1
|
Semenov VA, Krivdin LB. Stereochemical Study of the Super Large Tetrakis Alkaloid Alasmontamine A by Means of an Advanced Computational NMR. Int J Mol Sci 2023; 24:ijms24065572. [PMID: 36982653 PMCID: PMC10054784 DOI: 10.3390/ijms24065572] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 03/09/2023] [Accepted: 03/10/2023] [Indexed: 03/17/2023] Open
Abstract
1H and 13C NMR chemical shifts of the tetrakis monoterpene indole alkaloid alasmontamine A, with a molecular formula of C84H91N8O12, have been calculated within the DFT framework. Six minimum energy conformers of this alkaloid were identified, and three key configurations that contribute to its NMR shielding constants were established. Several ambiguities in the reported assignment of the NMR chemical shifts of alasmontamine A have been resolved.
Collapse
|
2
|
Cohen RD, Wood JS, Lam YH, Buevich AV, Sherer EC, Reibarkh M, Williamson RT, Martin GE. DELTA50: A Highly Accurate Database of Experimental 1H and 13C NMR Chemical Shifts Applied to DFT Benchmarking. Molecules 2023; 28:molecules28062449. [PMID: 36985422 PMCID: PMC10051451 DOI: 10.3390/molecules28062449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 02/23/2023] [Accepted: 02/28/2023] [Indexed: 03/30/2023] Open
Abstract
Density functional theory (DFT) benchmark studies of 1H and 13C NMR chemical shifts often yield differing conclusions, likely due to non-optimal test molecules and non-standardized data acquisition. To address this issue, we carefully selected and measured 1H and 13C NMR chemical shifts for 50 structurally diverse small organic molecules containing atoms from only the first two rows of the periodic table. Our NMR dataset, DELTA50, was used to calculate linear scaling factors and to evaluate the accuracy of 73 density functionals, 40 basis sets, 3 solvent models, and 3 gauge-referencing schemes. The best performing DFT methodologies for 1H and 13C NMR chemical shift predictions were WP04/6-311++G(2d,p) and ωB97X-D/def2-SVP, respectively, when combined with the polarizable continuum solvent model (PCM) and gauge-independent atomic orbital (GIAO) method. Geometries should be optimized at the B3LYP-D3/6-311G(d,p) level including the PCM solvent model for the best accuracy. Predictions of 20 organic compounds and natural products from a separate probe set had root-mean-square deviations (RMSD) of 0.07 to 0.19 for 1H and 0.5 to 2.9 for 13C. Maximum deviations were less than 0.5 and 6.5 ppm for 1H and 13C, respectively.
Collapse
Affiliation(s)
- Ryan D Cohen
- Analytical Research and Development, Merck & Co., Inc., Rahway, NJ 07065, USA
- Department of Chemistry and Biochemistry, Seton Hall University, South Orange, NJ 07079, USA
| | - Jared S Wood
- Analytical Research and Development, Merck & Co., Inc., Rahway, NJ 07065, USA
- Department of Chemistry and Biochemistry, University of North Carolina Wilmington, Wilmington, NC 28409, USA
| | - Yu-Hong Lam
- Department of Computational and Structural Chemistry, Merck & Co., Inc., Rahway, NJ 07065, USA
| | - Alexei V Buevich
- Analytical Research and Development, Merck & Co., Inc., Rahway, NJ 07065, USA
| | - Edward C Sherer
- Analytical Research and Development, Merck & Co., Inc., Rahway, NJ 07065, USA
| | - Mikhail Reibarkh
- Analytical Research and Development, Merck & Co., Inc., Rahway, NJ 07065, USA
| | - R Thomas Williamson
- Department of Chemistry and Biochemistry, University of North Carolina Wilmington, Wilmington, NC 28409, USA
| | - Gary E Martin
- Department of Chemistry and Biochemistry, Seton Hall University, South Orange, NJ 07079, USA
| |
Collapse
|
3
|
Krivdin LB. Computational 1 H and 13 C NMR in structural and stereochemical studies. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2022; 60:733-828. [PMID: 35182410 DOI: 10.1002/mrc.5260] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 02/14/2022] [Accepted: 02/16/2022] [Indexed: 06/14/2023]
Abstract
Present review outlines the advances and perspectives of computational 1 H and 13 C NMR applied to the stereochemical studies of inorganic, organic, and bioorganic compounds, involving in particular natural products, carbohydrates, and carbonium ions. The first part of the review briefly outlines theoretical background of the modern computational methods applied to the calculation of chemical shifts and spin-spin coupling constants at the DFT and the non-empirical levels. The second part of the review deals with the achievements of the computational 1 H and 13 C NMR in the stereochemical investigation of a variety of inorganic, organic, and bioorganic compounds, providing in an abridged form the material partly discussed by the author in a series of parent reviews. Major attention is focused herewith on the publications of the recent years, which were not reviewed elsewhere.
