scholarly journals Quantum Chemical and Experimental Studies of an Unprecedented Reaction Pathway of Nucleophilic Substitution of 2-Bromomethyl-1,3-thiaselenole with 1,3-Benzothiazole-2-thiol Proceeding Stepwise at Three Different Centers of Seleniranium Intermediates

Molecules ◽  
2021 ◽  
Vol 26 (21) ◽  
pp. 6685
Author(s):  
Svetlana V. Amosova ◽  
Vladimir A. Shagun ◽  
Nataliya A. Makhaeva ◽  
Irina A. Novokshonova ◽  
Vladimir A. Potapov
Keyword(s):  
Quantum Chemical ◽  
Ring Opening ◽  
Reaction Pathway ◽  
Experimental Studies ◽  
Selenium Atom ◽  
Reaction Products ◽  
Vinyl Sulfide ◽  
Thiolate Anion ◽  
High Yields ◽  
Membered Heterocycle

The results of quantum chemical and experimental studies of the reaction of 2-bromomethyl-1,3-thiaselenole with 1,3-benzothiazole-2-thiol made it possible to discover the unprecedented pathway of this reaction, which proceeds stepwise at three different centers of seleniranium intermediates. The first stage includes an attack of thiolate anion at the selenium atom of the seleniranium cation accompanied by ring opening with the formation of (Z)-2-[(1,3-benzothiazol-2-ylsulfanyl)selanyl]ethenyl vinyl sulfide, which is converted to six-membered heterocycle, 2-(2,3-dihydro-1,4-thiaselenin-2-ylsulfanyl)-1,3-benzothiazole, in a 99% yield. The latter compound undergoes rearrangement with ring contraction producing five-membered heterocycle, 2-[(1,3-thiaselenol-2-ylmethyl)sulfanyl]-1,3-benzothiazole, in a 99% yield (the thermodynamic product). The formation of 1,2-bis[(Z)-2-(vinylsulfanyl)ethenyl] diselenide is the result of the disproportionation of (Z)-2-[(1,3-benzothiazol-2-ylsulfanyl)selanyl]ethenyl vinyl sulfide. Thus, based on the quantum chemical and experimental studies, a regioselective synthesis of the reaction products in high yields was developed.

Mechanistic Investigation of Rh(I)-Catalyzed Asymmetric Suzuki-Miyaura Coupling with Racemic Allyl Halides

2019 ◽  
Author(s):  
Lucy van Dijk ◽  
Ruchuta Ardkhean ◽  
Mireia Sidera ◽  
Sedef Karabiyikoglu ◽  
Özlem Sari ◽  
...  
Keyword(s):  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Experimental Studies ◽  
Mechanistic Investigation ◽  
Allyl Halides

A mechanism for Rh(I)-catalyzed asymmetric Suzuki-Miyaura coupling with racemic allyl halides is proposed based on a combination of experimental studies and quantum chemical calculations. <br>

scholarly journals Synthesis and Antiproliferative Activity of Phosphorus Substituted 4-Cyanooxazolines, 2-Aminocyanooxazolines, 2-Iminocyanooxazolidines and 2-Aminocyanothiazolines by Rearrangement of Cyanoaziridines

Molecules ◽  
2021 ◽  
Vol 26 (14) ◽  
pp. 4265
Author(s):  
Victor Carramiñana ◽  
Ana M. Ochoa de Ochoa de Retana ◽  
Francisco Palacios ◽  
Jesús M. de los de los Santos
Keyword(s):  
Ring Opening ◽  
Human Lung ◽  
Ring Expansion ◽  
Moderate Activity ◽  
A549 Cell Line ◽  
One Pot ◽  
Acidic Conditions ◽  
Lung Adenocarcinoma A549 ◽  
High Yields

