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Kutaszewicz R, Grzeszczyk B, Górecki M, Staszewska-Krajewska O, Furman B, Chmielewski M. Bypassing the stereoselectivity issue: transformations of Kinugasa adducts from chiral alkynes and non-chiral acyclic nitrones. Org Biomol Chem 2019; 17:6251-6268. [PMID: 31184687 DOI: 10.1039/c9ob00940j] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An approach to β-lactams via a reaction between chiral copper acetylides and acyclic nitrones is reported. Electronic circular dichroism (ECD) in combination with NMR spectroscopy was used to determine the absolute configuration of all components of complex mixtures of azetidinones. Stereochemical preferences observed in the studied reactions are discussed and a model of a new reaction pathway supported by DFT conformational analysis is proposed. Subsequent transformations of the synthesized Kinugasa adducts followed by epimerization at the C-3 carbon atom led to trans-substituted azetidinones with improved stereoselectivity, mimicking a variety of important β-lactam structures. On the other hand, the oxidation of the furyl residue to the carboxylic group followed by oxidative decarboxylation with lead tetraacetate afforded the more thermodynamically stable trans-substituted 4-acetoxy azetidinone. The latter strategy is particularly attractive for the diastereomeric mixture in which isomers with the same configuration at the C-3 carbon atom dominate.
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Affiliation(s)
- Rafał Kutaszewicz
- Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland.
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2
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Abstract
Nitrones are important compounds and are highly useful in many aspects. The first part describes the methods for synthesis of nitrones, which are useful and environmentally friendly. Catalytic oxidations, condensations, and other useful reactions are described. The nitrones thus obtained are key intermediates for the synthesis of biologically important nitrogen compounds. The second part describes the fundamental transformations of nitrones, which will provide the strategies and means for the construction of nitrogen compounds. The reactions with nucleophiles or radicals, C-H functionalization, and various addition reactions are described. The last reactions are particularly important for highly selective carbon-carbon bond formations. 1,3-Dipolar cycloaddition reactions are excluded because the size of the review is limited and excellent reviews have been published in Chemical Reviews.
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Affiliation(s)
- Shun-Ichi Murahashi
- Department of Chemistry, Graduate School of Engineering Science , Osaka University , 1-3, Machikaneyama , Toyonaka , Osaka 560-8531 , Japan
| | - Yasushi Imada
- Department of Applied Chemistry , Tokushima University , 2-1, Minamijosanjima , Tokushima 770-8506 , Japan
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3
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Benfodda Z, Benimélis D, Reginato G, Meffre P. Ethynylglycine synthon, a useful precursor for the synthesis of biologically active compounds: an update. Part II: synthetic uses of ethynylglycine synthon. Amino Acids 2018; 50:1307-1328. [DOI: 10.1007/s00726-018-2628-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Accepted: 07/20/2018] [Indexed: 11/28/2022]
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4
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Darroudi M, Sarrafi Y, Hamzehloueian M. Theoretical exploration of mechanism of carbapenam formation in catalytic Kinugasa reaction. Tetrahedron 2017. [DOI: 10.1016/j.tet.2017.01.071] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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5
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Wolosewicz K, Michalak M, Adamek J, Furman B. Studies on the Enantioselective Kinugasa Reaction: Efficient Synthesis of β-Lactams Catalyzed byN-PINAP/CuX Complexes. European J Org Chem 2016. [DOI: 10.1002/ejoc.201600050] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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6
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Kumar Y, Singh P, Bhargava G. Recent developments in the synthesis of condensed β-lactams. RSC Adv 2016. [DOI: 10.1039/c6ra20973d] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
β-Lactams are important heterocycles with diverse pharmacological profiles and have emerged as useful organic synthons.
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Affiliation(s)
- Yogesh Kumar
- Department of Chemistry
- I. K. Gujral Punjab Technical University
- Kapurthala
- India
| | | | - Gaurav Bhargava
- Department of Chemistry
- I. K. Gujral Punjab Technical University
- Kapurthala
- India
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7
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Abstract
Various vinyl ketonitrones are prepared using new strategies and were applied to synthesize heterocycles in organic synthesis.
