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Petri M Pihko - One of the best experts on this subject based on the ideXlab platform.
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enantioselective synthesis of 2 Isoxazolines by a one flask conjugate addition oxime transfer process
Chemistry: A European Journal, 2009Co-Authors: Antti Pohjakallio, Petri M PihkoAbstract:Enantioselective Isoxazoline synthesis: A combination of 1) a catalytic enantioselective conjugate addition of oximes to α,β-unsaturated aldehydes and 2) an acid-catalyzed intramolecular oxime-transfer reaction lead to the first asymmetric synthesis of 3-unsubstituted 2-Isoxazolines (see scheme).
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enantioselective synthesis of 2 Isoxazolines by a one flask conjugate addition oxime transfer process
Chemistry: A European Journal, 2009Co-Authors: Antti Pohjakallio, Petri M PihkoAbstract:Enantioselective Isoxazoline synthesis: A combination of 1) a catalytic enantioselective conjugate addition of oximes to alpha,beta-unsaturated aldehydes and 2) an acid-catalyzed intramolecular oxime-transfer reaction lead to the first asymmetric synthesis of 3-unsubstituted 2-Isoxazolines (see scheme).
Olga García Mancheño - One of the best experts on this subject based on the ideXlab platform.
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Mild Radical Oxidative sp3-Carbon–Hydrogen Functionalization: Innovative Construction of Isoxazoline and Dibenz[b,f]oxepine/azepine Derivatives
Synlett, 2016Co-Authors: Andrea Gini, Olga García MancheñoAbstract:Direct carbon–hydrogen bond functionalization has emerged as a powerful synthetic method for the straightforward and modular functionalization of organic molecules. In this account, we described our latest contributions in the area of oxidative sp3-carbon–hydrogen bond functionalization using mild radical oxidants for the construction of structurally important heterocycles. We have developed two new methodologies in which a new class of substrate and an uncommon nucleophilic reagent have been introduced to the existing palette of reaction partners for oxidative carbon–hydrogen functionalization. To achieve these results, the 2,2,6,6-tetramethylpiperidinyloxyl (TEMPO) radical and a benzoyl peroxide/copper(I) system have been employed as oxidants for the dehydrogenative one-pot synthesis of N-alkoxycarbonyl-protected Isoxazolines from hydroxylamines and for the synthesis of dibenz[b,f]oxepines, dibenzo[b,f]thiepines, and dibenz[b,f]azepines from simple xanthenes, thioxanthenes, and acridanes, respectively. 1 Introduction 2 2,2,6,6-Tetramethylpiperidinyloxyl-Mediated Dehydrogenative Formation and Trapping of Unstable Nitrones: Synthesis of N-Alkoxycarbonyl-Protected Isoxazoline Derivatives 3 Oxidative sp3-Carbon–Hydrogen Bond Functionalization and Ring Expansion with Trimethylsilyldiazomethane: Synthesis of Dibenzoxepines, Dibenzothiepines, and Dibenzazepines 4 Conclusions and Outlook
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mild radical oxidative sp3 carbon hydrogen functionalization innovative construction of Isoxazoline and dibenz b f oxepine azepine derivatives
