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Alexander F. Khlebnikov - One of the best experts on this subject based on the ideXlab platform.
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buchner reaction azirine modification approach toward cycloheptatriene containing nitrogen heterocyclic scaffolds
Journal of Organic Chemistry, 2021Co-Authors: Ekaterina E. Galenko, Mikhail S. Novikov, Mariya A Kryukova, Vladimir A Bodunov, Alexander F. KhlebnikovAbstract:The reaction conditions for the Buchner reaction of 2-(diazoacetyl)-2H-azirines with benzene leading to 2-(cyclohepta-2,4,6-trien-1-yl)-2H-azirines have been found. The azirine fragment of these compounds was subsequently used to prepare 5-(cyclohepta-2,4,6-trien-1-yl)Isoxazoles and α-(cyclohepta-2,4,6-triene-1-ylcarbonyl)-1H-pyrroles. NMR and DFT calculations showed that the cycloheptatriene-norcaradiene valence isomerization in the corresponding moieties of synthesized azirines, Isoxazoles, and pyrroles is very fast at room temperature. Cycloheptatriene valence isomer predominates in azirines and pyrroles, while 5-(cycloheptatrienyl)Isoxazoles exist in a pure cycloheptatriene form at 25 °C in chloroform solution. In accordance with the X-ray analysis, two of the synthesized pyrroles crystallized as norcaradiene isomers from a solution of equilibrium mixture of valence isomers. Reductive isoxazole ring opening using the Mo(CO)6/H2O reductive system afforded (Z)-3-amino-3-aryl-1-(cyclohepta-2,4,6-trien-1-yl)prop-2-en-1-ones, which are pure cycloheptatriene isomers. α-(Cycloheptatrieneylcarbonyl)-1H-pyrroles were transformed into the α-(benzylcarbonyl)-1H-pyrroles under cooperative TFA/Rh2(TFA)4 catalysis.
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Synthesis of Isoxazole- and Oxazole-4-carboxylic Acids Derivatives by Controlled Isoxazole-Azirine-Isoxazole/Oxazole Isomerization.
The Journal of organic chemistry, 2019Co-Authors: Anna V Serebryannikova, Ekaterina E. Galenko, Mikhail S. Novikov, Alexander F. KhlebnikovAbstract:The first synthesis of isoxazole-4-carboxylic acid derivatives by domino isoxazole-isoxazole isomerization is reported. Fe(II)-catalyzed isomerization of 4-acyl-5-methoxy-/5-aminoIsoxazoles (dioxane, 105 °C) leads to the formation of isoxazole-4-carboxylic esters and amides in good yields. 4-Formyl-5-methoxyIsoxazoles give methyl oxazole-4-carboxylates under the same reaction conditions. Fe(II)-catalyzed isomerization of 4-acyl-5-methoxyIsoxazoles under milder conditions (MeCN, 50 °C) allows the preparation of transient 2-acyl-2-(methoxycarbonyl)-2H-azirines. The azirines isomerize quantitatively either into Isoxazoles under catalytic conditions (dioxane, 105 °C) or into oxazoles under noncatalytic thermolysis (o-dichlorobenzene, 170 °C). The mechanism of the isomerization and dependence of the reaction routes on substituents at starting isoxazole core and reaction conditions are discussed on the basis of DFT calculations.
