The Experts below are selected from a list of 273 Experts worldwide ranked by ideXlab platform
Atul Chaskar - One of the best experts on this subject based on the ideXlab platform.
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a multicomponent pathway inspired regioselective synthesis of 2 3 4 trisubstituted 1h Pyrroles via 3 2 cycloaddition reaction
New Journal of Chemistry, 2015Co-Authors: Hanuman P Kalmode, Kamlesh S Vadagaonkar, Kaliyappan Murugan, Atul ChaskarAbstract:A copper catalyzed regioselective synthesis of 2,3,4-trisubstituted 1H-Pyrroles using a novel three-component coupled domino reaction of aldehydes, ketones and alkyl isocyanoacetates is reported. This transformation proceeds through the formation of a chalcone followed by a [3+2] cycloaddition reaction to obtain α-cuprioisocyanide, a cyclic organocopper intermediate, which on copper–hydrogen exchange followed by oxidation exclusively offers 2,3,4-trisubstituted 1H-pyrrole.
Jonathan L Sessler - One of the best experts on this subject based on the ideXlab platform.
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Pyrrole- and Naphthobipyrrole-Strapped Calix[4]Pyrroles as Azide Anion Receptors
Journal of Organic Chemistry, 2018Co-Authors: Gabriela I. Vargas-zúñiga, Vincent M Lynch, Jonathan L SesslerAbstract:The binding interactions between the azide anion (N3–) and the strapped calix[4]Pyrroles 2 and 3 bearing auxiliary hydrogen bonding donors on the bridging moieties, as well as of normal calix[4]pyrrole 1, were investigated via 1H NMR spectroscopic and isothermal titration calorimetry analyses. The resulting data revealed that receptors 2 and 3 have significantly higher affinities for the azide anion in organic media as compared with the unfunctionalized calix[4]pyrrole 1 and other azide receptors reported to date. Single crystal X-ray diffraction analyses and calculations using density functional theory revealed that receptor 2 binds CsN3 in two distinct structural forms. As judged from the metric parameters, in the resulting complexes one limiting azide anion resonance contributor is favored over the other, with the specifics depending on the binding mode. In contrast to what is seen for 2, receptor 3 forms a CsN3 complex in 20% CD3OD in CDCl3, wherein the azide anion is bound only vertically to the NH p...
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calix 4 Pyrroles versatile molecular containers with ion transport recognition and molecular switching functions
Chemical Society Reviews, 2015Co-Authors: Jonathan L SesslerAbstract:Over the last two decades, calix[4]Pyrroles have attracted considerable attention as molecular containers. Used in this capacity, they have been exploited as strong and selective receptors and as extractants for both anions and ion pairs. More recently, calix[4]Pyrroles have found application as carriers, systems capable of transporting ions and ion pairs across lipophilic membranes. The use of calix[4]Pyrroles as building blocks for the preparation of stimulus-responsive material has also been demonstrated. In this latter context, as well as others, the conformational switching, from 1,3-alternate to cone upon anion binding has been exploited to control both structure and substrate binding. In this Review, we describe recent results involving the use of calix[4]pyrrole systems for ion transport. Also summarised is work devoted to the formation of higher order supramolecular aggregates and studies of their response to external stimuli. Taken together, these examples serve to highlight new uses of calix[4]Pyrroles as molecular containers.
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perrhenate and pertechnetate anion recognition properties of cyclo 8 pyrrole
Supramolecular Chemistry, 2015Co-Authors: Evgeny A Kataev, Grigory V Kolesnikov, Patricia Pantos, Elizabeth Karnas, Ivan G. Tananaev, Vincent M Lynch, Jonathan L SesslerAbstract:Cyclo[8]pyrrole, an octapyrrolic expanded porphyrin with no meso-linking atoms, was found to interact with a series of anions in the solid state and in a chloroform solution. The anion selectivities have been determined relative to a structurally characterised salt, H2cyclo[8]pyrrole2+·I− ·I3 − , via counter anion exchange. Although cyclo[8]pyrrole demonstrates a general selectivity for sulfate, it interacts well with both the pertechnetate and perrhenate anions. Moreover, it has been shown to act as a phase-transfer catalyst facilitating the extraction of pertechnetate from an aqueous to an organic phase in the presence of sulfate.