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Affiliation(s)
- Wei-Min Shi
- Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources
- Ministry of Education of China and School of Chemistry & Pharmaceutical Sciences
- Guangxi Normal University
- Guilin 541004
- China
| | - Xiao-Pan Ma
- Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources
- Ministry of Education of China and School of Chemistry & Pharmaceutical Sciences
- Guangxi Normal University
- Guilin 541004
- China
| | - Gui-Fa Su
- Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources
- Ministry of Education of China and School of Chemistry & Pharmaceutical Sciences
- Guangxi Normal University
- Guilin 541004
- China
| | - Dong-Liang Mo
- Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources
- Ministry of Education of China and School of Chemistry & Pharmaceutical Sciences
- Guangxi Normal University
- Guilin 541004
- China
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8
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Mucha Ł, Parda K, Staszewska-Krajewska O, Stecko S, Ulikowski A, Frelek J, Suszczyńska A, Chmielewski M, Furman B. Diastereoselective synthesis of β-lactams via Kinugasa reaction of acyclic chiral nitrones. ACTA ACUST UNITED AC 2016. [DOI: 10.1016/j.tetasy.2015.11.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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9
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Kabala K, Grzeszczyk B, Stecko S, Furman B, Chmielewski M. Approach to Monobactams and Nocardicins via Diastereoselective Kinugasa Reaction. J Org Chem 2015; 80:12038-46. [DOI: 10.1021/acs.joc.5b01979] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Kamil Kabala
- Institute of Organic Chemistry, Polish Academy of Sciences Kasprzaka
44/52, 01-224 Warsaw, Poland
| | - Barbara Grzeszczyk
- Institute of Organic Chemistry, Polish Academy of Sciences Kasprzaka
44/52, 01-224 Warsaw, Poland
| | - Sebastian Stecko
- Institute of Organic Chemistry, Polish Academy of Sciences Kasprzaka
44/52, 01-224 Warsaw, Poland
| | - Bartłomiej Furman
- Institute of Organic Chemistry, Polish Academy of Sciences Kasprzaka
44/52, 01-224 Warsaw, Poland
| | - Marek Chmielewski
- Institute of Organic Chemistry, Polish Academy of Sciences Kasprzaka
44/52, 01-224 Warsaw, Poland
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10
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Marquès S, Schuler M, Tatibouët A. Preparation of Pyranose-Based ThioimidateN-Oxides (TINOs). European J Org Chem 2015. [DOI: 10.1002/ejoc.201403619] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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11
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Ethynylglycine synthon, a useful precursor for the synthesis of biologically active compounds: an update: part I: preparations of ethynylglycine synthon. Amino Acids 2015; 47:271-9. [PMID: 25563810 DOI: 10.1007/s00726-014-1902-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Accepted: 12/11/2014] [Indexed: 10/24/2022]
Abstract
The ethynylglycine synthon {(R)-2,2-dimethyl-3-(tert-butoxycarbonyl)-4-ethynyloxazolidine} is a chiral compound with valuable synthetic interest. An update on the different routes for its synthesis is reviewed and discussed.
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12
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Stecko S, Furman B, Chmielewski M. Kinugasa reaction: an ‘ugly duckling’ of β-lactam chemistry. Tetrahedron 2014. [DOI: 10.1016/j.tet.2014.06.024] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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13
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Pitts CR, Lectka T. Chemical Synthesis of β-Lactams: Asymmetric Catalysis and Other Recent Advances. Chem Rev 2014; 114:7930-53. [DOI: 10.1021/cr4005549] [Citation(s) in RCA: 217] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Cody Ross Pitts
- Department of Chemistry, Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Thomas Lectka
- Department of Chemistry, Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
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Alcaide B, Almendros P, Luna A. Novel achievements with an old metal: copper-promoted synthesis of four-membered azacycles. RSC Adv 2014. [DOI: 10.1039/c3ra43861a] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
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15
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Zhao H, Wang WB, Nakagawa S, Jia YM, Hu XG, Fleet GW, Wilson FX, Nash RJ, Kato A, Yu CY. Novel 2-aryl-3,4,5-trihydroxypiperidines: Synthesis and glycosidase inhibition. CHINESE CHEM LETT 2013. [DOI: 10.1016/j.cclet.2013.06.027] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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16
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Khangarot RK, Kaliappan KP. Kinugasa Reaction: A Direct One-Pot Route to Highly Functionalized β-Lactams. European J Org Chem 2013. [DOI: 10.1002/ejoc.201300597] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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17
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Baeza B, Casarrubios L, Sierra MA. Towards a General Synthesis of 3-Metal-Substituted β-Lactams. Chemistry 2013; 19:11536-40. [DOI: 10.1002/chem.201301114] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Revised: 06/10/2013] [Indexed: 11/07/2022]
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18
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An efficient synthesis of aldohexose-derived piperidine nitrones: precursors of piperidine iminosugars. Molecules 2013; 18:6021-34. [PMID: 23698053 PMCID: PMC6270483 DOI: 10.3390/molecules18056021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Revised: 05/15/2013] [Accepted: 05/17/2013] [Indexed: 11/17/2022] Open
Abstract
d-Glucopyranose-derived and l-idopyranose-derived piperidine nitrones were synthesized in good overall yields through six-step reaction sequence starting from readily available 2,3,4,6-tetra-O-benzyl-d-glucopyranose. The method is efficient and could be general for the synthesis of aldohexose-derived piperidine nitrones which are precursors of piperidine iminosugars.