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synthesis of isoxazole and oxazole 4 carboxylic acids derivatives by controlled isoxazole azirine isoxazole oxazole isomerization
Journal of Organic Chemistry, 2019Co-Authors: Anna V Serebryannikova, Ekaterina E. Galenko, Mikhail S. Novikov, Alexander F. KhlebnikovAbstract:The first synthesis of isoxazole-4-carboxylic acid derivatives by domino isoxazole-isoxazole isomerization is reported. Fe(II)-catalyzed isomerization of 4-acyl-5-methoxy-/5-aminoIsoxazoles (dioxane, 105 °C) leads to the formation of isoxazole-4-carboxylic esters and amides in good yields. 4-Formyl-5-methoxyIsoxazoles give methyl oxazole-4-carboxylates under the same reaction conditions. Fe(II)-catalyzed isomerization of 4-acyl-5-methoxyIsoxazoles under milder conditions (MeCN, 50 °C) allows the preparation of transient 2-acyl-2-(methoxycarbonyl)-2H-azirines. The azirines isomerize quantitatively either into Isoxazoles under catalytic conditions (dioxane, 105 °C) or into oxazoles under noncatalytic thermolysis (o-dichlorobenzene, 170 °C). The mechanism of the isomerization and dependence of the reaction routes on substituents at starting isoxazole core and reaction conditions are discussed on the basis of DFT calculations.
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synthesis of 2 halo 2 н azirine 2 carboxylic acid amides and esters by isomerization of 5 dialkylamino alkoxy substituted Isoxazoles catalyzed by iron ii sulfate
Chemistry of Heterocyclic Compounds, 2017Co-Authors: Anastasiya V. Agafonova, Ilia A. Smetanin, Nikolai V. Rostovskii, Alexander F. Khlebnikov, Mikhail S. NovikovAbstract:N,N-Dialkylamides and esters of 2-(chloro/bromo/iodo)-2H-azirine-2-carboxylic acids were synthesized by isomerization of 4-halo-5-(dialkylamino/alkoxy)Isoxazoles in the presence of catalytic amounts of FeSO4·7H2O. The use of iron(II) sulfate as catalyst, compared to its chloride, provides the advantage of avoiding halide exchange products in isomerization reactions of 4-bromo- and 4-iodoIsoxazoles, as well as prevents catalyst deactivation by the 5-amino substituent of isoxazole, compared to rhodium(II) carboxylates.
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Synthesis of 2-halo-2Н-azirine-2-carboxylic acid amides and esters by isomerization of 5-(dialkylamino/alkoxy)-substituted Isoxazoles, catalyzed by iron(II) sulfate
Chemistry of Heterocyclic Compounds, 2017Co-Authors: Anastasiya V. Agafonova, Ilia A. Smetanin, Nikolai V. Rostovskii, Alexander F. Khlebnikov, Mikhail S. NovikovAbstract:N , N -Dialkylamides and esters of 2-(chloro/bromo/iodo)-2 H -azirine-2-carboxylic acids were synthesized by isomerization of 4-halo-5-(dialkylamino/alkoxy)Isoxazoles in the presence of catalytic amounts of FeSO_4·7H_2O. The use of iron(II) sulfate as catalyst, compared to its chloride, provides the advantage of avoiding halide exchange products in isomerization reactions of 4-bromo- and 4-iodoIsoxazoles, as well as prevents catalyst deactivation by the 5-amino substituent of isoxazole, compared to rhodium(II) carboxylates.
Mikhail S. Novikov - One of the best experts on this subject based on the ideXlab platform.
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buchner reaction azirine modification approach toward cycloheptatriene containing nitrogen heterocyclic scaffolds
Journal of Organic Chemistry, 2021Co-Authors: Ekaterina E. Galenko, Mikhail S. Novikov, Mariya A Kryukova, Vladimir A Bodunov, Alexander F. KhlebnikovAbstract:The reaction conditions for the Buchner reaction of 2-(diazoacetyl)-2H-azirines with benzene leading to 2-(cyclohepta-2,4,6-trien-1-yl)-2H-azirines have been found. The azirine fragment of these compounds was subsequently used to prepare 5-(cyclohepta-2,4,6-trien-1-yl)Isoxazoles and α-(cyclohepta-2,4,6-triene-1-ylcarbonyl)-1H-pyrroles. NMR and DFT calculations showed that the cycloheptatriene-norcaradiene valence isomerization in the corresponding moieties of synthesized azirines, Isoxazoles, and pyrroles is very fast at room temperature. Cycloheptatriene valence isomer predominates in azirines and pyrroles, while 5-(cycloheptatrienyl)Isoxazoles exist in a pure cycloheptatriene form at 25 °C in chloroform solution. In accordance with the X-ray analysis, two of the synthesized pyrroles crystallized as norcaradiene isomers from a solution of equilibrium mixture of valence isomers. Reductive isoxazole ring opening using the Mo(CO)6/H2O reductive system afforded (Z)-3-amino-3-aryl-1-(cyclohepta-2,4,6-trien-1-yl)prop-2-en-1-ones, which are pure cycloheptatriene isomers. α-(Cycloheptatrieneylcarbonyl)-1H-pyrroles were transformed into the α-(benzylcarbonyl)-1H-pyrroles under cooperative TFA/Rh2(TFA)4 catalysis.
