Direct Identification of the Carbon Skeleton of Organic Compounds using Double Quantum Coherence <sup>13</sup>C‐NMR Spectroscopy. The INADEQUATE Pulse Sequence

Buddrus, Joachim; Bauer, Hugo

doi:10.1002/anie.198706251

Cited by 102 publications

(42 citation statements)

References 118 publications

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“…As indicated above, the evolution of the density operator during ⌬ f 3 s is negligible. As the read pulse is followed by a registration period, z ordering and two-spin coherence may be omitted in : They do not contribute to 5 observable magnetization. Thus, we obtain the observable density operator of an AX spin system at the beginning of the registration:…”

Section: D Inadequatementioning

confidence: 99%

Multipulse NMR Part III. INADEQUATE pulse sequence

Podkorytov

1999

Concepts Magn. Reson.

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Section: D Inadequatementioning

confidence: 99%

Multipulse NMR Part III. INADEQUATE pulse sequence

Podkorytov

1999

Concepts Magn. Reson.

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“…O INADEQUATE 2D quando aplicado a moléculas com abundância natural em 13 C normalmente exige centenas de mg de amostra 11 e o espectro obtido apresenta correlações C-C contínu-as, permitindo desenhar a estrutura de toda a cadeia carbônica. No entanto, quando moléculas duplamente marcadas são empregadas, obtêm-se espectros rapidamente com a utilização de poucos mg de material.…”

Section: Marcação Duplaunclassified

“…A brevetoxina B biossintetizada a partir de acetato [1,[2][3][4][5][6][7][8][9][10][11][12][13] Mais recentemente, estas técnicas de marcação foram empregadas na elucidação das rotas de vários outros metabólitos policetídicos complexos de dinoflagelados 15 .…”

Section: (Esquema 12)unclassified

Espectroscopia de Ressonância Magnética Nuclear de 13C no estudo de rotas biossintéticas de produtos naturais

Júnior

de²

2007

Quím. Nova

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Recebido em 2/9/05; aceito em 19/1/06; publicado na web em 30/8/06 13 C NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY IN THE STUDIES OF BIOSYTHETIC ROUTES OF NATURAL PRODUCTS. During the last five decades, as a result of an interaction between natural product chemistry, synthetic organic chemistry, molecular biology and spectroscopy, scientists reached an extraordinary level of comprehension about the natural processes by which living organisms build up complex molecules. In this context, 13 C nuclear magnetic resonance spectroscopy, allied with isotopic labeling, played a determinant role. Nowadays, the widespread use of modern NMR techniques allows an even more detailed picture of the biochemical steps by accurate manipulation of the atomic nuclei. This article focuses on the development of such techniques and their impact on biosynthetic studies.Keywords: 13 C NMR; isotopic labeling; biosynthetic routes. INTRODUÇÃOOs organismos vivos produzem miríades de compostos orgâni-cos cuja grande maioria parece não participar diretamente do seu crescimento e desenvolvimento. No entanto, a apreciação crescente dos diversos efeitos biológicos produzidos por estas substânci-as, tradicionalmente denominadas metabólitos secundários, tem incitado uma reavaliação dos seus possíveis papéis, especialmente no contexto de interações ecológicas.Além disso, o reconhecimento das propriedades biológicas de ampla variedade de produtos naturais, termo empregado como sinônimo de metabólitos secundários, tem alimentado uma busca intensa por novos fármacos, antibióticos, inseticidas e herbicidas.Por estes motivos, a química de produtos naturais foi alvo de intensas investigações durante as últimas décadas, resultando no desenvolvimento de teorias biossintéticas e em maior compreensão dos mecanismos de ação das enzimas. Estas descobertas tiveram um grande impacto sobre a imaginação dos químicos orgânicos, e a mimetização de processos bioorgânicos em laboratório levou a importantes avanços nos métodos sintéticos.Muitos destes desenvolvimentos não teriam sido possíveis sem a ação de brilhantes pesquisas sobre as rotas biossintéticas de metabólitos secundários, onde a marcação isotópica tem desempenhado um papel fundamental.As primeiras aplicações destes experimentos consistiam na incorporação de substratos enriquecidos em elementos radioativos, os radioisótopos. O produto natural marcado era destruído através de sequências de degradações complexas e seus fragmentos eram monitorados quanto à emissão de radiação.Neste contexto, o uso de isótopos estáveis, aliado à espectroscopia de Ressonância Magnética Nuclear (RMN), consistindo em um método rápido e não destrutivo, surgiu como uma ferramenta poderosa para elucidação de mecanismos bioquímicos.Durante as primeiras aplicações da RMN a problemas biossintéticos 1 , no final dos anos 60, o destino de precursores enriquecidos em 13 C era monitorado a partir dos aumentos nas intensidades dos sinais de 13 C-H satélites no espectro de RMN de 1 H. Este método 2 , entretanto, não fornece informações de carbon...

