Chiral sulfonated phosphines. Rhodium(I)-catalyzed asymmetric hydrogenolysis of epoxides

Bakos, József; Orosz, Árpád; Cserépi, Stefánia Szűcsné; Tóth, Imre; Sinou, Denis

doi:10.1016/s1381-1169(96)00193-8

Cited by 29 publications

(15 citation statements)

References 27 publications

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“…[5] There have been no direct observations of 2-metallaoxetane intermediates in any of these reactions; mechanistic proposals have all been based on indirect evidence (e. g. kinetics). Reports on the reactivity of 2-metallaoxetanes are scarce and little is known about the properties of these strained four-membered metallacycles.…”

Section: Introductionmentioning

confidence: 99%

2-Rhodaoxetanes: Their Formation of Oxidation of [RhI(ethene)]+ and Their Reactivity upon Protonation

et al. 2000

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New cationic, pentacoordinate complexes [(TPA)Rh1(ethene)]+, [1a]+, and [(MeTPA)Rh1(ethene)]+, [1b]+, have been prepared (TPA = N,N,N-tri(2-pyridylmethyl)amine, MeTPA = N-[(6-methyl-2-pyridyl)-methyl]-N,N-di(2-pyridylmethyl)amine). Complex [1a]+ is selectively converted by aqueous HCl to [(TPA)RhIII-(ethyl)Cl]+, [2a]+. The same reaction with [1b]+ results in the [(MeTPA)RhIII-(ethyl)Cl]+ isomers [2b]+ and [2c]+. Treatment of [1a]+ and [1b]+ with aqueous H2O2 results in a selective oxygenation to the unsubstituted 2-rho-da(III)oxetanes (1-oxa-2-rhoda(III)cyclo-butanes) [(TPA)RhIII(kappa2-C,O-2-oxyethyl)]+, [3a]+, and [(MeTPA)RhIII(kappa2-C,O-2-oxyethyl)]+, [3b]+. The reactivity of 2-rhodaoxetanes [3a]+ and [3b]+ is dominated by the nucleophilic character of their 2-oxyethyl oxygen. Reaction of [3a]+ and [3b]+ with the non-coordinating acid HBAr(f)4 results in the dicationic protonated 2-rhodaoxetanes [(TPA)RhIII(kappa2-2-hydroxyethyl)]2+, [4a]2+, and [(MeTPA)RhIII(kappa2-2-hydroxyethyl)]2+, [4b]2+. These eliminate acetaldehyde at room temperature, probably via a coordinatively unsaturated kappa1-2-hydroxyethyl complex. In acetonitrile, complex [4a]2+ is stabilised as [(TPA)-RhIII(kappa1-2-hydroxyethyl)(MeCN)]2+, [5a]2+, whereas the MeTPA analogue [4b]2+ continues to eliminate acetaldehyde. Reaction of [3a]+ with NH4Cl and Mel results in the coordinatively saturated complexes [(TPA)RhIII(kappa1-2-hydroxyethyl)(Cl)]+, [6a]+, and [(TPA)-RhIII(kappa1-2-methoxyethyl)(I)+, [7a]+, respectively. Reaction of [3a]+ with NH4+ in MeCN results in formation of the dicationic metallacyclic amide [(TPA)-RhIII [kappa2-O,C-2-(acetylamino)ethyl]]2+, [9]2+, via the intermediates [4a]2+, [5a]2+ and the metallacyclic iminoester [(TPA)RhIII[kappa2-N,C-2-(acetimidoyloxy)ethyl]]2+, [8]2+. The observed overall conversion of the [Rh(I)(ethene)] complex [1a]+ to the metallacyclic amide [9]2+ via 2-rhodaoxetane [3a]+, provides a new route for the amidation of a [RhI(ethene)] fragment.

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Section: Introductionmentioning

confidence: 99%

2-Rhodaoxetanes: Their Formation of Oxidation of [RhI(ethene)]+ and Their Reactivity upon Protonation

et al. 2000

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“…Complexes bearing such ligands have been applied to various reactions in water . Furthermore, several water-soluble chiral ligands incorporating these substituents have been developed as well over the past decade, providing fair to good enantioselectivity in the hydrogenation and hydroformylation of alkenes and the hydrogenolysis of epoxides …”

Section: Introductionmentioning

confidence: 99%

Novel Water-Soluble Bisphosphinite Chiral Ligands Derived from α,α- and β,β-Trehalose. Application to Asymmetric Hydrogenation of Dehydroamino Acids and Their Esters in Water or an Aqueous/Organic Biphasic Medium

