1
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Kawamoto T, Fukuyama T, Picard B, Ryu I. New directions in radical carbonylation chemistry: combination with electron catalysis, photocatalysis and ring-opening. Chem Commun (Camb) 2022; 58:7608-7617. [PMID: 35758516 DOI: 10.1039/d2cc02700c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Radical carbonylation offers potent methods for introducing carbon monoxide into organic molecules. This feature article focuses on our current efforts to develop new strategies for radical carbonylation, which include electron-transfer carbonylation, site-selective C(sp3)-H carbonylation by a photocatalyst and ring-opening carbonylation.
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Affiliation(s)
- Takuji Kawamoto
- Department of Applied Chemistry, Yamaguchi University, Ube, Yamaguchi, 755-8611, Japan
| | - Takahide Fukuyama
- Department of Chemistry, Osaka Metropolitan University (OMU), Sakai, Osaka, 599-8531, Japan
| | - Baptiste Picard
- Organization for Research Promotion, Osaka Metropolitan University (OMU), Sakai, Osaka, 599-8531, Japan.
| | - Ilhyong Ryu
- Organization for Research Promotion, Osaka Metropolitan University (OMU), Sakai, Osaka, 599-8531, Japan. .,Department of Applied Chemistry, National Yang Ming Chiao Tung University (NYCU), Hsinchu, 30010, Taiwan
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2
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Picard B, Fukuyama T, Bando T, Hyodo M, Ryu I. Electron-Catalyzed Aminocarbonylation: Synthesis of α,β-Unsaturated Amides from Alkenyl Iodides, CO, and Amines. Org Lett 2021; 23:9505-9509. [PMID: 34844411 DOI: 10.1021/acs.orglett.1c03714] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Aminocarbonylation of alkenyl iodides with CO and amines proceeded under heating to produce α,β-unsaturated amides in good yields (23 examples, 71% average yield). This catalyst-free method exhibited good functional-group tolerance, and open a straightforward access to functionalized acrylamides, as illustrated by the synthesis of Ilepcimide. A hybrid radical/ionic mechanism involving chain electron transfer is proposed for this transformation.
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Affiliation(s)
- Baptiste Picard
- Organization for Research Promotion, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan
| | - Takahide Fukuyama
- Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan
| | - Takanobu Bando
- Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan
| | - Mamoru Hyodo
- Organization for Research Promotion, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan
| | - Ilhyong Ryu
- Organization for Research Promotion, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan.,Department of Applied Chemistry, National Yang Ming Chiao Tung University (NYCU), Hsinchu 30010, Taiwan
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3
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Guo RL, Zhu XQ, Zhang XL, Wang YQ. Synthesis of difluoromethylselenoesters from aldehydes via a radical process. Chem Commun (Camb) 2020; 56:8976-8979. [DOI: 10.1039/d0cc02912b] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Difluoromethylselenoester compounds are reported for the first time. They can be efficiently synthesized from aldehydes and BnSeCF2H under mild conditions.
