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  1. Article: Organocatalyzed enantioselective aldol reaction of 1H-pyrrole-2,3-diones

    Bhanushali, Mayur / Zhao, Cong-Gui

    Tetrahedron letters. 2012 Jan. 18, v. 53, no. 3

    2012  

    Abstract: The enantioselective cross aldol reaction of 1-benzyl 4,5-dioxo-2-aryl-4,5-dihydro-1H-pyrrole-3-carboxylates and ketones was studied with proline derivatives or cinchona alkaloid-derived primary amines as the catalysts for the first time. trans-4- ... ...

    Abstract The enantioselective cross aldol reaction of 1-benzyl 4,5-dioxo-2-aryl-4,5-dihydro-1H-pyrrole-3-carboxylates and ketones was studied with proline derivatives or cinchona alkaloid-derived primary amines as the catalysts for the first time. trans-4-Benzoyloxy-l-proline (15) was found to be the best catalyst for acyclic ketones. For cyclohexanone, the best results were achieved with 9-deoxy-9-epi-aminoquinine (18) as the catalyst in the presence of racemic 1,1′-binaphthyl-2,2′-diyl hydrogen phosphate (19) as the cocatalyst. Using these protocols, 3-alkyl-3-hydroxy-1H-pyrrol-2(3H)-one derivatives were obtained in excellent yields and good to high ee values (up to 94% ee).
    Keywords Cinchona ; catalysts ; chemical reactions ; enantiomers ; ketones ; primary amines ; proline
    Language English
    Dates of publication 2012-0118
    Size p. 359-362.
    Publishing place Elsevier Ltd
    Document type Article
    ZDB-ID 204287-3
    ISSN 1873-3581 ; 0040-4039
    ISSN (online) 1873-3581
    ISSN 0040-4039
    DOI 10.1016/j.tetlet.2011.11.056
    Database NAL-Catalogue (AGRICOLA)

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  2. Article: Developing novel organocatalyzed aldol reactions for the enantioselective synthesis of biologically active molecules.

    Bhanushali, Mayur / Zhao, Cong-Gui

    Synthesis

    2011  Volume 2011, Issue 12, Page(s) 1815–1830

    Abstract: Aldol reaction is one of the most important methods for the formation of carbon-carbon bonds. Because of its significance and usefulness, asymmetric versions of this reaction have been realized with different approaches in the past. Over the last decade, ...

    Abstract Aldol reaction is one of the most important methods for the formation of carbon-carbon bonds. Because of its significance and usefulness, asymmetric versions of this reaction have been realized with different approaches in the past. Over the last decade, the area of organocatalysis has made significant progresses. As one of most studied reactions in organocatalyses, organocatalyzed aldol reaction has emerged as a powerful tool for the synthesis of a large number of useful products in optically enriched forms. In this review, we summarize our efforts on the development of novel organocatalyzed aldol reactions for the enantioselective synthesis of biological active molecules. Literatures closely related to our studies are also covered.
    Language English
    Publishing date 2011-09-09
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 2033062-5
    ISSN 1437-210X ; 0039-7881
    ISSN (online) 1437-210X
    ISSN 0039-7881
    DOI 10.1055/s-0030-1260029
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article: Organocatalyzed enantioselective aldol reaction of 1H-pyrrole-2,3-diones.

    Bhanushali, Mayur / Zhao, Cong-Gui

    Tetrahedron letters

    2011  Volume 52, Issue 3, Page(s) 359–362

    Abstract: The enantioselective cross aldol reaction of 1-benzyl 4,5-dioxo-2-aryl-4,5-dihydro-1H-pyrrole-3-carboxylates and ketones was studied with proline derivatives or cinchona alkaloid-derived primary amines as the catalysts for the first time. trans-4- ... ...

    Abstract The enantioselective cross aldol reaction of 1-benzyl 4,5-dioxo-2-aryl-4,5-dihydro-1H-pyrrole-3-carboxylates and ketones was studied with proline derivatives or cinchona alkaloid-derived primary amines as the catalysts for the first time. trans-4-Benzoyloxy-L-proline (15) was found to be the best catalyst for acyclic ketones. For cyclohexanone, the best results were achieved with 9-deoxy-9-epi-aminoquinine (18) as the catalyst in the presence of racemic 1,1'-binaphthyl-2,2'-diyl hydrogen phosphate (19) as the cocatalyst. Using these protocols, 3-alkyl-3-hydroxy-1H-pyrrol-2(3H)-one derivatives were obtained in excellent yields and good to high ee values (up to 94% ee).
    Language English
    Publishing date 2011-11-19
    Publishing country England
    Document type Journal Article
    ZDB-ID 204287-3
    ISSN 1873-3581 ; 0040-4039
    ISSN (online) 1873-3581
    ISSN 0040-4039
    DOI 10.1016/j.tetlet.2011.11.056
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article: Organocatalytic enantioselective tandem aldol-cyclization reaction of α-isothiocyanato imides and activated carbonyl compounds.