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19
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Chen Z, Lin L, Wang M, Liu X, Feng X. Asymmetric Synthesis oftrans-β-Lactams by a Kinugasa Reaction on Water. Chemistry 2013; 19:7561-7. [DOI: 10.1002/chem.201204373] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2012] [Indexed: 12/18/2022]
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20
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Grzeszczyk B, Stecko S, Mucha Ł, Staszewska-Krajewska O, Chmielewski M, Furman B. A practical preparation of the key intermediate for penems and carbapenems synthesis. J Antibiot (Tokyo) 2013; 66:161-3. [DOI: 10.1038/ja.2013.8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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21
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Li J, Lian X, Liu X, Lin L, Feng X. Nickel(II)-Catalyzed Enantioselective 1,3-Dipolar Cycloaddition of Azomethine Imines with Alkylidene Malonates. Chemistry 2013; 19:5134-40. [DOI: 10.1002/chem.201203891] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Revised: 01/28/2013] [Indexed: 11/10/2022]
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22
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23
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Michalak M, Stodulski M, Stecko S, Wonica M, Staszewska-Krajewska O, Kalicki P, Furman B, Frelek J, Chmielewski M. Synthesis of N,4-diaryl substituted ?-lactams via Kinugasa cycloaddition/rearrangement reaction. Tetrahedron 2012. [DOI: 10.1016/j.tet.2011.11.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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24
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Khangarot RK, Kaliappan KP. A Stereoselective Route to Aza-C-aryl Glycosides from Arynes and Chiral Nitrones. European J Org Chem 2012. [DOI: 10.1002/ejoc.201200685] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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25
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Mandal B, Basu B. Synthesis of β-Lactams Through Alkyne–Nitrone Cycloadditions. ACTA ACUST UNITED AC 2012. [DOI: 10.1007/7081_2012_85] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/17/2023]
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26
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Lee SJ, Heo IJ, Cho CW. One-Pot Synthesis of Five-, Six-, and Seven-Membered Lactams via Bu3SnH-Mediated Reductive Cyclization of Azido Amides. B KOREAN CHEM SOC 2012. [DOI: 10.5012/bkcs.2012.33.2.739] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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27
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Heo IJ, Lee SJ, Cho CW. Direct Lactamization of Azido Amides via Staudinger-Type Reductive Cyclization. B KOREAN CHEM SOC 2012. [DOI: 10.5012/bkcs.2012.33.1.333] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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28
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Khangarot RK, Kaliappan KP. A Stereoselective Synthesis of Sugar-Derived Chiral β-Lactams. European J Org Chem 2011. [DOI: 10.1002/ejoc.201100953] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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29
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Michalak M, Stodulski M, Stecko S, Mames A, Panfil I, Soluch M, Furman B, Chmielewski M. A formal synthesis of ezetimibe via cycloaddition/rearrangement cascade reaction. J Org Chem 2011; 76:6931-6. [PMID: 21744801 DOI: 10.1021/jo2010846] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A formal synthesis of a powerful cholesterol inhibitor, ezetymibe 1, is described. The crucial step of the synthesis is based on Cu(I)-mediated Kinugasa cycloaddition/rearrangement cascade reaction between terminal acetylene derived from acetonide of L-glyceraldehyde and suitable C,N-diarylnitrone. The adduct with (3R,4S) configuration at the azetidinone ring, obtained with high stereoselectivity, was subsequently subjected to deprotection of the diol side chain followed by glycolic cleavage and base-induced isomerization at the C3 carbon atom to afford the (3S,4S) aldehyde, which has been already transformed into ezetimibe by the Schering-Plough group.
