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Afewerki, S. & Cordova, A. (2017). Cooperative Lewis Acids and Aminocatalysis. In: J. Mlynarski (Ed.), Chiral Lewis Acids in Organic Synthesis: (pp. 345-374). Wiley-Blackwell
Open this publication in new window or tab >>Cooperative Lewis Acids and Aminocatalysis
2017 (English)In: Chiral Lewis Acids in Organic Synthesis / [ed] J. Mlynarski, Wiley-Blackwell , 2017, p. 345-374Chapter in book (Refereed)
Abstract [en]

This chapter describes the cooperative strategy of combining metal catalyst activation with aminocatalysis, with a focus on the metal acting as a Lewis acid catalyst. It gives examples where the metal catalyst promotes the reactivity of different substrates by the formation of reactive intermediates. These intermediates can act either as electrophiles or nucleophiles, which in turn can couple with nucleophilic enamine or electrophilic iminium intermediates formed between the carbonyl compounds and aminocatalyst. The chemical transformation ensues via the merging of the enamine and π‐allyl‐Pd complex via asymmetric counteranion‐direct catalysis (ACDC). Subsequently, several groups reported different co‐catalytic systems and chemical strategies for the α‐allylic alkylation of aldehydes and ketones. Cordova and coworkers reported the first example where iminium activation catalysis is combined with metal catalyst activation cooperatively. The stratagem was demonstrated for the catalytic enantioselective conjugate silyl addition to α,β‐unsaturated aldehydes.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2017
Keywords
α-allylic alkylation, aldehydes, aminocatalysis, asymmetric counteranion-direct catalysis, cooperative Lewis acids, electrophilic iminium, ketones, metal catalyst activation, nucleophilic enamine
National Category
Chemical Engineering
Identifiers
urn:nbn:se:miun:diva-33342 (URN)10.1002/9783527802142.ch10 (DOI)
Available from: 2018-03-22 Created: 2018-03-22 Last updated: 2018-03-22Bibliographically approved
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., Alimohammadzadeh, R., Osong, S. H., Tai, C.-W., Engstrand, P. & Cordova, A. (2017). Sustainable Design for the Direct Fabrication and Highly Versatile Functionalization of Nanocelluloses. Global Challenges, 1(7), Article ID 1700045.
Open this publication in new window or tab >>Sustainable Design for the Direct Fabrication and Highly Versatile Functionalization of Nanocelluloses
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2017 (English)In: Global Challenges, ISSN 2056-6646, Vol. 1, no 7, article id 1700045Article in journal (Refereed) Published
Abstract [en]

This study describes a novel sustainable concept for the scalable direct fabrication and functionalization of nanocellulose from wood pulp with reduced energy consumption. A central concept is the use of metal-free small organic molecules as mediators and catalysts for the production and subsequent versatile surface engineering of the cellulosic nanomaterials via organocatalysis and click chemistry. Here, “organoclick” chemistry enables the selective functionalization of nanocelluloses with different organic molecules as well as the binding of palladium ions or nanoparticles. The nanocellulosic material is also shown to function as a sustainable support for heterogeneous catalysis in modern organic synthesis (e.g., Suzuki cross-coupling transformations in water). The reported strategy not only addresses obstacles and challenges for the future utilization of nanocellulose (e.g., low moisture resistance, the need for green chemistry, and energy-intensive production) but also enables new applications for nanocellulosic materials in different areas.

Place, publisher, year, edition, pages
Weinheim: Wiley-VCH Verlagsgesellschaft, 2017
Keywords
nanocellulose
National Category
Natural Sciences Engineering and Technology
Identifiers
urn:nbn:se:miun:diva-32620 (URN)10.1002/gch2.201700045 (DOI)000419793400002 ()
Funder
Swedish Research Council
Available from: 2017-12-24 Created: 2017-12-24 Last updated: 2018-03-23Bibliographically approved
Afewerki, S. & Cordova, A. (2016). Combinations of Aminocatalysts and Metal Catalysts: A Powerful Cooperative Approach in Selective Organic Synthesis. Chemical Reviews, 116(22), 13512-13570
Open this publication in new window or tab >>Combinations of Aminocatalysts and Metal Catalysts: A Powerful Cooperative Approach in Selective Organic Synthesis
2016 (English)In: Chemical Reviews, ISSN 0009-2665, E-ISSN 1520-6890, Vol. 116, no 22, p. 13512-13570Article, review/survey (Refereed) Published
Abstract [en]

