The Experts below are selected from a list of 267 Experts worldwide ranked by ideXlab platform
Jinao Duan - One of the best experts on this subject based on the ideXlab platform.
-
13C NMR Data of three important diterpenes isolated from euphorbia species
Molecules, 2009Co-Authors: Qicheng Wu, Yuping Tang, Anwei Ding, Li Zhang, Jinao DuanAbstract:Euphorbia species are widely distributed plants, many of which are used in folk medicine. Over the past twenty years, they have received considerable phytochemical and biological attention. Their diterpenoid constituents, especially those with abietane, tigliane, ingenane skeletons, are thought to be the main toxicant and bioactive factors. In this work, the utility of 13C-NMR spectroscopy for the structural elucidation of these compounds is briefly discussed.
A Van Veldhuizen - One of the best experts on this subject based on the ideXlab platform.
-
NMR studies on σ adducts of heterocyclic systems with nucleophiles part viii 13C NMR Data of pyridazines and some of their covalent amination products
Recueil des Travaux Chimiques des Pays-Bas, 2010Co-Authors: D E Klinge, H C Van Der Plas, A Van VeldhuizenAbstract:13C-NMR Data of several 3-mono- and 3,6-di-substituted pyridazines, 3-, 4- and 6-mono- and 3,6-di-substituted pyridazine 1-oxides and 4-nitro-3,6-disubstituted pyridazine 1-oxides are reported. 13C substituent effects of some substituents in the 3-, 4- and 6-position of the pyridazine ring and that of the N-oxide function are calculated. The 13C-NMR spectra of the σ-adducts of 4-nitro-3,6-disubstituted pyridazine 1-oxides with liquid ammonia are described.
-
NMR studies on σ‐adducts of heterocyclic systems with nucleophiles (Part VIII) 13C‐NMR Data of pyridazines and some of their covalent amination products
Recueil des Travaux Chimiques des Pays-Bas, 2010Co-Authors: D E Klinge, H C Van Der Plas, A Van VeldhuizenAbstract:13C-NMR Data of several 3-mono- and 3,6-di-substituted pyridazines, 3-, 4- and 6-mono- and 3,6-di-substituted pyridazine 1-oxides and 4-nitro-3,6-disubstituted pyridazine 1-oxides are reported. 13C substituent effects of some substituents in the 3-, 4- and 6-position of the pyridazine ring and that of the N-oxide function are calculated. The 13C-NMR spectra of the σ-adducts of 4-nitro-3,6-disubstituted pyridazine 1-oxides with liquid ammonia are described.
James E Thomson - One of the best experts on this subject based on the ideXlab platform.
-
the hancock alkaloids cuspareine galipinine galipeine and angustureine asymmetric syntheses and corrected 1h and 13C NMR Data
Journal of Natural Products, 2018Co-Authors: Stephen G Davies, Ai M Fletcher, Ian T T Houlsby, Paul M Roberts, James E Thomson, David ZimmerAbstract:The asymmetric syntheses of all members of the Hancock alkaloid family based upon a 2-substituted N-methyl-1,2,3,4-tetrahydroquinoline core are delineated. The conjugate addition of enantiopure lithium N-benzyl-N-(α-methyl-p-methoxybenzyl)amide to 5-(o-bromophenyl)-N-methoxy-N-methylpent-2-enamide is used to generate the requisite C-2 stereogenic center of the targets, while an intramolecular Buchwald–Hartwig coupling is used to form the 1,2,3,4-tetrahydroquinoline ring. Late-stage diversification completes construction of the C-2 side chains. Thus, (−)-cuspareine, (−)-galipinine, (−)-galipeine, and (−)-angustureine were prepared in overall yields of 30%, 28%, 15%, and 39%, respectively, in nine steps from commercially available 3-(o-bromophenyl)propanoic acid in all cases. Unambiguously corrected 1H and 13C NMR Data for the originally isolated samples of (−)-cuspareine, (−)-galipinine, and (−)-angustureine are also reported, representing a valuable reference resource for these popular synthetic targets.
-
The Hancock Alkaloids (−)-Cuspareine, (−)-Galipinine, (−)-Galipeine, and (−)-Angustureine: Asymmetric Syntheses and Corrected 1H and 13C NMR Data
Journal of Natural Products, 2018Co-Authors: Stephen G Davies, Ai M Fletcher, Ian T T Houlsby, Paul M Roberts, James E Thomson, David ZimmerAbstract:The asymmetric syntheses of all members of the Hancock alkaloid family based upon a 2-substituted N-methyl-1,2,3,4-tetrahydroquinoline core are delineated. The conjugate addition of enantiopure lithium N-benzyl-N-(α-methyl-p-methoxybenzyl)amide to 5-(o-bromophenyl)-N-methoxy-N-methylpent-2-enamide is used to generate the requisite C-2 stereogenic center of the targets, while an intramolecular Buchwald–Hartwig coupling is used to form the 1,2,3,4-tetrahydroquinoline ring. Late-stage diversification completes construction of the C-2 side chains. Thus, (−)-cuspareine, (−)-galipinine, (−)-galipeine, and (−)-angustureine were prepared in overall yields of 30%, 28%, 15%, and 39%, respectively, in nine steps from commercially available 3-(o-bromophenyl)propanoic acid in all cases. Unambiguously corrected 1H and 13C NMR Data for the originally isolated samples of (−)-cuspareine, (−)-galipinine, and (−)-angustureine are also reported, representing a valuable reference resource for these popular synthetic targets.
