The phenyl vinyl ether–methanol complex: a model system for quantum chemistry benchmarking

• Dominic Bernhard,
• Fabian Dietrich,
• Mariyam Fatima,
• Cristóbal Pérez,
• Hannes C. Gottschalk,
• Axel Wuttke,
• Ricardo A. Mata,
• Martin A. Suhm,
• Melanie Schnell and
• Markus Gerhards

Beilstein J. Org. Chem. 2018, 14, 1642–1654, doi:10.3762/bjoc.14.140

• -docking motifs via the phenyl and vinyl moieties, with an additional less populated OH∙∙∙P(phenyl)-bound isomer detected only by microwave spectroscopy. The correct prediction of the energetic order of the isomers using quantum-chemical calculations turns out to be challenging and succeeds with a

• electronically excited (S1) state is analyzed, in which a destabilization of the OH∙∙∙O structure compared to the S0 state is observed experimentally and theoretically. Keywords: dispersion interactions; IR spectroscopy; quantum-chemical calculations; rotational spectroscopy; structure determination; weak

• Fourier transform microwave (CP-FTMW) spectroscopy. Comparing spectroscopic results with quantum-chemical calculations is often mandatory for the interpretation of experiments. Furthermore, such comparison enables a critical evaluation of the approximations used, comparing the relative stability of

[3 + 2]-Cycloaddition reaction of sydnones with alkynes

• Veronika Hladíková,
• Jiří Váňa and
• Jiří Hanusek

Beilstein J. Org. Chem. 2018, 14, 1317–1348, doi:10.3762/bjoc.14.113

• quantum chemical calculations (DFT/B3LYP-6-31G*) [81] steric effects were identified as the main factor influencing the ratio of both regioisomers. These calculations clearly proved the almost apolar character of both possible transition states giving 3- and 4-BPin substituted pyrazoles through bicyclic

Volatiles from three genome sequenced fungi from the genus Aspergillus

• Jeroen S. Dickschat,
• Ersin Celik and
• Nelson L. Brock

Beilstein J. Org. Chem. 2018, 14, 900–910, doi:10.3762/bjoc.14.77

• product 9 is observed. From A, a second cyclisation event results in D that yields 12 upon deprotonation. Alternatively, A can react by a 1,5-proton shift to E, followed by cyclisation to F and deprotonation to H. This mechanism is favoured by quantum chemical calculations [35] and provides a reasonable

An uracil-linked hydroxyflavone probe for the recognition of ATP

• Márton Bojtár,
• Péter Zoltán Janzsó-Berend,
• Dávid Mester,
• Dóra Hessz,
• Mihály Kállay,
• Miklós Kubinyi and
• István Bitter

Beilstein J. Org. Chem. 2018, 14, 747–755, doi:10.3762/bjoc.14.63

• ratiometric fluorescent nature. First, we examined the possible structure and the supramolecular interactions by quantum chemical calculations of our target compound, UHF (uracil-hydroxyflavone) and ATP (see Figure 1 for structures). The theoretical results indicated the possibility of base-pairing

Investigations towards the stereoselective organocatalyzed Michael addition of dimethyl malonate to a racemic nitroalkene: possible route to the 4-methylpregabalin core structure

• Denisa Vargová,
• Rastislav Baran and
• Radovan Šebesta

Beilstein J. Org. Chem. 2018, 14, 553–559, doi:10.3762/bjoc.14.42

• % determined by NMR). Using quantum chemical calculations, we propose approximate transition state models for the stereoselective Michael addition (Figure 2). Geometrical optimizations were performed at HF/6-31G* level and energies were further refined using M06-2X functional with 6-311+G** basis set

• purity of the major diastereomer (er 99:1). With the help of quantum-chemical calculations, we have proposed a transition state model for the Michael addition. Structures of pregabalin and methylpregabalin. Transition state models for the reaction of (R)-6 with dimethyl malonate using catalyst C7 (M06-2X

Recent advances on organic blue thermally activated delayed fluorescence (TADF) emitters for organic light-emitting diodes (OLEDs)

• Thanh-Tuân Bui,
• Fabrice Goubard,
• Malika Ibrahim-Ouali,
• Didier Gigmes and
• Frédéric Dumur

