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Mechanochemistry and Eco-Bases for Sustainable Michael Addition Reactions. Molecules 2022; 27:molecules27103306. [PMID: 35630783 PMCID: PMC9144101 DOI: 10.3390/molecules27103306] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 05/13/2022] [Accepted: 05/19/2022] [Indexed: 02/01/2023] Open
Abstract
The Michael addition reaction was revisited with a full focus on sustainability combined with efficiency, using mechanochemistry in mild conditions. First, the synthesis of cyclopentenone derivatives was chosen as a model reaction to find optimal conditions in mechanochemistry while using classical but weak bases. The reaction was efficient (84–95% yields), fast (2–6 h), solvent free, and required 0.1 equivalent of base. Aiming to reach greener conditions, classical bases were then replaced using new bio-sourced bases, called Eco-bases, that were easily prepared from plants and led to heterogeneous catalysts. The composition and structure of Eco-bases were characterized by MP-AES, XRPD, EBSD/EDS, HRTEM/EDX and ion chromatography. Interestingly, a high ratio of potassium was observed with the presence of K2Ca(CO3)2 for the most effective Eco-base. The new Eco-bases were used for the mechanical-assisted construction of functionalized alkenone derivatives. The versatility of the method has been successfully applied with good to excellent yields to different Michael donors and acceptors. Eco-bases were recycled and reused four times with the same performances. Combining Eco-bases and mechanochemistry in Michael addition reactions allowed reaching a maximum degree of sustainability (efficient, rapid, low catalyst loading, solvent-free reactions with bio-sourced catalysts) and participating in the development of mechanochemistry in sustainable chemistry.
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2
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Embrey SJ, Barrios‐Perez C, Bunce RA. (±)‐
cis
‐4a‐alkyl
‐1,3,4,4a,9,
9a‐hexahydro‐2
H
‐carbazol‐2‐ones by domino nitro
reduction‐aza‐Michael
addition to enones. J Heterocycl Chem 2022. [DOI: 10.1002/jhet.4418] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Samuel J. Embrey
- Department of Chemistry Oklahoma State University Stillwater Oklahoma USA
| | | | - Richard A. Bunce
- Department of Chemistry Oklahoma State University Stillwater Oklahoma USA
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3
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Diddi N, Ward DE. Total Synthesis of Dolabriferol C by a Highly Stereoselective One-Pot Coupling of a meso-3,7-Diketone with Two Chiral Aldehydes. Angew Chem Int Ed Engl 2021; 60:26777-26782. [PMID: 34648679 DOI: 10.1002/anie.202111895] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Indexed: 11/09/2022]
Abstract
Total synthesis of the noncontiguous polypropionate dolabriferol C was achieved by retro-Claisen fragmentation of its putative contiguous precursor under mild conditions, thus establishing the former as a plausible isolation artifact. The precursor was prepared by a novel one-pot three-component bisaldol coupling of a meso (Z,Z)-bisenolate (generated in situ from a 3,7-diketone) with two enantioenriched aldehydes to set the absolute configuration of seven stereocenters in one step. The first aldol reaction proceeded with enantioselective desymmetrization of the bisenolate to produce an enantiomerically pure enolate-aldolate. Quenching at this stage enabled a streamlined synthesis of dolabriferol. Addition of a racemic aldehyde to the enolate-aldolate resulted in aldol coupling with kinetic resolution of the "matched" aldehyde; overall, a sequential enantiotopic-group-selective (SEGS) bisaldol reaction. Because the desired adduct results from the "mismatched" aldol reaction, use of enantioenriched aldehyde was required.
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Affiliation(s)
- Naveen Diddi
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, SK, S7N 5C9, Canada
| | - Dale E Ward
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, SK, S7N 5C9, Canada
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4
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Diddi N, Ward DE. Total Synthesis of Dolabriferol C by a Highly Stereoselective One‐Pot Coupling of a
meso‐
3,7‐Diketone with Two Chiral Aldehydes. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202111895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Naveen Diddi
- Department of Chemistry University of Saskatchewan 110 Science Place Saskatoon SK S7N 5C9 Canada
| | - Dale E. Ward
- Department of Chemistry University of Saskatchewan 110 Science Place Saskatoon SK S7N 5C9 Canada
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5
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Kreibich M, Petrović D, Brückner R. Mechanistic Studies of the Deslongchamps Annulation. J Org Chem 2018; 83:1116-1133. [PMID: 29131961 DOI: 10.1021/acs.joc.7b02341] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The Cs2CO3-mediated annulations ("Deslongchamps annulations") of three spirocyclic benzoquinone monoketals 5b-d with an ester or acyl substituent at C-2 to two tert-butyl esters of γ,δ-unsaturated β-ketocarboxyl acids ("Nazarov reagents"; 2a,b) were monitored 1H NMR spectroscopically. This revealed that a primary product, by all likelihood the Michael adduct, forms fast and prior to the appearance of the Deslongchamps adduct. These primary products form reversibly. This was proved by two crossover and four scavenging experiments. Therein, components already incorporated in one of the mentioned primary products ended up in Deslongchamps adducts different from the one, which would have resulted if the respective primary product had reacted alone. However, these experiments leave open whether our primary products are intermediates en route to Deslongchamps products or whether they represent dead ends.