et al. 1999

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Novel 2,3:4,6-di-O-isopropylidene-alpha-D-glucopyranosyl-(1,1)-4,6-O-isopropylidene-2,3-di-O-diphenylphosphino-alpha-D-glucopyranoside (2), 2,3:4,6-di-O-cyclohexylidene-alpha-D-glucopyranosyl-(1,1)-4,6-O-cyclohexylidene-2,3-di-O-diphenylphosphino-alpha-D-glucopyranoside (4), and 2,3:4,6-di-O-cyclohexylidene-beta-D-glucopyranosyl-(1,1)-4,6-O-cyclohexylidene-2,3-di-O-diphenylphosphino-beta-D-glucopyranoside (11) were prepared from the corresponding alpha,alpha- or beta,beta-trehalose. The ligands were transformed into cationic Rh complexes, such as [Rh(alpha-D-glucopyranosyl-(1,1)-2,3-di-O-diphenylphosphino-alpha-D-glucopyranoside)(cod)]BF(4) (3) and [Rh(beta-D-glucopyranosyl-(1,1)-2,3-di-O-diphenylphosphino-beta-D-glucopyranoside)(cod)]BF(4) (12) bearing free hydroxy groups. These complexes were soluble in water and were efficient catalysts for the asymmetric hydrogenation of dehydroamino acids and their esters in water or an aqueous/organic biphasic medium with high enantioselectivity (up to 99.9% ee). Aqueous biphasic systems offer an easy separation of the aqueous catalyst phase from the product phase and allow recycling of the catalyst phase without the loss of enantioselectivity.

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“…Potential of other ligands in the Rh‐catalyzed asymmetric hydrocarboxylation : We selected a set of ligands structurally different from SEGPHOS from the library of AARON [10a] ( L2 – L4 , Figure 3) and investigated their predicted enantioselectivities with DFT. The set includes one P , N ligand ( L2 : StackPhos), [11] an N , N ligand ( L3 : t Bu‐BOX) [12] and a P , P ligand ( L4 : BDPP) [13] . These ligands have shown good performance in other asymmetric transformations (allylation, aziridination, hydrovinylation), [14] and to our knowledge, they have not previously been used for Rh‐catalyzed hydrocarboxylation.…”

Section: Resultsmentioning

confidence: 99%

“…The set includes one P,N ligand (L2: StackPhos), [11] an N,N ligand (L3: t Bu-BOX) [12] and a P,P ligand (L4: BDPP). [13] These ligands have shown good performance in other asymmetric transformations (allylation, aziridination, hydrovinylation), [14] and to our knowledge, they have not previously been used for Rhcatalyzed hydrocarboxylation.…”

Section: Carboxylation Of 4-(tert-butyl)benzyl 2-phenylacrylatementioning

confidence: 99%

Computational and Experimental Insights into Asymmetric Rh‐Catalyzed Hydrocarboxylation with CO₂

et al. 2021

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The asymmetric Rh-catalyzed hydrocarboxylation of α,β-unsaturated carbonyl compounds was originally developed by Mikami and co-workers but gives only moderate enantiomeric excesses. In order to understand the factors controlling the enantioselectivity and to propose novel ligands for this reaction, we have used computational and experimental methods to study the Rh-catalyzed hydrocarboxylation with different bidentate ligands. The analysis of the CÀ CO 2 bond formation transition states with DFT methods shows a preference for outer-sphere CO 2 insertion, where CO 2 can undergo a backside or frontside reaction with the nucleophile. The two ligands that prefer a frontside reaction, StackPhos and t Bu-BOX, display an intriguing stacking interaction between CO 2 and an N-heterocyclic ring of the ligand (imidazole or oxazoline). Our experimental results support the computationally predicted low enantiomeric excesses and highlight the difficulty in developing a highly selective version of this reaction.

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Chiral sulfonated phosphines. Rhodium(I)-catalyzed asymmetric hydrogenolysis of epoxides

Cited by 29 publications

References 27 publications

2-Rhodaoxetanes: Their Formation of Oxidation of [RhI(ethene)]+ and Their Reactivity upon Protonation

2-Rhodaoxetanes: Their Formation of Oxidation of [RhI(ethene)]+ and Their Reactivity upon Protonation

Novel Water-Soluble Bisphosphinite Chiral Ligands Derived from α,α- and β,β-Trehalose. Application to Asymmetric Hydrogenation of Dehydroamino Acids and Their Esters in Water or an Aqueous/Organic Biphasic Medium

Computational and Experimental Insights into Asymmetric Rh‐Catalyzed Hydrocarboxylation with CO₂

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Chiral sulfonated phosphines. Rhodium(I)-catalyzed asymmetric hydrogenolysis of epoxides

Cited by 29 publications

References 27 publications

2-Rhodaoxetanes: Their Formation of Oxidation of [RhI(ethene)]+ and Their Reactivity upon Protonation

2-Rhodaoxetanes: Their Formation of Oxidation of [RhI(ethene)]+ and Their Reactivity upon Protonation

Novel Water-Soluble Bisphosphinite Chiral Ligands Derived from α,α- and β,β-Trehalose. Application to Asymmetric Hydrogenation of Dehydroamino Acids and Their Esters in Water or an Aqueous/Organic Biphasic Medium

Computational and Experimental Insights into Asymmetric Rh‐Catalyzed Hydrocarboxylation with CO2

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Computational and Experimental Insights into Asymmetric Rh‐Catalyzed Hydrocarboxylation with CO₂