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David A Nicewicz - One of the best experts on this subject based on the ideXlab platform.
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Nucleophilic Aromatic Substitution of Unactivated Fluoroarenes Enabled by Organic Photoredox Catalysis.
Journal of the American Chemical Society, 2020Co-Authors: Vincent A. Pistritto, Megan E. Schutzbach-horton, David A NicewiczAbstract:Nucleophilic Aromatic Substitution (SNAr) is a classical reaction with well-known reactivity toward electron-poor fluoroarenes. However, electron-neutral and electron-rich fluoro(hetero)arenes are considerably underrepresented. Herein, we present a method for the nucleophilic defluorination of unactivated fluoroarenes enabled by cation radical-accelerated nucleophilic Aromatic Substitution. The use of organic photoredox catalysis renders this method operationally simple under mild conditions and is amenable to various nucleophile classes, including azoles, amines, and carboxylic acids. Select fluorinated heterocycles can be functionalized using this method. In addition, the late-stage functionalization of pharmaceuticals is also presented. Computational studies demonstrate that the site selectivity of the reaction is dictated by arene electronics.
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Cation Radical-Accelerated Nucleophilic Aromatic Substitution for Amination of Alkoxyarenes
Organic letters, 2020Co-Authors: Nicholas J. Venditto, David A NicewiczAbstract:Nucleophilic Aromatic Substitution (SNAr) is a common method for arene functionalization; however, reactions of this type are typically limited to electron-deficient Aromatic halides. Herein, we describe a mild, metal-free, cation-radical accelerated nucleophilic Aromatic Substitution (CRA-SNAr) using a potent, highly oxidizing acridinium photoredox catalyst. Selective Substitution of arene C-O bonds on a wide array of aryl ether substrates was shown with a variety of primary amine nucleophiles. Mechanistic evidence is also presented that supports the proposed CRA-SNAr pathway.
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cation radical accelerated nucleophilic Aromatic Substitution via organic photoredox catalysis
Journal of the American Chemical Society, 2017Co-Authors: David A NicewiczAbstract:Nucleophilic Aromatic Substitution (SNAr) is a direct method for arene functionalization; however, it can be hampered by low reactivity of arene substrates and their availability. Herein we describe a cation radical-accelerated nucleophilic Aromatic Substitution using methoxy- and benzyloxy-groups as nucleofuges. In particular, lignin-derived Aromatics containing guaiacol and veratrole motifs were competent substrates for functionalization. We also demonstrate an example of site-selective substitutive oxygenation with trifluoroethanol to afford the desired trifluoromethylaryl ether.
Guillermo Penieres-carrillo - One of the best experts on this subject based on the ideXlab platform.
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Unusual nucleophilic versus electrophilic Aromatic Substitution on nitroanilines
Journal of Molecular Catalysis A-chemical, 2000Co-Authors: Cecilio Alvarez-toledano, Roberto Aguilar-pacheco, Oscar Baldovino-pantaleón, René Gutiérrez-pérez, René Miranda-ruvalcaba, Guillermo Penieres-carrilloAbstract:Abstract The reaction of the regioisomeric nitroanilines with KI and HNO 3 /bentonite system using microwave energy in solvent-free conditions is reported. In accordance with the obtained results, an unusual competence between nucleophilic Aromatic Substitution versus electrophilic Aromatic Substitution was detected. With the para isomer two products were obtained, one for each reaction type; however, with the meta -nitroaniline, only the nucleophilic Substitution product was detected, and finally with the ortho isomer in addition to the nucleophilic and electrophilic Substitution products, we detected the formation of 2,4-diiodonitrobenzene. In order to explain the achieved products, we propose that the last product is formed in two steps: firstly by a nucleophilic Aromatic Substitution, and secondly by an electrophilic Aromatic Substitution.
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Unusual nucleophilic versus electrophilic Aromatic Substitution on nitroanilines
Journal of Molecular Catalysis A: Chemical, 2000Co-Authors: Cecilio Alvarez-toledano, Roberto Aguilar-pacheco, Oscar Baldovino-pantaleón, René Gutiérrez-pérez, René Miranda-ruvalcaba, Guillermo Penieres-carrilloAbstract:The reaction of the regioisomeric nitroanilines with KI and HNOs/bentonite system using microwave energy in solvent-free conditions is reported. In accordance with the obtained results, an unusual competence between nucleophilic Aromatic Substitution versus electrophilic Aromatic Substitution was detected. With the para isomer two products were obtained, one for each reaction typ
Cecilio Alvarez-toledano - One of the best experts on this subject based on the ideXlab platform.
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Unusual nucleophilic versus electrophilic Aromatic Substitution on nitroanilines
Journal of Molecular Catalysis A-chemical, 2000Co-Authors: Cecilio Alvarez-toledano, Roberto Aguilar-pacheco, Oscar Baldovino-pantaleón, René Gutiérrez-pérez, René Miranda-ruvalcaba, Guillermo Penieres-carrilloAbstract:Abstract The reaction of the regioisomeric nitroanilines with KI and HNO 3 /bentonite system using microwave energy in solvent-free conditions is reported. In accordance with the obtained results, an unusual competence between nucleophilic Aromatic Substitution versus electrophilic Aromatic Substitution was detected. With the para isomer two products were obtained, one for each reaction type; however, with the meta -nitroaniline, only the nucleophilic Substitution product was detected, and finally with the ortho isomer in addition to the nucleophilic and electrophilic Substitution products, we detected the formation of 2,4-diiodonitrobenzene. In order to explain the achieved products, we propose that the last product is formed in two steps: firstly by a nucleophilic Aromatic Substitution, and secondly by an electrophilic Aromatic Substitution.