Several phosphorus-substituted N-acylated cyanoaziridines 2 and N-carbamoylated cyanoziridines 5 were prepared in good to high yields. N-Acylated cyanoaziridines 2 were used, after ring expansion, in an efficient synthesis of oxazoline derivative 3a and in a completely regio-controlled reaction in the presence of NaI. Conversely, N-carbamoyl cyanoaziridines 5 reacted with NaI to obtain a regioisomeric mixture of 2-aminocyanooxazolines 7. Mild acidic conditions can be used for the isomerization of N-thiocarbamoyl cyanoaziridine 6a into a 2-aminocyanothiazoline derivative 8a by using BF3·OEt2 as a Lewis acid. Likewise, a one pot reaction of NH-cyanoaziridines 1 with isocyanates obtained 2-iminocyanooxazolidines 9 regioselectively. This synthetic methodology involves the addition of isocyanates to starting cyanoaziridines to obtain N-carbamoyl cyanoaziridines 5, which after the ring opening, reacts with a second equivalent of isocyanate to give the final 2-imino cyanooxazolidines 9. In addition, the cytotoxic effect on the cell lines derived from human lung adenocarcinoma (A549) was also screened. 2-Iminooxazolidines 9 exhibited moderate activity against the A549 cell line in vitro. Furthermore, a selectivity towards cancer cells (A549) over non-malignant cells (MCR-5) was detected.

scholarly journals Prebiotic Route to Thymine from Formamide—A Combined Experimental–Theoretical Study

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2248
Author(s):  
Lukáš Petera ◽  
Klaudia Mrazikova ◽  
Lukas Nejdl ◽  
Kristyna Zemankova ◽  
Marketa Vaculovicova ◽  
...  
Keyword(s):  
Formic Acid ◽  
Quantum Chemical ◽  
Prebiotic Chemistry ◽  
Theoretical Study ◽  
Reaction Pathway ◽  
Hydrolysis Product ◽  
Current Paper ◽  
Reaction Conditions ◽  
Chemical Modeling ◽  
Chemistry Research

Synthesis of RNA nucleobases from formamide is one of the recurring topics of prebiotic chemistry research. Earlier reports suggest that thymine, the substitute for uracil in DNA, may also be synthesized from formamide in the presence of catalysts enabling conversion of formamide to formaldehyde. In the current paper, we show that to a lesser extent conversion of uracil to thymine may occur even in the absence of catalysts. This is enabled by the presence of formic acid in the reaction mixture that forms as the hydrolysis product of formamide. Under the reaction conditions of our study, the disproportionation of formic acid may produce formaldehyde that hydroxymethylates uracil in the first step of the conversion process. The experiments are supplemented by quantum chemical modeling of the reaction pathway, supporting the plausibility of the mechanism suggested by Saladino and coworkers.

Analysis of Ring-Opening Reaction between Bisphenol A and Epichlorohydrin by the Method of Quantum Chemical Calculating

2011 ◽  
Vol 221 ◽  
pp. 180-183 ◽  
Author(s):  
Jian Li ◽  
Xun Zhang Yu ◽  
Kai Zhang
Keyword(s):  
Bisphenol A ◽  
Density Function ◽  
Quantum Chemical ◽  
Ring Opening ◽  
Function Theory ◽  
Dft Method ◽  
Density Function Theory ◽  
Ring Opening Reaction ◽  
Calculation Results ◽  
Opening Process

The ring-opening reaction between bisphenol A and epichlorohydrin was calculated by Gaussian03. The Density Function Theory (DFT) method were employed to study the geometry structures of bisphenol A and epichlorohydrin and the product was obtained on the base of B3LYP/6-31G+ model in this paper. The transitional states (Ts1, Ts2) during the ring-opening process were found by TS method and the energy changing of the system was proved by IRC calculation. Results showed that the energy reduced by 64.37726kJ/mol during the ring-opening process. The product was confirmed to be thermodynamically stable.

scholarly journals Lactamomethylation of alkylphenols: synthesis and quantum-chemical study of the reaction pathway

2021 ◽  
pp. 103424
Author(s):  
Stepan V. Vorobyev ◽  
Olga V. Primerova ◽  
Sergey Yu. Bylikin ◽  
Vladimir N. Koshelev
Keyword(s):  
Quantum Chemical ◽  
Reaction Pathway ◽  
Quantum Chemical Study ◽  
Chemical Study

Theoretical and Experimental Studies of Third-Order Nonlinear Optical Susceptibilities of New p-N,N'-Diamethylaniline Tetrathiafulvalene Derivatives

2000 ◽  
Vol 660 ◽  
Author(s):  
B. Sahraoui ◽  
K.J. Pluciński ◽  
M. Makowaska-Janusik ◽  
I. V. Kityk ◽  
M. Salle ◽  
...  
Keyword(s):  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Nonlinear Optical ◽  
Experimental Studies ◽  
Physical Nature ◽  
Four Wave Mixing ◽  
Wave Mixing ◽  
Electronic Contribution ◽  
Optical Nonlinearities ◽  
Third Order

ABSTRACTA study was made of third-order nonlinear optical susceptibilities of new tetrathiafulvalene (TTF) derivatives, using the degenerate four wave mixing (DFWM) method, as well as complex quantum chemical calculations. To understand the physical nature of the optical nonlinearities, we separated their electronic and nuclear contributions. We found that the electronic contribution to these nonlinearities predominated. Our investigations suggest that TTF may be a highly promising material for nonlinear optics (NLO).

