Huayin Huang

Chinese Academy of Sciences, Peping, Beijing, China

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Publications (11)36.38 Total impact

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    ABSTRACT: In this work, we thoroughly investigated the effect of structural differentiation of a series of N, N-disubstituted chiral diamine ligands on the catalytic asymmetric aldol reactions between trifluoromethyl ketones and linear aliphatic ketones for the construction of chiral trifluoromethyl tertiary alcohols. A highly efficient primary-tertiary diamine ligand derived from (1R,2R)-1,2-diphenylethylenediamine was developed, which catalyzed the reactions with up to 99% yield and up to 94% enantioselectivity in the presence of p-toluenesulfonic acid (TsOH) using toluene as solvent.
    The Journal of Organic Chemistry 11/2014; · 4.64 Impact Factor
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    ABSTRACT: In this study, a series of mono- and dialkylated chiral 1,2-amino phosphinamide ligands derived from modular (1R,2R)-diphenylethylenediamine were successfully applied in the chiral 1,2-amino phosphinamide-Zn(II) catalyzed asymmetric Henry reaction between benzaldehyde and nitromethane. Although chiral N-monosubstituted and N, N-disubstituted 1,2-amino phosphinamide ligands gave the main alcohol products with opposite configurations, a validated QSAR (quantitative structure-activity relationship) mathematical model could be constructed between the physical Sterimol steric parameters of the N-substituents of the chiral ligands and the enantiomeric ratios of the alcohol products produced in the asymmetric Henry reaction. Since two sets of N-substituents are involved in QSAR model construction, appropriately assigning the N-substitutents is the key factor for successfully constructing a highly correlative and predictive model. Ligand optimization based on the established QSAR model led chiral 1,2-amino phosphinamide ligand 2r, which produced (R)-β-nitroalcohol in excellent yield and enantioselectivity (99% yield and 92% ee). In addition, quantitative correlation could also be established with the use of subtractive Sterimol parameters.
    The Journal of Organic Chemistry 09/2014; · 4.64 Impact Factor
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    ABSTRACT: Benzyl N-[(1R,2R)-2-[({[(1R,2R)-2-{[(benzyloxy)carbonyl]amino}-1,2-diphenyl ethyl]amino}(phenyl)thiophosphoryl)amino]-1,2-diphenylethyl]carbamateC50H47O4N4PS[α]D31=+28.8 (c 1.00, CH2Cl2)Source of chirality: (1R,2R)-(+)-1,2-diphenylethylenediamineAbsolute configuration: (1R,2R)
    Tetrahedron Asymmetry 07/2014; 25(2):170–180. · 2.17 Impact Factor
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    ABSTRACT: The binding interactions of citalopram (CIT), an efficient antidepressant, with human serum albumin (HSA) and bovine serum albumin (BSA) were investigated by a series of spectroscopic methods including fluorescence, UV–vis absorption, circular dichroism (CD) and 1H nuclear magnetic resonance (1H NMR). The fluorescence quenching and UV–vis absorption studies reveal that CIT could form complexes with both HSA and BSA. The CIT–BSA complex exhibits higher binding affinity than CIT–HSA complex. The thermodynamic study further suggests that the interactions between CIT and SAs are mainly driven by hydrophobic forces and hydrogen bonds. The 1H NMR analysis indicates that the participation of different functional groups of CIT is unequal in the complexation of CIT–HSA and CIT–BSA. Site marker competitive experiments show that the interactions between CIT and SAs primarily locate at sub-domain II A (site I). The effects of CIT on the conformation of SAs are further analyzed via synchronous fluorescence, three-dimensional fluorescence and CD spectra techniques. The results prove that the presence of CIT decreases the α-helical content of both SAs and induces the slight unfolding of the polypeptides of protein. Additionally, the conformational change of BSA induced by CIT is larger than that of HSA.
    Journal of Luminescence 02/2014; 146:114–122. · 2.37 Impact Factor
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    ABSTRACT: We have demonstrated that a validated QSAR (quantitative structure–activity relationship) model can be constructed between sterimol steric parameters of the N-substituents of chiral 1,2-amino-phosphoramide ligands and the enantiomeric ratios of alcohol products produced in the asymmetric additions of diethylzinc to acetophenone, which is powerful for predicting the steric effects of ligand substituents on enantioselectivities and instructive for ligand optimization.
    Tetrahedron 02/2014; 70(6):1289–1297. · 2.82 Impact Factor
