Isolation of intermediates in the synthesis of new 3,4-dihydro-2H-chromeno[2,3-d]pyrimidines

2018 ◽  
Vol 73 (8) ◽  
pp. 557-563
Author(s):  
Mehri Fattahi ◽  
Abolghasem Davoodnia ◽  
Mehdi Pordel ◽  
S. Ali Beyramabadi ◽  
Niloofar Tavakoli-Hoseini
Keyword(s):  
Sodium Carbonate ◽  
Density Functional ◽  
Nuclear Overhauser Effect ◽  
Noesy Spectrum ◽  
Functional Theory ◽  
Overhauser Effect ◽  
2D Noesy ◽  
Ft Ir ◽  
Nuclear Overhauser ◽  
C Nmr

AbstractReaction of N-alkyl-2-imino-2H-chromene-3-carboxamides with dimethyl acetylenedicarboxylate (DMAD) in the presence of sodium carbonate as catalyst in refluxing ethanol gave new tricyclic products identified as methyl 3-alkyl-2-(2-methoxy-2-oxoethyl)-4-oxo-3,4-dihydro-2H-chromeno[2,3-d]pyrimidine-2-carboxylates. In the absence of sodium carbonate, dimethyl 2-((E)-3-(alkylcarbamoyl)-2H-chromen-2-ylideneamino)fumarates were isolated as intermediates. These intermediates could be successfully converted to the same new tricyclic products by heating in ethanol containing sodium carbonate. All new synthetic compounds were characterized on the basis of their FT-IR, 1H and 13C NMR spectra, and microanalytical data. To identify the correct stereoisomer of the intermediates, in one case a 2D nuclear Overhauser effect (2D-NOESY) spectrum together with density functional theory (DFT) calculation at the B3LYP/6-311+G(d,p) level of theory was used.

scholarly journals In Silico Modeling of Spirolides and Gymnodimines: Determination of S Configuration at Butenolide Ring Carbon C-4

Toxins ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 685
Author(s):  
Christian Zurhelle ◽  
Tilmann Harder ◽  
Urban Tillmann ◽  
Jan Tebben
Keyword(s):  
In Silico ◽  
Density Functional ◽  
Nuclear Overhauser Effect ◽  
Resonance Spectroscopy ◽  
Functional Theory ◽  
Relative Configuration ◽  
Overhauser Effect ◽  
In Silico Modeling ◽  
Nuclear Overhauser

Only few naturally occurring cyclic imines have been fully structurally elucidated or synthesized to date. The configuration at the C-4 carbon plays a pivotal role in the neurotoxicity of many of these metabolites, for example, gymnodomines (GYMs) and spirolides (SPXs). However, the stereochemistry at this position is not accessible by nuclear Overhauser effect—nuclear magnetic resonance spectroscopy (NOE-NMR) due to unconstrained rotation of the single carbon bond between C-4 and C-5. Consequently, the relative configuration of GYMs and SPXs at C-4 and its role in protein binding remains elusive. Here, we determined the stereochemical configuration at carbon C-4 in the butenolide ring of spirolide- and gymnodimine-phycotoxins by comparison of measured 13C NMR shifts with values obtained in silico using force field, semiempirical and density functional theory methods. This comparison demonstrated that modeled data support S configuration at C-4 for all studied SPXs and GYMs, suggesting a biosynthetically conserved relative configuration at carbon C-4 among these toxins.

The isolation and structural elucidation of a new iridoid glycoside from Cymbaria dahurica L.

2018 ◽  
Vol 73 (6) ◽  
pp. 377-379 ◽  
Author(s):  
Cui-Lan Bai ◽  
Qing-Hu Wang ◽  
Yan-Hua Xu ◽  
Jun-Sheng Han ◽  
Yin-Ping Bao
Keyword(s):  
Quantum Coherence ◽  
Nuclear Overhauser Effect ◽  
Multiple Bond ◽  
2D Nmr ◽  
Iridoid Glycoside ◽  
Correlation Spectroscopy ◽  
Etoac Extract ◽  
Overhauser Effect ◽  
Nuclear Overhauser ◽  
C Nmr

