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  1. Article ; Online: Revisiting the Synthesis of Cellulose Acrylate and Its Modification via Michael Addition Reactions.

    Okamoto, Hiroya / Taniguchi, Tsuyoshi / Takekuma, Motohiro / Mashio, Asami S / Wong, Kuo H / Hasegawa, Hiroshi / Nishimura, Tatsuya / Maeda, Katsuhiro

    Biomacromolecules

    2023  Volume 24, Issue 8, Page(s) 3767–3774

    Abstract: ... on the reaction conditions due to the possible cross-linking oxa-Michael reaction between a remaining hydroxy ... such as secondary amines and thiols as a Michael donor. This method was applied to the synthesis of ...

    Abstract The synthesis of cellulose acrylate from cellulose with acryloyl chloride has been problematic due to unexpected gelation of the reaction mixture, but we discovered that the use of bulky amines was crucial for the reproducibility of the synthesis of cellulose acrylate. The solubility of the obtained cellulose acrylate depended on the reaction conditions due to the possible cross-linking oxa-Michael reaction between a remaining hydroxy group and the introduced acrylate group. The synthesized cellulose acrylate worked as a useful precursor of chemically modified cellulose materials because it reacted with various functionalized nucleophiles such as secondary amines and thiols as a Michael donor. This method was applied to the synthesis of
    MeSH term(s) Reproducibility of Results ; Cellulose ; Solubility ; Amines ; Acrylates
    Chemical Substances Cellulose (9004-34-6) ; Amines ; Acrylates
    Language English
    Publishing date 2023-07-25
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ISSN 1526-4602
    ISSN (online) 1526-4602
    DOI 10.1021/acs.biomac.3c00436
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Sixth Dedicated CSPS Annals-In Memory of Michael F. McGuire and Janet K. Salomonson.

    Wong, Michael S

    Annals of plastic surgery

    2017  Volume 78, Issue 5 Suppl 4, Page(s) S173–S174

    MeSH term(s) Anniversaries and Special Events ; California ; History, 21st Century ; Humans ; Periodicals as Topic ; Physician's Role ; Surgery, Plastic
    Language English
    Publishing date 2017
    Publishing country United States
    Document type Biography ; Historical Article ; Journal Article
    ZDB-ID 423835-7
    ISSN 1536-3708 ; 0148-7043
    ISSN (online) 1536-3708
    ISSN 0148-7043
    DOI 10.1097/SAP.0000000000001082
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    In stock of ZB MED Cologne/Königswinter

    Zs.A 1419: Show issues Location:
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  3. Article: Asymmetric Michael Addition of Dimethyl Malonate to 2-Cyclopenten-1-one Catalyzed by a Heterobimetallic Complex.

    Fastuca, Nicholas J / Wong, Alice R / Mak, Victor W / Reisman, Sarah E

    Organic syntheses; an annual publication of satisfactory methods for the preparation of organic chemicals

    2020  Volume 97, Page(s) 327–338

    Language English
    Publishing date 2020-11-06
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2247669-6
    ISSN 0078-6209
    ISSN 0078-6209
    DOI 10.15227/orgsyn.097.0327
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  4. Article ; Online: Cinchona Alkaloid-Squaramide Catalyzed Sulfa-Michael Addition Reaction: Mode of Bifunctional Activation and Origin of Stereoinduction.

    Guo, Jinlong / Wong, Ming Wah

    The Journal of organic chemistry

    2017  Volume 82, Issue 8, Page(s) 4362–4368

    Abstract: The mechanism of the enantioselective sulfa-Michael addition reaction catalyzed ... cinchona alkaloid-urea catalyzed sulfa-Michael addition reactions, also applies to the catalytic system under ...

