Synthesis, complexation behavior and application of a new diphosphite ligand in rhodium-catalyzed hydroformylation

Oxidative coupling of 3-(3-tert-butyl-4-hydroxyphenyl)propionic acid methyl ester (2) gave dimethyl 3,3′-(5,5′-di-tert-butyl-6,6′-dihydroxybiphenyl-3,3′-diyl)-dipropionate (1c), which upon phosphorylation/transesterification with a phosphochloridite derived from (R)-binaphthol, formed the new unsymmetrical binaphthol-bridged diphosphite 4. A rhodium catalyst based on 4 as ligand gave predominantly iso-selectivity in the hydroformylation of selected styrenes but opposite regioselectivity with 2,6-disubstituted derivatives. New chelate metal complexes (acac)RhL, PdCl₂L and PtCl₂L have been synthesized by reacting 4 with (acac)Rh(CO)₂, PdCl₂(MeCN)₂ and PtCl₂(COD), respectively. The structure of obtained compounds is determined based on ¹H, ¹³C, ³¹P and ¹⁹⁵Pt NMR spectroscopy and mass spectrometry data.     

A hybrid phosphorus ligand for highly enantioselective asymmetric hydroformylation

A new hybrid phosphorus ligand has been prepared starting from chiral NOBIN (2-amino-2'-hydroxy-1,1'-binaphthyl). Excellent enantioselectivities (up to 99% ee) have been achieved in the Rh-catalyzed asymmetric hydroformylations of styrene derivatives and vinyl acetate.     

Rhodium/bisphosphite catalytic system for hydroformylation of styrene and its derivatives

Different kinds of mono‐ and bidentate phosphite ligands were used in Rh‐catalyzed hydroformylation of styrene to illustrate the influence of steric and electronic properties of ligands on catalytic performance. High activity (99.9%) and good regioselectivity (85.4%) to the linear aldehyde were achieved under optimum conditions in the presence of Rh/bisphosphite complex (bisphosphite: 2,2′‐bis(dipyrrolylphosphinooxy)‐1,1′‐(±)‐binaphthyl). This system makes it possible to prepare functionalized terminal aldehydes from readily available styrene or its derivatives through hydroformylation with high linear selectivity. Copyright © 2013 John Wiley & Sons, Ltd.     

BINAS - synthesis and use of a new ligand for propylene hydroformylation

BINAS is a new, very efficient ligand for propylene hydroformylation. BINAS is made by the sulfonation of NAPHOS. Different synthetic routes to NAPHOS are discussed. A new two step synthesis starting from 2,2′-bis(bromomethyl)-1,1′-binaphthyl is described.     

Synthesis of new amidophosphite ligand and its application in Ir-catalyzed asymmetric hydrogenation of heterocyclic compounds

A new chiral amidophosphite ligand was synthesized and tested in the iridium-catalyzed hydrogenation of heterocyclic compounds. The enantioselectivity of hydrogenation of 2-methylquinoline considerably increases when piperidine hydrochloride is used as an additive. The hydrogenation reaction of 8-methyl-2,4,5,6-tetrahydro-1H-pyrazino[3,2,1-jk]carbazole by metal complex was conducted for the first time to prepare enantiomerically enriched antidepressant Pyrazidol.     

Synthesis of new monodentate spiro phosphoramidite ligand and its application in Rh-catalyzed asymmetric hydrogenation reactions

[reaction: see text] A new spirocyclic diol, 9,9'-spirobixanthene-1,1'-diol, was synthesized in two steps from readily available starting material m-phenoxyanisole. Resolution of the racemic diol was achieved by cocrystallization with N-benzylcinchonidinium chloride and N-benzylquininium chloride in acetonitrile. The corresponding spiro monodentate phosphoramidite ligand has been prepared for Rh-catalyzed asymmetric hydrogenation of alpha-dehydroamino acid derivatives and itaconic acid with excellent enantioselectivities (up to >99% ee).     

Synthesis of a fluorous ligand and its application for asymmetric addition of dimethylzinc to aldehydes

A new fluorous ligand was synthesized from the acetonide of dimethyl tartarate, which showed excellent asymmetric induction on the addition of dimethylzinc to aldehydes. This ligand will be useful for synthesis of bioactive compounds with a methyl carbinol moiety. It could be recycled without using a fluorous solvent or a fluorous column.     

Parallel ligand screening on olefin mixtures in asymmetric hydroformylation reactions

[reaction: see text] Herein we describe a new protocol for catalyst evaluation in asymmetric hydroformylation reactions where multisubstrate screening is performed in an array of parallel reactors. This method was successfully demonstrated using a mixture of styrene, allyl cyanide, and vinyl acetate. Using this screening methodology, a set of phosphite ligands was evaluated and led to the discovery of a bisphosphite ligand that gave 88% ee and unprecedented >100:1 branched:linear regioselectivity in asymmetric hydroformylation of vinyl acetate.     

Synthesis and resolution of a novel chiral diamine ligand and application to asymmetric lithiation-substitution

A short, efficient synthesis of chiral 1,5-diaza-cis-decalins (7) is presented. In the lithiation of N-Boc pyrrolidine, the ligands with the smallest most electron rich R groups (Me > Et > CH2tBu > CH2CF3 approximately Bn) were most effective. In the asymmetric deprotonation/substitution of benzylic substrates, (R,R)-7 (R = Me, R' = H) conferred modest selectivity. The ready availability of both enantiomers of the 1,5-diaza-cis-decalins and the ability to tune steric and electronic properties renders these compounds an attractive new class of diamine ligands.     