Synlett, 2016Co-Authors: Andrea Gini, Olga García MancheñoAbstract:Direct carbon–hydrogen bond functionalization has emerged as a powerful synthetic method for the straightforward and modular functionalization of organic molecules. In this account, we described our latest contributions in the area of oxidative sp3-carbon–hydrogen bond functionalization using mild radical oxidants for the construction of structurally important heterocycles. We have developed two new methodologies in which a new class of substrate and an uncommon nucleophilic reagent have been introduced to the existing palette of reaction partners for oxidative carbon–hydrogen functionalization. To achieve these results, the 2,2,6,6-tetramethylpiperidinyloxyl (TEMPO) radical and a benzoyl peroxide/copper(I) system have been employed as oxidants for the dehydrogenative one-pot synthesis of N-alkoxycarbonyl-protected Isoxazolines from hydroxylamines and for the synthesis of dibenz[b,f]oxepines, dibenzo[b,f]thiepines, and dibenz[b,f]azepines from simple xanthenes, thioxanthenes, and acridanes, respectively. 1 Introduction 2 2,2,6,6-Tetramethylpiperidinyloxyl-Mediated Dehydrogenative Formation and Trapping of Unstable Nitrones: Synthesis of N-Alkoxycarbonyl-Protected Isoxazoline Derivatives 3 Oxidative sp3-Carbon–Hydrogen Bond Functionalization and Ring Expansion with Trimethylsilyldiazomethane: Synthesis of Dibenzoxepines, Dibenzothiepines, and Dibenzazepines 4 Conclusions and Outlook
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dehydrogenative tempo mediated formation of unstable nitrones easy access to n carbamoyl Isoxazolines
ChemInform, 2016Co-Authors: Andrea Gini, Marwin H S Segler, Dominik Kellner, Olga García MancheñoAbstract:N-carbamoyl nitrones represent an important class of reagents for the synthesis of a variety of natural and biologically active compounds. These compounds are generally converted into valuable 4-Isoxazolines upon cyclization reaction with dipolarophiles. However, these types of N-protected nitrones are highly unstable, which limits their synthesis, storage and practical use, enforcing alternative lengthy or elaborated synthetic routes. In this work, a 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO)-mediated formal "dehydrogenation" of N-protected benzyl-, allyl- and alkyl-substituted hydroxylamines followed by in situ trapping of the generated unstable nitrones into N-carbamoyl 4-Isoxazolines is presented. A plausible mechanism is also proposed, in which the dipolarophile shows an important assistant role in the generation of the active nitrone intermediate. This simple protocol avoids the problematic isolation of N-carbamoyl protected nitrones, providing new synthetic possibilities in Isoxazoline chemistry.
Antti Pohjakallio - One of the best experts on this subject based on the ideXlab platform.
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enantioselective synthesis of 2 Isoxazolines by a one flask conjugate addition oxime transfer process
Chemistry: A European Journal, 2009Co-Authors: Antti Pohjakallio, Petri M PihkoAbstract:Enantioselective Isoxazoline synthesis: A combination of 1) a catalytic enantioselective conjugate addition of oximes to α,β-unsaturated aldehydes and 2) an acid-catalyzed intramolecular oxime-transfer reaction lead to the first asymmetric synthesis of 3-unsubstituted 2-Isoxazolines (see scheme).
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enantioselective synthesis of 2 Isoxazolines by a one flask conjugate addition oxime transfer process
Chemistry: A European Journal, 2009Co-Authors: Antti Pohjakallio, Petri M PihkoAbstract:Enantioselective Isoxazoline synthesis: A combination of 1) a catalytic enantioselective conjugate addition of oximes to alpha,beta-unsaturated aldehydes and 2) an acid-catalyzed intramolecular oxime-transfer reaction lead to the first asymmetric synthesis of 3-unsubstituted 2-Isoxazolines (see scheme).
Andrea Gini - One of the best experts on this subject based on the ideXlab platform.
