Asymmetric Transfer Hydrogenation of Ketones Using New Iron(II) (P‐NH‐N‐P′) Catalysts: Changing the Steric and Electronic Properties at Phosphorus P′

Smith, Samantha A. M.; Prokopchuk, Demyan E.; Morris, Robert H.

doi:10.1002/ijch.201700019

Cited by 24 publications

(10 citation statements)

References 52 publications

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“…Mechanistic investigations and ligand variations with respect to the backbone and phosphorus substituents gave additional insight. [435][436][437] While considerably more active than iron pincer catalysts, the PNNP systems are prone to reduced stereoselectivity due to racemization of the product alcohol. Scheme 34.…”

Section: Asymmetric Hydrogenation Of Ketonesmentioning

confidence: 99%

First-Row Transition Metal (De)Hydrogenation Catalysis Based On Functional Pincer Ligands

2018

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The use of 3d metals in de-/hydrogenation catalysis has emerged as a competitive field with respect to 'traditional' precious metal catalyzed transformations. The introduction of functional pincer ligands that can store protons and/or electrons as expressed by metal-ligand cooperativity and ligand redox-activity strongly stimulated this development as conceptual starting point for rational catalyst design. This reviews aims at providing a comprehensive picture of the utilization of functional pincer ligands in first-row transition metal hydrogenation and dehydrogenation catalysis and related synthetic concepts relying on these such as the hydrogen borrowing methodology. Particular emphasis is put on the implementation and relevance of cooperating and redox-active pincer ligands within the mechanistic scenarios.

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Section: Asymmetric Hydrogenation Of Ketonesmentioning

confidence: 99%

First-Row Transition Metal (De)Hydrogenation Catalysis Based On Functional Pincer Ligands

2018

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“…Later, related catalysts 12 and 13 bearing other phosphine substituents (R 3 = Et, o-Tol) were investigated in these reactions under the same conditions in order to evaluate the role of the steric properties of the phosphine groups on the activity and enantioselectivity. The asymmetric transfer hydrogenation of a range of alkyl aryl and dialkyl ketones was achieved with low to complete conversions (22->99%) and low to high enantioselectivities (12-90% ee), as shown in Scheme 6 [21]. The comparison of the results showed that by increasing the steric bulk at one phosphine (R 3 = Cy or o-Tol instead of Et), the enantioselectivity of the reaction increased.…”

Section: Asymmetric Transfer Hydrogenations Of Ketones and Iminesmentioning

confidence: 98%

Recent developments in enantioselective iron-catalyzed transformations

Pellissier

2019

Coordination Chemistry Reviews

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Scheme 2. Chiral iron catalysts described by Morris, Gao and Mezzetti groups [13,14,16]. Scheme 3. Transfer hydrogenation of alkyl aryl ketones catalyzed by chiral (NH) 2 P 2 macrocyclic iron complexes [17]. Scheme 4. Transfer hydrogenation of alkyl aryl ketones and a phosphinyl imine catalyzed by chiral (NH) 2 P 2 macrocyclic iron complexes [18]. Scheme 5. Transfer hydrogenation of benzyls without base additive [19]. Scheme 8. Hydrogenation of alkyl aryl ketones catalyzed by an iron catalyst derived from a chiral PNP' ligand [29]. Scheme 9. Hydrogenation of alkyl aryl ketones catalyzed by an iron catalyst derived from a chiral monohydride unsymmetrical PNHP' pincer ligand [30]. Scheme 10. Hydrogenation of ketones catalyzed by a chiral cyclopentadienone iron tricarbonyl complex [31]. Scheme 11. Hydrogenation of para-methoxyacetophenone catalyzed by a chiral cyclopentadienone iron tricarbonyl complex embedded in streptavidin [32]. Scheme 14. Hydrosilylation of alkyl aryl ketones catalyzed by a chiral iminopyridine-oxazoline iron complex [41]. Scheme 15. Hydrosilylation of para-phenyl acetophenone catalyzed by a chiral bis(oxazolinyl)phenyl iron complex [42]. Scheme 58. Synthesis of esomeprazole through sulfoxidation [104]. Scheme 59. CAH Alkylation of indoles with aromatic alkenes [105].

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“…Such complexes contain an iron(II) center coordinated to a chiral tetradentate P−N−N−P ligand, in which the two nitrogen donors can derive both from imines (complex 8 , Scheme 5A), [26] an imine and an amine (complexes 9 to 11 a – f ) [27] or two amines (complexes 12 a – e , Scheme 5A) [27c] . Complexes 8 – 12 showed noteworthy activity and enantioselectivity in the transfer hydrogenation of ketones: 98% ee , along with a conversion of 71%, was reached in the ATH (asymmetric transfer hydrogenation) of acetophenone to ( R )‐1‐phenylethanol catalyzed by complex 10 (Scheme 5B), and other ketones were reduced with ee s up to 99% [28] …”

Section: Octahedral Complexes In Asymmetric Reduction Reactionsmentioning

confidence: 99%

“…[27c] Complexes 8-12 showed noteworthy activity and enantioselectivity in the transfer hydrogenation of ketones: 98% ee, along with a conversion of 71%, was reached in the ATH (asymmetric transfer hydrogenation) of acetophenone to (R)-1-phenylethanol catalyzed by complex 10 (Scheme 5B), and other ketones were reduced with ees up to 99%. [28] These complexes have been isolated and characterized in the solid state both in the trans (complexes 8-10) and cis-β (complexes 11 a-f and 12 a-e) geometries, the latter with a well-defined helicity. However, the predominant species in solution, which is also the catalytically active one, was the trans-geometry, and thus enantioselectivity can be attributed to the chirality of the PÀ NÀ NÀ P ligands only.…”

Section: Octahedral Complexes In Asymmetric Reduction Reactionsmentioning

confidence: 99%

Chiral Iron Complexes in Asymmetric Organic Transformations

2021

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Transition metal chiral catalysts can feature metal stereocenters in different coordination geometries. In the case of iron, both octahedral and tetrahedral geometries possessing a chirotopic iron atom have been synthesized and tested in stereoselective organic transformations. The configurational stability of these complexes, which in some cases is hampered by decomplexation and recomplexation of labile ligands, is achieved by the use of multidentate ligands in octahedral complexes, and of cyclopentadienyl anions (half sandwich complexes) in the case of tetrahedral structures. The use of octahedral iron complexes featuring configurationally stable iron stereocenters is reviewed in highly enantioselective reductions (hydrogenation and transfer hydrogenation of ketones) and oxidations (cis‐dihydroxylation of alkenes, epoxidation, sulfoxidation), while the use tetradentate iron complexes is described in C−C bond‐forming reactions and reductions.

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Asymmetric Transfer Hydrogenation of Ketones Using New Iron(II) (P‐NH‐N‐P′) Catalysts: Changing the Steric and Electronic Properties at Phosphorus P′

Cited by 24 publications

References 52 publications

First-Row Transition Metal (De)Hydrogenation Catalysis Based On Functional Pincer Ligands

First-Row Transition Metal (De)Hydrogenation Catalysis Based On Functional Pincer Ligands

Recent developments in enantioselective iron-catalyzed transformations

Chiral Iron Complexes in Asymmetric Organic Transformations

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