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Synthesis of Isoxazole- and Oxazole-4-carboxylic Acids Derivatives by Controlled Isoxazole-Azirine-Isoxazole/Oxazole Isomerization.
The Journal of organic chemistry, 2019Co-Authors: Anna V Serebryannikova, Ekaterina E. Galenko, Mikhail S. Novikov, Alexander F. KhlebnikovAbstract:The first synthesis of isoxazole-4-carboxylic acid derivatives by domino isoxazole-isoxazole isomerization is reported. Fe(II)-catalyzed isomerization of 4-acyl-5-methoxy-/5-aminoIsoxazoles (dioxane, 105 °C) leads to the formation of isoxazole-4-carboxylic esters and amides in good yields. 4-Formyl-5-methoxyIsoxazoles give methyl oxazole-4-carboxylates under the same reaction conditions. Fe(II)-catalyzed isomerization of 4-acyl-5-methoxyIsoxazoles under milder conditions (MeCN, 50 °C) allows the preparation of transient 2-acyl-2-(methoxycarbonyl)-2H-azirines. The azirines isomerize quantitatively either into Isoxazoles under catalytic conditions (dioxane, 105 °C) or into oxazoles under noncatalytic thermolysis (o-dichlorobenzene, 170 °C). The mechanism of the isomerization and dependence of the reaction routes on substituents at starting isoxazole core and reaction conditions are discussed on the basis of DFT calculations.
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synthesis of isoxazole and oxazole 4 carboxylic acids derivatives by controlled isoxazole azirine isoxazole oxazole isomerization
Journal of Organic Chemistry, 2019Co-Authors: Anna V Serebryannikova, Ekaterina E. Galenko, Mikhail S. Novikov, Alexander F. KhlebnikovAbstract:The first synthesis of isoxazole-4-carboxylic acid derivatives by domino isoxazole-isoxazole isomerization is reported. Fe(II)-catalyzed isomerization of 4-acyl-5-methoxy-/5-aminoIsoxazoles (dioxane, 105 °C) leads to the formation of isoxazole-4-carboxylic esters and amides in good yields. 4-Formyl-5-methoxyIsoxazoles give methyl oxazole-4-carboxylates under the same reaction conditions. Fe(II)-catalyzed isomerization of 4-acyl-5-methoxyIsoxazoles under milder conditions (MeCN, 50 °C) allows the preparation of transient 2-acyl-2-(methoxycarbonyl)-2H-azirines. The azirines isomerize quantitatively either into Isoxazoles under catalytic conditions (dioxane, 105 °C) or into oxazoles under noncatalytic thermolysis (o-dichlorobenzene, 170 °C). The mechanism of the isomerization and dependence of the reaction routes on substituents at starting isoxazole core and reaction conditions are discussed on the basis of DFT calculations.
