Asymmetric Hydroformylation Using Taddol-Based Chiral Phosphine−Phosphite Ligands

Robert, Tobias; Abiri, Zohar; Wassenaar, Jeroen; Sandee, Albertus J.; Romanski, Steffen; Neudörfl, Jörg‐Martin; Schmalz, Hans‐Günther; Reek, Joost N. H.

doi:10.1021/om9009735

Cited by 80 publications

(31 citation statements)

References 36 publications

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“…Rapid interconversion of the two isomers, as described previously for diphosphite complexes, [24] interchanges the phosphorus atoms, and hence intermediate chemical shifts and coupling constants are observed. This has also been observed for other phosphine-phosphite ligand systems, [26,27] whereas systems with flexible bridges show static behaviour. This has also been observed for other phosphine-phosphite ligand systems, [26,27] whereas systems with flexible bridges show static behaviour.…”

Section: High-pressure Nmr Spectroscopysupporting

confidence: 72%

Synthesis and Reactivity of Chiral, Wide‐Bite‐Angle, Hybrid Diphosphorus Ligands

et al. 2013

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Keywords: P ligands / Synthesis design / Palladium catalysis / Rhodium catalysisEffective and modular synthetic approaches toward phosphine-phosphite ligands and phosphine-phosphonite ligands featuring a diphenyl ether backbone have been developed. The phosphine-phosphite ligands are obtained by a two-step protocol from 2-bromo-2Ј-methoxydiphenyl ether. The phosphine-phosphonite ligands are prepared in a fourstep synthetic protocol that involves a novel, unsymmetrical diphenyl ether derived phosphine-phosphorusdiamide as key building block. Structural studies on Pt II complexes with either phosphine-phosphite or phosphine-phosphonite ligands indicate strict cis coordination for these ligand systems. High-pressure NMR spectroscopy studies of Rh complexes under syngas indicate the presence of two ea isomers for Rh(H)(CO) 2 (PP). The existence of this mixture is further [a] EaSTCHEM, Scheme 1. Synthetic route to phosphine-phosphonite ligands.into the BH 3 -product 7-(BH 3 ) 2 . The 31 P NMR spectrum of 7-(BH 3 ) 2 in CD 2 Cl 2 at room temperature shows an AX spin system with broad doublets at δ = 17.8 and 88.8 ppm ( 1 J PB coupling constant of 105 Hz), assigned to the BH 3 adducts of the aminophosphine and diphenylphosphine groups, respectively.Compound 7-(BH 3 ) 2 is stable towards oxidation and hydrolysis and can be easily purified by precipitation from acetone and methanol in good yields (80 %). Crystals of 7-(BH 3 ) 2 suitable for X-ray crystallography were obtained by recrystallization by slow diffusion of hexane into a diethyl ether solution (Figure 4). The P-C bond length of the backbone to the diphenylphosphine group [1.815(4) Å] is virtually the same as the P-C bond length of the backbone to the diethylaminophosphine group [1.819(4) Å]. Both P-C bond lengths are similar to the values found for other widebite-angle ligands such as Xantphos. [16] The intramolecular distance between the two phosphorus atoms [5.803(2) Å] is larger than in Xantphos (4.080 Å), and obviously the flexible backbone has to rearrange to allow chelation of a metal atom. The P-B bonds lengths [1.910(4) and 1.918(6) Å] of both phosphorus groups are almost indistinguishable. The tetrahedral geometry is distorted around both phosphorus centres, judging from, for example, the B-P-C angles.The BH 3 protecting groups were quantitatively and smoothly removed by reaction with an equimolar amount of DABCO in toluene at 60°C overnight without affecting the P-NEt 2 bond. The 31 P NMR spectrum shows one singlet at δ = 90.9 ppm (aminophosphine) and one singlet at -18.0 ppm (phosphine). The chemical shifts of the aminophosphine and phosphine groups are in the same range as previously reported for related species. [11] Ultimately, two hybrid phosphine-phosphonite ligands were prepared by reacting (S)-BINOL derivatives with the aminophosphine moiety in refluxing toluene for one day (for 8a) or two days (8b). The longer reaction time for 8b was expected as this reaction can be hampered by steric hindrance when using too bulky diols, [19] The products we...

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Section: High-pressure Nmr Spectroscopysupporting

confidence: 72%

Synthesis and Reactivity of Chiral, Wide‐Bite‐Angle, Hybrid Diphosphorus Ligands

et al. 2013

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“…Firstly, based on the fact that the branched aldehyde is more liable to be yielded in the hydroformylation, styrene is usually regarded as a model substrate for asymmetric hydroformylation. [4] Secondly, the linear aldehyde could be employed as an important intermediate in organic synthesis, such as the production of detergents, plasticizers and spices. [5,6] The fact that the linear aldehyde has significant application potential caused researchers to investigate the hydroformylation of styrene more thoroughly.…”

Section: Introductionmentioning

confidence: 99%

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

Zheng

Mo²,

Liang

et al. 2013

Applied Organom Chemis

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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 0 -bis(dipyrrolylphosphinooxy)-1,1 0 -(AE)-binaphthyl). This system makes it possible to prepare functionalized terminal aldehydes from readily available styrene or its derivatives through hydroformylation with high linear selectivity.

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“…Based on the BINAPHOS structure, a new family of phosphine-phosphite and phosphine-phosphoramidite ligands was constituted using a Taddol-based backbone in the phosphite or phosphoramidite moiety, respectively (Scheme 9) [76,77]. These ligands were applied in the Rh-catalyzed asymmetric hydroformylation of styrene, allyl cyanide, and vinyl acetate with excellent regioselectivities (up to 98%) and good ees (up to 85%).…”

Section: Phosphine-phosphite Ligandsmentioning

confidence: 99%

Asymmetric Hydroformylation

Perandones

Godard

Claver

2013

Topics in Current Chemistry

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Rhodium is currently the metal of choice to achieve high enantioselectivities in the hydroformylation of a relatively wide variety of alkene substrates. The elucidation of the different steps of the catalytic cycle and the characterization of the resting state, together with the discovery of several types of ligands that are able to provide high enantioselectivities, have made the rhodium-catalyzed hydroformylation a synthetically useful tool. For years, ligands containing phosphite moieties such as diphosphites and phosphine-phosphites were considered the most successful ligands to achieve high enantioselectivities for classical substrates such as styrene and vinyl acetate. In fact, the phosphite-phosphine BINAPHOS (43) and its derivatives are still today the most successful ligands in terms of selectivity and scope. For more substituted substrates, general trends can be extracted. However, recent studies showed that these general trends can be sometimes reversed by the use of the appropriate catalyst and choice of reaction conditions, clearly showing that these trends are only indicative and that there are still many challenges to be tackled in this area.

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Asymmetric Hydroformylation Using Taddol-Based Chiral Phosphine−Phosphite Ligands

Cited by 80 publications

References 36 publications

Synthesis and Reactivity of Chiral, Wide‐Bite‐Angle, Hybrid Diphosphorus Ligands

Synthesis and Reactivity of Chiral, Wide‐Bite‐Angle, Hybrid Diphosphorus Ligands

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

Asymmetric Hydroformylation

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