Collapse
Affiliation(s)
- Leonid B Krivdin
- A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, Irkutsk, Russia
| |
Collapse
|
4
|
Semenov VA, Krivdin LB. Computational NMR of natural products: On the way to super large molecules exemplified with alasmontamine A. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2022; 60:515-524. [PMID: 35137439 DOI: 10.1002/mrc.5256] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 02/05/2022] [Accepted: 02/07/2022] [Indexed: 06/14/2023]
Abstract
1 H and 13 C nuclear magnetic resonance (NMR) chemical shifts of a tetrakis monoterpene indole alkaloid alasmontamine A with a molecular formula of C84 H91 N8 O12 have been calculated at the PBE0/pcSseg-2//pcseg-2 level of theory on M06-2X/aug-cc-pVDZ geometry. In the course of the preliminary conformational search, six true minimum energy conformers were identified that can contribute to the actual conformation of this huge alkaloid. Calculated chemical shifts generally demonstrated a good agreement with available experimental data characterized with a corrected mean absolute error of 0.10 ppm for the range of about 7 ppm for protons and 1.1 ppm for the range of about 160 ppm for carbons.
Collapse
Affiliation(s)
- Valentin A Semenov
- A.E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, Irkutsk, Russia
| | - Leonid B Krivdin
- A.E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, Irkutsk, Russia
| |
Collapse
|
5
|
Semenov VA, Krivdin LB. Combined Computational NMR and Molecular Docking Scrutiny of Potential Natural SARS-CoV-2 M pro Inhibitors. J Phys Chem B 2022; 126:2173-2187. [PMID: 35271277 PMCID: PMC8936056 DOI: 10.1021/acs.jpcb.1c10489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2021] [Revised: 02/25/2022] [Indexed: 11/30/2022]
Abstract
In continuation of the search for potential drugs that inhibit the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), in this work, a combined approach based on the modeling of NMR chemical shifts and molecular docking is suggested to identify the possible suppressors of the main protease of this virus among a number of natural products of diverse nature. Primarily, with the aid of an artificial neural network, the problem of the reliable determination of the stereochemical structure of a number of studied compounds was solved. Complementary to the main goal of this study, theoretical modeling of NMR spectral parameters made it feasible to perform a number of signal reassignments together with introducing some missing NMR data. Finally, molecular docking formalism was applied to the analysis of several natural products that could be chosen as prospective candidates for the role of potential inhibitors of the main protease. The results of this study are believed to assist in further research aimed at the development of specific drugs based on the natural products against COVID-19.
Collapse
Affiliation(s)
- Valentin A. Semenov
- A. E. Favorsky Irkutsk Institute of
Chemistry, Siberian Branch of the Russian
Academy of Sciences, Favorsky St. 1, 664033 Irkutsk, Russia
| | - Leonid B. Krivdin
- A. E. Favorsky Irkutsk Institute of
Chemistry, Siberian Branch of the Russian
Academy of Sciences, Favorsky St. 1, 664033 Irkutsk, Russia
| |
Collapse
|
6
|
Semenov VA, Krivdin LB. Computational NMR of natural products. RUSSIAN CHEMICAL REVIEWS 2022. [DOI: 10.1070/rcr5027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
7
|
Kurutos A, Kamounah FS, Dobrikov GM, Pittelkow M, Sauer SPA, Hansen PE. Azo-hydrazone molecular switches: Synthesis and NMR conformational investigation. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2021; 59:1116-1125. [PMID: 33860564 DOI: 10.1002/mrc.5164] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 04/05/2021] [Accepted: 04/10/2021] [Indexed: 06/12/2023]
Abstract
A series of five intramolecularly hydrogen-bonded arylhydrazone (aryl = phenol, p-nitrophenol, anisole, quinoline) derived molecular switches have been synthesized and characterized by NMR and HRMS techniques. It was found that the compounds exist as different isomers in solution. An investigation of both conformational and/or configurational changes of the azo-hydrazone compounds was carried out by 1D 1 H- and 13 C- spectra, 2D NOESY, COSY, HSQC, and HMBC techniques. It was found that these stimuli-responsive molecular switches exist mainly in the E form by intramolecularly hydrogen bonded between NH and the pyridine nitrogen at equilibrium. Deprotonation of the neutral E form yields the E' deprotonated isomer. Prediction of 13 C-NMR chemical shifts was achieved by DFT quantum mechanical calculations. Anions have traditionally been difficult to calculate correctly, so calculations of the anion using different functionals, basis sets, and solvent effects are also included. Deuterium isotope effects on the 13 C-NMR chemical shifts were employed in the assignments and furthermore utilized as indicators of intramolecular hydrogen bonding. Studies in various organic solvents including CDCl3 , CD3 CN, and DMSO-d6 were also performed aiming to monitor dynamic changes over several days. The effect of the hydrogen bonded solvents leads to Z forms.
