The Experts below are selected from a list of 219 Experts worldwide ranked by ideXlab platform
Athanassios K. Boudalis - One of the best experts on this subject based on the ideXlab platform.
-
aerobic feiii feii reduction in the presence of 2 4 6 tri 2 pyridyl 1 3 5 triazine and Benzilic Acid synthesis and characterization of a heptacoordinate feii nitrato complex
European Journal of Inorganic Chemistry, 2008Co-Authors: Catherine P. Raptopoulou, Yiannis Sanakis, Athanassios K. BoudalisAbstract:The simultaneous presence of Benzilic Acid [Ph2C(OH)CO2H] and tptz [2,4,6-tri(2-pyridyl)-1,3,5-triazine] in FeIII-containing reaction mixtures leads to partial and/or quantitative metal reduction. In the presence of the oxidative NO3– ions in the reaction mixture, partial reduction of the metal leads to the isolation of a heptacoordinate FeII–nitrato complex, [FeII(tptz)(NO3)(MeOH)2](NO3) (1), along with a FeIII complex (2). In the presence of perchlorate ions in the reaction mixture, the quantitative reduction of FeIII leads to the isolation of a hexacoordinate FeII complex, [FeII(tptzH)2](ClO4)4 (3). Complexes 1 and 3 have been structurally characterized and possess a pentagonal-bipyramidal and a distorted octahedral coordination geometry, respectively. In both complexes, tptz behaves as a tridentate ligand, adopting the terpy-like coordination mode, and is coordinated through the triazine nitrogen atom and the two adjacent pyridine nitrogen atoms. One asymmetrically coordinated chelate, NO3–, and two MeOH molecules complete the pentagonal-bipyramidal geometry around FeII in 1. On the basis of analytical, spectroscopic (IR, Mossbauer) and magnetic susceptibility data from polycrystalline samples of 2, an oxido-bridged diferric structure is proposed [ΔEQ(78 K) = 1.79 mm s–1, JFe–Fe = –117 cm–1]. The Mossbauer spectra of the polycrystalline samples of 1 and 3 are consistent with high-spin and low-spin FeII, respectively, in anN/O coordination environment. Variable-temperature and variable-field magnetic measurements of 1 suggest significant zero-field splitting of the ferrous ions (D = 5.5 cm–1).(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
-
Aerobic FeIII–FeII Reduction in the Presence of 2,4,6-Tri(2-pyridyl)-1,3,5-triazine and Benzilic Acid: Synthesis and Characterization of a Heptacoordinate FeII–Nitrato Complex
European Journal of Inorganic Chemistry, 2008Co-Authors: Catherine P. Raptopoulou, Yiannis Sanakis, Athanassios K. BoudalisAbstract:The simultaneous presence of Benzilic Acid [Ph2C(OH)CO2H] and tptz [2,4,6-tri(2-pyridyl)-1,3,5-triazine] in FeIII-containing reaction mixtures leads to partial and/or quantitative metal reduction. In the presence of the oxidative NO3– ions in the reaction mixture, partial reduction of the metal leads to the isolation of a heptacoordinate FeII–nitrato complex, [FeII(tptz)(NO3)(MeOH)2](NO3) (1), along with a FeIII complex (2). In the presence of perchlorate ions in the reaction mixture, the quantitative reduction of FeIII leads to the isolation of a hexacoordinate FeII complex, [FeII(tptzH)2](ClO4)4 (3). Complexes 1 and 3 have been structurally characterized and possess a pentagonal-bipyramidal and a distorted octahedral coordination geometry, respectively. In both complexes, tptz behaves as a tridentate ligand, adopting the terpy-like coordination mode, and is coordinated through the triazine nitrogen atom and the two adjacent pyridine nitrogen atoms. One asymmetrically coordinated chelate, NO3–, and two MeOH molecules complete the pentagonal-bipyramidal geometry around FeII in 1. On the basis of analytical, spectroscopic (IR, Mossbauer) and magnetic susceptibility data from polycrystalline samples of 2, an oxido-bridged diferric structure is proposed [ΔEQ(78 K) = 1.79 mm s–1, JFe–Fe = –117 cm–1]. The Mossbauer spectra of the polycrystalline samples of 1 and 3 are consistent with high-spin and low-spin FeII, respectively, in anN/O coordination environment. Variable-temperature and variable-field magnetic measurements of 1 suggest significant zero-field splitting of the ferrous ions (D = 5.5 cm–1).(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Gayle K. Schulte - One of the best experts on this subject based on the ideXlab platform.
