Structure Validation of Natural Products by Quantum-Mechanical GIAO Calculations of 13C NMR Chemical Shifts GIAO=gauge including atomic orbitals.

Barone, Giampaolo; Gomez‐Paloma, Luigi; Duca, Dario; Silvestri, Arturo; Riccio, Raffaele; Bifulco, Giuseppe

doi:10.1002/1521-3765(20020715)8:14<3233::aid-chem3233>3.0.co;2-0

Cited by 250 publications

(196 citation statements)

References 13 publications

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“…Although ab initio (quantum chemstry) calculation of NMR chemical shifts is a powerful tool for assigning stereochemistry to molecules 284,285 , having just one data set for a single diastereoisomer provides an additional challenge in determining the stereochemistry 283 . A probability method of determining stereochemistry that is based on conformational analysis of diastereomers has been successfully demonstrated for 36 structures 283 .…”

Section: Box 2: Advances In Nmr Techniquescontrasting

confidence: 57%

The re-emergence of natural products for drug discovery in the genomics era

Harvey

Edrada-Ebel

Quinn

2015

Nat Rev Drug Discov

2,112

1,410

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Natural products have been a rich source of compounds for drug discovery. However, their use has diminished in the past two decades in part because of technical barriers to screening natural products in high-throughput assays against molecular targets. Here, we review advances in chemical techniques for the isolation and structural elucidation of natural products that have reduced these technological barriers. We also assess the use of genomic and metabolomic approaches to augment traditional methods of studying natural products, and highlight recent examples of natural products in antimicrobial drug discovery and as inhibitors of protein protein interactions. The growing appreciation of functional assays and phenotypic screens may further contribute to a revival of interest in natural products for drug discovery.

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Section: Box 2: Advances In Nmr Techniquescontrasting

confidence: 57%

The re-emergence of natural products for drug discovery in the genomics era

Harvey

Edrada-Ebel

Quinn

2015

Nat Rev Drug Discov

2,112

1,410

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“…For the NMR calculations, molecular structures of optimized at B3LYP/6-31G(d) level in chloroform ( After optimization, 1 H and 13 GIAO method [23][24][25][26][27][28][29][30] in chloroform at the B3LYP/6 Relative chemical shifts were then estimated by using the corresponding TMS shieldings calculated in advance at the same theoretical levels isotropic chemical shieldings for TMS at the B3LYP/6 using the IEFPCM were 31.87 ppm and 183.76 ppm, respectively. Experimental chemical shieldings for TMS are given as pectroscopic and quantum mechanical investigations of two ferrocene derivatives Bull.…”

Section: Calculationsmentioning

confidence: 99%

“…The standard 1D and 2D hetero and homonuclear NMR experiments are enough to afford complete assignment of compounds and very useful to clarify molecular structures [20][21][22]. For the theoretical NMR investigations, the gauge including atomic orbitals/density functional theory (GIAO/DFT) approach is widely used for various types of compounds [23][24][25][26][27][28][29][30][31]. The DFT/B3LYP method exhibits good performance on electron affinities, excellent performance on bond energies and reasonably good performance on vibrational frequencies and geometries of inorganic or ionic compounds [32,33] as well as organic and neutral compounds [34][35][36][37][38][39][40].…”

Section: Introductionmentioning

confidence: 99%

“…After the optimization, in order to confirm the convergence to minima on the potential energies, harmonic vibrational frequencies of the present compounds were determined using analytic second derivatives with the ) and 0.967 (under 1800 absence of imaginary frequencies confirmed that the optimized PED calculations were carried out by vibrational 3pica were first fully = 4.9) using the IEFPCM method [27][28][29][30].…”

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confidence: 99%

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FT-IR, NMR spectroscopic and quantum mechanical investigations of two ferrocene derivatives

Alver¹,

Parlak²

2017

Bull. Chem. Soc. Eth.

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ABSTRACT. New ferrocene derivatives as N-(3-piperidin-1-ylpropyl)ferrocenamide and N-(pyridine-3-ylmethyl)ferrocenamide (Fc-3pica) and structural investigations were carried out with 1 H, 13 C, DEPT 45 or 135, HETCOR, COSY NMR and FT-IR spectroscopic techniques. Characterization of Fc-3ppa (FeC19H26N2O) and Fc-3pica (FeC17H16N2O) was also supported by density functional theory (DFT) used by B3LYP functional and 6-31G(d) or 6-311++G(d,p) basis sets. From the combination of all the results, it can be clearly seen that syntheses of Fc-3ppa and Fc-3pica have been successfully achieved. Theoretical values are successfully compared against experimental data and B3LYP method is able to provide satisfactory results for predicting NMR properties and vibrational frequencies of the synthesized ferrocene based systems.

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“…For example, the chemical shifts of nuclei such as 1 H (δ H ), 13 C (δ C ), and 15 N (δ N ); various spin-spin (scalar) coupling constants between nuclei such as 1 H and 1 H (J H,H ), 1 H and 13 C (J H,C ), and 1 H and 15 N (J H,N ); NOEs between nuclei such as 1 H and 1 H (η H,H ) and 1 H and 13 C (η H,C ). The prediction of NMR parameters [2,3] such as chemical shifts, but especially coupling constants, has come of age recently in terms of development and practical application [4][5][6], and especially with respect to conformational analysis [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Differentiation between 6- and 7-Membered Rings Based on Theoretical Calculation of NMR Parameters

Klika

2012

ISRN Spectroscopy

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The determination of ring size can vary from simple to complex, but the process in difficult cases can be advantageously augmented by DFT calculation of NMR parameters such as the chemical shifts of (), (), and other nuclei as well as pertinent spin-spin (scalar) coupling constants, for example, those between protons (). Differentiation between 6- and 7-membered ring formation in the case of 3,4-dihydro-2H-3-hydroxymethyl-1,4-benzoxazine and 2,3,4,5-tetrahydro-1,5-benzoxazepine-3-ol was evaluated with a view to not only affecting 6- versus 7-membered ring differentiation generally for cases on hand, but also in the case of literature reports where the assigned structures may be in doubt. Thus, the main focus was on the usually reported NMR parameters of , , and and wherein the analysis was found to be highly successful, particularly for , and thus potentially amenable for broad application.

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Structure Validation of Natural Products by Quantum-Mechanical GIAO Calculations of 13C NMR Chemical Shifts GIAO=gauge including atomic orbitals.

Cited by 250 publications

References 13 publications

The re-emergence of natural products for drug discovery in the genomics era

The re-emergence of natural products for drug discovery in the genomics era

FT-IR, NMR spectroscopic and quantum mechanical investigations of two ferrocene derivatives

Differentiation between 6- and 7-Membered Rings Based on Theoretical Calculation of NMR Parameters

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