Synthesis of a novel spiro bisphosphinite ligand and its application in Rh-catalyzed asymmetric hydrogenation

A novel, chiral bisphosphinite ligand (R)-SpiroBIP has been synthesized. The rhodium complex of the ligand was found to be highly enantioselective in the asymmetric hydrogenation of α-dehydroamino acid derivatives.     

New chiral aminophosphine carboxyphosphinite ligands (AMPCP). Synthesis and application in asymmetric hydrogenation and hydroformylation

The synthesis of the first three aminophosphine-carboxyphosphinite diphosphanes derived directly from α-amino acids is presented. These ligands were applied in the asymmetric hydrogenation of dihydro-2,4-dimethyl-2,3-furandione giving the corresponding pantolactone with up to 42% ee. They were also involved, in association with platinum, in the asymmetric hydroformylation of styrene giving the branched aldehyde with low ee (<5%).     

Synthesis of a new chiral N,N,N-tridentate pyridinebisimidazoline ligand library and its application in Ru-catalyzed asymmetric epoxidation

A small ligand library of chiral tridentate N,N,N-pyridinebisimidazolines have been synthesized for the first time. This new class of ligands can be easily tuned and synthesized on multi g-scale. The usefulness of the ligands is shown in the ruthenium-catalyzed asymmetric epoxidation with hydrogen peroxide as oxidant. Excellent yields (>99%) and good enantioselectivities (up to 71% ee) have been obtained for the epoxidation of aromatic olefins. [reaction: see text]     

Synthesis of a new chiral amino phosphine ligand and its application in the asymmetric allylic alkylation (AAA) reaction

This article describes the synthesis of a new chiral amino phosphine ligand based on an amino naphthol starting material, which is resolved efficiently by using l-tartaric acid. The asymmetric induction of the ligand in the Pd(0)-catalyzed allylic substitution of 1,3-diphenylprop-2-en-1-yl acetate with dimethyl malonate was investigated. Good yields and enantiomeric excesses up to 78% of the product were obtained.     

Coordination studies on supramolecular chiral ligands and application in asymmetric hydroformylation

In this study we introduce a series of monodentate pyridine-based ligands for which the phosphorus coordination mode to rhodium can be controlled by the binding of Zn(II)-templates to the pyridyl group. A series of monodentate phosphoroamidite and phosphite ligands have been prepared and studied under hydroformylation conditions by in situ high-pressure NMR and IR techniques. These studies reveal the exclusive formation of rhodium hydride complexes in which the phosphorus atom of the ligand resides in an axial position, trans to the hydride, but only after addition of Zn(II)-template. In the absence of these templates the usual mono-coordinated rhodium hydrido complexes are formed, with the phosphorus ligated in the equatorial plane, cis to the hydride. The catalytic performance of these complexes is evaluated in asymmetric hydroformylation of unfunctionalised internal alkenes in which the supramolecular change is reflected in higher activity and selectivity.     

Synthesis of a water-soluble cationic chiral diamine ligand bearing a diguanidinium and application in asymmetric transfer hydrogenation

A novel water-soluble cationic N-monosulfonated chiral diamine ligand diguanidinium 1c was easily prepared from (R,R)-DPEN and its rhodium complex and was successfully applied in the asymmetric transfer hydrogenation of prochiral ketones and imines in water by using sodium formate and formic acid as co-hydrogen donors. Various substrates were reduced with high yields and good to excellent enantioselectivities (up to >99% ee).     

Synthesis of ortho-phenyl substituted MeO-BIPHEP ligand and its application in Rh-catalyzed asymmetric hydrogenation

A new BIPHEP-type ligand with phenyl groups at the 3,3′-positions, o-Ph-MeO-BIPHEP 3 was prepared. This ligand afforded excellent enantioselectivities when used in the Rh-catalyzed asymmetric hydrogenation of α-dehydroamino acid derivatives. The strong influence of o-phenyl groups of the ligand on the enantioselectivities of the reaction has been demonstrated by a comparison with its parent ligand MeO-BIPHEP.     

New diphosphite ligands for enantioselective asymmetric hydroformylation

A series of new diphosphite ligands have been easily prepared from BINOL derivatives; moderate enantioselectivities (up to 80% ee) and excellent regioselectivities (b/l up to 98/2) have been achieved in the Rh-catalyzed asymmetric hydroformylation of vinyl acetate.     

Synthesis of (S)-N-(diphenylphosphinyl)-S-methyl-S-phenyl sulfoximide: a new ligand for asymmetric catalysis

The synthesis of (S)-N-(diphenylphosphinyl)-S-methyl-S-phenyl sulfoximide is reported. Preliminary investigations into the use of this novel sulfoximide as a ligand for asymmetric conjugate addition reactions are also described.     

First successful application of diphosphite ligands in the asymmetric hydroformylation of dihydrofurans

Good enantioselectivities and excellent regioselectivities are achieved in the Rh-catalyzed asymmetric hydroformylation of 2,5- and 2,3-dihydrofuran using diphosphite ligands; whereby the backbone of the ligand is crucial to suppressing isomerization and obtaining high ee's.     

A new type of L-Tertiary leucine-derived ligand: Synthesis and application in Cu(II)-catalyzed asymmetric Henry reactions

A new series of Schiff bases derived from amino acids were developed as chiral ligands for Cu(II)-catalyzed asymmetric Henry reactions. The optimum ligand 7d exhibited outstanding catalytic efficiency in the Cu(II)-catalyzed asymmetric Henry additions of four nitroalkanes to different kinds of aldehydes to produce 76 desired adducts in high yields (up to 96%) with excellent enantioselectivities, up to 99% enantiomeric excess (ee).