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Unusual nucleophilic versus electrophilic Aromatic Substitution on nitroanilines
Journal of Molecular Catalysis A: Chemical, 2000Co-Authors: Cecilio Alvarez-toledano, Roberto Aguilar-pacheco, Oscar Baldovino-pantaleón, René Gutiérrez-pérez, René Miranda-ruvalcaba, Guillermo Penieres-carrilloAbstract:The reaction of the regioisomeric nitroanilines with KI and HNOs/bentonite system using microwave energy in solvent-free conditions is reported. In accordance with the obtained results, an unusual competence between nucleophilic Aromatic Substitution versus electrophilic Aromatic Substitution was detected. With the para isomer two products were obtained, one for each reaction typ
Armido Studer - One of the best experts on this subject based on the ideXlab platform.
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Silyldefluorination of Fluoroarenes by Concerted Nucleophilic Aromatic Substitution.
Angewandte Chemie, 2018Co-Authors: Shubhadip Mallick, Ernst-ulrich Würthwein, Pan Xu, Armido StuderAbstract:: The reaction of readily generated silyl lithium reagents with various aryl fluorides to provide the corresponding aryl silanes is reported. DFT calculations reveal that the nucleophilic Aromatic Substitution of the fluoride anion by the silyl lithium reagent proceeds through concerted ipso Substitution. In contrast to the classical nucleophilic Aromatic Substitution, this concerted ionic silyldefluorination also occurs on more electron-rich aryl fluorides.
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6‐Aroylated Phenanthridines via Base Promoted Homolytic Aromatic Substitution (BHAS).
ChemInform, 2014Co-Authors: Dirk Leifert, Constantin G. Daniliuc, Armido StuderAbstract:The novel method for the synthesis of 6-aroylated phenanthridines involves the addition of acyl radicals to the isonitrile functionality of 2-isocyanobiphenyls and subsequent intramolecular base promoted homolytic Aromatic Substitution.
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6 aroylated phenanthridines via base promoted homolytic Aromatic Substitution bhas
Organic Letters, 2013Co-Authors: Dirk Leifert, Constantin G. Daniliuc, Armido StuderAbstract:Readily accessible 2-isocyanobiphenyls react with Aromatic aldehydes via base promoted homolytic Aromatic Substitution (BHAS) to give 6-aroylated phenanthridines. Reactions occur via addition of acyl radicals to the isonitrile functionality and subsequent intramolecular BHAS of the intermediate imidoyl radicals. Initiation of the radical chain reaction is best achieved with small amounts of FeCl3 (0.4 mol %), and the commercially available and cheap tBuOOH is used as the oxidant.
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cross dehydrogenative coupling via base promoted homolytic Aromatic Substitution bhas synthesis of fluorenones and xanthones
ChemInform, 2013Co-Authors: Sebastian Wertz, Dirk Leifert, Armido StuderAbstract:A series of fluorenones and xanthones are synthesized by cross dehydrogenative coupling reaction occurring via base-promoted homolytic Aromatic Substitution (BHAS).
René Miranda-ruvalcaba - One of the best experts on this subject based on the ideXlab platform.
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Unusual nucleophilic versus electrophilic Aromatic Substitution on nitroanilines
Journal of Molecular Catalysis A-chemical, 2000Co-Authors: Cecilio Alvarez-toledano, Roberto Aguilar-pacheco, Oscar Baldovino-pantaleón, René Gutiérrez-pérez, René Miranda-ruvalcaba, Guillermo Penieres-carrilloAbstract:Abstract The reaction of the regioisomeric nitroanilines with KI and HNO 3 /bentonite system using microwave energy in solvent-free conditions is reported. In accordance with the obtained results, an unusual competence between nucleophilic Aromatic Substitution versus electrophilic Aromatic Substitution was detected. With the para isomer two products were obtained, one for each reaction type; however, with the meta -nitroaniline, only the nucleophilic Substitution product was detected, and finally with the ortho isomer in addition to the nucleophilic and electrophilic Substitution products, we detected the formation of 2,4-diiodonitrobenzene. In order to explain the achieved products, we propose that the last product is formed in two steps: firstly by a nucleophilic Aromatic Substitution, and secondly by an electrophilic Aromatic Substitution.
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Unusual nucleophilic versus electrophilic Aromatic Substitution on nitroanilines
Journal of Molecular Catalysis A: Chemical, 2000Co-Authors: Cecilio Alvarez-toledano, Roberto Aguilar-pacheco, Oscar Baldovino-pantaleón, René Gutiérrez-pérez, René Miranda-ruvalcaba, Guillermo Penieres-carrilloAbstract:The reaction of the regioisomeric nitroanilines with KI and HNOs/bentonite system using microwave energy in solvent-free conditions is reported. In accordance with the obtained results, an unusual competence between nucleophilic Aromatic Substitution versus electrophilic Aromatic Substitution was detected. With the para isomer two products were obtained, one for each reaction typ