High-resolution methods for the measurement of scalar coupling constants

Lin, Yanqin; Zeng, Qing; Lin, Liangjie; Chen, Zhong; Barker, Peter B.

doi:10.1016/j.pnmrs.2018.08.003

Cited by 20 publications

(14 citation statements)

References 147 publications

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“…As an alternative approach, as used in previous works, all possible permutations of assignments were evaluated . Including CH 2 information in the proper way, that is, with ambiguous assignment, improves the structure selection and provides an assignment of diastereotopic protons at the same time.…”

Section: Methodsmentioning

confidence: 99%

“…With access to quantum‐chemical calculations, especially computationally cheap DFT calculations and even faster parameterizations of these calculations that provide coupling constants at sufficient accuracy, all available and experimentally accessible n J XY coupling constants can be utilized for structure elucidation as long as they are experimentally accessible. Recent excellent review articles show they are becoming increasingly accessible …”

Section: Methodsmentioning

confidence: 99%

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Computer‐Assisted 3D Structure Elucidation (CASE‐3D): The Structural Value of ²J_CH in Addition to ³J_CH Coupling Constants

et al. 2020

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We present a method to use long‐range CH coupling constants to derive the correct diastereoisomer from the molecular constitution of small molecules. A set of 79 2JCH and 3JCH values collected from a single HSQMBC experiment on a sample of strychnine were used in the CASE‐3D (computer‐assisted 3D structure elucidation) protocol. In addition to the most commonly used 3JCH coupling constants, the subset of 32 2JCH values alone showed an excellent degree of configuration selection. The study is mainly based on comparison of DFT‐calculated 2,3JCH values with experimental ones, critical for the case of 2JCH. But the configuration selection also works well using 3JCH values predicted from a semi‐empirical Karplus‐based equation limited to H−C−C−C fragments. The robustness, shown using strychnine as a proof of concept, makes the J‐based CASE‐3D analysis a viable option for the application in fields such as peptide and carbohydrate research, organic synthesis, natural‐product identification and analysis, as well as medicinal chemistry.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Computer‐Assisted 3D Structure Elucidation (CASE‐3D): The Structural Value of ²J_CH in Addition to ³J_CH Coupling Constants

et al. 2020

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“…To facilitate the chemical shift assignments, we then conducted 2D 1 H/ 13 C HSQC and DEPT experiments to identify the 1 H and 13 C chemical shifts of 1 and 2 (see Supplementary Figures S1-S4), respectively. The 1 H chemical shifts were further confirmed by 2D HMBC and COSY (correlation spectroscopy) experiments (Figures S5-S8).…”

Section: Chemical Shift Assignmentsmentioning

confidence: 99%

“…The 1 H chemical shifts were further confirmed by 2D HMBC and COSY (correlation spectroscopy) experiments (Figures S5-S8). Both the 1 H and 13 C chemical shift assignments were determined (Table 1 and Table S1). To confirm the spectral dissimilarity is mainly due to 1 H chemical shift differences but not associated J H-H coupling constant variations, we also carried out an iterative simulation analysis to unravel the J H-H values of 1 and 2 (Table 1), respectively, to be elaborated below.…”

Section: Chemical Shift Assignmentsmentioning

confidence: 99%

Resolving Entangled JH-H-Coupling Patterns for Steroidal Structure Determinations by NMR Spectroscopy

Carillo

Shie

et al. 2021

Molecules

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For decades, high-resolution 1H NMR spectroscopy has been routinely utilized to analyze both naturally occurring steroid hormones and synthetic steroids, which play important roles in regulating physiological functions in humans. Because the 1H signals are inevitably superimposed and entangled with various JH–H splitting patterns, such that the individual 1H chemical shift and associated JH–H coupling identities are hardly resolved. Given this, applications of thess information for elucidating steroidal molecular structures and steroid/ligand interactions at the atomic level were largely restricted. To overcome, we devoted to unraveling the entangled JH–H splitting patterns of two similar steroidal compounds having fully unsaturated protons, i.e., androstanolone and epiandrosterone (denoted as 1 and 2, respectively), in which only hydroxyl and ketone substituents attached to C3 and C17 were interchanged. Here we demonstrated that the JH–H values deduced from 1 and 2 are universal and applicable to other steroids, such as testosterone, 3β, 21-dihydroxygregna-5-en-20-one, prednisolone, and estradiol. On the other hand, the 1H chemical shifts may deviate substantially from sample to sample. In this communication, we propose a simple but novel scheme for resolving the complicate JH–H splitting patterns and 1H chemical shifts, aiming for steroidal structure determinations.

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“…The pros and cons with these have been comprehensively reviewed. [5][6][7] In short, no technique has so far proven to be a generally applicable method to measure long range couplings, but it is always a matter of choosing the most appropriate technique with regards to the amount of sample, the sample complexity (overlap), whether the carbon is protonated or not, and how many couplings need to be measured simultaneously.…”

Section: Introductionmentioning

confidence: 99%

CSSF-CLIP-HSQMBC: measurement of heteronuclear coupling constants in severely crowded spectral regions

2019

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High-resolution methods for the measurement of scalar coupling constants

Cited by 20 publications

References 147 publications

Computer‐Assisted 3D Structure Elucidation (CASE‐3D): The Structural Value of ²J_CH in Addition to ³J_CH Coupling Constants

Computer‐Assisted 3D Structure Elucidation (CASE‐3D): The Structural Value of ²J_CH in Addition to ³J_CH Coupling Constants

Resolving Entangled JH-H-Coupling Patterns for Steroidal Structure Determinations by NMR Spectroscopy

CSSF-CLIP-HSQMBC: measurement of heteronuclear coupling constants in severely crowded spectral regions

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High-resolution methods for the measurement of scalar coupling constants

Cited by 20 publications

References 147 publications

Computer‐Assisted 3D Structure Elucidation (CASE‐3D): The Structural Value of 2JCH in Addition to 3JCH Coupling Constants

Computer‐Assisted 3D Structure Elucidation (CASE‐3D): The Structural Value of 2JCH in Addition to 3JCH Coupling Constants

Resolving Entangled JH-H-Coupling Patterns for Steroidal Structure Determinations by NMR Spectroscopy

CSSF-CLIP-HSQMBC: measurement of heteronuclear coupling constants in severely crowded spectral regions

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Computer‐Assisted 3D Structure Elucidation (CASE‐3D): The Structural Value of ²J_CH in Addition to ³J_CH Coupling Constants

Computer‐Assisted 3D Structure Elucidation (CASE‐3D): The Structural Value of ²J_CH in Addition to ³J_CH Coupling Constants