AbstractA new iridoid glycoside, namely, cymdahoside A (1), together with two known ones, 2 and 3, were isolated from the EtOAc extract of Cymbaria dahurica. The structure elucidation of 1 was carried out by one-dimensional (1D) NMR (1H and 13C NMR) and 2D NMR (correlation spectroscopy, heteronuclear single-quantum coherence, heteronuclear multiple-bond correlation and nuclear Overhauser effect spectroscopy) spectral analyses.

scholarly journals Experimental and theoretical study of a novel naphthoquinone Schiff base

2018 ◽  
Vol 16 (1) ◽  
pp. 1115-1121
Author(s):  
Güvenç Görgülü
Keyword(s):  
Density Functional Theory ◽  
Schiff Base ◽  
Density Functional ◽  
Active Agent ◽  
Theoretical Data ◽  
Basis Set ◽  
Magnetic Data ◽  
Functional Theory ◽  
Ft Ir ◽  
C Nmr

AbstractA novel Schiff base was synthesized and characterized by spectroscopic and theoretical methods. A potentially active agent 4-(2-hydroxy-5-methylphenylimino)naphthalen-1(4H)-one (PINQ) was designed and synthesized. The synthesis was carried out by a condensation reaction of 1-4-naphthoquinone and 2-amino-4-methyl phenol. The spectral and structural properties of the PINQ molecule were investigated by elemental analysis, 1H- and 13C-NMR, FT-IR and Uv-vis spectroscopies. The energetic, atomic, electronic, molecular, vibrational and magnetic data were theoretically obtained using density functional theory (DFT) at B3LYP level with 6-311++G(d,p) basis set. Chemical shifts were calculated using gauge-invariant atomic orbital (GIAO) method. UV-vis spectrum for the title compound was also obtained by time-dependent density functional theory (TD-DFT). The theoretical and experimental results were compared and interpreted. The theoretical data obtained from 1H- and 13C-NMR, FT-IR and Uv-vis spectroscopies were quite compatible with experimental ones.

Nontemplate synthesis, characterization and theoretical study of tetraazamacrocycles

2012 ◽  
Vol 23 (1) ◽  
pp. 121-127
Author(s):  
İbrahim Șen ◽  
Cem Burak Yildiz ◽  
Akın Azizoğlu
Keyword(s):  
Density Functional ◽  
Basis Sets ◽  
Frontier Molecular Orbital ◽  
Spectroscopic Techniques ◽  
Functional Theory ◽  
Hartree Fock ◽  
H Nmr ◽  
Ft Ir ◽  
Molecular Electrostatic Potential Maps ◽  
C Nmr

Abstract The syntheses of new tetraaza macrocyclic compounds of variable ring sizes by non-template methods and their characterization with the help of elemental analysis and spectroscopic techniques (FT-IR, 1H-NMR, and 13C-NMR) have been reported in detail. The vibrational frequencies determined experimentally are compared with those obtained theoretically from density functional theory (DFT) and Hartree-Fock (HF) calculations. The comparisons between the experimental and theoretical results indicate that B3LYP level with both the 3-21G(d) and 6-31G+(d,p) basis sets is able to provide satisfactory results for predicting IR properties. The frontier molecular orbital diagrams and molecular electrostatic potential maps of title compounds have been also calculated and visualized at the B3LYP/6-31G+(d,p) level of theory.

scholarly journals Spectroscopic (FT-IR, FT-Raman, UV, 1H and 13C NMR) insights, electronic profiling and DFT computations on ({(E)-[3-(1H-imidazol-1-yl)-1-phenylpropylidene] amino}oxy)(4-nitrophenyl)methanone, an imidazole-bearing anti-Candida agent

2018 ◽  
Vol 16 (1) ◽  
pp. 50-63 ◽  
Author(s):  
Lamya H. Al-Wahaibi ◽  
Munusamy Govindarajan ◽  
Ali A. El-Emam ◽  
Mohamed I. Attia
Keyword(s):  
Density Functional Theory ◽  
Title Compound ◽  
Density Functional ◽  
Orbital Method ◽  
Functional Theory ◽  
Nmr Characterization ◽  
Td Dft ◽  
Ft Ir ◽  
C Nmr ◽  
Ft Raman