The cooperation and interplay between organic and metal catalyst Arninocatalysis systems is of utmost importance in nature and chemical synthesis. Here innovative and selective cooperative catalyst systems can be designed by combining two catalysts that complement rather than inhibit one another. This refined strategy can permit chemical transformations unmanageable by either of the catalysts alone. This review summarizes innovations and developments in selective organic synthesis that have used cooperative dual catalysis by combining simple aminocatalysts with metal catalysts. Considerable efforts have been devoted to this fruitful field. This emerging area employs the different activation modes of amine and metal catalysts as a platform to address challenging reactions. Here, aminocatalysis (e.g., enamine activation catalysis, iminium activation catalysis, single occupied molecular orbital (SOMO) activation catalysis, and photoredox activation catalysis) is employed to activate unreactive carbonyl substrates. The transition metal catalyst complements by activating a variety of substrates through a range of interactions (e.g., electrophilic pi-allyl complex formation, Lewis acid activation, allenylidene complex formation, photoredox activation, C-H activation, etc.), and thereby novel concepts within catalysis are created. The inclusion of heterogeneous catalysis strategies allows for "green" chemistry development, catalyst recyclability, and the more eco-friendly synthesis of valuable compounds.

National Category
Chemical Sciences
Identifiers
urn:nbn:se:miun:diva-29763 (URN)10.1021/acs.chemrev.6b00226 (DOI)000388913000006 ()2-s2.0-84998980146 (Scopus ID)
Available from: 2016-12-22 Created: 2016-12-22 Last updated: 2017-11-29Bibliographically approved
Xu, C., Afewerki, S., Tai, C.-W., Cordova, A. & Hedin, N. (2016). Cyclopalladated Azo-linked Porous Polymers in C-C Bond Forming Reactions. CHEMISTRYSELECT, 1(18), 5801-5804
Open this publication in new window or tab >>Cyclopalladated Azo-linked Porous Polymers in C-C Bond Forming Reactions
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2016 (English)In: CHEMISTRYSELECT, ISSN 2365-6549, Vol. 1, no 18, p. 5801-5804Article in journal (Refereed) Published
Abstract [en]

We designed a new cyclopalladated porous polymer (cyclo-Pd (II)/PP-2) with up to 20.7 wt% of Pd and investigated it as a heterogeneous catalyst for C-C bond-forming transformations. It was also shown to be an effective scavenger for Pd2+ in solution. The palladacycles formed along the backbone of the azo-linked porous polymer (PP-2) with (Pd-N) and (Pd-C) bonds as were confirmed by a combination of spectroscopies. The cyclo-Pd(II)/PP-2 decomposed when used for Suzuki and Heck cross-coupling reactions, and acyclic-Pd/PP-2 formed with Pd nanoparticles (NPs) bound to the PP-2. The Suzuki couplings were highly efficient in water and exhibited excellent recyclability. The cyclo-Pd(II)/PP-2 was also an effective heterogeneous Lewis-acid catalyst for stereoselective carbocyclization reactions.

