The Experts below are selected from a list of 42 Experts worldwide ranked by ideXlab platform
Anup Bhattacharjya - One of the best experts on this subject based on the ideXlab platform.
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divergent cycloaddition and ring closing metathesis approaches to indolizidine and pyrrolo 1 2 a Azepine skeletons from a chiral precursor an expeditious route to 8 epi swainsonine triacetate
Organic Letters, 2006Co-Authors: Madhumita Nath, Ranjan Mukhopadhyay, Anup BhattacharjyaAbstract:A divergent strategy for the synthesis of diverse azabicyclic ring systems has been developed in which a chiral N-allylpyrrolidine Derivative, obtained from a carbohydrate precursor was converted to (-)-8-epi-swainsonine triacetate by RCM and to a pyrrolo[1,2-a]Azepine Derivative and a 3-hydroxymethyl-substituted indolizidine by N-allylcarbohydrate nitrone and nitrile oxide cycloadditions.
Madhumita Nath - One of the best experts on this subject based on the ideXlab platform.
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divergent cycloaddition and ring closing metathesis approaches to indolizidine and pyrrolo 1 2 a Azepine skeletons from a chiral precursor an expeditious route to 8 epi swainsonine triacetate
Organic Letters, 2006Co-Authors: Madhumita Nath, Ranjan Mukhopadhyay, Anup BhattacharjyaAbstract:A divergent strategy for the synthesis of diverse azabicyclic ring systems has been developed in which a chiral N-allylpyrrolidine Derivative, obtained from a carbohydrate precursor was converted to (-)-8-epi-swainsonine triacetate by RCM and to a pyrrolo[1,2-a]Azepine Derivative and a 3-hydroxymethyl-substituted indolizidine by N-allylcarbohydrate nitrone and nitrile oxide cycloadditions.
Joanna Wiśniewska - One of the best experts on this subject based on the ideXlab platform.
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a mechanistic study on the oxidative degradation of dibenzAzepine Derivatives by manganese iii complexes in acidic sulfate media
International Journal of Chemical Kinetics, 2015Co-Authors: Joanna Wiśniewska, Grzegorz WrzeszczAbstract:The oxidative degradation of tricyclic antidepressants (TCA) was studied in the presence of a large excess of the oxidizing agent manganese(III) and its reduced form manganese(II) sulfate in acidic media. The products were detected and identified using UV–vis, ESI-MS, IR, and EPR methods. The mechanism of the reaction was studied for the following two classes of TCA: 10,11-dihydro-5H-dibenz[b, f]Azepines and dibenz[b, f]Azepines. The oxidative degradation between dibenz[b, f]Azepines and the manganese(III) ions resulted in the formation of substituted acridine with the same substituent as in the origin dibenz[b, f]Azepine Derivative. The pseudo–first-order rate constants (kobs) were determined for the degradation process. The dependences of the observed rate constants on the [MnIII] with a zero intercept were linear. The reaction between 10,11-dihydro-5H-dibenz[b, f]Azepines, and the manganese(III) sulfate ion resulted in oxidative dehydrogenation, which proceeded via the formation of the following two intermediates: a free organic radical and a dimer. Further oxidation of the second intermediate led to a positively charged radical dimer as the single final product. Linear dependences of the pseudo–first-order rate constants (kobs) on the [MnIII] with a zero intercept were established for the degradation of 10,11-dihydro-5H-dibenz[b, f]Azepines. The observed rate constants were dependent on the [H+] and independent of the [TCA] within the excess concentration range of the manganese(III) complexes used in the isolation method. The radical product of the degradation of 10,11-dihydro-5H-dibenz[b, f]Azepines was not stable in the aqueous solution and was subsequently transformed to a nonradical dimer in the next slower step. The observed rate constants were independent of the [MnIII], independent of the [H+] and increased slightly with increasing TCA concentrations when TCA was used in excess. The mechanistic consequences of all of these results are discussed.