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Affiliation(s)
- Rui-Li Guo
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, College of Chemistry & Materials Science
- Northwest University
- Xi’an 710069
- People's Republic of China
| | - Xue-Qing Zhu
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, College of Chemistry & Materials Science
- Northwest University
- Xi’an 710069
- People's Republic of China
| | - Xing-Long Zhang
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, College of Chemistry & Materials Science
- Northwest University
- Xi’an 710069
- People's Republic of China
| | - Yong-Qiang Wang
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, College of Chemistry & Materials Science
- Northwest University
- Xi’an 710069
- People's Republic of China
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4
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Fukuyama T, Okada T, Nakashima N, Ryu I. Radical Mediated Aza‐
Pauson‐Khand
Reaction of Acetylenes, Imines, and CO Leading to Five‐Membered Unsaturated Lactams. Helv Chim Acta 2019. [DOI: 10.1002/hlca.201900186] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Takahide Fukuyama
- Department of Chemistry, Graduate School of ScienceOsaka Prefecture University, Sakai Osaka 599-8531 Japan
| | - Takuma Okada
- Department of Chemistry, Graduate School of ScienceOsaka Prefecture University, Sakai Osaka 599-8531 Japan
| | - Nao Nakashima
- Department of Chemistry, Graduate School of ScienceOsaka Prefecture University, Sakai Osaka 599-8531 Japan
| | - Ilhyong Ryu
- Department of Chemistry, Graduate School of ScienceOsaka Prefecture University, Sakai Osaka 599-8531 Japan
- Department of Applied ChemistryNational Chiao Tung University Hsinchu 30010 Taiwan
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5
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Cartier A, Levernier E, Corcé V, Fukuyama T, Dhimane A, Ollivier C, Ryu I, Fensterbank L. Carbonylation of Alkyl Radicals Derived from Organosilicates through Visible‐Light Photoredox Catalysis. Angew Chem Int Ed Engl 2019; 58:1789-1793. [DOI: 10.1002/anie.201811858] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Indexed: 12/21/2022]
Affiliation(s)
- Alex Cartier
- Department of ChemistryGraduate School of ScienceOsaka Prefecture University Sakai Osaka 599-8531 Japan
| | - Etienne Levernier
- Sorbonne UniversitéCNRSInstitut Parisien de Chimie Moléculaire 4 Place Jussieu, CC 229 75252 Paris Cedex 05 France
| | - Vincent Corcé
- Sorbonne UniversitéCNRSInstitut Parisien de Chimie Moléculaire 4 Place Jussieu, CC 229 75252 Paris Cedex 05 France
| | - Takahide Fukuyama
- Department of ChemistryGraduate School of ScienceOsaka Prefecture University Sakai Osaka 599-8531 Japan
| | - Anne‐Lise Dhimane
- Sorbonne UniversitéCNRSInstitut Parisien de Chimie Moléculaire 4 Place Jussieu, CC 229 75252 Paris Cedex 05 France
| | - Cyril Ollivier
- Sorbonne UniversitéCNRSInstitut Parisien de Chimie Moléculaire 4 Place Jussieu, CC 229 75252 Paris Cedex 05 France
| | - Ilhyong Ryu
- Department of ChemistryGraduate School of ScienceOsaka Prefecture University Sakai Osaka 599-8531 Japan
- Department of Applied ChemistryNational Chiao Tung University Hsinchu Taiwan
| | - Louis Fensterbank
- Sorbonne UniversitéCNRSInstitut Parisien de Chimie Moléculaire 4 Place Jussieu, CC 229 75252 Paris Cedex 05 France
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6
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Cartier A, Levernier E, Corcé V, Fukuyama T, Dhimane A, Ollivier C, Ryu I, Fensterbank L. Carbonylation of Alkyl Radicals Derived from Organosilicates through Visible‐Light Photoredox Catalysis. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201811858] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Alex Cartier
- Department of ChemistryGraduate School of ScienceOsaka Prefecture University Sakai Osaka 599-8531 Japan
| | - Etienne Levernier