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Affiliation(s)
- Michael Kreibich
- Institut für Organische Chemie, Albert-Ludwigs-Universität , Albertstraße 21, D-79104 Freiburg im Breisgau, Germany
| | - Denis Petrović
- Institut für Organische Chemie, Albert-Ludwigs-Universität , Albertstraße 21, D-79104 Freiburg im Breisgau, Germany.,Noramco GmbH , Badische Bahnhofstrasse 16, CH-8212 Neuhausen, Switzerland
| | - Reinhard Brückner
- Institut für Organische Chemie, Albert-Ludwigs-Universität , Albertstraße 21, D-79104 Freiburg im Breisgau, Germany
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6
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Stark DG, Young CM, O'Riordan TJC, Slawin AMZ, Smith AD. Enantioselective isothiourea-catalysed trans-dihydropyridinone synthesis using saccharin-derived ketimines: scope and limitations. Org Biomol Chem 2016; 14:8068-73. [PMID: 27492887 DOI: 10.1039/c6ob01473a] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The catalytic enantioselective synthesis of a range of trans-dihydropyridinones from aryl-, heteroaryl- and alkenylacetic acids and saccharin-derived ketimines with good to excellent stereocontrol (15 examples, up to >95 : 5 dr, up to >99 : 1 er) is reported. After extensive optimisation, HyperBTM proved the optimal isothiourea catalyst for this transformation at -78 °C, giving trans-dihydropyridones with generally excellent levels of diastereo- and enantioselectivity.
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Affiliation(s)
- Daniel G Stark
- EaStCHEM, School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife KY16 9ST, UK.
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7
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Jagtap PR, Ford L, Deister E, Pohl R, Císařová I, Hodek J, Weber J, Mackman R, Bahador G, Jahn U. Highly functionalized and potent antiviral cyclopentane derivatives formed by a tandem process consisting of organometallic, transition-metal-catalyzed, and radical reaction steps. Chemistry 2014; 20:10298-304. [PMID: 25043655 DOI: 10.1002/chem.201402595] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Indexed: 11/11/2022]
Abstract
A simple modular tandem approach to multiply substituted cyclopentane derivatives is reported, which succeeds by joining organometallic addition, conjugate addition, radical cyclization, and oxygenation steps. The key steps enabling this tandem process are the thus far rarely used isomerization of allylic alkoxides to enolates and single-electron transfer to merge the organometallic step with the radical and oxygenation chemistry. This controlled lineup of multiple electronically contrasting reactive intermediates provides versatile access to highly functionalized cyclopentane derivatives from very simple and readily available commodity precursors. The antiviral activity of the synthesized compounds was screened and a number of compounds showed potent activity against hepatitis C and dengue viruses.
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Affiliation(s)
- Pratap R Jagtap
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo namesti 2, 16610 Prague (Czech Republic)
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8
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Kang B, Jakubec P, Dixon DJ. Strategies towards the synthesis of calyciphylline A-type Daphniphyllum alkaloids. Nat Prod Rep 2014; 31:550-62. [PMID: 24595901 DOI: 10.1039/c3np70115h] [Citation(s) in RCA: 94] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The Daphniphyllum alkaloids are a diverse family of natural products rich in number and structural diversity that have been known for many decades. However, the structurally unique subclass of calyciphylline A-type alkaloids has only recently been discovered and is relatively unexplored. Several noteworthy core syntheses and the development of a wide range of novel synthetic strategies have been achieved. This includes strategies based on intramolecular Michael addition, Pd-catalysis, cycloaddition, and Mannich-type reactions. This review will provide an overview of these synthetic studies.
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Affiliation(s)
- Baldip Kang
- The Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK.