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synthesis of 2 halo 2 н azirine 2 carboxylic acid amides and esters by isomerization of 5 dialkylamino alkoxy substituted Isoxazoles catalyzed by iron ii sulfate
Chemistry of Heterocyclic Compounds, 2017Co-Authors: Anastasiya V. Agafonova, Ilia A. Smetanin, Nikolai V. Rostovskii, Alexander F. Khlebnikov, Mikhail S. NovikovAbstract:N,N-Dialkylamides and esters of 2-(chloro/bromo/iodo)-2H-azirine-2-carboxylic acids were synthesized by isomerization of 4-halo-5-(dialkylamino/alkoxy)Isoxazoles in the presence of catalytic amounts of FeSO4·7H2O. The use of iron(II) sulfate as catalyst, compared to its chloride, provides the advantage of avoiding halide exchange products in isomerization reactions of 4-bromo- and 4-iodoIsoxazoles, as well as prevents catalyst deactivation by the 5-amino substituent of isoxazole, compared to rhodium(II) carboxylates.
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Synthesis of 2-halo-2Н-azirine-2-carboxylic acid amides and esters by isomerization of 5-(dialkylamino/alkoxy)-substituted Isoxazoles, catalyzed by iron(II) sulfate
Chemistry of Heterocyclic Compounds, 2017Co-Authors: Anastasiya V. Agafonova, Ilia A. Smetanin, Nikolai V. Rostovskii, Alexander F. Khlebnikov, Mikhail S. NovikovAbstract:N , N -Dialkylamides and esters of 2-(chloro/bromo/iodo)-2 H -azirine-2-carboxylic acids were synthesized by isomerization of 4-halo-5-(dialkylamino/alkoxy)Isoxazoles in the presence of catalytic amounts of FeSO_4·7H_2O. The use of iron(II) sulfate as catalyst, compared to its chloride, provides the advantage of avoiding halide exchange products in isomerization reactions of 4-bromo- and 4-iodoIsoxazoles, as well as prevents catalyst deactivation by the 5-amino substituent of isoxazole, compared to rhodium(II) carboxylates.
Robert N Hanson - One of the best experts on this subject based on the ideXlab platform.
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synthesis and evaluation of 4 substituted styryl alkenyl 3 5 bis 4 hydroxyphenyl Isoxazoles as ligands for the estrogen receptor
ChemInform, 2013Co-Authors: Terra D Haddad, Rachel Gershman, Robert Dilis, David Labaree, Richard B Hochberg, Robert N HansonAbstract:4-(Substituted styryl/alkenyl)-3,5-bis(4-hydroxyphenyl)-Isoxazoles of type (III) and (VII) are prepared and evaluated as ligands for the estrogen receptor-alpha (ERα) The 4-(4-hydroxy-styryl) derivative (VII) displays binding properties similar to those of the previously described pyrazole class of ER ligands, indicating that the ERα-LBD tolerates the presence of the added vinyl group at the 4-position of the isoxazole ring.
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synthesis and evaluation of 4 substituted styryl alkenyl 3 5 bis 4 hydroxyphenyl Isoxazoles as ligands for the estrogen receptor
Bioorganic & Medicinal Chemistry Letters, 2012Co-Authors: Terra D Haddad, Rachel Gershman, Robert Dilis, David Labaree, Richard B Hochberg, Robert N HansonAbstract:A series of 3,5-bis (4-hydroxyphenyl) Isoxazoles bearing a styryl/alkyl vinyl group at the 4-position were prepared and evaluated as ligands for the estrogen receptor-alpha (ERα). The target compounds were prepared using the Suzuki reaction to couple an iodo-isoxazole intermediate with a series of styryl/alkenyl boronic acids, followed by O-demethylation. The products were evaluated for their estrogen receptor-α ligand binding domain (ERα-LBD) binding affinity using a competitive binding assay. The 4-(4-hydroxystyryl) derivative 4h displays binding properties similar to those of the previously described pyrazole class of ER ligands, indicating that the ERα-LBD tolerates the presence of the added vinyl group at the 4-position of the isoxazole ring.
Weicheng Yuan - One of the best experts on this subject based on the ideXlab platform.