-
Synthesis and characterization of pyrrolinone carboxylates formed by reaction of vicinal tricarbonyl derivatives with aldehyde Schiff bases
HETEROCYCLES, 1993Co-Authors: Harry H. Wasserman, David S. Ennis, Gayle K. Schulte, Morton E. Munk, Mark S. Madison, Kolandai V. VelusamyAbstract:A series of vicinal trcarbonyl derivatives undergo reaction with aldehyde Schiff bases forming pyrrolinone derivatives by Benzilic Acid-related rearrangements. The structures were established by X-ray analyses and, independently by the SESAMI NMR-based computer program
-
Benzilic Acid rearrangements in the reactions of aryl vicinal tricarbonyl derivatives with aldehyde Schiff bases
Tetrahedron Letters, 1991Co-Authors: Harry H. Wasserman, David S. Ennis, Gayle K. SchulteAbstract:Abstract Reactions of aryl and hetero vicinal tricarbonyl derivatives with aldehyde Schiff bases of the general structure RCH2CHO lead to pyrrolinone derivatives by Benzilic Acid-related rearrangements, driven, most probably, by iminium ion intermediates.
Hitoshi Takeshita - One of the best experts on this subject based on the ideXlab platform.
-
synthetic photochemistry lxvii a total synthesis of hinesol and agarospirol via retro Benzilic Acid rearrangement
Bulletin of the Chemical Society of Japan, 1995Co-Authors: Toshihide Hatsui, Jinjun Wang, Hitoshi TakeshitaAbstract:A mild base-catalyzed retro-Benzilic Acid rearrangement of a proto-photocycloadduct, formed in highly stereoselective photoaddition of methyl 2,4-dioxopentanoate to 1,5-dimethyl-6-methylene-1-cyclohexene, afforded a spiro[4.5]decenedione derivative. Reductive elimination of the α-dicarbonyl function and C1-homologation furnished (±)-hinesol and (±)-agarospirol.
-
synthetic photochemistry lxiv mild base induced retro Benzilic Acid rearrangement of isolated proto photocycloadducts of methyl 2 4 dioxopentanoate to terpinolene facile synthesis of α chamigrene and α chamigren 3 one
Bulletin of the Chemical Society of Japan, 1994Co-Authors: Toshihide Hatsui, Jinjun Wang, Hitoshi TakeshitaAbstract:In the photoaddition reaction of terpinolene with methyl 2,4-dioxopentanoate, the products derived from the tetrasubstituted C=C were four proto-[2+2] photocycloadducts, together with ene reaction products. When these proto-cycloadducts were treated with aqueous sodium carbonate, a facile retro-Benzilic Acid rearrangement to form substituted cyclopentenone derivatives occurred. The product from the other trisubstituted C=C was an ordinary retro-aldol product of the [2+2] cycloadduct and an ene reaction product. One of the proto-photocycloadducts was transformed into α-chamigren-3-one and further to α-chamigrene.
-
one pot formation of functionalized cyclopentenone derivatives via retro Benzilic Acid rearrangement of the proto photocycloadducts of methyl 2 4 dioxopentanoate to methylenecycloalkanes
Chemistry Letters, 1992Co-Authors: Toshihide Hatsui, Shinya Ikeda, Hitoshi TakeshitaAbstract:The proto-Photocycloadducts of methyl 2,4-dioxopentanoate to several methylenecycloalkanes and -alkenes spontaneously caused retro-Benzilic Acid rearrangement, exclusively. The reaction proceeded quite cleanly, and a simple work-up without chromatographic separation allowed to isolate the products directly in very good material balance.
Kazuo Nagasawa - One of the best experts on this subject based on the ideXlab platform.
-
Enantioselective Total Synthesis of (+)-Stephadiamine through Bioinspired Aza-Benzilic Acid Type Rearrangement.
Journal of the American Chemical Society, 2021Co-Authors: Minami Odagi, Taisei Matoba, Keisuke Hosoya, Kazuo NagasawaAbstract:We report the first enantioselective total syntheses of the hasubanan alkaloid (-)-metaphanine and the norhasubanan alkaloid (+)-stephadiamine. Key features of these syntheses include diastereoselective oxidative phenolic coupling reaction and subsequent regioselective intramolecular aza-Michael reaction, which efficiently construct the hasubanan skeleton with the all-carbon quaternary stereogenic center at C13. Based on our hypothesis regarding the biosynthetic pathway of (+)-stephadiamine, we found that (-)-metaphanine is easily converted to (+)-stephadiamine via aza-Benzilic Acid type rearrangement reaction.
-
enantioselective total synthesis of stephadiamine through bioinspired aza Benzilic Acid type rearrangement
Journal of the American Chemical Society, 2021Co-Authors: Minami Odagi, Taisei Matoba, Keisuke Hosoya, Kazuo NagasawaAbstract:We report the first enantioselective total syntheses of the hasubanan alkaloid (-)-metaphanine and the norhasubanan alkaloid (+)-stephadiamine. Key features of these syntheses include diastereoselective oxidative phenolic coupling reaction and subsequent regioselective intramolecular aza-Michael reaction, which efficiently construct the hasubanan skeleton with the all-carbon quaternary stereogenic center at C13. Based on our hypothesis regarding the biosynthetic pathway of (+)-stephadiamine, we found that (-)-metaphanine is easily converted to (+)-stephadiamine via aza-Benzilic Acid type rearrangement reaction.