    Guang, Jie / Zhao, Cong-Gui

    Tetrahedron, asymmetry

    2011  Volume 22, Issue 11, Page(s) 1205–1211

    Abstract: The organocatalytic enantioselective tandem aldol-cyclization reactions of α-isothiocyanato imides and activated carbonyl compounds, such as isatins, an α-ketolactone and a 1,2-dione, have been studied with cinchona alkaloid-derived thiourea-catalysts. ... ...

    Abstract The organocatalytic enantioselective tandem aldol-cyclization reactions of α-isothiocyanato imides and activated carbonyl compounds, such as isatins, an α-ketolactone and a 1,2-dione, have been studied with cinchona alkaloid-derived thiourea-catalysts. This methodology provided an easy way to access enantiomerically enriched spirobicyclic thiocarbamates with high yields and good to excellent stereoselectivity, which have been demonstrated to be useful precursors for the synthesis of biologically active molecules.
    Language English
    Publishing date 2011-09-15
    Publishing country England
    Document type Journal Article
    ZDB-ID 1015012-2
    ISSN 0957-4166
    ISSN 0957-4166
    DOI 10.1016/j.tetasy.2011.06.028
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    Zs.A 2858: Show issues Location:
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  5. Article: Primary Amine-Catalyzed Biginelli Reaction for the Enantioselective Synthesis of 3,4-Dihydropyrimidin-2(1H)-ones.

    Ding, Derong / Zhao, Cong-Gui

    European journal of organic chemistry

    2010  Volume 2010, Issue 20, Page(s) 3802–3805

    Abstract: Several chiral primary amines, mainly those derived from the cinchona alkaloids, were evaluated as the organocatalysts for the asymmetric Biginelli reaction. With the quinine-derived amine catalyst 1 and after extensive optimization of the reaction ... ...

    Abstract Several chiral primary amines, mainly those derived from the cinchona alkaloids, were evaluated as the organocatalysts for the asymmetric Biginelli reaction. With the quinine-derived amine catalyst 1 and after extensive optimization of the reaction conditions, 3,4-dihydropyrimidin-2(1H)-ones were obtained in moderate to good yields and 51-78% ee from a three-component reaction of aryl and aliphatic aldehydes, urea, and acetoacetate.
    Language English
    Publishing date 2010-12-05
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 1475010-7
    ISSN 1099-0690 ; 1434-193X
    ISSN (online) 1099-0690
    ISSN 1434-193X
    DOI 10.1002/ejoc.201000448
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article: A new catalytic mode of the modularly designed organocatalysts (MDOs): enantioselective synthesis of dihydropyrano[2,3-c]pyrazoles

    Muramulla, Savitha / Zhao, Cong-Gui

    Tetrahedron letters. 2011 July 27, v. 52, no. 30

    2011  

    Abstract: The enantioselective tandem Michael addition–cyclization reaction between 3-methyl-2-pyrazolin-5-one and benzylidenemalononitriles was studied with modularly designed organocatalysts (MDOs) to yield 6-amino-5-cyanodihydropyrano[2,3-c]pyrazoles in high ... ...

    Abstract The enantioselective tandem Michael addition–cyclization reaction between 3-methyl-2-pyrazolin-5-one and benzylidenemalononitriles was studied with modularly designed organocatalysts (MDOs) to yield 6-amino-5-cyanodihydropyrano[2,3-c]pyrazoles in high yields and moderate to good enantioselectivities. Most importantly, a new catalytic mode of the MDOs was established. Instead of being used as a nucleophile to form an enamine intermediate, the reaction center modules (amino acids) of the MDOs are now used as a Lewis base in this base-catalyzed reaction. Since there are more reactions catalyzed by Lewis bases than by the enamine mechanism, this finding greatly expands the scope of the MDOs in organic reactions. On the other hand, because the stereocontrolling modules (cinchona alkaloid derivatives) themselves may be used as Lewis base catalysts, this new method may also be viewed as an expeditious way for the modification of the reaction center of the cinchona alkaloid catalysts.
    Keywords Cinchona ; alkaloids ; amino acids ; catalysts ; chemical reactions ; enantiomers ; methodology ; pyrazoles ; synthesis
    Language English
    Dates of publication 2011-0727
    Size p. 3905-3908.
    Publishing place Elsevier Ltd
    Document type Article
    ZDB-ID 204287-3
    ISSN 1873-3581 ; 0040-4039
    ISSN (online) 1873-3581
    ISSN 0040-4039
    DOI 10.1016/j.tetlet.2011.05.092
    Database NAL-Catalogue (AGRICOLA)

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  7. Article: Organocatalyzed enantioselective synthesis of 6-amino-5-cyanodihydropyrano[2,3-c]pyrazoles.