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Affiliation(s)
- Michał Michalak
- Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
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30
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Verma D, Mobin S, Namboothiri INN. Highly Selective Synthesis of Pyrazole and Spiropyrazoline Phosphonates via Base-Assisted Reaction of the Bestmann–Ohira Reagent with Enones. J Org Chem 2011; 76:4764-70. [DOI: 10.1021/jo200582z] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Deepti Verma
- Department of Chemistry and ‡National Single-Crystal X-ray Diffraction Facility, Indian Institute of Technology Bombay, Mumbai 400 076, India
| | - Shaikh Mobin
- Department of Chemistry and ‡National Single-Crystal X-ray Diffraction Facility, Indian Institute of Technology Bombay, Mumbai 400 076, India
| | - Irishi N. N. Namboothiri
- Department of Chemistry and ‡National Single-Crystal X-ray Diffraction Facility, Indian Institute of Technology Bombay, Mumbai 400 076, India
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31
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Worgull D, Dickmeiss G, Jensen KL, Franke PT, Holub N, Jørgensen KA. Optically Active Bicyclic N-Heterocycles by Organocatalytic Asymmetric Michael Addition/Cyclization Sequences. Chemistry 2011; 17:4076-80. [DOI: 10.1002/chem.201100233] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2011] [Indexed: 11/08/2022]
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32
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33
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Synthesis of iminosugars via 1,3-dipolar cycloaddition reactions of nitrones to α,β-unsaturated sugar aldonolactones. CR CHIM 2011. [DOI: 10.1016/j.crci.2010.09.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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34
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Mames A, Stecko S, Mikołajczyk P, Soluch M, Furman B, Chmielewski M. Direct, catalytic synthesis of carbapenams via cycloaddition/rearrangement cascade reaction: unexpected acetylenes' structure effect. J Org Chem 2010; 75:7580-7. [PMID: 20961063 DOI: 10.1021/jo101355h] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Reactions of acetylenes derived from glyceraldehyde and propargyl aldehyde show remarkable reactivity in Kinugasa cycloaddition/rearrangement cascade process catalyzed by Cu(I) ion. Reactions proceed by formation of a rigid dinuclear copper(I) complex in which each copper ion is coordinated to one or both oxygen atoms in the acetylene molecule and to both triple bonds. It has been demonstrated that one oxygen atom can be replaced by the phenyl ring, which is able to coordinate the copper ion by the aromatic sextet. Kinugasa reactions that proceed in a high yield can also be performed in the presence of a catalytic amount of the copper salt to provide products in an acceptable yield without a decrease of diastereoselectivity.
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Affiliation(s)
- Adam Mames
- Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
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35
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Woźnica M, Masnyk M, Stecko S, Mames A, Furman B, Chmielewski M, Frelek J. Structure−Chiroptical Properties Relationship of Carbapenams by Experiment and Theory. J Org Chem 2010; 75:7219-26. [DOI: 10.1021/jo101429k] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Magdalena Woźnica
- Institute of Organic Chemistry of the Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Marek Masnyk
- Institute of Organic Chemistry of the Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Sebastian Stecko
- Institute of Organic Chemistry of the Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Adam Mames
- Institute of Organic Chemistry of the Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Bartłomiej Furman
- Institute of Organic Chemistry of the Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Marek Chmielewski
- Institute of Organic Chemistry of the Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Jadwiga Frelek
- Institute of Organic Chemistry of the Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
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Muruganantham R, Namboothiri I. Phosphonylpyrazoles from Bestmann-Ohira reagent and nitroalkenes: synthesis and dynamic NMR studies. J Org Chem 2010; 75:2197-205. [PMID: 20218559 DOI: 10.1021/jo902595e] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Application of diethyl 1-diazo-2-oxopropylphosphonate (Bestmann-Ohira reagent) as a cycloaddition partner with nitroalkenes has been extensively investigated. Base-mediated reaction of the Bestmann-Ohira reagent with various nitroalkenes such as beta-substituted, alpha,beta-disubstituted, and nitroethylene that are part of a carbocyclic or heterocyclic ring provided functionalized phosphonylpyrazoles through a one-pot regioselective reaction at room temperature in high yield. The substituted nitroalkenes employed in these reactions also included Morita-Baylis-Hillman adducts of conjugated nitroalkenes with various electrophiles. Detailed dynamic NMR studies were performed on the prototropic tautomerism exhibited by the phosphonylpyrazoles using CDCl(3) and DMSO-d(6) as solvents and (1)H and (31)P as the probe nuclei. These studies unraveled the existence of two tautomers in solution with a small energy difference but considerable barrier to interconversion.
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Schleiss J, Rollin P, Tatibouët A. Palladium-Catalyzed Coupling Reactions of Thioimidate N-Oxides: Access to α-Alkenyl- and α-Aryl-Functionalized Cyclic Nitrones. Angew Chem Int Ed Engl 2010. [DOI: 10.1002/ange.200905188] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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38
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Schleiss J, Rollin P, Tatibouët A. Palladium-Catalyzed Coupling Reactions of Thioimidate N-Oxides: Access to α-Alkenyl- and α-Aryl-Functionalized Cyclic Nitrones. Angew Chem Int Ed Engl 2009; 49:577-80. [DOI: 10.1002/anie.200905188] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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