<i>syn</i>-Selective Catalytic Asymmetric Nitro-Mannich Reactions Using a Heterobimetallic Cu−Sm−Schiff Base Complex

Handa, Shinya; Gnanadesikan, Vijay; Matsunaga, Shigeki; Shibasaki, Masakatsu

doi:10.1021/ja0701560

Cited by 237 publications

(123 citation statements)

References 9 publications

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“…Thea bsorpton correction was based on fitting a function to the empirical transmission surface as sampled by multiple equivalent measurements [18]. [10,11] as well as homogenous catalysts [12,13]. We previously have reported the synthesis of the title compound and from solution NMR deduced that this Schiff base is present as the keto-imine tautomeric form [14].…”

Section: Methodsmentioning

confidence: 99%

Crystal structure of 5-methyl-4-[1-(5-methyl-4-phenyl-thiazol-2-ylamino)- ethylidene]-2-p-tolyl-2,4-dihydro-pyrazol-3-one, C23H22N4OS

Thakar

Friedrich

Joshi³

et al. 2013

Zeitschrift Für Kristallographie - New Crystal Structures

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Source of materialAs olutiono f4 -acetyl-5-methyl-2-p-tolyl-2,4-dihydro-pyrazol-3-one (1.00 g, 4.3mmol) in methanol (30 mL) was addedtoanother solution of 5-methyl-4-phenyl-thiazol-2-ylamine (0.83 g, 4.3 mmol) in methanol (20 mL) under an inert atmosphere. The reaction mixture was refluxed for two hours. Completion of the reaction was monitored by thin layer chromatography (TLC) usinghexane/ethylacetate (7:3). The reaction was allowed to cool to room temperature and then stirred overnight. Ayellow precipitate formed whichw as then filtered and washed with methanol (10 mL). The crude product was purified by crystallization from ethanol yielding brown crystals. (1.38 g, 79% yield). M.p. =495-496 K. Crystals suitable for X-ray diffraction were obtained by slow evaporation of asolution of the title compound in amixture of dichloromethane and hexane at room temperature. Experimental detailsAll Hatomswere positioned geometrically and allowed to ride on their respective parent atoms.A ll Ha toms were refined isotropically. Thea bsorpton correction was based on fitting a function to the empirical transmission surface as sampled by multiple equivalent measurements [18]. . In thisreport we demonstrate that this is also the dominant isomerinthe solid phase. This phenomenon has been reported for derivatives of the samegeneral family of molecules [15][16][17]. The diffraction data revealed an intramolcularhydrogen bond N3-H3A···O1 2.6445(13) Å (Fig.). Discussion

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Section: Methodsmentioning

confidence: 99%

Crystal structure of 5-methyl-4-[1-(5-methyl-4-phenyl-thiazol-2-ylamino)- ethylidene]-2-p-tolyl-2,4-dihydro-pyrazol-3-one, C23H22N4OS

Thakar

Friedrich

Joshi³

et al. 2013

Zeitschrift Für Kristallographie - New Crystal Structures

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Section: Scheme 2 Asymmetric Nitroaldol Reaction Catalysed By 2b-cu(mentioning

confidence: 99%

“…Hence, the catalytic amount of the ligand 2a-Cu(OAc) 2 .H 2 O was increased from 5 mol% to 10 mol%. With 10 mol% of the ligand 2a-Cu(OAc) 2 .H 2 O at room temperature, the enantiomeric excess of the nitroaldol was increased to 54% with full conversion (Table 1, entry 5). Hence, it was decided that 10 mol% of the ligand 2a with Cu(OAc) 2 .H 2 O is sufficient to carry out the asymmetric Henry reactions.…”

Section: Scheme 2 Asymmetric Nitroaldol Reaction Catalysed By 2b-cu(mentioning

confidence: 99%

“…The addition is facilitated either by a Lewis acid catalyst or by a suitable bifunctional catalyst, while the former activates the carbonyl partner, the latter works as a Lewis acid-Bronsted base which activates and bring both reactants together. 2 The current study is to identify a weakly Lewis acidic system bearing moderately basic charged ligands that would facilitate the deprotonation of nitroalkanes for the Henry reaction to proceed. We felt that, divalent metal acetate-chiral ligand combination will meet these requirements because, acetate ion has been employed as a Bronsted base in the enantioselective nitroaldol reaction.…”

Section: Introductionmentioning

confidence: 99%

“…To the best of our knowledge there is no report for these salen ligands to catalyse the asymmetric Henry reaction. Hence in this paper, we report the synthesis of chiral Schiff bases from salicylaldehyde and L-valinol and L-diphenylvalinol and their potential with Cu(OAc) 2 . H 2 O to catalyse the asymmetric nitroaldol reaction.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Salicylaldimine based copper (II) complex-potential catalyst for asymmetric Henry reaction

Velmathi¹,

Ananthi²,

Balakrishnan³

2011

Arkivoc

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The chiral ligand synthesized from L-diphenylvalinol and salicylaldehyde is found to catalyse the asymmetric Henry reaction with copper(II)acetate monohydrate. Various nitroaldols were formed with 77-95% ee and good yield. The mechanism for the formation of a particular enantiomer is also discussed. The enantioselection in the formation of the chiral nitroaldol is discussed in terms of steric bulkiness of the catalytic system.

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1-Nitropropane

Zajac¹,

Lindsay²

2012

Encyclopedia of Reagents for Organic Synthesis

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syn-Selective Catalytic Asymmetric Nitro-Mannich Reactions Using a Heterobimetallic Cu−Sm−Schiff Base Complex

Cited by 237 publications

References 9 publications

Crystal structure of 5-methyl-4-[1-(5-methyl-4-phenyl-thiazol-2-ylamino)- ethylidene]-2-p-tolyl-2,4-dihydro-pyrazol-3-one, C23H22N4OS

Crystal structure of 5-methyl-4-[1-(5-methyl-4-phenyl-thiazol-2-ylamino)- ethylidene]-2-p-tolyl-2,4-dihydro-pyrazol-3-one, C23H22N4OS

Salicylaldimine based copper (II) complex-potential catalyst for asymmetric Henry reaction

1-Nitropropane

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