Beilstein J. Org. Chem. 2018, 14, 282–308, doi:10.3762/bjoc.14.18

• ° between the donor unit and the nearby phenylene linker for T29 and T30 was confirmed by quantum chemical calculations. Resulting from the almost perfect orthogonality, a good confinement of the electronic density of the two orbitals was obtained with a HOMO level predominantly located on the donor and a

Halogen-containing thiazole orange analogues – new fluorogenic DNA stains

• Aleksey A. Vasilev,
• Meglena I. Kandinska,
• Stanimir S. Stoyanov,
• Stanislava B. Yordanova,
• David Sucunza,
• Juan J. Vaquero,
• Obis D. Castaño,
• Stanislav Baluschev and
• Silvia E. Angelova

Beilstein J. Org. Chem. 2017, 13, 2902–2914, doi:10.3762/bjoc.13.283

• the newly synthesized dyes as DNA fluorogenic binders. A further study of several aspects (including quantum chemical calculations and experimental studies on the DNA binding mechanism) should be carried out on these dyes in order to exploit in details their promising properties. Experimental

Structure–property relationships and third-order nonlinearities in diketopyrrolopyrrole based D–π–A–π–D molecules

• Jan Podlesný,
• Lenka Dokládalová,
• Oldřich Pytela,
• Adam Urbanec,
• Milan Klikar,
• Numan Almonasy,
• Tomáš Mikysek,
• Jaroslav Jedryka,
• Iwan V. Kityk and
• Filip Bureš

Beilstein J. Org. Chem. 2017, 13, 2374–2384, doi:10.3762/bjoc.13.235

• generation. The experimental data were completed by quantum-chemical calculations and structure–property relationships were elucidated. Keywords: calculations; diketopyrrolopyrrole; electrochemistry; electronic spectra; push–pull; third-harmonic generation; Introduction Known for more than 40 years

Conjugated nitrosoalkenes as Michael acceptors in carbon–carbon bond forming reactions: a review and perspective

• Yaroslav D. Boyko,
• Valentin S. Dorokhov,
• Alexey Yu. Sukhorukov and
• Sema L. Ioffe

Beilstein J. Org. Chem. 2017, 13, 2214–2234, doi:10.3762/bjoc.13.220

• phosphinyl nitrosoalkenes NSA15 (derived from the corresponding α-bromooximes) with electron-rich nitrogen heterocycles to give adducts 69 is described and the comparison of electrophilic aromatic substitution (1) and cycloaddition (2) routes is discussed [59] (Scheme 24). Quantum-chemical calculations

Complexation of molecular clips containing fragments of diphenylglycoluril and benzocrown ethers with paraquat and its derivatives

• Leonid S. Kikot',
• Catherine Yu. Kulygina,
• Alexander Yu. Lyapunov,
• Svetlana V. Shishkina,
• Roman I. Zubatyuk,
• Tatiana Yu. Bogaschenko and
• Tatiana I. Kirichenko

Beilstein J. Org. Chem. 2017, 13, 2056–2067, doi:10.3762/bjoc.13.203

• paraquat (7) in solution is well correlated with the data for these complexes in the crystalline state revealed by quantum chemical calculations [41] except complexes with paraquat derivative 10 (Table 4). The calculated data show that the main contribution to the stabilization of the complexes in the

• with clips 1–6. Complex stability constants of molecular clips 1–5 with guests 7–10 in acetonitrile at 20 °C. Contribution of polyether oxygen atoms of molecular clips 1–5 to the binding of paraquat. The host–guest interaction energies are estimated by quantum chemical calculations (b97-D3/def2-tzvp

• (Figure 7). Within the row molecules are arranged by π–π stacking interactions between the side aromatic fragments of the clips with a centroid–centroid distance in the range of 3.51–3.71 Å. There are acetonitrile solvate molecules and hexafluorophosphate anions between neighboring rows. Quantum chemical

New electroactive asymmetrical chalcones and therefrom derived 2-amino- / 2-(1H-pyrrol-1-yl)pyrimidines, containing an N-[ω-(4-methoxyphenoxy)alkyl]carbazole fragment: synthesis, optical and electrochemical properties

• Daria G. Selivanova,
• Alexei A. Gorbunov,
• Olga A. Mayorova,
• Alexander N. Vasyanin,
• Igor V. Lunegov,
• Elena V. Shklyaeva and
• Georgii G. Abashev