    Abstract The mechanism of the enantioselective sulfa-Michael addition reaction catalyzed by a cinchona alkaloid-squaramide bifunctional organocatalyst was studied using density functional theory (DFT). Four possible modes of dual activation mechanism via hydrogen bonds were considered. Our study showed that Houk's bifunctional Brønsted acid-hydrogen bonding model, which works for cinchonidine or cinchona alkaloid-urea catalyzed sulfa-Michael addition reactions, also applies to the catalytic system under investigation. In addition, we examined the origin of the stereoselectivity by identifying stereocontrolling transition states. Distortion-interaction analysis revealed that attractive interaction between the substrates and catalyst in the C-S bond forming transition state is the key reason for stereoinduction in this catalytic reaction. Noncovalent interaction (NCI) analysis showed that a series of more favorable cooperative noncovalent interactions, namely, hydrogen bond, π-stacking, and C-H···π interaction and C-H···F interactions, in the major R-inducing transition state. The predicted enantiometric excess is in good accord with the observed value.
    Language English
    Publishing date 2017-04-21
    Publishing country United States
    Document type Journal Article
    ZDB-ID 123490-0
    ISSN 1520-6904 ; 0022-3263
    ISSN (online) 1520-6904
    ISSN 0022-3263
    DOI 10.1021/acs.joc.7b00388
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    In stock of ZB MED Cologne/Königswinter

    Zs.A 4473: Show issues Location:
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  5. Article ; Online: Three-component reactions of isocyanoacetates, amines and 3-formylchromones initiated by an unexpected aza-Michael addition.

    Liao, Jia-Yu / Yap, Wei Jie / Wu, Ji'En / Wong, Ming Wah / Zhao, Yu

    Chemical communications (Cambridge, England)

    2017  Volume 53, Issue 65, Page(s) 9067–9070

    Abstract: ... initiated by a facile aza-Michael addition instead of the conventional imine condensation. This catalytic ...

    Abstract We present herein a new mode of three-component reactions between isocyanoacetates, amines and 3-formylchromones. Both experimental and DFT studies revealed that this Ag-catalyzed unusual transformation is initiated by a facile aza-Michael addition instead of the conventional imine condensation. This catalytic method enables an efficient synthesis of polysubstituted pyrroles.
    Language English
    Publishing date 2017-08-10
    Publishing country England
    Document type Journal Article
    ZDB-ID 1472881-3
    ISSN 1364-548X ; 1359-7345 ; 0009-241X
    ISSN (online) 1364-548X
    ISSN 1359-7345 ; 0009-241X
    DOI 10.1039/c7cc03468g
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: Sequential catalytic role of bifunctional bicyclic guanidine in asymmetric phospha-Michael reaction.

    Cho, Bokun / Tan, Choon-Hong / Wong, Ming Wah

    Organic & biomolecular chemistry

    2011  Volume 9, Issue 12, Page(s) 4550–4557

    Abstract: ... Michael reaction between diphenyl phosphine oxide and β-nitrostyrene were investigated by DFT calculations ...

    Abstract The catalytic mechanism and origin of enantioselectivity of bicyclic guanidine-catalyzed phospha-Michael reaction between diphenyl phosphine oxide and β-nitrostyrene were investigated by DFT calculations at M06-2X/cc-pVTZ//M06-2X/cc-pVDZ level in conjunction with the implicit SMD solvation method. The catalyst is found to be involved in all 3 steps of the proposed catalytic cycle, namely (1) tautomerization of phosphine oxide, (2) C-P bond formation and (3) concerted hydrogen transfer. The bifunctional role of the guanidine catalyst is clearly demonstrated in all 3 key steps. Due to the geometry of the bicyclic guanidine catalyst, the preferred orientation of the reactants in the transition state of enantioselective C-P bond forming step favours the R enantiomer, in excellent accord with the observed enantioselectivity. Analysis of various transition states suggests that the asymmetric C-P bond formation is controlled by the hydrogen bonding interaction and steric effect between the catalyst and substrate. Various weaker C-H···X (X = N, O and π) interactions also play a role in stabilizing the key transition states.
    MeSH term(s) Bridged Bicyclo Compounds/chemistry ; Catalysis ; Chemistry, Organic ; Crystallography, X-Ray ; Guanidine/chemistry ; Hydrogen/chemistry ; Hydrogen Bonding ; Models, Molecular ; Phenyl Ethers/chemistry ; Phosphines/chemistry ; Quantum Theory ; Stereoisomerism ; Styrenes/chemistry
    Chemical Substances Bridged Bicyclo Compounds ; Phenyl Ethers ; Phosphines ; Styrenes ; beta-nitrostyrene (5287E3OUAV) ; Hydrogen (7YNJ3PO35Z) ; phosphine (FW6947296I) ; Guanidine (JU58VJ6Y3B)
    Language English
    Publishing date 2011-06-21
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2097583-1
    ISSN 1477-0539 ; 1477-0520
    ISSN (online) 1477-0539
    ISSN 1477-0520
    DOI 10.1039/c1ob05186e
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article: Cinchona Alkaloid-Squaramide Catalyzed Sulfa-Michael Addition Reaction: Mode of Bifunctional Activation and Origin of Stereoinduction

