Density Functional Theory Calculation of <sup>13</sup>C NMR Shifts of Diazaphenanthrene Alkaloids: Reinvestigation of the Structure of Samoquasine A

Timmons, Cody; Wipf, Peter

doi:10.1021/jo801735e

Cited by 43 publications

(40 citation statements)

References 20 publications

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“…These coupling constants were compared with the measured values that were experimentally obtained, showing RMSD values of 1.45 Hz for DFT B3LYP 6-31G(d) and 1.25 Hz for 6-311++G(2d,p). The UV spectra were calculated using the RTD-B3LYP-FC functional and 6-31G(d) and 6-311G++(2d,p) basis set [22,23]. The NBO values were obtained with NBO 3.1, as implemented in the Gaussian 03 package using the 6-31G(d) basis set and the B3LYP functional.…”

Section: Methodsmentioning

confidence: 99%

Structural, Vibrational, and Electronic Properties of the Glucoalkaloid Strictosidine: A Combined Experimental and Theoretical Study

Costa

Pinheiro

Oliveira

et al. 2016

Journal of Chemistry

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A detailed structural analysis and spectral behavior of the glucoalkaloid strictosidine, a precursor of all monoterpene indole alkaloids, are discussed. The experimental NMR, FTIR, and UV results were compared to the theoretical DFT spectra calculated by Becke using the three-parameter Lee-Yang-Parr (B3LYP) function with 6-31G(d) and 6-311++G(2d,p) basis sets. The theoretical geometry optimization data were compared with the X-ray data for precursors and similar structures in the associated literature. The similarity between the theoretical and experimental coupling constants values made it possible to affirm the values of dihedral angles and their configuration, reinforcing findings from previous stereochemical studies. Theoretical UV analysis agreed well with the measured experimental data, with bands assigned. Calculated HOMO/LUMO gaps show low excitation energy for strictosidine, justifying its stability and reaction kinetics. The molecular electrostatic potential map shows opposite potentials regions that form hydrogen bonds that stabilize the dimeric form, which were confirmed by excellent agreement of the dimeric form theoretical wavenumbers with the experimental IR spectrum. ESI-MS/MS data revealed patterns for the fragmentation of the protonated strictosidine molecule outlined by an NBO study.

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Section: Methodsmentioning

confidence: 99%

Structural, Vibrational, and Electronic Properties of the Glucoalkaloid Strictosidine: A Combined Experimental and Theoretical Study

Costa

Pinheiro

Oliveira

et al. 2016

Journal of Chemistry

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“…13) with a benzo[h]quinazoline ring system was isolated from seeds of the custard apple Annona squamosa. [158][159][160][161] It showed significant cytotoxic activity against murine lymphoma L1210 cells (IC 50 1.94 M). 158 However, the original published structure was reinvestigated and revised.…”

Section: Quinazoline Alkaloidsmentioning

confidence: 99%

Biologically active quinoline and quinazoline alkaloids part I

Shang

Morris‐Natschke

Liu

et al. 2017

Medicinal Research Reviews

307

166

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Quinoline and quinazoline alkaloids, two important classes of N-based heterocyclic compounds, have attracted tremendous attention from researchers worldwide since the 19th century. Over the past 200 years, many compounds from these two classes were isolated from natural sources, and most of them and their modified analogs possess significant bioactivities. Quinine and camptothecin are two of the most famous and important quinoline alkaloids, and their discoveries opened new areas in antimalarial and anticancer drug development, respectively. In this review, we survey the literature on bioactive alkaloids from these two classes and highlight research achievements prior to the year 2008 (Part I). Over 200 molecules with a broad range of bioactivities, including antitumor, antimalarial, antibacterial and antifungal, antiparasitic and insecticidal, antiviral, antiplatelet, anti-inflammatory, herbicidal, antioxidant and other activities, were reviewed. This survey should provide new clues or possibilities for the discovery of new and better drugs from the original naturally occurring quinoline and quinazoline alkaloids.

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“…The first is to use a reference compound, for example, tetramethylsilane (TMS). The compound of interest and reference compound are calculated using the same method, and the reference compound is used to obtain the conversion factor shown in the following equation;

δ_{i} = σ_{ref} - σ_{i} + δ_{ref}

where

δ_{i}

is the chemical shift of interest,

δ_{ref}

is the chemical shift of reference compound, and

σ_{ref}

and

σ_{i}

are the calculated isotropic magnetic shielding tensor for the reference and compound of interest, respectively …”

Section: Introductionmentioning

confidence: 99%

“…the chemical shift of reference compound, and r ref and r i are the calculated isotropic magnetic shielding tensor for the reference and compound of interest, respectively. [19][20][21][22] The second and more accepted method is by linear regression. In this method several reference compounds are examined and their calculated NMR isotropic shielding tensors are plotted against their experimental chemical shifts.…”

Section: Introductionmentioning

confidence: 99%

¹H and ¹³C NMR scaling factors for the calculation of chemical shifts in commonly used solvents using density functional theory

2014

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Calculation of NMR chemical shifts and coupling constants using quantum mechanical calculations [density functional theory (DFT)], has become a very popular tool for the determination of conformation and the assignment of stereochemistry within a molecule. We present the scaling factors (linear regression parameters) from 10 DFT methods for 10 commonly used NMR solvents using the same set of reference compounds. The results were compared with the corresponding gas-phase calculations to assess the inclusion of the polarizable continuum model for solvent effects.

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Density Functional Theory Calculation of ¹³C NMR Shifts of Diazaphenanthrene Alkaloids: Reinvestigation of the Structure of Samoquasine A

Abstract: The (13)C NMR shifts of 48 diazaphenanthrene-type alkaloids have been calculated at the B3LYP/6-311+G(2d,p) level of theory. The results support the structural reassignment of samoquasine A as 2.

Cited by 43 publications

References 20 publications

Structural, Vibrational, and Electronic Properties of the Glucoalkaloid Strictosidine: A Combined Experimental and Theoretical Study

Structural, Vibrational, and Electronic Properties of the Glucoalkaloid Strictosidine: A Combined Experimental and Theoretical Study

Biologically active quinoline and quinazoline alkaloids part I

¹H and ¹³C NMR scaling factors for the calculation of chemical shifts in commonly used solvents using density functional theory

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Density Functional Theory Calculation of 13C NMR Shifts of Diazaphenanthrene Alkaloids: Reinvestigation of the Structure of Samoquasine A

Abstract: The (13)C NMR shifts of 48 diazaphenanthrene-type alkaloids have been calculated at the B3LYP/6-311+G(2d,p) level of theory. The results support the structural reassignment of samoquasine A as 2.

Cited by 43 publications

References 20 publications

Structural, Vibrational, and Electronic Properties of the Glucoalkaloid Strictosidine: A Combined Experimental and Theoretical Study

Structural, Vibrational, and Electronic Properties of the Glucoalkaloid Strictosidine: A Combined Experimental and Theoretical Study

Biologically active quinoline and quinazoline alkaloids part I

1H and 13C NMR scaling factors for the calculation of chemical shifts in commonly used solvents using density functional theory

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Density Functional Theory Calculation of ¹³C NMR Shifts of Diazaphenanthrene Alkaloids: Reinvestigation of the Structure of Samoquasine A

¹H and ¹³C NMR scaling factors for the calculation of chemical shifts in commonly used solvents using density functional theory