Potassium and silver chiral cobaltate(III) complexes as precatalysts for asymmetric C–C bond formation

Belokoń, Yuri N.; Maleev, Victor I.; Kataev, D. A.; Malfanov, Ilya L.; Bulychev, A. G.; Москаленко, М. А.; Savel’eva, T. F.; Skrupskaya, T. V.; Lyssenko, Konstantin А.; Godovikov, Ivan A.; North, Michael

doi:10.1016/j.tetasy.2008.03.010

Cited by 42 publications

(27 citation statements)

References 25 publications

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“…The absolute configuration of the major product was determined by comparison with the reported value of the specific rotation. 13 The enantiomeric purity of the synthesized Michael adducts was determined by chiral HPLC analysis (Chiralpak AS-H chiral stationary phase, iPrOH-hexane/1:9, 210 nm). The absolute configuration of the major product was determined by comparison with the reported value of the specific rotation.…”

Section: Methodsmentioning

confidence: 99%

“…11 A practically important application of LiCB 11 Me 12 is catalysis of the radical polymerization of alkenes also reported by Michl. 12 In previous work 13 we demonstrated that chiral anionic complexes of potassium and silver K-or D-bis[N-salicylidene-(S)-aminoacidato]cobaltates 14 can be used as Lewis acid catalysts in asymmetric trimethylsilylcyanation of aldehydes and Mukayama aldol reaction. It was deemed interesting to extend this approach to examine C-C bond-forming reactions catalyzed by lithium Kor D-bis[N-salicylidene-(S)-aminoacidato]cobaltates.…”

Section: Introductionmentioning

confidence: 99%

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Chiral ion pairs in catalysis: lithium salts of chiral metallocomplex anions as catalysts for asymmetric C–C bond formation

Belokoń

Maleev

Kataev

et al. 2009

Tetrahedron: Asymmetry

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Chiral ion pairs in catalysis: lithium salts of chiral metallocomplex anions as catalysts for asymmetric C–C bond formation

Belokoń

Maleev

Kataev

et al. 2009

Tetrahedron: Asymmetry

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“…We recently introduced octahedral chiral-at-metal [22][23][24][25][26][27][28][29][30][31][32][33][34][35] iridium(III) complexes as inert templates for the design of lowloading asymmetric hydrogen bonding catalysts 36,37 . Octahedral stereocenter [38][39][40] permit the straightforward generation of compounds with high shape and stereochemical complexity and should therefore be highly suitable as structural templates for multifunctional catalysts.…”

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confidence: 99%

Metal-templated chiral Brønsted base organocatalysis

Ding

et al. 2014

Nat Commun

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Inert octahedral chiral-at-metal complexes are an emerging class of asymmetric catalysts that exploit the globular, rigid nature and stereochemical options of octahedral compounds. While the central transition metal serves as a structural anchorpoint and provides metal centrochirality, catalysis is mediated through the organic ligand sphere, thereby merging the branches of transition metal catalysis and organocatalysis. Here we report the development of inert octahedral 3-aminopyrazolato iridium(III) complexes as novel chiral Brønsted base catalysts and demonstrate their merit with applications to highly effective asymmetric sulfaMichael and aza-Henry reactions, permitting catalyst loadings down to 0.02 and 0.25 mol%, respectively. The observed high stereocontrol can be rationalized by a bifunctional mode of action in which the iridium catalyst, after the initial proton transfer, controls a ternary complex through defined hydrogen bonding interactions. This work reveals the potential of octahedral metal complexes as chiral scaffolds for the design of high-performance asymmetric catalysts.