Keywords
C-C bond formation, heterogeneous catalysis, palladacycle, Pd nanoparticle, porous polymer
National Category
Natural Sciences
Identifiers
urn:nbn:se:miun:diva-30653 (URN)10.1002/slct.201601296 (DOI)000395427600031 ()
Available from: 2017-04-24 Created: 2017-04-24 Last updated: 2017-04-24Bibliographically approved
Palo-Nieto, C., Afewerki, S., Anderson, M., Tai, C.-W., Berglund, P. & Cordova, A. (2016). Integrated Heterogeneous Metal/Enzymatic Multiple Relay Catalysis for Eco-Friendly and Asymmetric Synthesis. ACS Catalysis, 6(6), 3932-3940
Open this publication in new window or tab >>Integrated Heterogeneous Metal/Enzymatic Multiple Relay Catalysis for Eco-Friendly and Asymmetric Synthesis
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2016 (English)In: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 6, no 6, p. 3932-3940Article in journal (Refereed) Published
Abstract [en]

Organic synthesis is in general performed using stepwise transformations where isolation and purification of key intermediates is often required prior to further reactions. Herein we disclose the concept of integrated heterogeneous metal/enzymatic multiple relay catalysis for eco-friendly and asymmetric synthesis of valuable molecules (e.g., amines and amides) in one-pot using a combination of heterogeneous metal and enzyme catalysts. Here reagents, catalysts, and different conditions can be introduced throughout the one-pot procedure involving multistep catalytic tandem operations. Several novel cocatalytic relay sequences (reductive amination/amidation, aerobic oxidation/reductive amination/amidation, reductive amination/kinetic resolution and reductive amination/ dynamic kinetic resolution) were developed. They were next applied to the direct synthesis of various biologically and optically active amines or amides in one-pot from simple aldehydes, ketones, or alcohols, respectively.

Keywords
heterogeneous metal, enzyme, reductive amination, relay catalysis, heterogeneous catalysis, tandem reactions, kinetic resolution, dynamic kinetic resolution
National Category
Chemical Sciences
Identifiers
urn:nbn:se:miun:diva-28476 (URN)10.1021/acscatal.6b01031 (DOI)000377326700066 ()2-s2.0-84973911460 (Scopus ID)
Available from: 2016-07-21 Created: 2016-07-21 Last updated: 2017-11-28Bibliographically approved
Osong, S. H., Norgren, S., Pettersson, G., Engstrand, P., Còrdova, A., Afewerki, S. & Alimohammadzadeh, R. (2016). Processing of nanocellulose and applications relating to CTMP-based paperboard and foams. In: International Mechanical Pulping Conference 2016, IMPC 2016: . Paper presented at International Mechanical Pulping Conference 2016, IMPC 2016; Jacksonville; United States; 26 September 2016 through 28 September 2016 (pp. 87-93). TAPPI Press
Open this publication in new window or tab >>Processing of nanocellulose and applications relating to CTMP-based paperboard and foams
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2016 (English)In: International Mechanical Pulping Conference 2016, IMPC 2016, TAPPI Press, 2016, p. 87-93Conference paper, Published paper (Refereed)
Abstract [en]

Although remarkable success has been made in the production of nanocellulose through several processing methods, it still remain a challenge to reduce the overall energy consumption, to use green chemistry and sustainable approach in order to make it feasible for industrial production of this novel nanomaterial. Herein, we have developed a new eco-friendly and sustainable approach to produce nanocellulose using organic acid combined with high-shear homogenisation, made hydrophobisation of nanocellulose and cross-linked the modified nanocellulosic material. Also, TEMPO-mediated oxidised nanocellulose was produced in order to compare the processing route with that of mild organic acid hydrolysis. Freeze-dried 3D structure of TEMPO-derived nanocellulose foam materials made fi-om bleached sulphite pulp and CTMP, respectively. Further, there is growing interest in using nanocellulose or microfibrillated cellulose (MFC) as an alternative paper sfrength additive in papermaking, and in using chemi-thermomechanical pulp (CTMP) with high freeness in producing CTMP-based paperboard with high bulk properties. To achieve greater strength improvement results, particularly for packaging paperboards, different proportions of cationic starch (CS) or MFC can be used to significantly improve the z-strength, with only a slight increase in sheet density. Research in this area is exploring CS or MFC as potential strength additives in CTMP-based paperboard, which is interesting from an industrial perspective. The mean grammage of the CTMP handsheets produced was approximately 150 g m~, and it was found that blending CTMP with CS or MFC yielded handsheets with significantly improved z-strength, tensile index, burst index and other strength properties at similar sheet densities.