Catherine P. Raptopoulou - One of the best experts on this subject based on the ideXlab platform.
-
aerobic feiii feii reduction in the presence of 2 4 6 tri 2 pyridyl 1 3 5 triazine and Benzilic Acid synthesis and characterization of a heptacoordinate feii nitrato complex
European Journal of Inorganic Chemistry, 2008Co-Authors: Catherine P. Raptopoulou, Yiannis Sanakis, Athanassios K. BoudalisAbstract:The simultaneous presence of Benzilic Acid [Ph2C(OH)CO2H] and tptz [2,4,6-tri(2-pyridyl)-1,3,5-triazine] in FeIII-containing reaction mixtures leads to partial and/or quantitative metal reduction. In the presence of the oxidative NO3– ions in the reaction mixture, partial reduction of the metal leads to the isolation of a heptacoordinate FeII–nitrato complex, [FeII(tptz)(NO3)(MeOH)2](NO3) (1), along with a FeIII complex (2). In the presence of perchlorate ions in the reaction mixture, the quantitative reduction of FeIII leads to the isolation of a hexacoordinate FeII complex, [FeII(tptzH)2](ClO4)4 (3). Complexes 1 and 3 have been structurally characterized and possess a pentagonal-bipyramidal and a distorted octahedral coordination geometry, respectively. In both complexes, tptz behaves as a tridentate ligand, adopting the terpy-like coordination mode, and is coordinated through the triazine nitrogen atom and the two adjacent pyridine nitrogen atoms. One asymmetrically coordinated chelate, NO3–, and two MeOH molecules complete the pentagonal-bipyramidal geometry around FeII in 1. On the basis of analytical, spectroscopic (IR, Mossbauer) and magnetic susceptibility data from polycrystalline samples of 2, an oxido-bridged diferric structure is proposed [ΔEQ(78 K) = 1.79 mm s–1, JFe–Fe = –117 cm–1]. The Mossbauer spectra of the polycrystalline samples of 1 and 3 are consistent with high-spin and low-spin FeII, respectively, in anN/O coordination environment. Variable-temperature and variable-field magnetic measurements of 1 suggest significant zero-field splitting of the ferrous ions (D = 5.5 cm–1).(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
-
Aerobic FeIII–FeII Reduction in the Presence of 2,4,6-Tri(2-pyridyl)-1,3,5-triazine and Benzilic Acid: Synthesis and Characterization of a Heptacoordinate FeII–Nitrato Complex
European Journal of Inorganic Chemistry, 2008Co-Authors: Catherine P. Raptopoulou, Yiannis Sanakis, Athanassios K. BoudalisAbstract:The simultaneous presence of Benzilic Acid [Ph2C(OH)CO2H] and tptz [2,4,6-tri(2-pyridyl)-1,3,5-triazine] in FeIII-containing reaction mixtures leads to partial and/or quantitative metal reduction. In the presence of the oxidative NO3– ions in the reaction mixture, partial reduction of the metal leads to the isolation of a heptacoordinate FeII–nitrato complex, [FeII(tptz)(NO3)(MeOH)2](NO3) (1), along with a FeIII complex (2). In the presence of perchlorate ions in the reaction mixture, the quantitative reduction of FeIII leads to the isolation of a hexacoordinate FeII complex, [FeII(tptzH)2](ClO4)4 (3). Complexes 1 and 3 have been structurally characterized and possess a pentagonal-bipyramidal and a distorted octahedral coordination geometry, respectively. In both complexes, tptz behaves as a tridentate ligand, adopting the terpy-like coordination mode, and is coordinated through the triazine nitrogen atom and the two adjacent pyridine nitrogen atoms. One asymmetrically coordinated chelate, NO3–, and two MeOH molecules complete the pentagonal-bipyramidal geometry around FeII in 1. On the basis of analytical, spectroscopic (IR, Mossbauer) and magnetic susceptibility data from polycrystalline samples of 2, an oxido-bridged diferric structure is proposed [ΔEQ(78 K) = 1.79 mm s–1, JFe–Fe = –117 cm–1]. The Mossbauer spectra of the polycrystalline samples of 1 and 3 are consistent with high-spin and low-spin FeII, respectively, in anN/O coordination environment. Variable-temperature and variable-field magnetic measurements of 1 suggest significant zero-field splitting of the ferrous ions (D = 5.5 cm–1).(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)