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9
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Lee ASY, Lin MC, Wang SH, Lin LS. A Mild Isomerization Reaction for β,γ-Unsaturated Ketone to α,β-Unsaturated Ketone. J CHIN CHEM SOC-TAIP 2013. [DOI: 10.1002/jccs.200400058] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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10
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Lee ASY, Lin MC, Lin CC, Chang YT. Me3SiOTf Promoted Aza-Michael Addition Reaction of 1°-Amides with α,β-Unsaturated Ketones. J CHIN CHEM SOC-TAIP 2013. [DOI: 10.1002/jccs.201000110] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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11
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Denmark SE, Wilson TW. Silyl ketene imines: highly versatile nucleophiles for catalytic, asymmetric synthesis. Angew Chem Int Ed Engl 2012; 51:9980-92. [PMID: 22968901 DOI: 10.1002/anie.201202139] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2012] [Indexed: 11/09/2022]
Abstract
This Minireview provides an overview on the development of silyl ketene imines and their recent applications in catalytic, enantioselective reactions. The unique structure of the ketene imine allows a diverse range of reactivity patterns and provides solutions to existing challenges in the enantioselective construction of quaternary stereogenic carbon centers and cross-benzoin adducts. A variety of reactions for which silyl ketene imines have been applied are presented with an overall goal of inspiring new uses for these underutilized nucleophiles.
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Affiliation(s)
- Scott E Denmark
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
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12
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Denmark SE, Wilson TW. Silylketenimine - vielseitige Nucleophile für die katalytische asymmetrische Synthese. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201202139] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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13
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Holan M, Pohl R, Císařová I, Jahn U. Polyfunctional β-Dicarbonyl Compounds by Michael Addition Reactions of Ester Enolates to α-Benzylidene and α-Alkylidene-β-dicarbonyl Compounds. European J Org Chem 2012. [DOI: 10.1002/ejoc.201200077] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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14
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Gilles P, Py S. SmI2-Mediated Cross-Coupling of Nitrones with β-Silyl Acrylates: Synthesis of (+)-Australine. Org Lett 2012; 14:1042-5. [DOI: 10.1021/ol203396s] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Pierre Gilles
- Département de Chimie Moléculaire (SERCO) UMR-5250, ICMG FR-2607, CNRS, Université Joseph Fourier, BP 53, 38041 Grenoble Cedex 09, France
| | - Sandrine Py
- Département de Chimie Moléculaire (SERCO) UMR-5250, ICMG FR-2607, CNRS, Université Joseph Fourier, BP 53, 38041 Grenoble Cedex 09, France
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15
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Abstract
The strategic use of thiopyran templates to facilitate polypropionate synthesis was first demonstrated in Woodward's landmark total synthesis of erythromycin A in 1981 where the topology of a fused bicyclic system was exploited. In the ensuing three decades, various alternative strategic applications of thiopyran motifs to achieve key stereoselective transformations have emerged including, inter alia, unique substrates for chemoenzymatic syntheses, surrogates for 3-pentanone in enantioselective aldol reactions, and templates for enantiotopic group selective reactions. This review summarizes these developments.
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Affiliation(s)
- Dale E Ward
- Department of Chemistry, University of Saskatchewan, Saskatoon, SK S7N 5C9, Canada.
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16
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Tacheva D, Ivanova BB, Mayer-Figge H, Sheldrick WS, Spiteller M. Properties of the Michael's adducts of the substituted 2-amino-5-oxonitriles. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2010; 77:588-593. [PMID: 20685157 DOI: 10.1016/j.saa.2010.06.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2010] [Revised: 05/18/2010] [Accepted: 06/04/2010] [Indexed: 05/29/2023]
Abstract
A series of five substituted 2-amino-5-oxonitriles, obtained by the Michael reaction have been designed, synthesised, isolated and spectroscopically and structurally elucidated by means of single crystal X-ray diffraction, linear-polarized infrared (IR-LD) and UV-spectroscopy, (1)H NMR, mass spectrometry and thermal methods. Theoretical quantum chemical calculations were carried out, thus supporting the experimental optical properties and electronic structure of compounds studied.
