Disulfonimide‐Catalyzed Asymmetric Reduction of <i>N</i>‐Alkyl Imines

Wakchaure, Vijay N.; Kaib, Philip S. J.; Leutzsch, Markus; List, Benjamin

doi:10.1002/anie.201504052

Cited by 90 publications

(73 citation statements)

References 81 publications

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“…[9] As one of the important reactions, enantioselective transfer hydrogenations of ketimines with HSiCl 3 has been a powerful method to access chiral amines, an important pharmacophores in biologically active molecules and agrochemical compounds, [10] and thus stands out among series of important reactions, such as asymmetric tandem reactions using HSiCl 3 . [14] Many transfer hydrogenations of β-enamino esters with HSiCl 3 or using ammonia borane reported recently [15] exhibited very good enantioselectivities. [14] Many transfer hydrogenations of β-enamino esters with HSiCl 3 or using ammonia borane reported recently [15] exhibited very good enantioselectivities.…”

Section: Abstract: Enantioselective Hydrogenation; N-o Alcohol; Ts; Mmentioning

confidence: 99%

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Catalytic Mechanism Study on the 1,2‐ and 1,4‐Transfer Hydrogenation of Ketimines and β‐Enamino Esters Catalyzed by Axially Chiral Biscarboline‐Based Alcohols

Dong

Wang

et al. 2019

Adv Synth Catal

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Axial N-O alcohols, which have two large carboline moieties connected to the axis were synthesized and used in catalytic enantioselective 1,2-and 1,4-transfer hydrogenations of total 26 ketimines and β-enamino esters. Excellent levels of enantioselectivity ranging from 91% to 99% were achieved by using catalyst (aS)-2oxide. Interestingly, a mixture of (aS)-(S)-3,3'-bis ((S)-2-(hydroxymethyl)pyrrolidine-1-carbonyl)-9,9'dimethyl- 9H,9'H-[1,1'-bipyrido[3,4-b]indole] 2oxide and (aR)-(S)-3,3'-bis((S)-2-(hydroxymethyl) pyrrolidine-1-carbonyl)-9,9'-dimethyl-9H,9'H-[1,1'bipyrido[3,4-b]indole] 2-oxide was also able to provide high enantioselectivities up to 95% that is the same as that using pure (aS)-(S)-3,3'-bis((S)-2-(hydroxymethyl)pyrrolidine-1-carbonyl)-9,9'dimethyl- 9H,9'H-[1,1'-bipyrido[3,4-b]indole] 2oxide. A plausible catalytic mechanism was suggested and total four kinds of transition states (TS) including almost 60 TS structures were investigated using density functional theory (DFT) with different basis sets such as 6-311G(2d,p). The predicted activation energy data are consistent with the experimental results.

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Section: Abstract: Enantioselective Hydrogenation; N-o Alcohol; Ts; Mmentioning

confidence: 99%

“…The enantioselectivities in 1,2-transfer hydrogenations of fourteen ketimines(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22) catalyzed by (aS)-7A. [a] Isolated yields in percentage (%).…”

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confidence: 99%

Catalytic Mechanism Study on the 1,2‐ and 1,4‐Transfer Hydrogenation of Ketimines and β‐Enamino Esters Catalyzed by Axially Chiral Biscarboline‐Based Alcohols

Dong

Wang

et al. 2019

Adv Synth Catal

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“…[4] However, asymmetric transfer hydrogenations with ammonia boranes have lagged behind. [5] Very recently,our group developed afrustrated Lewis pair (FLP) [6] of (R)-tert-butylsulfinamide and HB(C 6 F 5 ) 2 for asymmetric transfer hydrogenations of imines [7] with ammonia borane as ahydrogen source for regeneration of the chiral FLP catalyst ( Figure 1). [5] Very recently,our group developed afrustrated Lewis pair (FLP) [6] of (R)-tert-butylsulfinamide and HB(C 6 F 5 ) 2 for asymmetric transfer hydrogenations of imines [7] with ammonia borane as ahydrogen source for regeneration of the chiral FLP catalyst ( Figure 1).…”

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confidence: 99%

A Continuously Regenerable Chiral Ammonia Borane for Asymmetric Transfer Hydrogenations

et al. 2018

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An ovel chiral ammonia borane was designed and developed through the dehydrogenation of ammonia borane with ac hiral phosphoric acid, whichw as highly effective for the asymmetric transfer hydrogenation of imines and b-enamino esters to afford high levels of reactivities and enantioselectivities.S ignificantly,t his chiral ammonia borane can be continuously regenerated during the transfer hydrogenation with the assistance of water and ammonia borane, which made it possible to obtain satisfactory results using only 0.1 mol %o ft he chiral phosphoric acid. Notably,t he role of chiral phosphoric acid is to produce the chiral ammonia borane.