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Mild Radical Oxidative sp3-Carbon–Hydrogen Functionalization: Innovative Construction of Isoxazoline and Dibenz[b,f]oxepine/azepine Derivatives
Synlett, 2016Co-Authors: Andrea Gini, Olga García MancheñoAbstract:Direct carbon–hydrogen bond functionalization has emerged as a powerful synthetic method for the straightforward and modular functionalization of organic molecules. In this account, we described our latest contributions in the area of oxidative sp3-carbon–hydrogen bond functionalization using mild radical oxidants for the construction of structurally important heterocycles. We have developed two new methodologies in which a new class of substrate and an uncommon nucleophilic reagent have been introduced to the existing palette of reaction partners for oxidative carbon–hydrogen functionalization. To achieve these results, the 2,2,6,6-tetramethylpiperidinyloxyl (TEMPO) radical and a benzoyl peroxide/copper(I) system have been employed as oxidants for the dehydrogenative one-pot synthesis of N-alkoxycarbonyl-protected Isoxazolines from hydroxylamines and for the synthesis of dibenz[b,f]oxepines, dibenzo[b,f]thiepines, and dibenz[b,f]azepines from simple xanthenes, thioxanthenes, and acridanes, respectively. 1 Introduction 2 2,2,6,6-Tetramethylpiperidinyloxyl-Mediated Dehydrogenative Formation and Trapping of Unstable Nitrones: Synthesis of N-Alkoxycarbonyl-Protected Isoxazoline Derivatives 3 Oxidative sp3-Carbon–Hydrogen Bond Functionalization and Ring Expansion with Trimethylsilyldiazomethane: Synthesis of Dibenzoxepines, Dibenzothiepines, and Dibenzazepines 4 Conclusions and Outlook
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mild radical oxidative sp3 carbon hydrogen functionalization innovative construction of Isoxazoline and dibenz b f oxepine azepine derivatives
Synlett, 2016Co-Authors: Andrea Gini, Olga García MancheñoAbstract:Direct carbon–hydrogen bond functionalization has emerged as a powerful synthetic method for the straightforward and modular functionalization of organic molecules. In this account, we described our latest contributions in the area of oxidative sp3-carbon–hydrogen bond functionalization using mild radical oxidants for the construction of structurally important heterocycles. We have developed two new methodologies in which a new class of substrate and an uncommon nucleophilic reagent have been introduced to the existing palette of reaction partners for oxidative carbon–hydrogen functionalization. To achieve these results, the 2,2,6,6-tetramethylpiperidinyloxyl (TEMPO) radical and a benzoyl peroxide/copper(I) system have been employed as oxidants for the dehydrogenative one-pot synthesis of N-alkoxycarbonyl-protected Isoxazolines from hydroxylamines and for the synthesis of dibenz[b,f]oxepines, dibenzo[b,f]thiepines, and dibenz[b,f]azepines from simple xanthenes, thioxanthenes, and acridanes, respectively. 1 Introduction 2 2,2,6,6-Tetramethylpiperidinyloxyl-Mediated Dehydrogenative Formation and Trapping of Unstable Nitrones: Synthesis of N-Alkoxycarbonyl-Protected Isoxazoline Derivatives 3 Oxidative sp3-Carbon–Hydrogen Bond Functionalization and Ring Expansion with Trimethylsilyldiazomethane: Synthesis of Dibenzoxepines, Dibenzothiepines, and Dibenzazepines 4 Conclusions and Outlook
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dehydrogenative tempo mediated formation of unstable nitrones easy access to n carbamoyl Isoxazolines
ChemInform, 2016Co-Authors: Andrea Gini, Marwin H S Segler, Dominik Kellner, Olga García MancheñoAbstract:N-carbamoyl nitrones represent an important class of reagents for the synthesis of a variety of natural and biologically active compounds. These compounds are generally converted into valuable 4-Isoxazolines upon cyclization reaction with dipolarophiles. However, these types of N-protected nitrones are highly unstable, which limits their synthesis, storage and practical use, enforcing alternative lengthy or elaborated synthetic routes. In this work, a 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO)-mediated formal "dehydrogenation" of N-protected benzyl-, allyl- and alkyl-substituted hydroxylamines followed by in situ trapping of the generated unstable nitrones into N-carbamoyl 4-Isoxazolines is presented. A plausible mechanism is also proposed, in which the dipolarophile shows an important assistant role in the generation of the active nitrone intermediate. This simple protocol avoids the problematic isolation of N-carbamoyl protected nitrones, providing new synthetic possibilities in Isoxazoline chemistry.
John E Casida - One of the best experts on this subject based on the ideXlab platform.
