeOH. Fluoroalkylated BINAP ligands have been evaluated in the ruthenium-catalysed asymmetric hydrogenation of dimethyl itaconate in both MeOH and supercritical CO 2 (scCO 2 ). The reaction proceeds slower and gives a lower enantioselectivity in the latter, which is probably due to the lower polarity of scCO 2 .

The Absolute Configuration of the Products of the Enantioselective Rhodium(I)/BINAP‐Catalyzed Enyne Cyclization

AbstractThe absolute configuration of the product 7 obtained from a rhodium‐catalyzed enyne cyclization of 6 with the (R)‐BINAP ligand was determined by anomalous diffraction in the X‐ray crystal structure analysis.

Recovery and recycle of fluoroalkyl-derivatised BINAP ligands using FRP silica gel

Three chiral perfluoroalkylated bidentate phosphorus(III) ligands have been prepared and characterised. These ligands have been evaluated in the asymmetric hydrogenation of methyl acetoacetate in dichloromethane and compared with the parent, non-fluorinated, ruthenium catalyst systems. After catalysis, recovery and reuse of the ligands has been achieved.

A Comparison of Palladium Complexes of BINAP and Diphenylphosphinooxazoline Ligands in the Catalytic Asymmetric Synthesis of cis‐Decalins.

AbstractFor Abstract see ChemInform Abstract in Full Text.