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    ABSTRACT: A simple chiral bisthiourea has been used as a highly effective and practical chemical solvating agent (CSA) for diverse α-carboxylic acids in the presence of DMAP. Excellent enantiodiscrimination based on well-resolved α-H NMR signals of the enantiomers of carboxylic acids can be obtained without interference from the chiral bisthiourea and DMAP. To check the practicality of the chiral bisthiourea/DMAP for enantiomeric determination, the ee values of mandelic acid (MA) samples over a wide ee range were determined by integration of the α-H signal of MA in (1)H NMR. A discrimination mechanism is proposed, that the formation of two diasteromeric ternary complexes between the chiral bisthiourea and two in situ formed enantiomeric carboxylate-DMAPH(+) ion pairs discriminates the enantiomers of carboxylic acids. Computational modeling studies show that the chemical shift value of α-H of (S)-MA is greater than that of (R)-MA in ternary complexes, which is consistent with experimental observation. 1D and 2D NOESY spectra demonstrate the intermolecular noncovalent interactions between the protons on the aromatic rings of chiral bisthiourea and α-H of the enantiomers of racemic α-methoxy phenylacetic acids in the complexes.
    The Journal of Organic Chemistry 09/2013; 78(18):9137-42. · 4.64 Impact Factor
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    ABSTRACT: New chiral phosphoramide ligands derived from cinchona alkaloids were developed, which react with diethylzinc to form chiral phosphoramide-Zn(II) complexes containing two Lewis bases and one Lewis acid. These trifunctional complexes can serve as highly efficient chiral catalysts for triple activation of enantioselective addition reactions of diethylzinc with aldehydes to give desired alcohol products with excellent yields and enantiomeric excess (ee) values up to 99%. Chirality 00:000-000, 2013. © 2013 Wiley Periodicals, Inc.
    Chirality 06/2013; · 1.72 Impact Factor
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    ABSTRACT: Our investigation has shown that achiral quaternary ammonium salt has a significant synergistic effect on the asymmetric additions of diethylzinc to aldehydes catalyzed by chiral phosphoramide–Zn(II) complex. The addition of 10 mol % NBu4X can dramatically reduce the loading amount of chiral ligand without sacrificing the excellent reactivity and enantioselectivity of the asymmetric reaction.
    Tetrahedron Letters 05/2013; 54(21):2722–2725. · 2.39 Impact Factor
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    ABSTRACT: Using the asymmetric addition reaction of diethylzinc with benzylaldehyde as a model, we have demonstrated that excellent correlations exist between steric reference parameters (Charton and Sterimol values) for appropriate sets of substituents present on chiral 1,2-amino-phosphoramide ligands and the enantiomeric ratios of alcohol products produced in this process.
    The Journal of Organic Chemistry 11/2012; · 4.64 Impact Factor
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    ABSTRACT: A series of new camphorsulfonylated ligands derived from chiral 2-amino-2'-hydroxy-1,1'-binaphthyl (NOBIN) and (+)-camphorsulfonic acid were synthesized by a short and simple synthetic sequence, and their enantioselective catalytic activities were assessed in the nucleophilic addition reaction of dialkylzinc reagents to aldehydes in the presence of titanium tetraisopropoxide. The most efficient ligand, N-hydroxycamphorsulfonylated (S)-NOBIN, gave (S)-addition products with good yields and up to 87% of ee value. The (1) H nuclear magnetic resonance (NMR) and (13) C NMR results of the titanium titration experiments on this ligand indicate that the most likely catalytic reactive species involved in this catalytic asymmetric addition is a bimetallic titanium complex. A possible catalytic reaction mechanism is proposed. Chirality 24:825-832, 2012. © 2012 Wiley Periodicals, Inc.
    Chirality 06/2012; 24(10):825-32. · 1.72 Impact Factor
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    ABSTRACT: On the basis of the investigation of the combinational effect of quaternary ammonium salts and organic bases, an added-metal-free catalytic system for nucleophilic addition reactions of a variety of Grignard reagents to diverse ketones in THF solvent has been developed to produce tertiary alcohols in good to excellent yields. By using tetrabutylammonium chloride (NBu(4)Cl) as a catalyst and diglyme (DGDE) as an additive, this system strongly enhances the efficiency of addition at the expense of enolization and reduction. NBu(4)Cl should help to shift the Schlenk equilibrium of Grignard reagents to the side of dimeric Grignard reagents to favor the additions of Grignard reagents to ketones via a favored six-membered transition state to form the desired tertiary alcohols, and DGDE should increase the nucleophilic reactivities of Grignard reagents by coordination. This catalytic system has been applied in the efficient synthesis of Citalopram, an effective U.S. FDA-approved antidepressant, and a recyclable version of this catalytic synthesis has also been devised.
    The Journal of Organic Chemistry 04/2012; 77(10):4645-52. · 4.64 Impact Factor