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regio and stereoselective 3 2 cycloaddition reaction access to isoxazole dispirobisoxindoles featuring three contiguous stereocenters
Organic and Biomolecular Chemistry, 2019Co-Authors: Shuang Chen, Guanlian Wang, Minyi Tian, Shengwen Xu, Min Zhang, Weicheng YuanAbstract:A novel methodology toward the diversity-oriented asymmetric construction of densely functionalized isoxazole-dispirobisoxindoles was developed. This approach is distinguished by an organocatalytic stereo- and appealing β-regioselective [3 + 2] cycloaddition reaction of 3-methyl-4-nitro-5-isatylidenyl-Isoxazoles and 3-isothiocyanato oxindoles. Complex polycyclic oxindoles 3 featuring two different oxindole moieties and three contiguous stereocenters were smoothly afforded in up to 96% yield, 96% ee, and >20 : 1 dr. The described method, which is different from our previous work of α-regioselective asymmetric annulation of 3-methyl-4-nitro-5-isatylidenyl-Isoxazoles, is the first β-regioselective asymmetric annulation.
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enantioselective 1 6 michael addition of anthrone to 3 methyl 4 nitro 5 alkenyl Isoxazoles catalyzed by bifunctional thiourea tertiary amines
ChemInform, 2011Co-Authors: Hongwei Sun, Yuhua Liao, Haoyu Wang, Xiaomei Zhang, Weicheng YuanAbstract:A simple and efficient method for the enantioselective 1,6-Michael addition reaction of anthrone to a series of 3-methyl-4-nitro-5-alkenyl-Isoxazoles with a bifunctional thiourea-tertiary amine as catalyst is described. This transformation proceeds smoothly with 10 mol % catalyst and provides a series of Michael adducts bearing 3-methyl-4-nitro-isoxazole and anthrone units with good to high enantioselectivities (up to 96% ee) and in very high yields (up to 99%).
Terra D Haddad - One of the best experts on this subject based on the ideXlab platform.
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synthesis and evaluation of 4 substituted styryl alkenyl 3 5 bis 4 hydroxyphenyl Isoxazoles as ligands for the estrogen receptor
ChemInform, 2013Co-Authors: Terra D Haddad, Rachel Gershman, Robert Dilis, David Labaree, Richard B Hochberg, Robert N HansonAbstract:4-(Substituted styryl/alkenyl)-3,5-bis(4-hydroxyphenyl)-Isoxazoles of type (III) and (VII) are prepared and evaluated as ligands for the estrogen receptor-alpha (ERα) The 4-(4-hydroxy-styryl) derivative (VII) displays binding properties similar to those of the previously described pyrazole class of ER ligands, indicating that the ERα-LBD tolerates the presence of the added vinyl group at the 4-position of the isoxazole ring.
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synthesis and evaluation of 4 substituted styryl alkenyl 3 5 bis 4 hydroxyphenyl Isoxazoles as ligands for the estrogen receptor
Bioorganic & Medicinal Chemistry Letters, 2012Co-Authors: Terra D Haddad, Rachel Gershman, Robert Dilis, David Labaree, Richard B Hochberg, Robert N HansonAbstract:A series of 3,5-bis (4-hydroxyphenyl) Isoxazoles bearing a styryl/alkyl vinyl group at the 4-position were prepared and evaluated as ligands for the estrogen receptor-alpha (ERα). The target compounds were prepared using the Suzuki reaction to couple an iodo-isoxazole intermediate with a series of styryl/alkenyl boronic acids, followed by O-demethylation. The products were evaluated for their estrogen receptor-α ligand binding domain (ERα-LBD) binding affinity using a competitive binding assay. The 4-(4-hydroxystyryl) derivative 4h displays binding properties similar to those of the previously described pyrazole class of ER ligands, indicating that the ERα-LBD tolerates the presence of the added vinyl group at the 4-position of the isoxazole ring.