Place, publisher, year, edition, pages
TAPPI Press, 2016
Keywords
Cationic starch, Chemi-thermomechanical pulp, Microfibrillated cellulose, Paperboard, Strength additive, TEMPO
National Category
Chemical Engineering
Identifiers
urn:nbn:se:miun:diva-29834 (URN)2-s2.0-85006448740 (Scopus ID)978-151083073-8 (ISBN)
Conference
International Mechanical Pulping Conference 2016, IMPC 2016; Jacksonville; United States; 26 September 2016 through 28 September 2016
Note

Funding details: Mid Sweden University

Available from: 2017-01-09 Created: 2017-01-09 Last updated: 2017-01-09Bibliographically 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
Xu, C., Deiana, L., Afewerki, S., Incerti-Pradillos, C., Cordova, O., Guo, P., . . . Hedin, N. (2015). The Use of Porous Palladium(II)-polyimine in Cooperatively-catalyzed Highly Enantioselective Cascade Transformations. Advanced Synthesis and Catalysis, 357(9), 2150-2156
Open this publication in new window or tab >>The Use of Porous Palladium(II)-polyimine in Cooperatively-catalyzed Highly Enantioselective Cascade Transformations
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2015 (English)In: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 357, no 9, p. 2150-2156Article in journal (Refereed) Published
Abstract [en]

Porous organic polymers have prospects as functional substrates for catalysis, with quite different molecular properties from inorganic substrates. Here we disclose for the first time that porous palladium(II)-polyimines are excellent catalysts for cooperatively catalyzed and enantioselective cascade reactions. In synergy with a chiral amine co-catalyst, polysubstituted cyclopentenes and spirocyclic oxindoles, including the all-carbon quaternary stereocenter, were synthesized in high yields. High diastereo- and enantioselectivities were achieved for these dynamic kinetic asymmetric transformations (DYKAT) of enals with propargylic nucleophiles.

Keywords
cascade reaction, cooperative catalysis, enantioselective synthesis, heterogeneous catalysis, palladium, porous organic polymers
National Category
Chemical Sciences
Identifiers
urn:nbn:se:miun:diva-25680 (URN)10.1002/adsc.201500100 (DOI)000356373200023 ()2-s2.0-84931268905 (Scopus ID)
Available from: 2015-08-27 Created: 2015-08-18 Last updated: 2017-12-04Bibliographically approved
Deiana, L., Jiang, Y., Palo-Nieto, C., Afewerki, S., Incerti-Pradillos, C. A., Verho, O., . . . Cordova, A. (2014). Combined Heterogeneous Metal/Chiral Amine: Multiple Relay Catalysis for Versatile Eco-Friendly Synthesis. Angewandte Chemie International Edition, 53(13), 3447-3451
Open this publication in new window or tab >>Combined Heterogeneous Metal/Chiral Amine: Multiple Relay Catalysis for Versatile Eco-Friendly Synthesis
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2014 (English)In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 53, no 13, p. 3447-3451Article in journal (Refereed) Published
Abstract [en]

Herein is described a versatile and broad synergistic strategy for expansion of chemical space and the synthesis of valuable molecules (e.g. carbocycles and heterocycles), with up to three quaternary stereocenters, in a highly enantioselective fashion from simple alcohols (31examples, 95:5 to >99.5:0.5 e.r.) using integrated heterogeneous metal/chiral amine multiple relay catalysis and air/O-2 as the terminal oxidant. A novel highly 1,4-selective heterogeneous metal/amine co-catalyzed hydrogenation of enals was also added to the relay catalysis sequences.

Keywords
alcohols, heterogeneous catalysis, homogeneous catalysis, hydrogenation, oxidation
National Category
Chemical Sciences
Identifiers
urn:nbn:se:miun:diva-21995 (URN)10.1002/anie.201310216 (DOI)000333001500028 ()2-s2.0-84896451294 (Scopus ID)
Available from: 2014-06-04 Created: 2014-05-28 Last updated: 2017-12-05Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-5108-6487

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