AbstractThe anti-Candida agent, ({(E)-[3-(1H-imidazol-1-yl)-1-phenylpropylidene]amnio}oxy(4-nitropheny) methanone (IPAONM), was subjected to comprehensive spectroscopic (FT-IR, FT-Raman, UV–Vis 1H and 13C NMR) characterization as well as Hartree Fock and density functional theory computation studies. The selected optimized geometric bond lengths and bond angles of the IPAONM molecule were compared with the experimental values. The calculated wavenumbers have been scaled and compared with the experimental spectra. Mulliken charges and natural bond orbital analysis of the title molecule were calculated and interpreted. The energy and oscillator strengths of the IPAONM molecule were calculated by time-dependent density functional theory (TD-DFT). In addition, frontier molecular orbitals and molecular electrostatic potential diagram of the title compound were computed and analyzed. A study on the electronic properties, such as HOMO, HOMO-1, LUMO and LUMO+1 energies was carried out using TD-DFT approach. The 1H and 13C NMR chemical shift values of the title compound were calculated by the gauge independent atomic orbital method and compared with the experimental results.

Preparation, characterization, and antioxidant properties of polystyrenes with 4-methoxyphenol end groups

1983 ◽  
Vol 61 (1) ◽  
pp. 124-127 ◽  
Author(s):  
Brian K. Hunter ◽  
Kenneth E. Russell ◽  
Ataa K. Zaghloul
Keyword(s):  
Molecular Weight ◽  
Nuclear Overhauser Effect ◽  
Average Molecular Weight ◽  
Antioxidant Properties ◽  
Low Molecular Weight ◽  
Nmr Studies ◽  
Overhauser Effect ◽  
End Groups ◽  
Nuclear Overhauser ◽  
C Nmr

Polystyrenes with 4-methoxyphenol end groups have been prepared by the cationic polymerization of styrene in the presence of the phenol. The products range from 1:1 adduct to polymer of number-average molecular weight close to 3000. The 1:1 adduct separated from the reaction mixture was shown by nuclear Overhauser effect studies to be 2-(1-methylbenzyl)-4-methoxyphenol. Only about half of the polymer molecules have 4-methoxyphenol end groups. 13C nmr studies indicate that the polystyrene chains are attached principally at the 2-position of the phenol. The activity of the polymer as an antioxidant is comparable to that of corresponding low molecular weight methoxyphenols including butylated hydroxyanisole.

Synthesis and spectral evaluation of 5,10,15,20-tetrakis(3,4-dibenzyloxyphenyl)porphyrin

2017 ◽  
Vol 23 (2) ◽  
pp. 79-83
Author(s):  
Cynthia P. Tidwell ◽  
Prakash Bharara ◽  
Kenneth A. Belmore ◽  
Qiaoli Liang ◽  
Gregory W. Dye ◽  
...  
Keyword(s):  
High Resolution Mass Spectrometry ◽  
Nuclear Overhauser Effect ◽  
Soret Band ◽  
Molar Absorptivity ◽  
H Nmr ◽  
Maldi Tof ◽  
Overhauser Effect ◽  
Spectral Evaluation ◽  
Nuclear Overhauser ◽  
C Nmr

AbstractPorphyrins are of interest in many applications that involve electron transfer and absorption of light, such as solar energy and photodynamic cancer therapy. The newly synthesized 5,10,15,20-tetrakis(3,4-dibenzyloxyphenyl)porphyrin, TDBOPP, was characterized using 1H NMR, 13C NMR, UV-vis and fluorescence spectroscopy and MALDI-TOF/TOF high resolution mass spectrometry. Standard 1H NMR and 13C NMR experiments coupled with nuclear Overhauser effect (NOE) experiments confirmed the structure of the compound. The expected M+ and [M+H]+ ions are observed in the MALDI-TOF/TOF mass spectrum. The UV-vis absorption spectrum of TDBOPP shows a Soret band at 424 nm and three Q bands at 519 nm, 556 nm, and 650 nm with molar absorptivity 3.6×105 cm−1m−1, 1.6×104 cm−1m−1, 1.0×104 cm−1m−1 and 5.3×103 cm−1m−1, respectively. Excitation at 424 nm gives emission at 650 nm. The quantum yield of the porphyrin is 0.11.

