The Experts below are selected from a list of 57 Experts worldwide ranked by ideXlab platform
Rodney A Fernandes - One of the best experts on this subject based on the ideXlab platform.
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total synthesis of the sensitive triyne natural product 4s 5s 4 8 dihydroxy 3 4 dihydrovernoniyne and all of its stereoisomers
Organic Letters, 2019Co-Authors: Gujjula V Ramakrishna, Rodney A FernandesAbstract:An efficient total synthesis of the revised structure of the sensitive triyne natural product, (4S,5S)-4,8-dihydroxy-3,4-dihydrovernoniyne, and all of its stereoisomers, that is, the previously proposed (4S,5R), (4R,5R), and (4R,5S), has been accomplished from chiral pool compounds l-mannonic-γ-lactone and d-glucono-δ-lactone. The key features involve a one-pot conversion of the chiral pool compounds into the γ-vinyl-β-hydroxy-γ-lactones, the heteroatom-directed Wacker oxidation, the Seyferth-Gilbert reaction, and Cadiot-Chodkiewicz Coupling. The synthesis also involves minimal protecting groups (only tert-butyldimethylsilyl) and is completed in seven to eight steps.
Gujjula V Ramakrishna - One of the best experts on this subject based on the ideXlab platform.
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total synthesis of the sensitive triyne natural product 4s 5s 4 8 dihydroxy 3 4 dihydrovernoniyne and all of its stereoisomers
Organic Letters, 2019Co-Authors: Gujjula V Ramakrishna, Rodney A FernandesAbstract:An efficient total synthesis of the revised structure of the sensitive triyne natural product, (4S,5S)-4,8-dihydroxy-3,4-dihydrovernoniyne, and all of its stereoisomers, that is, the previously proposed (4S,5R), (4R,5R), and (4R,5S), has been accomplished from chiral pool compounds l-mannonic-γ-lactone and d-glucono-δ-lactone. The key features involve a one-pot conversion of the chiral pool compounds into the γ-vinyl-β-hydroxy-γ-lactones, the heteroatom-directed Wacker oxidation, the Seyferth-Gilbert reaction, and Cadiot-Chodkiewicz Coupling. The synthesis also involves minimal protecting groups (only tert-butyldimethylsilyl) and is completed in seven to eight steps.
Ra Fernandes - One of the best experts on this subject based on the ideXlab platform.
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Total Synthesis of the Sensitive Triyne Natural Product (4S,5S)-4,8-Dihydroxy-3,4-dihydrovernoniyne and All of Its Stereoisomers
AMER CHEMICAL SOC, 2019Co-Authors: Gv Ramakrishna, Ra FernandesAbstract:An efficient total synthesis of the revised structure of the sensitive triyne natural product, (4S,5S)-4,8-dihydroxy-3,4-dihydrovernoniyne, and all of its stereoisomers, that is, the previously proposed (4S,5R), (4R,5R), and (4R,5S), has been accomplished from chiral pool compounds L-mannonic-gamma-lactone and D-glucono-delta-lactone. The key features involve a one-pot conversion of the chiral pool compounds into the gamma-vinyl-beta-hydroxy-gamma-lactones, the heteroatom-directed Wacker oxidation, the Seyferth-Gilbert reaction, and Cadiot-Chodkiewicz Coupling. The synthesis also involves minimal protecting groups (only tert-butyldimethylsilyl) and is completed in seven to eight steps
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A Catalytic Asymmetric Protecting-Group-Free Total Synthesis of (4S,5S)-4,8-Dihydroxy-3,4-dihydrovernoniyne and Its Enantiomer
AMER CHEMICAL SOC, 2019Co-Authors: Gv Ramakrishna, Ra FernandesAbstract:A catalytic asymmetric second generation synthesis of (4S,5S)-4,8-dihydroxy-3,4-dihydrovernoniyne has been completed employing the asymmetric dihydroxylation strategy. Further, a four-step protecting-group-free synthesis of the natural product and its enantiomer has been achieved through the modified Knoevenagel reaction, asymmetric dihydroxylation, and Cadiot-Chodkiewicz Coupling. The protecting-group-free synthesis is completed in four steps and 41% overall yield
Gv Ramakrishna - One of the best experts on this subject based on the ideXlab platform.
