The Experts below are selected from a list of 15123 Experts worldwide ranked by ideXlab platform
Hans-joachim Knölker - One of the best experts on this subject based on the ideXlab platform.
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first total synthesis of the cytotoxic Carbazole alkaloid excavatine a and regioselective annulation to pyrano 2 3 a Carbazoles and 1 4 oxazepino 2 3 4 jk Carbazoles
European Journal of Organic Chemistry, 2017Co-Authors: Christian Brütting, Arndt W. Schmidt, Olga Kataeva, Hans-joachim KnölkerAbstract:We describe the first total synthesis of the cytotoxic Carbazole alkaloid excavatine-A (1). The Carbazole framework was constructed via double C-H bond activation of a diarylamine using our palladium(II)-catalyzed oxidative cyclization. Treatment of the intermediate 8-hydroxyCarbazoles 8 with prenal (7) and different additives led either to the pyrano[2,3-a]Carbazoles 6 or the [1,4]oxazepino[2,3,4-jk]Carbazoles 15. The pyran annulation was investigated to determine the influence of substitution pattern, additives, and reaction time on the selectivity.
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synthesis of prenyl and geranyl substituted Carbazole alkaloids by dibal h promoted reductive pyran ring opening of dialkylpyrano 3 2 a Carbazoles
Chemistry: A European Journal, 2014Co-Authors: Ronny Hesse, Arndt W. Schmidt, Olga Kataeva, Hans-joachim KnölkerAbstract:The DIBAL-H promoted reductive pyran ring opening of dialkylpyrano[3,2-a]Carbazoles provides a direct access to a broad range of prenyl- and geranyl-substituted Carbazoles. Formation of a pyran ring followed by reductive ring opening represents a new method for the introduction of prenyl and geranyl groups. In the course of the present work, we achieved the first total syntheses of the following eight Carbazole alkaloids: clauraila-E, 7-hydroxyheptaphylline, 7-methoxyheptaphylline, mukoenine-B (clausenatine-A), mukoenine-A (girinimbilol), mahanimbinol (mahanimbilol), euchrestine-A, and isomurrayafoline-B.
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Synthesis of Pyrrole and Carbazole Alkaloids
Topics in current chemistry, 2011Co-Authors: Ingmar Bauer, Hans-joachim KnölkerAbstract:An overview of recent transition metal-catalyzed syntheses of pyrroles and Carbazoles is presented. The focus is on methods which have been applied to the preparation of biologically active naturally occurring pyrrole and Carbazole alkaloids. For pyrroles, special attention is paid to silver(I)-catalyzed cyclization reactions. For Carbazoles, iron(0)-mediated and palladium(0/II)-catalyzed cyclization reactions are highlighted and their broad range of applications is discussed.
Jun Yeob Lee - One of the best experts on this subject based on the ideXlab platform.
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molecular design featuring Carbazole decorated 15h diindolo 2 3 b 1 2 3 lm Carbazole for improved efficiency and lifetime of thermally activated delayed fluorescence emitters
Journal of Materials Chemistry C, 2020Co-Authors: Rajendra Kumar Konidena, Kyung Hyung Lee, Jun Yeob LeeAbstract:In this report, we developed a novel electron donor named 12-(9-phenyl-9H-carbazol-3-yl)-15H-diindolo[2,3-b:1′,2′,3′-lm]Carbazole (CzDICz) by introducing a Carbazole unit into the rigid 15H-diindolo[2,3-b:1′,2′,3′-lm]Carbazole (DICz) donor for designing a stable green thermally activated delayed fluorescence (TADF) emitter, 5-(4,6-diphenyl-1,3,5-triazin-2-yl)-2-(12-(9-phenyl-9H-carbazol-3-yl)-15H-diindolo[2,3-b:1′,2′,3′-lm]carbazol-15-yl)benzonitrile (CzDICzTrz). The effect of the additional Carbazole unit in the CzDICz donor on photophysical and electroluminescence properties was unveiled by comparing the CzDICzTrz with the control molecule viz. 2-(15H-diindolo[2,3-b:1′,2′,3′-lm]carbazol-15-yl)-5-(4,6-diphenyl-1,3,5-triazin-2-yl)benzonitrile (DICzTrz) featuring the DICz donor. Photophysical analysis revealed that the CzDICzTrz exhibited small singlet–triplet energy splitting, a short delayed fluorescence lifetime (td), fast reverse intersystem crossing (RISC) and high photoluminescence quantum efficiency compared to DICzTrz. Therefore, the organic light emitting diode fabricated with CzDICzTrz showed superior device performance with a maximum external quantum efficiency (EQE) of 19.9% and a current efficiency of 62.3 cd A−1 compared to its congener DICzTrz, which showed a maximum EQE of 12.9% and a current efficiency of 38.6 cd A−1. Moreover, CzDICzTrz based devices achieved 40 times extended operational lifetime up to 80% of its initial luminance (L0 = 1000 cd m−2) of 446 h compared to 11 h of DICzTrz due to its stable CzDICz donor, short td and fast RISC. We believe that the CzDICz donor can contribute to the development of efficient TADF emitters with long operational stability and uncompromised EQE.