An investigation of the rotational isomers of N-acetyl-2,2-dimethyloxazolidine and related compounds by nuclear magnetic resonance spectroscopy and molecular mechanics

1992 ◽  
Vol 70 (1) ◽  
pp. 165-172 ◽  
Author(s):  
Wesley G. Taylor ◽  
Tse Wai Hall ◽  
Carl E. Schreck
Keyword(s):  
Nmr Spectroscopy ◽  
Molecular Mechanics ◽  
Nuclear Overhauser Effect ◽  
Resonance Spectroscopy ◽  
Rotational Isomer ◽  
Rotational Isomers ◽  
Overhauser Effect ◽  
Nuclear Overhauser ◽  
Related Compounds ◽  
C Nmr

The 15 2,2-dimethyloxazolidines described here were found to exist in solution predominantly as a single rotational isomer, unlike N-acetyloxazolidine (1), N-acetyl-2-methyloxazolidine (2), N-acetyl-2-(n-octyl)oxazolidine (3), and other known 2-substituted N-acyloxazolidines. Using 13C NMR spectroscopy, activation energies for interconversion of the E (minor) and Z (major) rotational isomers of 1–3 were determined from coalescence temperature measurements in pyridine-d5. A sample of N-acetyl-2,2-dimethyloxazolidine (4) was isolated for comparison. The rotational isomer of 4 was found by two-dimensional nuclear Overhauser effect spectroscopy (NOESY) to possess the Z (or trans) stereochemistry. Molecular mechanics (MMX) calculations on the E and Z isomers of 1–4 helped to account for these findings. The conformation of the energy-minimized structures resembled a C-5 envelope. Samples of N-aroyl-2,2-dimethyloxazolidines (5a–5n) were isolated and the rotational isomers were assigned the Z stereochemistry by NOESY and 13C NMR experiments. Most of these 2,2-dimethyloxazolidines were ineffective in a bioassay for mosquito repellent activity. Keywords: N-acyloxazolidines, N-aroyloxazolidines, NMR spectroscopy, rotational isomerism, molecular mechanics.

Synthesis of New α-Amino Phosphonates Containing 3-Amino-4(3H) Quinazolinone Moiety as Anticancer and Antimicrobial Agents: DFT, NBO, and Vibrational Studies

2018 ◽  
Vol 15 (2) ◽  
pp. 286-296 ◽  
Author(s):  
Mohamed K. Awad ◽  
Mahmoud F. Abdel-Aal ◽  
Faten M. Atlam ◽  
Hend A. Hekal
Keyword(s):  
Biological Activity ◽  
Cell Line ◽  
Quantum Chemical ◽  
Density Functional ◽  
Carcinoma Cell ◽  
Liver Carcinoma ◽  
Anticancer Activities ◽  
Functional Theory ◽  
Ft Ir ◽  
Good Agreement

Aim and Objective: Synthesis of new .-aminophosphonates containing quinazoline moiety through Kabachnik-Fields reaction in the presence of copper triflate catalyst [32], followed by studying their antimicrobial activities and in vitro anticancer activities against liver carcinoma cell line (HepG2) with the hope that new anticancer agents could be developed. Also, the quantum chemical calculations are performed using density functional theory (DFT) to study the effect of the changes of molecular and electronic structures on the biological activity of the investigated compounds. Materials and Method: The structures of the synthesized compounds are confirmed by FT-IR, 1H NMR, 13C NMR, 31P NMR and MS spectral data. The synthesized compounds show significant antimicrobial and also remarkable cytotoxicity anticancer activities against liver carcinoma cell line (HepG2). Density functional theory (DFT) was performed to study the effect of the molecular and electronic structure changes on the biological activity. Results: It was found that the electronic structure of the substituents affects on the reaction yield. The electron withdrawing substituent, NO2 group 3b, on the aromatic aldehydes gave a good yield more than the electron donating substituent, OH group 3c. The electron deficient on the carbon atom of the aldehydic group may increase the interaction of the Lewis acid (Cu(OTf)2) and the Lewis base (imine nitrogen), and accordingly, facilitate the formation of imine easily, which is attacked by the nucleophilic phosphite species to give the α- aminophosphonates. Conclusion: The newly synthesized compounds exhibit a remarkable inhibition of the growth of Grampositive, Gram-negative bacteria and fungi at low concentrations. The cytotoxicity of the synthesized compounds showed a significant cytotoxicity against the liver cancer cell line (HepG 2). Also, it was shown from the quantum chemical calculations that the electron-withdrawing substituent increases the biological activity of the α-aminophosphonates more than the electron donating group which was in a good agreement with the experimental results. Also, a good agreement between the experimental FT-IR and the calculated one was found.

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