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Total Synthesis of the Sensitive Triyne Natural Product (4S,5S)-4,8-Dihydroxy-3,4-dihydrovernoniyne and All of Its Stereoisomers
AMER CHEMICAL SOC, 2019Co-Authors: Gv Ramakrishna, Ra FernandesAbstract:An efficient total synthesis of the revised structure of the sensitive triyne natural product, (4S,5S)-4,8-dihydroxy-3,4-dihydrovernoniyne, and all of its stereoisomers, that is, the previously proposed (4S,5R), (4R,5R), and (4R,5S), has been accomplished from chiral pool compounds L-mannonic-gamma-lactone and D-glucono-delta-lactone. The key features involve a one-pot conversion of the chiral pool compounds into the gamma-vinyl-beta-hydroxy-gamma-lactones, the heteroatom-directed Wacker oxidation, the Seyferth-Gilbert reaction, and Cadiot-Chodkiewicz Coupling. The synthesis also involves minimal protecting groups (only tert-butyldimethylsilyl) and is completed in seven to eight steps
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A Catalytic Asymmetric Protecting-Group-Free Total Synthesis of (4S,5S)-4,8-Dihydroxy-3,4-dihydrovernoniyne and Its Enantiomer
AMER CHEMICAL SOC, 2019Co-Authors: Gv Ramakrishna, Ra FernandesAbstract:A catalytic asymmetric second generation synthesis of (4S,5S)-4,8-dihydroxy-3,4-dihydrovernoniyne has been completed employing the asymmetric dihydroxylation strategy. Further, a four-step protecting-group-free synthesis of the natural product and its enantiomer has been achieved through the modified Knoevenagel reaction, asymmetric dihydroxylation, and Cadiot-Chodkiewicz Coupling. The protecting-group-free synthesis is completed in four steps and 41% overall yield
Mayor Marcel - One of the best experts on this subject based on the ideXlab platform.
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Shape-persistent macrocycles comprising perfluorinated benzene subunits : synthesis, aggregation behaviour and unexpected mu-rod formation
'Royal Society of Chemistry (RSC)', 2009Co-Authors: Shu Lijin, Mueri Marcel, Krupke Ralph, Mayor MarcelAbstract:The synthesis of a series of shape-persistent macrocycles (SPMs) (1-4 and 6) comprising different numbers and/or spatial arrangement of meta-substituted tetrafluorobenzene and benzene subunits interlinked with diacetylenes is described. To increase their solubility, all five SPMs were functionalized by four peripheral hexyl chains. These SPMs were assembled from common diacetylene building blocks by a modular synthetic strategy based on palladium and/or copper catalyzed versions of acetylene Coupling reactions (oxidative acetylene Coupling and Cadiot-Chodkiewicz Coupling). The aggregation properties in chloroform of SPMs 1-6 were investigated by concentration-and temperature-dependent H-1-NMR investigations and by vapour pressure osmometry studies. Aggregation constants and thermodynamic data of the process were obtained by least-squares fitting of the NMR data and by van`t Hoff analysis respectively. Aggregation was only observed for SPMs 2-6 comprising electron deficient tetrafluorobenzene corner units. While dimerization was the major aggregation process for SPMs 3-6, the formation of larger aggregates in solution was only observed for SPM 2. The formation of aggregates is in all cases enthalpically driven. As the largest and the smallest enthalpic contribution and entropic loss in the series of aggregating SPMs were found for the two SPMs 3 and 4, each comprising two fluorinated corner units, the spatial arrangement of these subunits within the macrocycle seems to be at least equally important as the ratio of tetrafluorobenzene and benzene moieties. Interestingly, micro-scaled hexagonal rods were formed from SPM 3 upon heating in toluene, presumably consisting of mixtures of oligomers arising from covalently interlinked macrocycles
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Shape-persistent macrocycles comprising perfluorinated benzene subunits: synthesis, aggregation behaviour and unexpected μ-rod formation
'Royal Society of Chemistry (RSC)', 2009Co-Authors: Shu Lijin, Krupke Ralph, Müri Marcel, Mayor MarcelAbstract:The synthesis of a series of shape-persistent macrocycles (SPMs) (1–4 and 6) comprising different numbers and/or spatial arrangement of meta-substituted tetrafluorobenzene and benzene subunits interlinked with diacetylenes is described. To increase their solubility, all five SPMs were functionalized by four peripheral hexyl chains. These SPMs were assembled from common diacetylene building blocks by a modular synthetic strategy based on palladium and/or copper catalyzed versions of acetylene Coupling reactions (oxidative acetylene Coupling and Cadiot–Chodkiewicz Coupling). The aggregation properties in chloroform of SPMs 1–6 were investigated by concentration- and temperature-dependent 1H-NMR investigations and by vapour pressure osmometry studies. Aggregation constants and thermodynamic data of the process were obtained by least-squares fitting of the NMR data and by van't Hoff analysis respectively. Aggregation was only observed for SPMs 2–6 comprising electron deficient tetrafluorobenzene corner units. While dimerization was the major aggregation process for SPMs 3–6, the formation of larger aggregates in solution was only observed for SPM 2. The formation of aggregates is in all cases enthalpically driven. As the largest and the smallest enthalpic contribution and entropic loss in the series of aggregating SPMs were found for the two SPMs 3 and 4, each comprising two fluorinated corner units, the spatial arrangement of these subunits within the macrocycle seems to be at least equally important as the ratio of tetrafluorobenzene and benzene moieties. Interestingly, micro-scaled hexagonal rods were formed from SPM 3 upon heating in toluene, presumably consisting of mixtures of oligomers arising from covalently interlinked macrocycles