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synthesis of novel benzothiophene derivative as a host material for blue phosphorescent organic light emitting diodes
Dyes and Pigments, 2017Co-Authors: Chohyun Seo, Jun Yeob Lee, Jeong Min Choi, Seongsoo Hong, Sungyong SeoAbstract:Abstract An organic compound having Carbazole, benzothiophene, and phosphine oxide moieties, (5-(9 H -carbazol-9-yl)benzo[ b ]thiophen-2-yl)diphenylphosphine oxide (CBTPO), was synthesized and employed as a blue host material to harvest triplet excitons from blue triplet emitters. The CBTPO material is a bipolar host material because it includes Carbazole and diphenylphosphine oxide charge transport units with both a high triplet energy of 2.76 eV and a high quantum efficiency of 19.1% in blue phosphorescent device.
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above 30 external quantum efficiency in green delayed fluorescent organic light emitting diodes
ACS Applied Materials & Interfaces, 2015Co-Authors: Dong Ryun Lee, Bo Seong Kim, Chil Won Lee, Kyoung Soo Yook, Seokho Hwang, Jun Yeob LeeAbstract:Highly efficient green thermally activated delayed fluorescent organic light-emitting diodes with an external quantum efficiency of 31.2% were investigated by using 3-(3-(Carbazole-9-yl)phenyl) pyrido[3′,2′:4,5]furo[2,3-b]pyridine (3CzPFP) derived from Carbazole and pyrido[3′,2′:4,5]furo[2,3-b]pyridine. The host material showed well-matched photoluminescence emission with absorption of the green dopant material, (4s,6s)-2,4,5,6-tetra(9H-carbazol-9-yl)isophthalonitrile (4CzIPN) and harvested all excitons of 4CzIPN. The 3CzPFP:4CzIPN film exhibited high photoluminescence quantum yield of 100%, and the green delayed fluorescence device employing the 3CzPFP host showed high maximum quantum efficiency of 31.2 ± 0.5% at 1% doping after optimization of the device structure.
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phosphine oxide type bipolar host material for high quantum efficiency in thermally activated delayed fluorescent device
ACS Applied Materials & Interfaces, 2014Co-Authors: Bo Seong Kim, Jun Yeob LeeAbstract:Highly efficient thermally activated delayed fluorescence devices were developed using a bipolar host material, 2,7-bis(diphenylphosphoryl)-9-phenyl-9H-Carbazole (PPO27), derived from Carbazole and diphenylphosphine oxide. The PPO27 host was effective for good charge balance and energy transfer from the PPO27 host to thermally activated delayed fluorescence dopant. The PPO27 device doped with (4s,6s)-2,4,5,6-tetra(9H-carbazol-9-yl)isophthalonitrile dopant could realize a high quantum efficiency of 24.2%.
Arndt W. Schmidt - One of the best experts on this subject based on the ideXlab platform.
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first total synthesis of the cytotoxic Carbazole alkaloid excavatine a and regioselective annulation to pyrano 2 3 a Carbazoles and 1 4 oxazepino 2 3 4 jk Carbazoles
European Journal of Organic Chemistry, 2017Co-Authors: Christian Brütting, Arndt W. Schmidt, Olga Kataeva, Hans-joachim KnölkerAbstract:We describe the first total synthesis of the cytotoxic Carbazole alkaloid excavatine-A (1). The Carbazole framework was constructed via double C-H bond activation of a diarylamine using our palladium(II)-catalyzed oxidative cyclization. Treatment of the intermediate 8-hydroxyCarbazoles 8 with prenal (7) and different additives led either to the pyrano[2,3-a]Carbazoles 6 or the [1,4]oxazepino[2,3,4-jk]Carbazoles 15. The pyran annulation was investigated to determine the influence of substitution pattern, additives, and reaction time on the selectivity.