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Affiliation(s)
- D Tacheva
- University of Sofia, Department of Organic Chemistry, Sofia 1164, Bulgaria
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17
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Kaneda K, Hara T, Hashimoto N, Mitsudome T, Mizugaki T, Jitsukawa K. Creation of a monomeric vanadate species in an apatite framework as an active heterogeneous base catalyst for Michael reactions in water. Catal Today 2010. [DOI: 10.1016/j.cattod.2009.08.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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18
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Kim SI, Hwang SJ, Park YM, Um IH. Michael-type Reactions of 1-(X-substituted phenyl)-2-propyn-1-ones with Alicyclic Secondary Amines in MeCN and H2O: Effect of Medium on Reactivity and Transition-State Structure. B KOREAN CHEM SOC 2010. [DOI: 10.5012/bkcs.2010.31.5.1199] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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19
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Borths CJ, Carrera DE, MacMillan DWC. Development of a general, enantioselective organocatalytic Mukaiyama-Michael reaction with α,β-unsaturated aldehydes. Tetrahedron 2009; 65:6746-6753. [PMID: 25214677 DOI: 10.1016/j.tet.2009.06.066] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
LUMO-lowering organocatalysis has been extended to promote the conjugate addition of S-alkyl and -pyrrolyl silylketene acetals to α,β-unsaturated aldehydes, yielding both, syn and anti Mukaiyama-Michael products with high levels of enantioselectivity. This strategy allows for the generation of chemically useful 1,5-dicarbonyl systems and again highlights the utility of organocatalysis.
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Affiliation(s)
- Christopher J Borths
- Merck Center for Catalysis, Princeton University, Princeton, NJ 08544, United States ; The Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, United States
| | - Diane E Carrera
- Merck Center for Catalysis, Princeton University, Princeton, NJ 08544, United States ; The Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, United States
| | - David W C MacMillan
- Merck Center for Catalysis, Princeton University, Princeton, NJ 08544, United States ; The Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, United States
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Ray S, Shaikh MM, Ghosh P. Nickel Complexes ofN/O-Functionalized N-Heterocyclic Carbenes as Precatalysts for Michael Reactions in Air at Room Temperature Under the Much Preferred Base-Free Conditions. Eur J Inorg Chem 2009. [DOI: 10.1002/ejic.200801060] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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21
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Hydrated ferric perchlorate, Fe(ClO4)3.XH2O in organic synthesis. A short review. JOURNAL OF THE IRANIAN CHEMICAL SOCIETY 2007. [DOI: 10.1007/bf03247223] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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22
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Tasheva D, Petrova A, Simova S. Convenient Synthesis of Some Substituted 5‐Oxonitriles under Aqueous Conditions: Synthesis of 3,4‐Dihydro‐2H‐pyrrole‐2‐carbonitriles. SYNTHETIC COMMUN 2007. [DOI: 10.1080/00397910701572746] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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23
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Forzato C, Nitti P, Pitacco G, Valentin E, Morganti S, Rizzato E, Spinelli D, Dell'Erba C, Petrillo G, Tavani C. Nitroalkylation and nitroalkenylation reactions of γ-lactone enolates. A facile ring switch from polysubstituted γ-lactones to polysubstituted γ-lactams. Tetrahedron 2004. [DOI: 10.1016/j.tet.2004.07.084] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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The thiopyran route to polypropionates. Asymmetric synthesis of the building blocks by enantioselective protonation. ACTA ACUST UNITED AC 2004. [DOI: 10.1016/j.tetasy.2004.06.027] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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25
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Christoffers J, Mann A. New auxiliaries for copper-catalyzed asymmetric Michael reactions: generation of quaternary stereocenters at room temperature. Chemistry 2001; 7:1014-27. [PMID: 11303862 DOI: 10.1002/1521-3765(20010302)7:5<1014::aid-chem1014>3.0.co;2-x] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Dialkyl amides of L-valine, L-isoleucine, and L-tert-leucine (2) are excellent chiral auxiliaries for the construction of quaternary stereocenters at ambient temperature. Enaminoesters 3, prepared from these auxiliaries 2 and Michael donors 1, undergo a copper-catalyzed asymmetric Michael reaction with methyl vinyl ketone (MVK, 4) to afford products 5 in 70-90% yield and 90-99% ee (enantiomeric excess). The exclusion of moisture or oxygen is not necessary. The auxiliaries 2 are readily available by standard procedures. After workup they can be recovered almost quantitatively.
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Affiliation(s)
- J Christoffers
- Institut für Organische Chemie, Universität Stuttgart, Germany.