    Guo, Jinlong / Wong Ming Wah

    Journal of organic chemistry. 2017 Apr. 21, v. 82, no. 8

    2017  

    Abstract: The mechanism of the enantioselective sulfa-Michael addition reaction catalyzed ... cinchona alkaloid-urea catalyzed sulfa-Michael addition reactions, also applies to the catalytic system under ...

    Abstract The mechanism of the enantioselective sulfa-Michael addition reaction catalyzed by a cinchona alkaloid-squaramide bifunctional organocatalyst was studied using density functional theory (DFT). Four possible modes of dual activation mechanism via hydrogen bonds were considered. Our study showed that Houk’s bifunctional Brønsted acid–hydrogen bonding model, which works for cinchonidine or cinchona alkaloid-urea catalyzed sulfa-Michael addition reactions, also applies to the catalytic system under investigation. In addition, we examined the origin of the stereoselectivity by identifying stereocontrolling transition states. Distortion–interaction analysis revealed that attractive interaction between the substrates and catalyst in the C–S bond forming transition state is the key reason for stereoinduction in this catalytic reaction. Noncovalent interaction (NCI) analysis showed that a series of more favorable cooperative noncovalent interactions, namely, hydrogen bond, π-stacking, and C–H···π interaction and C–H···F interactions, in the major R-inducing transition state. The predicted enantiometric excess is in good accord with the observed value.
    Keywords catalysts ; catalytic activity ; chemical reactions ; chemical structure ; Cinchona ; enantioselectivity ; hydrogen bonding ; methodology ; models ; organic chemistry ; organic compounds
    Language English
    Dates of publication 2017-0421
    Size p. 4362-4368.
    Publishing place American Chemical Society
    Document type Article
    ZDB-ID 123490-0
    ISSN 1520-6904 ; 0022-3263
    ISSN (online) 1520-6904
    ISSN 0022-3263
    DOI 10.1021%2Facs.joc.7b00388
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    In stock of ZB MED Bonn / Germany

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  8. Article: Three-component reactions of isocyanoacetates, amines and 3-formylchromones initiated by an unexpected aza-Michael addition

    Liao, Jia-Yu / Yap, Wei Jie / Wu, Ji'En / Wong, Ming Wah / Zhao, Yu

    Chemical communications. 2017 Aug. 10, v. 53, no. 65

    2017  

    Abstract: ... initiated by a facile aza-Michael addition instead of the conventional imine condensation. This catalytic ...

    Abstract We present herein a new mode of three-component reactions between isocyanoacetates, amines and 3-formylchromones. Both experimental and DFT studies revealed that this Ag-catalyzed unusual transformation is initiated by a facile aza-Michael addition instead of the conventional imine condensation. This catalytic method enables an efficient synthesis of polysubstituted pyrroles.
    Keywords amines ; chemical reactions ; imines ; pyrroles
    Language English
    Dates of publication 2017-0810
    Size p. 9067-9070.
    Publishing place The Royal Society of Chemistry
    Document type Article
    ZDB-ID 1472881-3
    ISSN 1364-548X ; 1359-7345 ; 0009-241X
    ISSN (online) 1364-548X
    ISSN 1359-7345 ; 0009-241X
    DOI 10.1039/c7cc03468g
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  9. Article ; Online: (S)-Proline-catalyzed nitro-Michael reactions: towards a better understanding of the catalytic mechanism and enantioselectivity.