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Formation and properties of cyclo[6]pyrrole and cyclo[7]pyrrole.
Journal of the American Chemical Society, 2003Co-Authors: Thomas Köhler, Vincent M Lynch, Daniel Seidel, Zhongping Ou, Karl M. Kadish, Jonathan L SesslerAbstract:Oxidative coupling of a tetraalkylbipyrrole under FeIII-mediated coupling conditions in the presence of HCl results in a mixture of cyclo[6]- and cyclo[7]Pyrroles, as well as the known cyclo[8]pyrrole. This “matched set” of heteroannulenes was analyzed by spectroscopic, electrochemical, and X-ray diffraction methods.
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a building block approach to functionalized calix 4 Pyrroles
Tetrahedron Letters, 2000Co-Authors: Hidekazu Miyaji, Jonathan L Sessler, Wataru Sato, Vincent M LynchAbstract:Abstract Iodocalix[4]pyrrole 2 and trimethylsilylethynylcalix[4]pyrrole 3 are key intermediates en route to the preparation of the alkynyl-substituted calix[4]pyrrole system 4 . This latter species, in turn, provides a versatile precursor that can be used to prepare a range of arylalkynyl-functionalized calix[4]Pyrroles (viz . , 5 – 9 ) by reacting with an appropriate aryl iodide under Sonogashira conditions (i.e., in the presence of tetrakis(triphenylphosphine)palladium(0)). Significant red-shifts in the λ max values and broadenings of the absorption peaks are seen in the UV–vis spectra of systems 6 and 7 upon addition of anions ( e.g ., F − , Cl − , H 2 PO 4 − ) in CH 2 Cl 2 , a finding that leads to the suggestion that these or other analogous systems could find application as anion sensors.
Hanuman P Kalmode - One of the best experts on this subject based on the ideXlab platform.
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a multicomponent pathway inspired regioselective synthesis of 2 3 4 trisubstituted 1h Pyrroles via 3 2 cycloaddition reaction
New Journal of Chemistry, 2015Co-Authors: Hanuman P Kalmode, Kamlesh S Vadagaonkar, Kaliyappan Murugan, Atul ChaskarAbstract:A copper catalyzed regioselective synthesis of 2,3,4-trisubstituted 1H-Pyrroles using a novel three-component coupled domino reaction of aldehydes, ketones and alkyl isocyanoacetates is reported. This transformation proceeds through the formation of a chalcone followed by a [3+2] cycloaddition reaction to obtain α-cuprioisocyanide, a cyclic organocopper intermediate, which on copper–hydrogen exchange followed by oxidation exclusively offers 2,3,4-trisubstituted 1H-pyrrole.
Vincent M Lynch - One of the best experts on this subject based on the ideXlab platform.
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Pyrrole- and Naphthobipyrrole-Strapped Calix[4]Pyrroles as Azide Anion Receptors
Journal of Organic Chemistry, 2018Co-Authors: Gabriela I. Vargas-zúñiga, Vincent M Lynch, Jonathan L SesslerAbstract:The binding interactions between the azide anion (N3–) and the strapped calix[4]Pyrroles 2 and 3 bearing auxiliary hydrogen bonding donors on the bridging moieties, as well as of normal calix[4]pyrrole 1, were investigated via 1H NMR spectroscopic and isothermal titration calorimetry analyses. The resulting data revealed that receptors 2 and 3 have significantly higher affinities for the azide anion in organic media as compared with the unfunctionalized calix[4]pyrrole 1 and other azide receptors reported to date. Single crystal X-ray diffraction analyses and calculations using density functional theory revealed that receptor 2 binds CsN3 in two distinct structural forms. As judged from the metric parameters, in the resulting complexes one limiting azide anion resonance contributor is favored over the other, with the specifics depending on the binding mode. In contrast to what is seen for 2, receptor 3 forms a CsN3 complex in 20% CD3OD in CDCl3, wherein the azide anion is bound only vertically to the NH p...