- Sorbonne UniversitéCNRSInstitut Parisien de Chimie Moléculaire 4 Place Jussieu, CC 229 75252 Paris Cedex 05 France
| | - Vincent Corcé
- Sorbonne UniversitéCNRSInstitut Parisien de Chimie Moléculaire 4 Place Jussieu, CC 229 75252 Paris Cedex 05 France
| | - Takahide Fukuyama
- Department of ChemistryGraduate School of ScienceOsaka Prefecture University Sakai Osaka 599-8531 Japan
| | - Anne‐Lise Dhimane
- Sorbonne UniversitéCNRSInstitut Parisien de Chimie Moléculaire 4 Place Jussieu, CC 229 75252 Paris Cedex 05 France
| | - Cyril Ollivier
- Sorbonne UniversitéCNRSInstitut Parisien de Chimie Moléculaire 4 Place Jussieu, CC 229 75252 Paris Cedex 05 France
| | - Ilhyong Ryu
- Department of ChemistryGraduate School of ScienceOsaka Prefecture University Sakai Osaka 599-8531 Japan
- Department of Applied ChemistryNational Chiao Tung University Hsinchu Taiwan
| | - Louis Fensterbank
- Sorbonne UniversitéCNRSInstitut Parisien de Chimie Moléculaire 4 Place Jussieu, CC 229 75252 Paris Cedex 05 France
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Matsubara H, Kawamoto T, Fukuyama T, Ryu I. Applications of Radical Carbonylation and Amine Addition Chemistry: 1,4-Hydrogen Transfer of 1-Hydroxylallyl Radicals. Acc Chem Res 2018; 51:2023-2035. [PMID: 30137961 DOI: 10.1021/acs.accounts.8b00278] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
1,4-Hydrogen transfer from the 1-hydroxyallyl radical to give the enoxyl (α-keto) radical is an exothermic process with a high activation energy based on DFT calculations. The lack of experimental examples of such 1,4-H shift reactions lies in the difficulty of generating the 1-hydroxyallyl radical. We have shown that radical carbonylation of alkenyl radicals with CO followed by nucleophilic trapping of the carbonyl portion of the resulting radical by amines gives rise to 1-amino-substituted 1-hydroxyallyl radicals in situ. At the outset of this chemistry, we examined intramolecular trapping reactions via radical carbonylation of alkynylamines mediated by tributyltin hydride. Consequently, α-methylene lactams were obtained, for which the initially formed 1-amino-substituted 1-hydroxyallyl radical underwent a 1,4-H shift followed by subsequent β-scission, which led to the expulsion of a tributyltin radical. A competing pathway of the 1,4-H shift of 1-amino-substituted 1-hydroxyallyl radicals involving hydrogen abstraction was observed, which led to the formation of α-stannylmethylene lactams as a major byproduct. However, in contrast, when intermolecular trapping of α-ketenyl radicals by amines was carried out, the 1,4-H shift from the 1-amino-substituted 1-hydroxyallyl radical became the major pathway, which gave good yields of α,β-unsaturated amides. Thus, we were able to develop three-component reactions comprising terminal alkynes, CO, and amines that led to α,β-unsaturated amides via the 1,4-H shift reaction. DFT calculations support the observation that the 1,4-H shift is more facile when 1-hydroxyallyl radicals have both 1-amino and 3-tin substituents. The choice of substituents on the amine nitrogen is also important, since N-C bond cleavage via an SH2-type reaction can become a competing pathway. Such an unusual SH2-type reaction at the amine nitrogen is favored when the leaving alkyl radicals are stable, such as PhC(•)H(CH3) and t-Bu•. Interestingly, even nucleophilic attack of tertiary amines onto α-ketenyl radicals causes cleavage of the C-N bond. For this reaction, DFT calculations predict an indirect homolytic substitution mechanism involving expulsion of alkyl radicals through the zwitterionic radical intermediate arising from nucleophilic amine addition onto the α-ketenyl radical. In contrast, the carbonylation of aryl radicals, generated from aryl iodides, in the presence of amines gave aromatic carboxylic amides in good yields. It is proposed that radical anions originating from acyl radicals and amines undergo electron transfer to aryl iodides to give aminocarbonylation products.