    Gogoi, Sanjib / Zhao, Cong-Gui

    Tetrahedron letters

    2009  Volume 50, Issue 19, Page(s) 2252–2255

    Abstract: The first enantioselective synthesis of biologically active 6-amino-5-cyanodihydropyrano[2,3-c]pyrazoles has been achieved through a cinchona alkaloid-catalyzed tandem Michael addition and Thorpe-Ziegler type reaction between 2-pyrazolin-5-ones and ... ...

    Abstract The first enantioselective synthesis of biologically active 6-amino-5-cyanodihydropyrano[2,3-c]pyrazoles has been achieved through a cinchona alkaloid-catalyzed tandem Michael addition and Thorpe-Ziegler type reaction between 2-pyrazolin-5-ones and benzylidenemalononitriles. The reaction may also be carried out in a three-component or a four-component fashion via the in situ formation of these two components from simple and readily available starting materials. The desired products were obtained in excellent yields with mediocre to excellent enantioselectivities (up to >99% ee).
    Language English
    Publishing date 2009-11-16
    Publishing country England
    Document type Journal Article
    ZDB-ID 204287-3
    ISSN 1873-3581 ; 0040-4039
    ISSN (online) 1873-3581
    ISSN 0040-4039
    DOI 10.1016/j.tetlet.2009.02.210
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Article: Organocatalyzed synthesis of 2-amino-8-oxo-5,6,7,8-tetrahydro-4H-chromene-3-carbonitriles.

    Ding, Derong / Zhao, Cong-Gui

    Tetrahedron letters

    2009  Volume 51, Issue 9, Page(s) 1322

    Abstract: 2-Amino-8-oxo-tetrahydro-4H-chromene-3-carbonitriles were synthesized for the first time from a tandem Michael addition - cyclization reaction between cyclohexane-1,2-dione and benzylidenemalononitriles. An enantioselective synthesis of these compounds ... ...

    Abstract 2-Amino-8-oxo-tetrahydro-4H-chromene-3-carbonitriles were synthesized for the first time from a tandem Michael addition - cyclization reaction between cyclohexane-1,2-dione and benzylidenemalononitriles. An enantioselective synthesis of these compounds was achieved in moderate ee values (up to 63% ee) by using a cinchona alkaloid-derived thiouea catalyst.
    Language English
    Publishing date 2009-10-12
    Publishing country England
    Document type Journal Article
    ZDB-ID 204287-3
    ISSN 1873-3581 ; 0040-4039
    ISSN (online) 1873-3581
    ISSN 0040-4039
    DOI 10.1016/j.tetlet.2009.12.139
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article ; Online: Modularly designed organocatalytic assemblies for direct nitro-Michael addition reactions.

    Mandal, Tanmay / Zhao, Cong-Gui

    Angewandte Chemie (International ed. in English)

    2008  Volume 47, Issue 40, Page(s) 7714–7717

    Language English
    Publishing date 2008
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 2011836-3
    ISSN 1521-3773 ; 1433-7851
    ISSN (online) 1521-3773
    ISSN 1433-7851
    DOI 10.1002/anie.200803236
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article: Enantioselective synthesis of alpha-aminopropargylphosphonates.

    Dodda, Rajasekhar / Zhao, Cong-Gui

    Tetrahedron letters

    2008  Volume 48, Issue 25, Page(s) 4339–4342

    Abstract: alpha-Aminopropargylphosphonates have been synthesized for the first time in good yields and enantiomeric excesses (up to 81% ee) by using a copper(I)-pybox complex as the catalyst. ...

    Abstract alpha-Aminopropargylphosphonates have been synthesized for the first time in good yields and enantiomeric excesses (up to 81% ee) by using a copper(I)-pybox complex as the catalyst.
    Language English
    Publishing date 2008-06-18
    Publishing country England
    Document type Journal Article
    ZDB-ID 204287-3
    ISSN 1873-3581 ; 0040-4039
    ISSN (online) 1873-3581
    ISSN 0040-4039
    DOI 10.1016/j.tetlet.2007.04.124
    Database MEDical Literature Analysis and Retrieval System OnLINE

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