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golden age of ryr and gaba r diamide and Isoxazoline insecticides common genesis serendipity surprises selectivity and safety
Chemical Research in Toxicology, 2015Co-Authors: John E CasidaAbstract:The serendipitous observation of the insecticidal activity of a candidate herbicide was the first in a series of surprises that changed the course of insecticide research and opened the “Golden Age of Diamide and Isoxazoline Insecticides” which have a common genesis. Two novel modes of action were discovered, one involving the γ-aminobutyric acid (GABA) receptor of the chloride channel and the other the ryanodine receptor (RyR) of the calcium-activated calcium channel. These are old insecticide targets, but physiological assays and radioligand binding studies reveal that the new diamides and Isoxazolines act at previously unrecognized sites without cross-resistance to other chemotypes and more important differing between insects and mammals resulting in selective toxicity and mechanistically based safety. The phthalic diamide flubendiamide and anthranilic diamides chlorantraniliprole and cyantraniliprole act at an allosteric site of the RyR to activate calcium release in insects but not mammals. They are ...
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insect γ aminobutyric acid receptors and Isoxazoline insecticides toxicological profiles relative to the binding sites of h fluralaner h 4 ethynyl 4 n propylbicycloorthobenzoate and h avermectin
Journal of Agricultural and Food Chemistry, 2014Co-Authors: Chunqing Zhao, John E CasidaAbstract:Isoxazoline insecticides, such as fluralaner (formerly A1443), are noncompetitive γ-aminobutyric acid (GABA) receptor (GABA-R) antagonists with selective toxicity for insects versus mammals. The Isoxazoline target in house fly ( Musca domestica ) brain has subnanomolar affinity for [³H]fluralaner and a unique pattern of sensitivity to Isoxazolines and avermectin B(1a) (AVE) but not to fipronil and α-endosulfan. Inhibitor specificity profiles for 15 Isoxazolines examined with Musca GABA-R and [³H]fluralaner, [³H]-4'-ethynyl-4-n-propylbicycloorthobenzoate ([³H]EBOB), and [³H]AVE binding follow the same structure-activity trends although without high correlation. The 3 most potent of the 15 Isoxazolines tested in Musca [³H]fluralaner, [³H]EBOB, and [³H]AVE binding assays and in honeybee (Apis mellifera) brain [³H]fluralaner assays are generally those most toxic to Musca and four agricultural pests. Fluralaner does not inhibit [³H]EBOB binding to the human GABA-R recombinant β₃ homopentamer, which is highly sensitive to all of the commercial GABAergic insecticides. The unique Isoxazoline binding site may resurrect the GABA-R as a major insecticide target.
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insect γ aminobutyric acid receptors and Isoxazoline insecticides toxicological profiles relative to the binding sites of 3h fluralaner 3h 4 ethynyl 4 n propylbicycloorthobenzoate and 3h avermectin
Journal of Agricultural and Food Chemistry, 2014Co-Authors: Chunqing Zhao, John E CasidaAbstract:Isoxazoline insecticides, such as fluralaner (formerly A1443), are noncompetitive γ-aminobutyric acid (GABA) receptor (GABA-R) antagonists with selective toxicity for insects versus mammals. The Isoxazoline target in house fly (Musca domestica) brain has subnanomolar affinity for [3H]fluralaner and a unique pattern of sensitivity to Isoxazolines and avermectin B1a (AVE) but not to fipronil and α-endosulfan. Inhibitor specificity profiles for 15 Isoxazolines examined with Musca GABA-R and [3H]fluralaner, [3H]-4′-ethynyl-4-n-propylbicycloorthobenzoate ([3H]EBOB), and [3H]AVE binding follow the same structure–activity trends although without high correlation. The 3 most potent of the 15 Isoxazolines tested in Musca [3H]fluralaner, [3H]EBOB, and [3H]AVE binding assays and in honeybee (Apis mellifera) brain [3H]fluralaner assays are generally those most toxic to Musca and four agricultural pests. Fluralaner does not inhibit [3H]EBOB binding to the human GABA-R recombinant β3 homopentamer, which is highly sensi...