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“…Additional supporting data were obtained by the 2D-INADEQUATE test. 29,30 The INADEQUATE correlation peaks were determined at 3660 Hz (14 ppm methanol-water = 9:1. 31.9 ppm).…”

Section: Evaluation With Nmr Spectroscopymentioning

confidence: 99%

Conformational Effect of Silica-supported Poly(octadecyl acrylate) on Molecular-Shape Selectivity of Polycyclic Aromatic Hydrocarbons in RP-HPLC

et al. 2004

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Hydrophobized silicas, such as octadecylated silicas, are very useful as packing materials for reversed-phase high performance liquid chromatography, RP-HPLC. A simple modification of the mobile phase has expanded their applicability in analytical chemistry and separation technology. Similarly, a chemical modification of an organic phase on silica has provided versatility in the separation mode even in RP-HPLC. For these reasons, unique organic stationary phases have been created during the past decade. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] Fullerene C60 bonded silica 3,4 showed higher selectivity for calixarene isomers, fullerenes C60 and C70, and polycyclic aromatic hydrocarbons (PAHs). The stationary phases containing heavy atoms, such as sulfur, chlorine and bromine resulted in longer retentions of fullerenes. 2Various porphyrin-silica stationary phases, [6][7][8] alkyl diphenyl-silicas 1 and (2,4,6-tri-tertbutylphenoxy)dimethyl-silicas 5 exhibited extraordinary shape selectivity in the separation of PAHs and fullerenes. We have reported that polymer-grafted silica exhibited selective separation in HPLC. Polymers with trimethoxysilyl terminal groups were synthesized using the telomerization method and chemically-grafted on silica particles. A number of synthetic polymers, such as poly(styrene), 10 poly(acrylonitrile), 11 poly(methylacrylate), 9,12 poly(vinylpyridine) 16 and poly(Lalanine), 14,15 were used to develop the polymer-silica hybrid materials as a stationary phase of HPLC. On the other hand, we have proposed that self-assembled systems, such as lipid aggregates, can provide a highly-ordered microenvironment leading to unique host-guest chemistry exceeding the functions of the original lipid. 17 Based on these points, we have focused on the ordered structures of poly(octadecyl acrylate), ODAn and the ODAn-grafted silica for applying to RP-HPLC.18 Through these studies, we recognize that the weak subsidiary effects due to the carbonyl groups in the polymer work as main driving force for molecular-shape selectivity toward π-electron-containing compounds and the selectivity is specifically enhanced by ordering of the long-chain alkyl moieties. [19][20][21][22] The present study is aimed at controlling the ordered state of ODAn (Fig. 1) by the polymerization condition, and evaluating its effect on the selectivity, with HPLC toward the structural isomers of terphenyls and four-ring polyaromatic hydrocarbons and with differential scanning calorimetry and NMR spectroscopy. Chemistry & Engineering, Kyushu University, Japan Poly(octadecyl acrylate) with a terminal reactive group was synthesized by radical telomerization in various solvents. The polymers were grafted onto porous silica for use in RP-HPLC, and the molecular recognition ability was investigated along with the selectivity for the structural isomers of polycyclic aromatic hydrocarbons. The mechanism of selectivity was also investigated with differential scanning calorimetry and NMR spectroscopic observations. Experimental

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Direct Identification of the Carbon Skeleton of Organic Compounds using Double Quantum Coherence ¹³C‐NMR Spectroscopy. The INADEQUATE Pulse Sequence

Cited by 102 publications

References 118 publications

Multipulse NMR Part III. INADEQUATE pulse sequence

Multipulse NMR Part III. INADEQUATE pulse sequence

Espectroscopia de Ressonância Magnética Nuclear de 13C no estudo de rotas biossintéticas de produtos naturais

Conformational Effect of Silica-supported Poly(octadecyl acrylate) on Molecular-Shape Selectivity of Polycyclic Aromatic Hydrocarbons in RP-HPLC

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Direct Identification of the Carbon Skeleton of Organic Compounds using Double Quantum Coherence 13C‐NMR Spectroscopy. The INADEQUATE Pulse Sequence

Cited by 102 publications

References 118 publications

Multipulse NMR Part III. INADEQUATE pulse sequence

Multipulse NMR Part III. INADEQUATE pulse sequence

Espectroscopia de Ressonância Magnética Nuclear de 13C no estudo de rotas biossintéticas de produtos naturais

Conformational Effect of Silica-supported Poly(octadecyl acrylate) on Molecular-Shape Selectivity of Polycyclic Aromatic Hydrocarbons in RP-HPLC

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Direct Identification of the Carbon Skeleton of Organic Compounds using Double Quantum Coherence ¹³C‐NMR Spectroscopy. The INADEQUATE Pulse Sequence