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Affiliation(s)
- Hiroshi Matsubara
- Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan
| | - Takuji Kawamoto
- Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan
| | - Takahide Fukuyama
- Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan
| | - Ilhyong Ryu
- Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan
- Department of Applied Chemistry, National Chiao Tung University, Hsinchu, Taiwan 300, ROC
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8
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Matsubara H, Kawamoto T, Fukuyama T, Ryu I. Theoretical Calculations for the 1,4-Hydrogen Shift of 1-Hydroxyallyl Radicals Leading to α-Keto Radicals; Prediction of Facilitation by 1-Amino and 3-Tin Substituents. CHEM LETT 2018. [DOI: 10.1246/cl.180522] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Hiroshi Matsubara
- Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan
| | - Takuji Kawamoto
- Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan
| | - Takahide Fukuyama
- Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan
| | - Ilhyong Ryu
- Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan
- Department of Applied Chemistry, National Chiao Tung University, Hsinchu, Taiwan
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9
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Guo SH, Wang MY, Pan GF, Zhu XQ, Gao YR, Wang YQ. Synthesis of Monofluoromethylthioesters from Aldehydes. Adv Synth Catal 2018. [DOI: 10.1002/adsc.201800136] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Shi-Huan Guo
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education; Department of Chemistry & Materials Science; Northwest University; Xi'an 710069 People's Republic of China
| | - Meng-Yue Wang
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education; Department of Chemistry & Materials Science; Northwest University; Xi'an 710069 People's Republic of China
| | - Gao-Fei Pan
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education; Department of Chemistry & Materials Science; Northwest University; Xi'an 710069 People's Republic of China
| | - Xue-Qing Zhu
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education; Department of Chemistry & Materials Science; Northwest University; Xi'an 710069 People's Republic of China
| | - Ya-Ru Gao
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education; Department of Chemistry & Materials Science; Northwest University; Xi'an 710069 People's Republic of China
| | - Yong-Qiang Wang
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education; Department of Chemistry & Materials Science; Northwest University; Xi'an 710069 People's Republic of China
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10
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Guo SH, Zhang XL, Pan GF, Zhu XQ, Gao YR, Wang YQ. Synthesis of Difluoromethylthioesters from Aldehydes. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201710731] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Shi-Huan Guo
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, Department of Chemistry & Materials Science; Northwest University; Xi'an 710069 P.R. China
| | - Xing-Long Zhang
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, Department of Chemistry & Materials Science; Northwest University; Xi'an 710069 P.R. China
| | - Gao-Fei Pan
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, Department of Chemistry & Materials Science; Northwest University; Xi'an 710069 P.R. China
| | - Xue-Qing Zhu
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, Department of Chemistry & Materials Science; Northwest University; Xi'an 710069 P.R. China
| | - Ya-Ru Gao
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, Department of Chemistry & Materials Science; Northwest University; Xi'an 710069 P.R. China
| | - Yong-Qiang Wang
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, Department of Chemistry & Materials Science; Northwest University; Xi'an 710069 P.R. China
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11
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Guo SH, Zhang XL, Pan GF, Zhu XQ, Gao YR, Wang YQ. Synthesis of Difluoromethylthioesters from Aldehydes. Angew Chem Int Ed Engl 2018; 57:1663-1667. [DOI: 10.1002/anie.201710731] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 11/28/2017] [Indexed: 01/05/2023]
Affiliation(s)
- Shi-Huan Guo
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, Department of Chemistry & Materials Science; Northwest University; Xi'an 710069 P.R. China
| | - Xing-Long Zhang
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, Department of Chemistry & Materials Science; Northwest University; Xi'an 710069 P.R. China
| | - Gao-Fei Pan
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, Department of Chemistry & Materials Science; Northwest University; Xi'an 710069 P.R. China
| | - Xue-Qing Zhu
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, Department of Chemistry & Materials Science; Northwest University; Xi'an 710069 P.R. China
| | - Ya-Ru Gao
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, Department of Chemistry & Materials Science; Northwest University; Xi'an 710069 P.R. China
| | - Yong-Qiang Wang
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, Department of Chemistry & Materials Science; Northwest University; Xi'an 710069 P.R. China
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12
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Affiliation(s)
- Ilhyong Ryu
- Graduate School of Sciences, Osaka Prefecture University
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13
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14
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Ryu IH, Fukuyama T, Nobuta O, Uenoyama Y. Stannylcarbonylation of Hydroxy-substituted Alkynes. Intramoleuclar Trapping of α-Ketenyl Radicals by a Hydroxy Group Leading to Lactols. B KOREAN CHEM SOC 2010. [DOI: 10.5012/bkcs.2010.31.03.545] [Citation(s) in RCA: 7] [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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15
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Ryu I, Kobayashi S, Hirao H, Kawauchi T. Novel Radical Cyclization Method Accompanied by Elimination of Hydrazyl Radical. HETEROCYCLES 2010. [DOI: 10.3987/com-09-s(s)115] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Abstract
All in one pot! Radical, radical-ionic, and radical-organometallic MCR are highly convergent processes, representing a useful pathway to molecular and structural diversity (see scheme). This concept article highlights recent developments in the field and shows the potential of the strategy for the economical elaboration of various kinds of organic substrates.Progress in multicomponent reactions (MCRs) based on ionic and organometallic processes has recently allowed the synthesis, with high efficiency, of large collections of drug-like molecules. In contrast, MCRs based on cascade radical reactions appear to have attracted, so far, much less interest. This concept article highlights the latest progress in the field and underlines the potential of such an approach. The collected examples demonstrate that radical and radical-ionic MCRs are highly convergent processes leading to useful structural diversity.
