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Guangning, Ma
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Publications (7 of 7) Show all publications
Mridha, M., Ma, G., Palo-Nieto, C., Afewerki, S. & Cordova, A. (2017). Development of an Amino Acid/Hydroxy Oxime Dual Catalyst System for Highly Stereoselective Direct Asymmetric Aldol Reactions in the Presence of Water. Synthesis (Stuttgart), 49(2), 383-390, Article ID ss-2015-z0592-op.
Open this publication in new window or tab >>Development of an Amino Acid/Hydroxy Oxime Dual Catalyst System for Highly Stereoselective Direct Asymmetric Aldol Reactions in the Presence of Water
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2017 (English)In: Synthesis (Stuttgart), ISSN 0039-7881, E-ISSN 1437-210X, Vol. 49, no 2, p. 383-390, article id ss-2015-z0592-opArticle in journal (Refereed) Published
Abstract [en]

An eco-friendly dual catalyst system for stereoselective aldol reactions in the presence of water is described. It is based on the cooperative action of acyclic amino acids and H-bond donating hydroxy oxime catalysts. The synthetic utility of this dual catalyst system was further demonstrated by applying it as the key step in the expeditious and highly stereoselective total synthesis of D-lyxo-phytosphingosine (29% overall yield). Here the amino acid/hydroxy oxime system significantly accelerated the direct aldol reactions in the presence of water as compared to organic solvents. The stereo-and chemoselectivity were also significantly increased.

Keywords
aldol reaction, total synthesis, phytosphingosine, stereoselectivity, dual catalysis
National Category
Chemical Sciences
Identifiers
urn:nbn:se:miun:diva-30470 (URN)10.1055/s-0036-1588089 (DOI)000393232500018 ()2-s2.0-84994573336 (Scopus ID)
Note

Financial support was provided by Mid Sweden University and the Swedish National Research Council (VR).

Available from: 2017-03-20 Created: 2017-03-20 Last updated: 2017-12-19Bibliographically approved
Afewerki, S., Ma, G., Ibrahem, I., Liu, L., Sun, J. & Cordova, A. (2015). Highly Enantioselective Control of Dynamic Cascade Transformations by Dual Catalysis: Asymmetric Synthesis of Polysubstituted Spirocyclic Oxindoles. ACS Catalysis, 5(2), 1266-1272
Open this publication in new window or tab >>Highly Enantioselective Control of Dynamic Cascade Transformations by Dual Catalysis: Asymmetric Synthesis of Polysubstituted Spirocyclic Oxindoles
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2015 (English)In: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 5, no 2, p. 1266-1272Article in journal (Refereed) Published
Abstract [en]

The highly enantioselective (up to >99.5:0.5 er) synthesis of polysubstituted spirocyclic oxindoles with four new contiguous stereocenters, including the spiro all-carbon quaternary center, is disclosed. It is accomplished by the highly stereoselective control of a dynamic conjugate/intramolecular allylic alkylation relay sequence based on the synergistic cooperation of metal and chiral amine catalysts in which the careful selection of organic Nand, metal complex, and chiral amine is essential. The intermolecular C-C bond-forming step occurred only when both the metal and chiral amine catalysts were present.

Keywords
all-carbon quaternary stereocenter, asymmetric cocatalysis, dynamic transformations, polysubstituted, spirocyclic oxindoles, α, β-unsaturated aldehydes
National Category
Chemical Sciences
Identifiers
urn:nbn:se:miun:diva-24590 (URN)10.1021/cs501975u (DOI)000349275300086 ()2-s2.0-84922713231 (Scopus ID)
Available from: 2015-03-17 Created: 2015-03-17 Last updated: 2017-12-04Bibliographically approved
Afewerki, S., Guangning, M., Ibrahem, I. & Cordova, A. (2014). Highly enantioselective organo/metal cooperative catalysis for construction of spirocyclopentaneoxindoles. Paper presented at 248th National Meeting of the American-Chemical-Society (ACS), AUG 10-14, 2014, San Francisco, CA. Abstract of Papers of the American Chemical Society, 248, Article ID 173-ORGN.
Open this publication in new window or tab >>Highly enantioselective organo/metal cooperative catalysis for construction of spirocyclopentaneoxindoles
2014 (English)In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 248, article id 173-ORGNArticle in journal, Meeting abstract (Other academic) Published
National Category
Chemical Sciences
Identifiers
urn:nbn:se:miun:diva-24667 (URN)000349167402638 ()
Conference
248th National Meeting of the American-Chemical-Society (ACS), AUG 10-14, 2014, San Francisco, CA
Available from: 2015-08-28 Created: 2015-03-20 Last updated: 2017-12-04Bibliographically approved
Ma, G., Afewerki, S., Deiana, L., Palo-Nieto, C., Liu, L., Sun, J., . . . Córdova, A. (2013). A palladium/chiral amine co-catalyzed enantioselective dynamic cascade reaction: Synthesis of polysubstituted carbocycles with a quaternary carbon stereocenter. Angewandte Chemie International Edition, 52(23), 6050-6054
Open this publication in new window or tab >>A palladium/chiral amine co-catalyzed enantioselective dynamic cascade reaction: Synthesis of polysubstituted carbocycles with a quaternary carbon stereocenter
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2013 (English)In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 52, no 23, p. 6050-6054Article in journal (Refereed) Published
Abstract [en]

Polysubstituted 5- and 6-membered carbocycles were synthesized by the title reaction. The one-pot dynamic relay process generates four new stereocenters, including a quaternary carbon center, in a highly enantioselective fashion (99.5:0.5→99:0.5 e.r.) by using a simple combination of palladium and chiral amine co-catalysts. 