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synthesis of prenyl and geranyl substituted Carbazole alkaloids by dibal h promoted reductive pyran ring opening of dialkylpyrano 3 2 a Carbazoles
Chemistry: A European Journal, 2014Co-Authors: Ronny Hesse, Arndt W. Schmidt, Olga Kataeva, Hans-joachim KnölkerAbstract:The DIBAL-H promoted reductive pyran ring opening of dialkylpyrano[3,2-a]Carbazoles provides a direct access to a broad range of prenyl- and geranyl-substituted Carbazoles. Formation of a pyran ring followed by reductive ring opening represents a new method for the introduction of prenyl and geranyl groups. In the course of the present work, we achieved the first total syntheses of the following eight Carbazole alkaloids: clauraila-E, 7-hydroxyheptaphylline, 7-methoxyheptaphylline, mukoenine-B (clausenatine-A), mukoenine-A (girinimbilol), mahanimbinol (mahanimbilol), euchrestine-A, and isomurrayafoline-B.
Olga Kataeva - One of the best experts on this subject based on the ideXlab platform.
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first total synthesis of the cytotoxic Carbazole alkaloid excavatine a and regioselective annulation to pyrano 2 3 a Carbazoles and 1 4 oxazepino 2 3 4 jk Carbazoles
European Journal of Organic Chemistry, 2017Co-Authors: Christian Brütting, Arndt W. Schmidt, Olga Kataeva, Hans-joachim KnölkerAbstract:We describe the first total synthesis of the cytotoxic Carbazole alkaloid excavatine-A (1). The Carbazole framework was constructed via double C-H bond activation of a diarylamine using our palladium(II)-catalyzed oxidative cyclization. Treatment of the intermediate 8-hydroxyCarbazoles 8 with prenal (7) and different additives led either to the pyrano[2,3-a]Carbazoles 6 or the [1,4]oxazepino[2,3,4-jk]Carbazoles 15. The pyran annulation was investigated to determine the influence of substitution pattern, additives, and reaction time on the selectivity.
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synthesis of prenyl and geranyl substituted Carbazole alkaloids by dibal h promoted reductive pyran ring opening of dialkylpyrano 3 2 a Carbazoles
Chemistry: A European Journal, 2014Co-Authors: Ronny Hesse, Arndt W. Schmidt, Olga Kataeva, Hans-joachim KnölkerAbstract:The DIBAL-H promoted reductive pyran ring opening of dialkylpyrano[3,2-a]Carbazoles provides a direct access to a broad range of prenyl- and geranyl-substituted Carbazoles. Formation of a pyran ring followed by reductive ring opening represents a new method for the introduction of prenyl and geranyl groups. In the course of the present work, we achieved the first total syntheses of the following eight Carbazole alkaloids: clauraila-E, 7-hydroxyheptaphylline, 7-methoxyheptaphylline, mukoenine-B (clausenatine-A), mukoenine-A (girinimbilol), mahanimbinol (mahanimbilol), euchrestine-A, and isomurrayafoline-B.
Christian Brütting - One of the best experts on this subject based on the ideXlab platform.
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first total synthesis of the cytotoxic Carbazole alkaloid excavatine a and regioselective annulation to pyrano 2 3 a Carbazoles and 1 4 oxazepino 2 3 4 jk Carbazoles
European Journal of Organic Chemistry, 2017Co-Authors: Christian Brütting, Arndt W. Schmidt, Olga Kataeva, Hans-joachim KnölkerAbstract:We describe the first total synthesis of the cytotoxic Carbazole alkaloid excavatine-A (1). The Carbazole framework was constructed via double C-H bond activation of a diarylamine using our palladium(II)-catalyzed oxidative cyclization. Treatment of the intermediate 8-hydroxyCarbazoles 8 with prenal (7) and different additives led either to the pyrano[2,3-a]Carbazoles 6 or the [1,4]oxazepino[2,3,4-jk]Carbazoles 15. The pyran annulation was investigated to determine the influence of substitution pattern, additives, and reaction time on the selectivity.