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“…[7b] To demonstrate the efficiency of catalyst 3c further, the synthesis of chiral amine 6e was successfully accomplished on am ultigram scale: by using 10 mg of catalyst almost 10 go fe nantiopure amine was obtained, after as ingle crystallization, without the need for any chromatographic purification[ Table 2, Eq. [16] In view of ap ossible extension of this catalytic methodology to the industrial scale, the possibility to perform the reaction in flow reactorsw as also preliminarily investigated (Scheme 2). [15] To test the general applicabilityo fc atalysts 3c and 4, the reduction of aw ide varietyo fi mines was investigated (Table 3).…”

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confidence: 99%

A New Class of Low‐Loading Catalysts for Highly Enantioselective, Metal‐Free Imine Reduction of Wide General Applicability

et al. 2017

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An ew class of chiral Lewis bases for the enantioselective HSiCl 3 -mediated reduction of imines was developed. Through extensive catalyst structureo ptimization,a ne xtremelya ctive speciesw as identified that was able to promote the reduction of al arge variety of functionalized substrates in high yields with enantioselectivities typicallya bove 90 %w ith catalyst loadings as lowa s0 .1-1 mol %. The simple experimental procedure, the low cost of the reagents,t he mild reaction conditions, and the straightforward isolation of the product make the methodology attractive for large-scale applications.I ts synthetic potentiality was demonstrated by the preparation of advancedi ntermediates of important active pharmaceutical ingredients used in the treatmento fA lzheimer's and Parkinson's diseases,h yperparathyroidism,n europathic pains, and neurological disorders. The reactionw as also successfully performed in flow reactors, which thus demonstrated the possibility to realize in continuo processes to yield multigram quantities of product.The stereoselective reduction of C=Nb onds is probably the most popular approach to synthesize chiral amines. [1] Although in the last few years remarkable progress hasb een made in the development of efficient chiral organometallicc omplexes for the hydrogenationo fi mines, [2] the high costs of the precious metal species and their lack of general applicability make the discoveryo fn ew,h ighly performant catalysts greatly desirable. Moreover,i nt he case of C=N bond reduction, very often quite high catalyst loadings are required. [3] Metal-free catalytic methodologies represent av iable alternative option, and some efficient catalytic systemsh ave been reported, [4] but in these cases, high catalyst loadings are also necessary.Despitea ll the recent achievements in the field, the combination of inexpensive, nontoxic, easily available catalysts capable of performing at the very low loadings typical of organometallicc atalysis is an unmet challenge forp resent-day orga-nocatalysis. [5] Trichlorosilane-based reduction methods may offer an interesting opportunity in this sense. [6] Given that it is aw aste product of the silicon industry,H SiCl 3 is an extremely cheap reagent that is readily availableinlarge quantities andi s capable of reducing C=Nb onds with amazing chemoselectivity.I ts coordination with chiral Lewis bases hasa llowed the development of methods for the highly enantioselective catalytic reduction of imines. [7] Herein,w er eport the design and optimization of an ew class of enantiopure chiral picolinamides, easily preparedi nafew steps from amino acids, such as phenylalanine and tyrosine ( Figure 1). An extremely active species was identified that was able to promote the reduction of al arge variety of functionalizeds ubstrates in high yields with enantioselectivities typicallyh igher than 90 %a nd with catalyst loadings ranging from 0.1 to 1mol %, al evel that is exceptionally low for organocatalysis. Remarkably,t he new catalysts showed aw ide scope and were appli...

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Disulfonimide‐Catalyzed Asymmetric Reduction of N‐Alkyl Imines

Cited by 90 publications

References 81 publications

Catalytic Mechanism Study on the 1,2‐ and 1,4‐Transfer Hydrogenation of Ketimines and β‐Enamino Esters Catalyzed by Axially Chiral Biscarboline‐Based Alcohols

Catalytic Mechanism Study on the 1,2‐ and 1,4‐Transfer Hydrogenation of Ketimines and β‐Enamino Esters Catalyzed by Axially Chiral Biscarboline‐Based Alcohols

A Continuously Regenerable Chiral Ammonia Borane for Asymmetric Transfer Hydrogenations

A New Class of Low‐Loading Catalysts for Highly Enantioselective, Metal‐Free Imine Reduction of Wide General Applicability

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