One-Step Simultaneous Differential Scanning Calorimetry-FTIR Microspectroscopy to Quickly Detect Continuous Pathways in the Solid-State Glucose/Asparagine Maillard Reaction

2013 ◽  
Vol 96 (6) ◽  
pp. 1362-1364 ◽  
Author(s):  
Deng-Fwu Hwang ◽  
Tzu-Feng Hsieh ◽  
Shan-Yang Lin
Keyword(s):  
Differential Scanning Calorimetry ◽  
Solid State ◽  
Maillard Reaction ◽  
Reaction Pathway ◽  
Molar Ratio ◽  
Maillard Reaction Products ◽  
Reaction Products ◽  
Scanning Calorimetry ◽  
Ftir Microspectroscopy ◽  
Amadori Product

Abstract The stepwise reaction pathway of the solid-state Maillard reaction between glucose (Glc) and asparagine (Asn) was investigated using simultaneous differential scanning calorimetry (DSC)-FTIR microspectroscopy. The color change and FTIR spectra of Glc-Asn physical mixtures (molar ratio = 1:1) preheated to different temperatures followed by cooling were also examined. The successive reaction products such as Schiff base intermediate, Amadori product, and decarboxylated Amadori product in the solid-state Glc-Asn Maillard reaction were first simultaneously evidenced by this unique DSC-FTIR microspectroscopy. The color changed from white to yellow-brown to dark brown, and appearance of new IR peaks confirmed the formation of Maillard reaction products. The present study clearly indicates that this unique DSC-FTIR technique not only accelerates but also detects precursors and products of the Maillard reaction in real time.

scholarly journals Premium biofuels from straw – production of advanced biofuels using the Sylvan process

Paliva ◽  
2020 ◽  
pp. 87-92
Author(s):  
Jaroslav Aubrecht ◽  
David Kubička
Keyword(s):  
Heterogeneous Catalysts ◽  
Cetane Number ◽  
Reaction Products ◽  
Advanced Biofuels ◽  
Transportation Fuels ◽  
Noble Metal Catalysts ◽  
Eu Directive ◽  
Increasing Demand ◽  
High Yields ◽  
Middle Distillates

The increasing demand for transportation fuels, especially middle distillates, stimulates the research of new strategies to obtain or synthesize biofuels. The processing of lignocellulosic biomass (for example straw) is a process of great interest, because after its hydrolysis and subsequent dehydration of the resulting sugar monomers, very valuable substances including furfural are obtained. Then, furfural is selectively hydrogenated to 2-methylfuran, sylvan, that is the basic “building block” in the Sylvan process. This manuscript summarizes the knowledge on Sylvan process as a promising way of biofuels synthesis. By sylvan condensing with aldehydes, ketones or even 2-methylfuran itself, it is possible to prepare C13-C16 oxygenates in high yields up to 100 % under mild reaction conditions (30 - 60 °C) over various heterogeneous catalysts. Based on the overview, the heterogeneous catalysts are preferred and the immobilized sulfonic acids are the most active catalysts, however, expensive. The reaction products then may be hydrodeoxygenated commonly over supported noble metal catalysts to provide premium quality C13-C16 hydrocarbons to produce diesel or kerosene. These fractions have great low-temperature properties such as CFPP (-50 °C) or cetane number (70-72). According to the proposed sustainability prediction, this process could be sustainable in the Czech Republic, where 30 % of produced wheat straw could be used for the production of 130 kt advanced biofuels by Sylvan process required by EU directive RED II. Finally, the future approaches have been suggested.

scholarly journals Reactions of Titanocene- and Zirconocene-Bis(trimethylsilyl)acetylene Complexes with Selected Heterocyclic and Aromatic NH and OH Acid Compounds

