Backbone-Modified Bisdiazaphospholanes for Regioselective Rhodium-Catalyzed Hydroformylation of Alkenes

Wildt, Julia; Brezny, Anna C.; Landis, Clark R.

doi:10.1021/acs.organomet.7b00475

Cited by 16 publications

(6 citation statements)

References 69 publications

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“…Overall, the catalytic activity and selectivity of the Rh– L /Rh–H L complexes (in the absence of added free phosphine ligands) are similar to those reported for analogous complexes with coordinated 1′-(diphenylphosphino)ferrocene-1-carboxylic acid (Hdpf) and the corresponding carboxylate (dpf – ) but rather low in comparison with the state-of-the-art hydroformylation catalysts. , The catalytic activity of the Rh– L /Rh–H L complexes appears to be mainly affected by low solubility of these compounds in both pure educts and even in biphase reaction systems . Without added free ligands, the tested compounds are likely to convert under the reaction conditions (at least partly) into dissociation products such as [RhH(CO) 2 (PR 3 )] , (or even phosphine-free Rh(I) carbonyl complexes [RhH(CO) n ] and carbonyl clusters) that become the real (but less selective, especially in terms of the n / iso ratio) catalysts in the studied system …”

Section: Resultssupporting

confidence: 68%

“…NMR spectra were recorded at 25 °C on Varian UNITY Inova 400 or Bruker Avance III 600 spectrometers. Chemical shifts (δ in ppm) are given in relation to internal tetramethylsilane ( 1 H and 13 C) and to external 85% aqueous H 3 PO 4 , all set to 0 ppm. Apart from the standard notation of signal multiplicity (s = singlet, d = doublet, t = triplet, etc.…”

Section: Methodsmentioning

confidence: 99%

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Synthesis, Structural Characterization, and Hydroformylation Activity of Rhodium(I) Complexes with a Polar Phosphinoferrocene Sulfonate Ligand

et al. 2018

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1′-(Diphenylphosphino)ferrocene-1-sulfonic acid (HL), isolated from the salt (Et3NH)L on an ion exchanger, reacts with Rh(I) complexes [Rh(acac)(CO)(PR3)] (acac = acetylacetonato-κ2 O,O′) to give complexes of the type [Rh(CO)(PR3)(Ph2PfcSO3-κ2 O,P)] (1a–d; R = Ph (a), Cy (b), 2-furyl (c), and OMe (d); fc = ferrocene-1,1′-diyl). In an analogous reaction with [Rh(acac)(nbd)] (nbd = η2:η2-norbornadiene), HL produces [Rh(nbd)(Ph2PfcSO3-κ2 O,P)] (2). Adding (Et3NH)L (2 equiv per Rh) to [Rh(μ-Cl)(CO)2]2 and [Rh(acac)(CO)2] gives rise to the cationic complexes trans-(Et3NH)2[RhCl(CO)(Ph2PfcSO3-κP)2] (3) and (Et3NH)[Rh(CO)(Ph2PfcSO3-κ2O,P)(Ph2PfcSO3-κP)] (4), respectively. In complex 4, resulting from the simultaneous substitution of a CO ligand and acid–base replacement of the acac ligand, the P-monodentate and O,P-chelating phosphinoferrocene sulfonate ligands rapidly interconvert (in a solution). All compounds were characterized by spectroscopic methods and by elemental analysis, and the crystal structures of 1a·Me2CO, solvated 1b, 2, and 4·H2O were determined. Furthermore, the catalytic activity of all Rh(I) complexes was assessed in hydroformylation of vinyl acetate under solvent-free conditions at 80 °C and at 20 bar of synthesis gas (H2/CO = 1:1). High conversion with good selectivity to iso-aldehyde was observed for 1a·1/2H2O and 4·1/2H2O. When applied to “on-water” hydroformylation of 1-hexene (80 °C/10 bar), the complexes mainly promoted 1-hexene isomerization to 2-hexene. However, two of them, 1a·1/2H2O and 1c, exhibited reasonable selectivity to aldehydes and preferentially produced the linear product (n/iso ratios up to 3).

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Section: Resultssupporting

confidence: 68%

Section: Methodsmentioning

confidence: 99%

Synthesis, Structural Characterization, and Hydroformylation Activity of Rhodium(I) Complexes with a Polar Phosphinoferrocene Sulfonate Ligand

et al. 2018

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“…Recent work from Clarke and co-workers, which used Rh(acac)(CO) 2 with ( S ax , S , S )-bobphos catalyst system, achieved significant regioselectivities and enantioselectivities for a variety of simple 1-alkenes ( Table ). Our group has recently reported the synthesis of reduced backbone BDPs that yield high branched selectivity for difficult allyl substrates (Table ), though the origin of this preference is not clear.…”

Section: Recent Advancements In the Accessibility Of Ahfmentioning

confidence: 99%

Recent Developments in the Scope, Practicality, and Mechanistic Understanding of Enantioselective Hydroformylation