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perrhenate and pertechnetate anion recognition properties of cyclo 8 pyrrole
Supramolecular Chemistry, 2015Co-Authors: Evgeny A Kataev, Grigory V Kolesnikov, Patricia Pantos, Elizabeth Karnas, Ivan G. Tananaev, Vincent M Lynch, Jonathan L SesslerAbstract:Cyclo[8]pyrrole, an octapyrrolic expanded porphyrin with no meso-linking atoms, was found to interact with a series of anions in the solid state and in a chloroform solution. The anion selectivities have been determined relative to a structurally characterised salt, H2cyclo[8]pyrrole2+·I− ·I3 − , via counter anion exchange. Although cyclo[8]pyrrole demonstrates a general selectivity for sulfate, it interacts well with both the pertechnetate and perrhenate anions. Moreover, it has been shown to act as a phase-transfer catalyst facilitating the extraction of pertechnetate from an aqueous to an organic phase in the presence of sulfate.
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Formation and properties of cyclo[6]pyrrole and cyclo[7]pyrrole.
Journal of the American Chemical Society, 2003Co-Authors: Thomas Köhler, Vincent M Lynch, Daniel Seidel, Zhongping Ou, Karl M. Kadish, Jonathan L SesslerAbstract:Oxidative coupling of a tetraalkylbipyrrole under FeIII-mediated coupling conditions in the presence of HCl results in a mixture of cyclo[6]- and cyclo[7]Pyrroles, as well as the known cyclo[8]pyrrole. This “matched set” of heteroannulenes was analyzed by spectroscopic, electrochemical, and X-ray diffraction methods.
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a building block approach to functionalized calix 4 Pyrroles
Tetrahedron Letters, 2000Co-Authors: Hidekazu Miyaji, Jonathan L Sessler, Wataru Sato, Vincent M LynchAbstract:Abstract Iodocalix[4]pyrrole 2 and trimethylsilylethynylcalix[4]pyrrole 3 are key intermediates en route to the preparation of the alkynyl-substituted calix[4]pyrrole system 4 . This latter species, in turn, provides a versatile precursor that can be used to prepare a range of arylalkynyl-functionalized calix[4]Pyrroles (viz . , 5 – 9 ) by reacting with an appropriate aryl iodide under Sonogashira conditions (i.e., in the presence of tetrakis(triphenylphosphine)palladium(0)). Significant red-shifts in the λ max values and broadenings of the absorption peaks are seen in the UV–vis spectra of systems 6 and 7 upon addition of anions ( e.g ., F − , Cl − , H 2 PO 4 − ) in CH 2 Cl 2 , a finding that leads to the suggestion that these or other analogous systems could find application as anion sensors.
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Hexaalkyl Terpyrrole: A New Building Block for the Preparation of Expanded Porphyrins
Chemistry: A European Journal, 1995Co-Authors: Jonathan L Sessler, Steven Jeremy Weghorn, Yoshio Hiseada, Vincent M LynchAbstract:A new, general synthesis of the first β-substituted tetra- and hexaalkyl terPyrroles is described. Also described are two new classes of expanded porphyrins derived from the hexaalkyl terpyrrole. The key step in the terpyrrole formation is the copper(II)-mediated oxidative coupling of the LDA-derived enolates of α-keto Pyrroles. The first new expanded porphyrin reported here, the so-called “orangarin”, contains five pyrrolic subunits and two bridging carbon atoms, and is formally a 20π-electron nonaromatic macrocycle. The second new class of expanded porphyrins, the “amethyrins”, are 24π-electron nonaromatic macrocycles containing six pyrrole units. Both of these new macrocycles, as well as one of the new terpyrrolic precursors have been structurally characterized by single crystal X-ray diffraction analysis.
Kamlesh S Vadagaonkar - One of the best experts on this subject based on the ideXlab platform.
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a multicomponent pathway inspired regioselective synthesis of 2 3 4 trisubstituted 1h Pyrroles via 3 2 cycloaddition reaction
New Journal of Chemistry, 2015Co-Authors: Hanuman P Kalmode, Kamlesh S Vadagaonkar, Kaliyappan Murugan, Atul ChaskarAbstract:A copper catalyzed regioselective synthesis of 2,3,4-trisubstituted 1H-Pyrroles using a novel three-component coupled domino reaction of aldehydes, ketones and alkyl isocyanoacetates is reported. This transformation proceeds through the formation of a chalcone followed by a [3+2] cycloaddition reaction to obtain α-cuprioisocyanide, a cyclic organocopper intermediate, which on copper–hydrogen exchange followed by oxidation exclusively offers 2,3,4-trisubstituted 1H-pyrrole.