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27
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Viteva L, Stefanovski Y, Gospodova T, Mazières MR, Wolf JG. First examples of lithium reagents addition in cyanine dyes series. Tetrahedron Lett 2000. [DOI: 10.1016/s0040-4039(00)00205-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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28
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29
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Christoffers J, Rößler U, Werner T. Construction of Quaternary Stereocenters by Nickel-Catalysis of Asymmetric Michael Reactions. European J Org Chem 2000. [DOI: 10.1002/(sici)1099-0690(200003)2000:5<701::aid-ejoc701>3.0.co;2-5] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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30
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Pattenden G, Plowright AT. Synthetic studies towards phorboxazole A. Stereoselective synthesis of the C3–C19 bis-oxane oxazole portion of the phorboxazole macrolide. Tetrahedron Lett 2000. [DOI: 10.1016/s0040-4039(99)02187-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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31
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Yamazaki T, Shinohara N, Kitazume T, Sato S. Michael addition of organocopper species to 3-[(E)-4,4,4-trifluorobut-2-enoyl]oxazolidin-2-ones. J Fluor Chem 1999. [DOI: 10.1016/s0022-1139(99)00034-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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32
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Synthesis of an analog of the cytotoxic marine diterpene helioporin C exploiting arene-Cr(CO)3 chemistry. Tetrahedron 1999. [DOI: 10.1016/s0040-4020(99)00346-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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34
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35
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Bernardi A, Karamfilova K, Sanguinetti S, Scolastico C. Enantioselective conjugate additions of silylketene acetals to 2-carboxycyclopentenones promoted by chiral Ti complexes. Tetrahedron 1997. [DOI: 10.1016/s0040-4020(97)00825-9] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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36
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37
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38
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Shi Y, Wulff WD, Yap GPA, Rheingold AL. Asymmetric synthesis of δ-keto esters via Michael additions of chiral carbene complexes. Chem Commun (Camb) 1996. [DOI: 10.1039/cc9960002601] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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39
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Mladenova M, Biserkova M, Kaneti J. REGIOSELECTIVITY OF THE ADDITION OF α-METALLATED N,N-DIMETHYL SULFONAMIDES TO α,β-UNSATURATED CARBONYL COMPOUNDS. PHOSPHORUS SULFUR 1995. [DOI: 10.1080/10426509508042587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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40
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Kobayashi S, Horibe M, Hachiya I. Molecular recognition by artificial chiral catalysts utilizing a metal chelate. A remarkable difference in reactivity between geometrical isomers of silyl enolates in asymmetric aldol reactions using chiral tin(II) catalysts. Tetrahedron Lett 1995. [DOI: 10.1016/0040-4039(95)00505-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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41
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Bernardi A, Karamfilova K, Boschin G, Scolastico C. Enantioselective michael-mukaiyama additions of silylketene acetals to 2-carboxycyclopentenones promoted by chiral Ti complexes. Tetrahedron Lett 1995. [DOI: 10.1016/0040-4039(94)02478-t] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Bernardi A, Marchionni C, Pilati T, Scolastico C. Stereoselective conjugate addition of propionate Ti ate enolate to unsaturated chiral ketones: A new insight in the reaction mechanism. Tetrahedron Lett 1994. [DOI: 10.1016/s0040-4039(00)73432-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
43
|
Taguchi T, Shibuya A, Sasaki H, Endo JI, Morikawa T, Shiro M. Asymmetric synthesis of difluorocyclopropanes. ACTA ACUST UNITED AC 1994. [DOI: 10.1016/0957-4166(94)80101-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
44
|
Enders D, Scherer HJ, Runsink J. Diastereo- und enantioselektive Synthese 1,2-trans-substituierter Cycloalkancarbonsäureester und Sulfone durch Michael-initiierte Cyclisierungen via SAMP-/RAMP-Hydrazone[1,2]. ACTA ACUST UNITED AC 1993. [DOI: 10.1002/cber.19931260825] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
45
|
The control of diastereoselectivity in the Michael reaction of ketonic enolates with crotonic acid derivatives. Tetrahedron Lett 1993. [DOI: 10.1016/s0040-4039(00)60431-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
|
46
|
|
47
|
Lhara M, Suzuki S, Taniguchi N, Fukumoto K. Intramolecular Michael reaction using trialkylsilyl trifluoromethanesulfonates and tertiary amine system: total synthesis of (±)-ricciocarpin A. ACTA ACUST UNITED AC 1993. [DOI: 10.1039/c39930000755] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
48
|
Stereoselective Michael additions of titanium “ate” complexes of ketone and ester enolates. Tetrahedron 1992. [DOI: 10.1016/0040-4020(92)80010-d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
|
49
|
Yamazaki T, Haga J, Kitazume T. Stereoselective Michael Addition Reactions of Acylated Oxazolidinones to Ethyl 3-Trifluoromethylacrylate. CHEM LETT 1991. [DOI: 10.1246/cl.1991.2175] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|
50
|
Sato T, Wakahara Y, Otera J, Nozaki H. Organotin triflate as practical catalyst for Michael addition of enol silyl ethers. Tetrahedron 1991. [DOI: 10.1016/s0040-4020(01)80717-1] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
|