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the oxidative degradation of dibenzoAzepine Derivatives by cerium iv complexes in acidic sulfate media
Dalton Transactions, 2012Co-Authors: Marzanna Kurzawa, Joanna Wiśniewska, Grzegorz Wrzeszcz, Rudi Van EldikAbstract:The kinetics of the oxidation of imipramine and desipramine using cerium(IV) complexes were studied in the presence of a large excess of Azepine Derivative (TCA) in acidic sulfate media using UV-Vis spectroscopy. The reaction proceeds viadibenzoAzepine radical formation, identified by EPR measurements. The kinetics of the first degradation step were studied independently of the further slower degradation reactions. Linear dependences, with zero intercept, of the pseudo-first-order rate constants (kobs) on [TCA] were established for both dibenzoAzepine radical formation processes. Rates of reactions decreased with increasing concentration of the H+ ion indicating that cerium(IV) as well as both reductants exist in an equilibrium with their protolytic forms. The activation parameters for the degradation of dibenzoAzepine Derivatives in the first oxidation stage were as follows: ΔH≠ = 39 ± 2 kJ mol−1, ΔS≠ = −28 ± 8 J K−1 mol−1 for imipramine and ΔH≠ = 39 ± 2 kJ mol−1, ΔS≠ = −28 ± 6 J K−1 mol−1 for desipramine, respectively. Imipramine and desipramine radicals dimerized leading to an intermediate radical dimer, which decayed in a first-order consecutive decay process. These two further reactions proceed with rates which are characterized by non-linear dependences of the pseudo-first-order rate constants (kobs) on [TCA]. The degradation reaction of the intermediate radical dimer leads to an uncharged dimer as a final product. Mechanistic consequences of all the results are discussed.
Ranjan Mukhopadhyay - One of the best experts on this subject based on the ideXlab platform.
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divergent cycloaddition and ring closing metathesis approaches to indolizidine and pyrrolo 1 2 a Azepine skeletons from a chiral precursor an expeditious route to 8 epi swainsonine triacetate
Organic Letters, 2006Co-Authors: Madhumita Nath, Ranjan Mukhopadhyay, Anup BhattacharjyaAbstract:A divergent strategy for the synthesis of diverse azabicyclic ring systems has been developed in which a chiral N-allylpyrrolidine Derivative, obtained from a carbohydrate precursor was converted to (-)-8-epi-swainsonine triacetate by RCM and to a pyrrolo[1,2-a]Azepine Derivative and a 3-hydroxymethyl-substituted indolizidine by N-allylcarbohydrate nitrone and nitrile oxide cycloadditions.
Rudi Van Eldik - One of the best experts on this subject based on the ideXlab platform.
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the oxidative degradation of dibenzoAzepine Derivatives by cerium iv complexes in acidic sulfate media
Dalton Transactions, 2012Co-Authors: Marzanna Kurzawa, Joanna Wiśniewska, Grzegorz Wrzeszcz, Rudi Van EldikAbstract:The kinetics of the oxidation of imipramine and desipramine using cerium(IV) complexes were studied in the presence of a large excess of Azepine Derivative (TCA) in acidic sulfate media using UV-Vis spectroscopy. The reaction proceeds viadibenzoAzepine radical formation, identified by EPR measurements. The kinetics of the first degradation step were studied independently of the further slower degradation reactions. Linear dependences, with zero intercept, of the pseudo-first-order rate constants (kobs) on [TCA] were established for both dibenzoAzepine radical formation processes. Rates of reactions decreased with increasing concentration of the H+ ion indicating that cerium(IV) as well as both reductants exist in an equilibrium with their protolytic forms. The activation parameters for the degradation of dibenzoAzepine Derivatives in the first oxidation stage were as follows: ΔH≠ = 39 ± 2 kJ mol−1, ΔS≠ = −28 ± 8 J K−1 mol−1 for imipramine and ΔH≠ = 39 ± 2 kJ mol−1, ΔS≠ = −28 ± 6 J K−1 mol−1 for desipramine, respectively. Imipramine and desipramine radicals dimerized leading to an intermediate radical dimer, which decayed in a first-order consecutive decay process. These two further reactions proceed with rates which are characterized by non-linear dependences of the pseudo-first-order rate constants (kobs) on [TCA]. The degradation reaction of the intermediate radical dimer leads to an uncharged dimer as a final product. Mechanistic consequences of all the results are discussed.