Collapse
Affiliation(s)
- Atanas Kurutos
- Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev str., bl. 9, Sofia, 1113, Bulgaria
| | - Fadhil S Kamounah
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, Copenhagen Ø, DK-2100, Denmark
| | - Georgi M Dobrikov
- Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev str., bl. 9, Sofia, 1113, Bulgaria
| | - Michael Pittelkow
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, Copenhagen Ø, DK-2100, Denmark
| | - Stephan P A Sauer
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, Copenhagen Ø, DK-2100, Denmark
| | - Poul Erik Hansen
- Department of Science and Environment, Roskilde University, Roskilde, DK-4000, Denmark
| |
Collapse
|
8
|
DFT Calculations of 1H NMR Chemical Shifts of Geometric Isomers of Conjugated Linolenic Acids, Hexadecatrienyl Pheromones, and Model Triene-Containing Compounds: Structures in Solution and Revision of NMR Assignments. Molecules 2021; 26:molecules26113477. [PMID: 34200468 PMCID: PMC8201138 DOI: 10.3390/molecules26113477] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 06/02/2021] [Accepted: 06/04/2021] [Indexed: 11/29/2022] Open
Abstract
A DFT study of the 1H NMR chemical shifts, δ(1H), of geometric isomers of 18:3 conjugated linolenic acids (CLnAs), hexadecatrienyl pheromones, and model triene-containing compounds is presented, using standard functionals (B3LYP and PBE0) as well as corrections for dispersion interactions (B3LYP-D3, APFD, M06–2X and ωB97XD). The results are compared with literature experimental δ(1H) data in solution. The closely spaced “inside” olefinic protons are significantly more deshielded due to short-range through-space H…H steric interactions and appear close to or even beyond δ-values of aromatic systems. Several regularities of the computational δ(1H) of the olefinic protons of the conjugated double bonds are reproduced very accurately for the lowest-energy DFT-optimized single conformer for all functionals used and are in very good agreement with experimental δ(1H) in solution. Examples are provided of literature studies in which experimental resonance assignments deviate significantly from DFT predictions and, thus, should be revised. We conclude that DFT calculations of 1H chemical shifts of trienyl compounds are powerful tools (i) for the accurate prediction of δ(1H) even with less demanding functionals and basis sets; (ii) for the unequivocal identification of geometric isomerism of conjugated trienyl systems that occur in nature; (iii) for tackling complex problems of experimental resonance assignments due to extensive signal overlap; and (iv) for structure elucidation in solution.
Collapse
|
9
|
The Advantage of Automatic Peer-Reviewing of 13C-NMR Reference Data Using the CSEARCH-Protocol. Molecules 2021; 26:molecules26113413. [PMID: 34200052 PMCID: PMC8200238 DOI: 10.3390/molecules26113413] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 05/25/2021] [Accepted: 05/31/2021] [Indexed: 11/23/2022] Open
Abstract
A systematic investigation of the experimental 13C-NMR spectra published in Molecules during the period of 1996 to 2015 with respect to their quality using CSEARCH-technology is described. It is shown that the systematic application of the CSEARCH-Robot-Referee during the peer-reviewing process prohibits at least the most trivial assignment errors and wrong structure proposals. In many cases, the correction of the assignments/chemical shift values is possible by manual inspection of the published tables; in certain cases, reprocessing of the original experimental data might help to clarify the situation, showing the urgent need for a public domain repository. A comparison of the significant key numbers derived for Molecules against those of other important journals in the field of natural product chemistry shows a quite similar level of quality for all publishers responsible for the six journals under investigation. From the results of this study, general rules for data handling, data storage, and manuscript preparation can be derived, helping to increase the quality of published NMR-data and making these data available as validated reference material.
Collapse
|