2007 ◽  
Vol 72 (4) ◽  
pp. 475-491 ◽  
Author(s):  
Perdita Arndt ◽  
Vladimir V. Burlakov ◽  
Ulrike Jäger-Fiedler ◽  
Marcus Klahn ◽  
Anke Spannenberg ◽  
...  
Keyword(s):  
Bond Activation ◽  
Reaction Pathway ◽  
Reaction Products ◽  
X Ray ◽  
X Ray Crystallography

The titanocene complexes Cp'2Ti(η2-Me3SiC2SiMe3) (Cp' = Cp (1), Cp* (2)) react with pyrrole under the formation of the titanium(III) mono-N-pyrrolides Cp'2Ti(NC4H4) (Cp' = Cp (6), Cp* (7)); whereas the corresponding zirconocene system Cp2Zr(η2-Me3SiC2SiMe3)(thf) (3) forms in a different reaction pathway first the Cp2Zr(NC4H4)[C(SiMe3)=CH(SiMe3)] (8) and then the zirconium(IV) bis-N-pyrrolide Cp2Zr(NC4H4)2 (11). With Cp*2Zr(η2-Me3SiC2SiMe3) (4) and pyrrole, the zirconium(IV) mono-N-pyrrolide with an agostic alkenyl group Cp*2Zr(NC4H4)[C(SiMe3)=CH(SiMe3)] (9) was obtained. In the reaction of the ethylenebistetrahydroindenyl (ebthi) complex rac-(ebthi)Zr(η2-Me3SiC2SiMe3) (5) with 2,3,5,6-tetrafluoroaniline under N-H bond activation, a complex with an agostic alkenyl group rac-(ebthi)Zr(NH-C6HF4)[C(SiMe3)=CH(SiMe3)] (10) was formed. Compound 10 reacts with additional 2,3,5,6-tetrafluoroaniline to give the bisanilide rac-(ebthi)Zr(NH-C6HF4)2 (12) which was obtained directly from 5 with two equivalents of 2,3,5,6-tetrafluoroaniline. In reactions of complex 5 with unsubstituted aniline to rac-(ebthi)Zr(NH-C6H5)2 (13) and with pentafluorophenol to bisphenolate rac-(ebthi)Zr(O-C6F5)2 (14), no intermediates could be isolated. The new reaction products 6, 9, 10, 12, 13 and 14 were investigated by X-ray crystallography.

scholarly journals Multi Component Reactions under Increased Pressure: On the Mechanism of Formation of Pyridazino[5,4,3-de][1,6]naphthyridine Derivatives from Reaction of Malononitrile, Aldehyde and 2-Oxoglyoxalarylhydrazones in Q-Tubes

2017 ◽  
Author(s):  
Majdah A. AL-Johani ◽  
Khadijah M. Al-Zaydi ◽  
Sameera M. Mousally ◽  
Norah F. Alqahtani ◽  
Mohamed H. Elnagdi
Keyword(s):  
Crystal Structure ◽  
Reaction Pathway ◽  
Aromatic Aldehydes ◽  
Reaction Products ◽  
Mechanism Of Formation ◽  
X Ray ◽  
Alternate Pathway ◽  
Considerable Research ◽  
Increased Pressure ◽  
Chemical Evidence

The considerable biological and medicinal activities of pyridazines has stimulated considerable research on efficient syntheses of these derivatives. In the last decade, microwave irradiation has generally been used for the energy source. As demonstrated in recent studies, pressure reactor &ldquo;Q-tubes&rdquo; may be used to accelerate several of these reactions in a more optimal and safer manner (compared to microwaves). In these studies there has been postulated a pathway for the formation of pyridazino[5,4,3-de][1,6]naphthyridine derivatives . In this paper we consider this pathway, and an alternate pathway, for several reactions. Contrary to the suggestion in these studies the pathway in which initial dimerization of malononitrile was postulated could be excluded based on chemical evidence. The reactions performed were the reaction of arylhydrazonals 1a,b with benzylidinemalononitrile which afforded in Q-tube the 3-acyl-4-aryl-1-phenyl-6-amino-1,4-dihydropyridazines, and the reaction of arylhydrazonals 1a,b, malononitrile 9 and aromatic aldehydes 10a-g in Q-tubes which afforded the tricyclic systems 12a-n whose structure could be established by X-ray crystal structure determination. In conclusion, we have added to the work of the recent studies by excluding a reaction pathway for one of their reaction products.

Sign in / Sign up

Export Citation Format

Share Document