-
Structural Revision of the Hancock Alkaloid (−)-Galipeine
Journal of Organic Chemistry, 2017Co-Authors: Stephen G Davies, Ai M Fletcher, Ian T T Houlsby, Paul M Roberts, James E ThomsonAbstract:The 1H and 13C NMR Data of synthetic samples of (S)-N(1)-methyl-2-[2′-(3″-hydroxy-4″-methoxyphenyl)ethyl]-1,2,3,4-tetrahydroquinoline, the originally proposed structure of the Hancock alkaloid (−)-galipeine, do not match those of the natural product. Herein, the preparation of the regioisomer (S)-N(1)-methyl-2-[2′-(3″-methoxy-4″-hydroxyphenyl)ethyl]-1,2,3,4-tetrahydroquinoline is reported, the 1H and 13C NMR Data of which are in excellent agreement with those of (−)-galipeine. Comparison of specific rotation Data enables assignment of the absolute (S)-configuration of the alkaloid, and together, these Data engender the structural revision of (−)-galipeine to (S)-N(1)-methyl-2-[2′-(3″-methoxy-4″-hydroxyphenyl)ethyl]-1,2,3,4-tetrahydroquinoline.
Stephen G Davies - One of the best experts on this subject based on the ideXlab platform.
-
the hancock alkaloids cuspareine galipinine galipeine and angustureine asymmetric syntheses and corrected 1h and 13C NMR Data
Journal of Natural Products, 2018Co-Authors: Stephen G Davies, Ai M Fletcher, Ian T T Houlsby, Paul M Roberts, James E Thomson, David ZimmerAbstract:The asymmetric syntheses of all members of the Hancock alkaloid family based upon a 2-substituted N-methyl-1,2,3,4-tetrahydroquinoline core are delineated. The conjugate addition of enantiopure lithium N-benzyl-N-(α-methyl-p-methoxybenzyl)amide to 5-(o-bromophenyl)-N-methoxy-N-methylpent-2-enamide is used to generate the requisite C-2 stereogenic center of the targets, while an intramolecular Buchwald–Hartwig coupling is used to form the 1,2,3,4-tetrahydroquinoline ring. Late-stage diversification completes construction of the C-2 side chains. Thus, (−)-cuspareine, (−)-galipinine, (−)-galipeine, and (−)-angustureine were prepared in overall yields of 30%, 28%, 15%, and 39%, respectively, in nine steps from commercially available 3-(o-bromophenyl)propanoic acid in all cases. Unambiguously corrected 1H and 13C NMR Data for the originally isolated samples of (−)-cuspareine, (−)-galipinine, and (−)-angustureine are also reported, representing a valuable reference resource for these popular synthetic targets.
-
The Hancock Alkaloids (−)-Cuspareine, (−)-Galipinine, (−)-Galipeine, and (−)-Angustureine: Asymmetric Syntheses and Corrected 1H and 13C NMR Data
Journal of Natural Products, 2018Co-Authors: Stephen G Davies, Ai M Fletcher, Ian T T Houlsby, Paul M Roberts, James E Thomson, David ZimmerAbstract:The asymmetric syntheses of all members of the Hancock alkaloid family based upon a 2-substituted N-methyl-1,2,3,4-tetrahydroquinoline core are delineated. The conjugate addition of enantiopure lithium N-benzyl-N-(α-methyl-p-methoxybenzyl)amide to 5-(o-bromophenyl)-N-methoxy-N-methylpent-2-enamide is used to generate the requisite C-2 stereogenic center of the targets, while an intramolecular Buchwald–Hartwig coupling is used to form the 1,2,3,4-tetrahydroquinoline ring. Late-stage diversification completes construction of the C-2 side chains. Thus, (−)-cuspareine, (−)-galipinine, (−)-galipeine, and (−)-angustureine were prepared in overall yields of 30%, 28%, 15%, and 39%, respectively, in nine steps from commercially available 3-(o-bromophenyl)propanoic acid in all cases. Unambiguously corrected 1H and 13C NMR Data for the originally isolated samples of (−)-cuspareine, (−)-galipinine, and (−)-angustureine are also reported, representing a valuable reference resource for these popular synthetic targets.
-
Structural Revision of the Hancock Alkaloid (−)-Galipeine
Journal of Organic Chemistry, 2017Co-Authors: Stephen G Davies, Ai M Fletcher, Ian T T Houlsby, Paul M Roberts, James E ThomsonAbstract:The 1H and 13C NMR Data of synthetic samples of (S)-N(1)-methyl-2-[2′-(3″-hydroxy-4″-methoxyphenyl)ethyl]-1,2,3,4-tetrahydroquinoline, the originally proposed structure of the Hancock alkaloid (−)-galipeine, do not match those of the natural product. Herein, the preparation of the regioisomer (S)-N(1)-methyl-2-[2′-(3″-methoxy-4″-hydroxyphenyl)ethyl]-1,2,3,4-tetrahydroquinoline is reported, the 1H and 13C NMR Data of which are in excellent agreement with those of (−)-galipeine. Comparison of specific rotation Data enables assignment of the absolute (S)-configuration of the alkaloid, and together, these Data engender the structural revision of (−)-galipeine to (S)-N(1)-methyl-2-[2′-(3″-methoxy-4″-hydroxyphenyl)ethyl]-1,2,3,4-tetrahydroquinoline.
Qicheng Wu - One of the best experts on this subject based on the ideXlab platform.
-
13C NMR Data of three important diterpenes isolated from euphorbia species
Molecules, 2009Co-Authors: Qicheng Wu, Yuping Tang, Anwei Ding, Li Zhang, Jinao DuanAbstract:Euphorbia species are widely distributed plants, many of which are used in folk medicine. Over the past twenty years, they have received considerable phytochemical and biological attention. Their diterpenoid constituents, especially those with abietane, tigliane, ingenane skeletons, are thought to be the main toxicant and bioactive factors. In this work, the utility of 13C-NMR spectroscopy for the structural elucidation of these compounds is briefly discussed.