2018

Self Cite

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In the nearly 80 years since catalytic hydroformylation was first reported, hundreds of billions of pounds of aldehyde have been produced by this atom efficient one-carbon homologation of alkenes in the presence of H and CO. Despite the economy and demonstrated scalability of hydroformylation, the enantioselective process (asymmetric hydroformylation, AHF) currently does not contribute significantly to the production of chiral aldehydes and their derivatives. Current impediments to practical application of AHF include low diversity of chiral ligands that provide effective rates and selectivities, limited exploration of substrate scope, few demonstrations of efficient flow reactor processes, and incomplete mechanistic understanding of the factors that control reaction selectivity and rate. This Account summarizes developments in ligand design, substrate scope, reactor technology, and mechanistic understanding that advance AHF toward practical and atom-efficient production of chiral α-stereogenic aldehydes. Initial applications of AHF were limited to activated terminal alkenes such as styrene, but recent developments enable high selectivity for unactivated olefins and more complex substrates such as 1,1'- and 1,2-disubstituted alkenes. Expanded substrate scope primarily results from new chiral phosphine ligands, especially phospholanes and bisdiazaphospholanes (BDPs). These ligands are now more accessible due to improved synthesis and resolution procedures. One of the virtues of diazaphospholanes is the relative ease of derivatization, including attachment to heterogeneous supports. Hydroformylation involves toxic and flammable reactants, a serious concern in pharmaceutical production facilities. Flow reactors offer many process benefits for handling dangerous reagents and for systematically moving from research to production scales. New approaches to achieving good gas-liquid mixing in flow reactors have been demonstrated with BDP-derived catalyst systems and lend assurance that AHF can be practically implemented by the pharmaceutical and fine chemical industries. To date, progress in AHF has been empirically driven, because hydroformylation is a complex, multistep process for which the origins of chemo-, regio-, and enantioselectivity are difficult to elucidate. Mechanistic complexity arises from three concurrent catalytic cycles (linear and two diastereomeric branched paths), significant pooling of catalyst as off-cycle species, and multiple elementary steps that are kinetically competitive. Addressing such complexity requires new approaches to collecting kinetic and extra-kinetic information and analyzing these data. In this Account, we describe our group's progress toward understanding the complex kinetics and mechanism of AHF as catalyzed by rhodium bis(diazaphospholane) catalysts. Our strategy features both "outside-in" (i.e., monitoring catalytic rates and selectivities as a function of reactant concentration and temperature) and "inside-out" (i.e., building kinetic models based on the rates of component st...

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“…In general, optimization of the catalyst and the reaction conditions (e. g. ligand or syngas pressure variation) can lead to the formation of a single regioisomer with high selectivity. [23,37,[45][46][47][48][49][50][51][52] However, this strategy falls short for substrates where the reactivity of the alkene is not biased to a single product or alternatively, the reactive alkene is biased to a product that is different from the desired product. [25,[53][54][55][56][57][58][59] Using the supramolecular substrate preorganization strategy, our group and the group of Breit et al were able to control the regioselectivity of challenging substrates in the hydroformylation reaction using a carboxylate directing group.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Unraveling the Origin of the Regioselectivity of a Supramolecular Hydroformylation Catalyst

Linnebank

Kluwer²,

Reek

2022

ChemCatChem

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Supramolecular substrate preorganization using DIMPHos ligands, which are bisphosphine ligands equipped with a carboxylate binding site, allows for control over the regioselectivity in the hydroformylation reaction. In all reported examples, the aldehyde product in which the CO was inserted farthest from the directing group, was formed in excess (for terminal alkenes the linear aldehyde). We report here an in-depth DFT study to provide mechanistic insight into this selective transformation. These calculations show large energy differences between the different hydride migration steps of competing pathways that lead to either the linear or branched aldehyde product, in line with the experimentally found selectivity. Through the use of calculated model systems of the catalyst, it is shown that the substrate binding event itself plays an important role in determining these large energy differences. Following ditopic substrate binding, the product forming pathways that lead to the minor isomeric product is particularly disfavored by the steric repulsion between the ditopically bound substrate and the apical coordinated CO ligand.

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Backbone-Modified Bisdiazaphospholanes for Regioselective Rhodium-Catalyzed Hydroformylation of Alkenes

Cited by 16 publications

References 69 publications

Synthesis, Structural Characterization, and Hydroformylation Activity of Rhodium(I) Complexes with a Polar Phosphinoferrocene Sulfonate Ligand

Synthesis, Structural Characterization, and Hydroformylation Activity of Rhodium(I) Complexes with a Polar Phosphinoferrocene Sulfonate Ligand

Recent Developments in the Scope, Practicality, and Mechanistic Understanding of Enantioselective Hydroformylation

Unraveling the Origin of the Regioselectivity of a Supramolecular Hydroformylation Catalyst

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