    Yang, Hui / Wong, Ming Wah

    Organic & biomolecular chemistry

    2012  Volume 10, Issue 16, Page(s) 3229–3235

    Abstract: S)-Proline-catalyzed nitro-Michael additions of aldehydes and ketones to β-nitrostyrene were ... in organocatalysis, the lowest-energy transition states of proline-catalyzed nitro-Michael reactions do not ... for Michael additions of aldehyde and ketone substrates are in good agreement with experimental findings. ...

    Abstract (S)-Proline-catalyzed nitro-Michael additions of aldehydes and ketones to β-nitrostyrene were investigated computationally (MP2/6-311+G**//M06-2X/6-31G**). Contrary to what is usually assumed in organocatalysis, the lowest-energy transition states of proline-catalyzed nitro-Michael reactions do not necessarily involve the carboxylic acid group of the proline moiety directing the incoming nitroalkene to the same face through hydrogen bonding. For the aldehyde substrates examined, the TS leading to the major (R,S) product was found to involve the anti-enamine and nitroalkene approaching from the opposite face of the carboxyl group. In the case of ketone substrates, the lowest-energy TSs leading to both enantiomeric products are characterized by the absence of hydrogen bonds and s-cis conformation of the carboxyl group, which functions as an electron donor to stablize the developing iminium. When both hydrogen bonded and non-hydrogen bonded types of TSs are considered, the calculated enantioselectivities for Michael additions of aldehyde and ketone substrates are in good agreement with experimental findings.
    MeSH term(s) Aldehydes/chemistry ; Catalysis ; Ketones/chemistry ; Models, Molecular ; Proline/chemistry ; Stereoisomerism ; Styrenes/chemistry
    Chemical Substances Aldehydes ; Ketones ; Styrenes ; beta-nitrostyrene (5287E3OUAV) ; Proline (9DLQ4CIU6V)
    Language English
    Publishing date 2012-04-28
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2097583-1
    ISSN 1477-0539 ; 1477-0520
    ISSN (online) 1477-0539
    ISSN 1477-0520
    DOI 10.1039/c2ob06993h
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article ; Online: Origin of asymmetric induction in bicyclic guanidine-catalyzed thio-Michael reaction: a bifunctional mode of Lewis acid-Brønsted acid activation.

    Cho, Bokun / Tan, Choon-Hong / Wong, Ming Wah

    The Journal of organic chemistry

    2012  Volume 77, Issue 15, Page(s) 6553–6562

    Abstract: ... Michael reaction. This activation mode provides an alternate reaction pathway for the C-S bond forming ...

    Abstract In addition to a bifunctional Brønsted acid activation mode, an unconventional bifunctional mode of Lewis and Brønsted acid activations was revealed in a DFT study of bicyclic guanidine-catalyzed thio-Michael reaction. This activation mode provides an alternate reaction pathway for the C-S bond forming step and influences the final stereochemical outcome. The calculated turnover frequencies of the R- and S-products, based on the energetic span model, are in good accord with the observed high stereoselectivity toward the S-product.
    MeSH term(s) Acids/chemistry ; Bridged Bicyclo Compounds/chemistry ; Catalysis ; Guanidine/chemistry ; Molecular Structure ; Quantum Theory ; Sulfhydryl Compounds/chemical synthesis ; Sulfhydryl Compounds/chemistry
    Chemical Substances Acids ; Bridged Bicyclo Compounds ; Sulfhydryl Compounds ; Guanidine (JU58VJ6Y3B)
    Language English
    Publishing date 2012-08-03
    Publishing country United States
    Document type Journal Article
    ZDB-ID 123490-0
    ISSN 1520-6904 ; 0022-3263
    ISSN (online) 1520-6904
    ISSN 0022-3263
    DOI 10.1021/jo301158c
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    In stock of ZB MED Cologne/Königswinter

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