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Affiliation(s)
- Edouard Godineau
- University Bordeaux-1, Institut des Sciences Moléculaires, ISM-UMR 5255, 351, cours de la libération 33405 Talence Cedex, France
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Schiesser CH, Wille U, Matsubara H, Ryu I. Radicals masquerading as electrophiles: dual orbital effects in nitrogen-philic acyl radical cyclization and related addition reactions. Acc Chem Res 2007; 40:303-13. [PMID: 17444607 DOI: 10.1021/ar600015v] [Citation(s) in RCA: 128] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Free-radical chemistry has come a long way in a relatively short period of time. The synthetic practitioner takes for granted the wealth of mechanistic and rate constant data now available and can apply free-radical techniques to the synthesis of many different classes of target molecule with confidence. Despite this, there are still mechanistic anomalies that need to be addressed. This Account highlights recent work involving nucleophilic radicals with low-lying unoccupied orbitals, such as acyl, oxyacyl, silyl, stannyl, and germyl radicals. Through interesting singly occupied molecular orbital (SOMO)-pi* and highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) interactions during these reactions, the radicals involved are able to mask as electrophiles, providing high levels of regiocontrol and efficient methods for the synthesis of important heterocycles.
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Affiliation(s)
- Carl H Schiesser
- School of Chemistry, The University of Melbourne, Victoria, Australia
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Matsubara H, Ryu I, Schiesser CH. An ab initio and DFT study of some halogen atom transfer reactions from alkyl groups to acyl radical. Org Biomol Chem 2007; 5:3320-4. [PMID: 17912385 DOI: 10.1039/b710449a] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Ab initio calculations using the 6-311G**, cc-pVDZ, and (valence) double-zeta pseudopotential (DZP) basis sets, with (MP2, QCISD, CCSD(T)) and without (HF) the inclusion of electron correlation, and density functional (BHandHLYP, B3LYP) calculations predict that the transition states for the reaction of acetyl radical with several alkyl halides adopt an almost collinear arrangement of attacking and leaving radicals at the halogen atom. Energy barriers (DeltaE(double dagger)) for these halogen transfer reactions of between 89.2 (chlorine transfer from methyl group) and 25.3 kJ mol(-1) (iodine transfer from tert-butyl group) are calculated at the BHandHLYP/DZP level of theory. While the difference in forward and reverse energy barriers for iodine transfer to acetyl radical is predicted to be 15.1 kJ mol(-1) for primary alkyl iodide, these values are calculated to be 6.7 and -4.2 kJ mol(-1) for secondary and tertiary alkyl iodide respectively. These data are in good agreement with available experimental data in that atom transfer radical carbonylation reactions are sluggish with primary alkyl iodides, but proceed smoothly with secondary and tertiary alkyl iodides. These calculations also predict that bromine transfer reactions involving acyl radical are also feasible at moderately high temperature.
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Affiliation(s)
- Hiroshi Matsubara
- Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan
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