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H and 13 C NMR chemical shifts, δ (ppm), multiplicities and coupling constants, J(H,H) (Hz), for compound 1 a
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![Fig. 2. Optimized structures for compound 1 [17].](profile/Paulo-Donate/publication/7721070/figure/fig2/AS:277841099935766@1443253888896/Optimized-structures-for-compound-1-17_Q320.jpg)
A detailed analysis with total assignment of (1)H and (13)C NMR spectral data for a cycloheptenone derivative, a key intermediate for the synthesis of perhydroazulene terpenoids, is related. These assignments are based on 1D (1)H and (13)C NMR and on 2D NMR techniques including gCOSY, gHSQC, gHMBC, J-resolved and NOEDIF experiments. The unequivocal...
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... The protocol used for these calculations is commonly found in the literature [41,42]. The geometries of the cis and trans isomer structures were first optimized using the MP2 method [43] and the cc-pVDZ [44,45] basis sets and included the solvent effect (chloroform) from the polarizable continuum model [46]. ...
As part of our continuing chemical and biological analyses of Rubiaceae species from Cerrado, we isolated novel alkaloids 1 and 2, along with known compounds epicatechin, ursolic acid, and oleanolic acid, from Galianthe ramosa. Alkaloid 2 inhibited malate synthase from the pathogenic fungus Paracoccidioides spp. This enzyme is considered an important molecular target because it is not found in humans. Molecular docking simulations were used to describe the interactions between the alkaloids and malate synthase.
... The protocol used for these calculations is commonly found in the literature [41,42]. The geometries of the cis and trans isomer structures were first optimized using the MP2 method [43] and the cc-pVDZ [44,45] basis sets and included the solvent effect (chloroform) from the polarizable continuum model [46]. ...
As part of our continuing chemical and biological
analyses of Rubiaceae species from Cerrado, we
isolated novel alkaloids 1 and 2, along with
known compounds epicatechin, ursolic acid, and
oleanolic acid, from Galianthe ramosa. Alkaloid 2
inhibited malate synthase from the pathogenic
fungus Paracoccidioides spp. This enzyme is considered
an important molecular target because it
is not found in humans. Molecular docking simulations
were used to describe the interactions between
the alkaloids and malate synthase.
... The highly reliable results of theoretical calculations of chemical and physical properties, in special by ab initio and density functional theory methods, have become important tools for interpreting experimental data [10,11] The theoretical calculations of magnetic properties can be performed through different methods, among which we can highlight: gauge-independent atomic orbital (GIAO), [12] continuous set of gauge transformations (CSGT) [13,14] and individual gauges for atoms in molecules (IGAIM). [15] These methods have in common the use of gauge theory to describe the origin of the vector potential. ...
This work aims at using theoretical calculations of shielding tensors (σ) through different methods [gauge-independent atomic orbital (GIAO), continuous set of gauge transformations (CSGT) and individual gauges for atoms in molecules (IGAIM)] and spin-spin coupling constants J using GIAO method to compare these methods and to corroborate the data obtained with the assignment of all of (1)H and (13)C NMR signals and the relative stereochemistry of the 1,6-epoxycarvone and the α-epoxypinene. All the (1)H and (13)C NMR signals were assigned unequivocally. The stereochemistry for the epoxides is trans and the B3LYP theory level with CSGT and IGAIM methods is the best choice to evaluate theoretical chemical shifts for compounds studied.
Cardanol was obtained by vacuum distillation of ‘‘cashew nut shell liquid’’ (CNSL). Cardanol is a by-product of cashew production and a building block for chemical synthesis; cardanol and its derivatives can be used for different types of applications. Three of these compounds are the subject of the present NMR study and theoretical comparison. ¹H and ¹³C NMR signals were assigned using 1D and 2D NMR experiments. The DFT/B3LYP method using the cc-pVTZ basis set was employed for the calculations of the ¹H and ¹³C NMR chemical shifts (δ). The obtained data were used as an auxiliary tool for unequivocal assignment of all ¹H and ¹³C NMR signals. For these compounds, the adopted theoretical model was sufficient to obtain a good description of the chemical shifts.
This document is part of Part 1 ‘Aliphatic Compounds’ of Subvolume D 'Chemical Shifts and Coupling Constants for Carbon-13' of Landolt-Börnstein III/35 'Nuclear Magnetic Resonance Data', Group III 'Condensed Matter’. It contains the chemical shift, coupling constant, structural diagram, and solvent of C11H17BrO. Hill Formula: C11H17BrO SpringerMaterial s Volume III/ 35D1 General Introduction to NMR Introduction to Carbon-13 NMR Index of Substances
This document is part of Part 1 ‘Aliphatic Compounds’ of Subvolume D 'Chemical Shifts and Coupling Constants for Carbon-13' of Landolt-Börnstein III/35 'Nuclear Magnetic Resonance Data', Group III 'Condensed Matter’. It contains the chemical shift, coupling constant, structural diagram, and solvent of C11H15BrO. Hill Formula: C11H15BrO SpringerMaterial s Volume III/ 35D1 General Introduction to NMR Introduction to Carbon-13 NMR Index of Substances
A computational quantum chemistry experiment is described of Diels-Alder reactions between 2-cycloenones and cyclopentadiene. The effects of FMO-Frontier Molecular Orbitals (HOMO-LUMO) and of the withdrawing nature of substituents at the C=C bond of cycloenones were evaluated. The calculations were made using HF/STO-3G and B3LYP/6-31+G(d,p) methods. The FMO based indexes are in agreement with the experimentally observed reactivity order. NBO - Natural Bond Orbitals - analysis was used to ascertain the effect of C=C substituents on the dienophile reactivity.
DFT/B3LYP/6-311++G(d,p) calculation of the relative stable conformations of (3R,4R,6S)-trihydroxyazepane are presented. The GIAO/DFT/OPBE, GIAO/DFT/B3LYP and GIAO/HF single point calculations with 6-311++G(d,p), 6-311+G(2d,p), cc-pVDZ and cc-pVTZ basis sets of (3R,4R,6S)-trihydroxyazepane were conducted to generate their 13C NMR chemical shifts. According to calculation results, 14 (3R,4R,6S)-trihydroxyazepane with optimized structure were generated. There were three conformers which contain the intramolecular hydrogen bonding exhibit a lowest electronic energies and TCN1(eq) was the most stable conformer than others. Boltzmann weighting factor analysis exhibits that TCN1(eq), TCN3(eq) and TCN5(eq) dominate a major contribution among the 14 conformers. The individual calculated NMR results of TCN1(eq), TCN3(eq) and TCN5(eq) represents a quite close correlation with experimental data. Moreover, the experimental 13C NMR chemical shifts gave only the average contribution of all conformers. In our investigation, the calculated 13C NMR chemical shifts of mixture (3R,4R,6S)-trihydroxyazepane exhibit a good agreement with the experimental NMR data. Calculated NMR results of mixture (3R,4R,6S)-trihydroxyazepane conformers display a remarkable MAE and RMS improvement over that of each individual conformer. A good calculation method and basis set choice to evaluate the theoretical chemical shifts for these conformers is HF/cc-pVTZ.