Keywords
aldehydes, asymmetric catalysis, carbocycles, co-catalysis, quaternary carbon stereocenters
National Category
Organic Chemistry
Identifiers
urn:nbn:se:miun:diva-19359 (URN)10.1002/anie.201300559 (DOI)000319742400028 ()2-s2.0-84878387915 (Scopus ID)
Note

:doi 10.1002/anie.201300559

Available from: 2013-09-05 Created: 2013-06-19 Last updated: 2017-12-06Bibliographically approved
Ibrahem, I., Ma, G., Afewerki, S. & Córdova, A. (2013). Palladium/Chiral Amine Co-catalyzed Enantioselective beta-Arylation of alpha,beta-Unsaturated Aldehydes. Angewandte Chemie International Edition, 52(3), 878-882
Open this publication in new window or tab >>Palladium/Chiral Amine Co-catalyzed Enantioselective beta-Arylation of alpha,beta-Unsaturated Aldehydes
2013 (English)In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 52, no 3, p. 878-882Article in journal (Refereed) Published
Abstract [en]

Palladium and a simple chiral amine are used as co-catalysts for the enantioselective conjugate addition of aryl boronic acids to α,β-unsaturated aldehydes (see scheme). The synthetic utility of this co-catalyzed reaction was demonstrated in the short total syntheses of (R)-(-)-curcumene and 4-aryl-2-ones. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Keywords
aldehydes; asymmetric catalysis; boronic acids; co-catalysts; total synthesis
National Category
Organic Chemistry
Identifiers
urn:nbn:se:miun:diva-18083 (URN)10.1002/ange.201208634 (DOI)000313688100012 ()2-s2.0-84872316330 (Scopus ID)
Note

Article first published online: 23 NOV 2012

Available from: 2012-12-20 Created: 2012-12-20 Last updated: 2017-12-06Bibliographically approved
Ma, G., Lin, S., Ibrahem, I., Kubik, G., Liu, L., Sun, J. & Cordova, A. (2012). Achiral Co-Catalyst Induced Switches in Catalytic Asymmetric Reactions on Racemic Mixtures (RRM): From Stereodivergent RRM to Stereoconvergent Deracemization by Combination of Hydrogen Bond Donating and Chiral Amine Catalysts. Advanced Synthesis and Catalysis, 354(14-15), 2865-2872
Open this publication in new window or tab >>Achiral Co-Catalyst Induced Switches in Catalytic Asymmetric Reactions on Racemic Mixtures (RRM): From Stereodivergent RRM to Stereoconvergent Deracemization by Combination of Hydrogen Bond Donating and Chiral Amine Catalysts
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2012 (English)In: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 354, no 14-15, p. 2865-2872Article in journal (Refereed) Published
Abstract [en]

A stereochemical divergent approach for the highly enantioselective synthesis of distinct bicyclic products with multiple stereocenters from a racemate using a single chiral catalyst is disclosed. It is based on switches of the overall reaction pathways in the chiral amine-catalyzed cascade reactions between racemic ?-nitro ketones and a,beta-unsaturated aldehydes using different achiral co-catalysts. The utility of the method is exemplified by the highly diasteroselective switch and stereoconvergent deracemization process by combination of chiral amine and achiral hydrogen-bond-donating catalysts.

Keywords
cascade reactions; deracemization; dynamic asymmetric catalysis; hydrogen-bond donor; organocatalysis; reactions on racemic mixtures; stereodivergence
National Category
Organic Chemistry
Identifiers
urn:nbn:se:miun:diva-17532 (URN)10.1002/adsc.201200357 (DOI)000309907300037 ()2-s2.0-84869031085 (Scopus ID)
Available from: 2012-11-30 Created: 2012-11-30 Last updated: 2017-12-07Bibliographically approved
Ma, G., Bartoszewicz, A., Ibrahem, I. & Córdova, A. (2011). Highly Enantioselective Co-Catalytic Direct Aldol reactions by Combination of Hydrogen-Bond Donating and Acyclic Amino Acid Catalysts. Advanced Synthesis and Catalysis, 353(17), 3114-3122
Open this publication in new window or tab >>Highly Enantioselective Co-Catalytic Direct Aldol reactions by Combination of Hydrogen-Bond Donating and Acyclic Amino Acid Catalysts
2011 (English)In: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 353, no 17, p. 3114-3122Article in journal (Refereed) Published
Abstract [en]

Highly enantioselective co-catalytic direct aldol reactions by a combination of simple hydrophobic acyclic amino acid and hydrogen-bond donating catalysts are presented. The corresponding aldol products are formed in high yields with high regio-, diastereo- (anti or syn) and enantioselectivity (up to 99.5:0.5 er). The catalyst loadings can be decreased to as little as 2 mol%.

Keywords
aldol reaction, amino acids, asymmetric catalysis, co-catalysis, hydrogen-bond donating
National Category
Organic Chemistry
Identifiers
urn:nbn:se:miun:diva-14751 (URN)10.1002/adsc.201100408 (DOI)000298171500007 ()2-s2.0-82055208588 (Scopus ID)
Available from: 2011-11-17 Created: 2011-11-17 Last updated: 2017-12-08Bibliographically approved
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