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“…7 It is considered that among alkali metals the lithium cation possesses the highest Lewis acidity. 8 It was shown 9 that a solution of lithium salt of permethylated icosahe dral monocarbadodecaborate LiCB 11 Me 12 in benzene is an efficient catalyst for pericyclic reactions. It seems prac tically important to use LiCB 11 Me 12 as a catalyst of alk ene radical polymerization.…”

mentioning

confidence: 99%

“…It seems prac tically important to use LiCB 11 Me 12 as a catalyst of alk ene radical polymerization. 10 In the previous work, 11 we used the chiral anionic com plexes of Λ and Δ bis[N salicylidene (S) aminoacidato] cobaltates 12 with potassium, sodium, and silver cations as Lewis acids in the asymmetric trimethylsilylcyanation of aldehydes and in the Mukayama reaction. We assumed that the rate of benzaldehyde trimethylsilylcyanation should increase with stronger Lewis acids, viz., complexes containing the lithium ion in the outer sphere.…”

mentioning

confidence: 99%

Lithium salts of chiral metallocomplex anions as catalysts for asymmetric trimethylsilylcyanation of aldehydes

et al. 2010

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A series of the anionic Co III complexes based on optically active amino acids containing the lithium cation in the external sphere of the complex was synthesized. The synthesized com pounds were used as catalysts in the asymmetric addition of trimethylsilyl cyanide to aldehydes. The influence of the temperature, catalyst concentration, and modification of the chiral anion structure on the enantioselectivity of catalysis was studied.In vast majority of the cases, metal complexes with chirality in the cationic part are used in asymmetric catal ysis. 1 An alternative strategy, which involved the com pounds bearing the chiral anion responsible for stereodif ferentiation as catalysts, is very rare. 2 A specific feature of these catalytic systems is that the negative charge is delo calized inside rather bulky fragment and, hence, the charge of the outer sphere cation is compensated to a less extent. Therefore, the cation is a stronger Lewis acid than the same ion chelated by chiral ligands. Thus, even alkali metal cations can be "transformed" into efficient Lewis acids.Only several examples of asymmetric reactions catalyzed by the ion pairs [alkali metal cation] + [chiral anion] -were described. 3-7 A family of heterobimetallic cata lysts representing rare earth metal complexes with chiral binaphthol and alkali metal cations in the outer sphere of the complex has previously 3 been synthesized. They were used in the aldol reaction and the Michael asym metric addition. Binaphthol monolithium salt was used in the asymmetric trimethylsilylcyanation of aldehydes. 4The influence of water additives on the enantioselectivity of this reaction was studied. 5 The cyanosilylation of ketones in the presence of lithium salts of phosphoric ac ids based on binaphthol was studied. 6 3,3´ Dichlorobi naphthol dilithium salt was used in the asymmetric aldol reaction. 7 It is considered that among alkali metals the lithium cation possesses the highest Lewis acidity. 8 It was shown 9 that a solution of lithium salt of permethylated icosahe dral monocarbadodecaborate LiCB 11 Me 12 in benzene is an efficient catalyst for pericyclic reactions. It seems prac tically important to use LiCB 11 Me 12 as a catalyst of alk ene radical polymerization. 10 In the previous work, 11 we used the chiral anionic com plexes of Λ and Δ bis[N salicylidene (S) aminoacidato] cobaltates 12 with potassium, sodium, and silver cations as Lewis acids in the asymmetric trimethylsilylcyanation of aldehydes and in the Mukayama reaction. We assumed that the rate of benzaldehyde trimethylsilylcyanation should increase with stronger Lewis acids, viz., complexes containing the lithium ion in the outer sphere. Indeed, it turned out that the half conversion time of the addition of trimethylsilyl cyanide (TMSCN) to benzaldehyde (Scheme 1) catalyzed by the complex Li + [Δ 1] -(the struc ture of the complex is shown in Scheme 2) is 1.3 min and the enantioselectivity reaches 23%, whereas for the com plexes Na + [Δ 1] -and K + [Δ 1] -the half conversion peri od is 5 and 6 min, res...

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Potassium and silver chiral cobaltate(III) complexes as precatalysts for asymmetric C–C bond formation

Cited by 42 publications

References 25 publications

Chiral ion pairs in catalysis: lithium salts of chiral metallocomplex anions as catalysts for asymmetric C–C bond formation

Chiral ion pairs in catalysis: lithium salts of chiral metallocomplex anions as catalysts for asymmetric C–C bond formation

Metal-templated chiral Brønsted base organocatalysis

Lithium salts of chiral metallocomplex anions as catalysts for asymmetric trimethylsilylcyanation of aldehydes

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