Beilstein J. Org. Chem. 2017, 13, 1583–1595, doi:10.3762/bjoc.13.158

• comparison with the ground state takes place, as evidenced by the quantum-chemical calculations carried out with the help of the Fire Fly package [30][31] on a PGU Tesla supercomputer. All calculations of the dipole moments, HOMO and LUMO energies were performed on the B3LYP/6-31G* level for the gas phase

Conformational study of L-methionine and L-cysteine derivatives through quantum chemical calculations and ³J_HH coupling constant analyses

• Weslley G. D. P. Silva,
• Carolyne B. Braga and
• Roberto Rittner

Beilstein J. Org. Chem. 2017, 13, 925–937, doi:10.3762/bjoc.13.94

• analysis; cysteine; methionine; NMR spectroscopy; quantum chemical calculations; Introduction Amino acids constitute the building blocks of proteins and peptides, which play an important role in numerous biological processes [1][2]. However, their studies in both isolated and condensed phases have been

• quantum chemical calculations [16][17][18][19]. In spite of these many studies performed, there is still a lack of information about the effects that rule their conformational isomerism. Additionally, the conformational flexibility of both amino acids leads to a variety of low energy geometries, which

• insights about the main conformers and the operating effects in the compounds, both in isolated phase and in various aprotic solvents, 1H NMR spectroscopy and quantum chemical calculations, including natural bond orbitals (NBO), quantum theory of atoms in molecules (QTAIM), and noncovalent interactions

Metal-free hydroarylation of the side chain carbon–carbon double bond of 5-(2-arylethenyl)-3-aryl-1,2,4-oxadiazoles in triflic acid

• Anna S. Zalivatskaya,
• Dmitry S. Ryabukhin,
• Marina V. Tarasenko,
• Alexander Yu. Ivanov,
• Irina A. Boyarskaya,
• Elena V. Grinenko,
• Ludmila V. Osetrova,
• Eugeniy R. Kofanov and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2017, 13, 883–894, doi:10.3762/bjoc.13.89

• nitrogen may be protonated depending on the substituents attached to the heterocyclic system [50]. To investigate this issue in more detail we undertook a theoretical study on the protonation of 5-(2-phenylethenyl)-3-phenyl-1,2,4-oxadiazole (1a) by quantum-chemical calculations. Table 1 contains data

Synthesis and optical properties of new 5'-aryl-substituted 2,5-bis(3-decyl-2,2'-bithiophen-5-yl)-1,3,4-oxadiazoles

• Anastasia S. Kostyuchenko,
• Tatyana Yu. Zheleznova,
• Anton J. Stasyuk,
• Aleksandra Kurowska,
• Wojciech Domagala,
• Adam Pron and
• Alexander S. Fisyuk

Beilstein J. Org. Chem. 2017, 13, 313–322, doi:10.3762/bjoc.13.34

• induce non-planarity due to steric hindrance, which lowers the effective conjugation. This problem will be discussed in detail in the section devoted to quantum chemical calculations. When excited by UV light, all studied compounds emit blue (468, 473 nm) or bluish-green (499, 501) light (Table 2

• observed in D–A–D-type conjugated molecules [28]. DFT calculations To gain a deeper understanding of the electronic and photophysical properties of the synthesized 5'-aryl-substituted 2,5-bis(3-decyl-2,2'-bithiophen-5-yl)-1,3,4-oxadiazoles we have performed quantum-chemical calculations for four

Regiochemistry of cyclocondensation reactions in the synthesis of polyazaheterocycles

• Patrick T. Campos,
• Leticia V. Rodrigues,
• Andrei L. Belladona,
• Caroline R. Bender,
• Juliana S. Bitencurt,
• Fernanda A. Rosa,
• Davi F. Back,
• Helio G. Bonacorso,
• Nilo Zanatta,
• Clarissa P. Frizzo and
• Marcos A. P. Martins

Beilstein J. Org. Chem. 2017, 13, 257–266, doi:10.3762/bjoc.13.29

• quantum-chemical calculations were used to understand the regiochemistry of the obtained products. Results and Discussion β-Enaminodiketone 1, which is a key precursor for the synthesis of polyazaheterocyclic compounds, was synthesized by methods previously described by our research group [17][18][19][20

Benzothiadiazole oligoene fatty acids: fluorescent dyes with large Stokes shifts

• Lukas J. Patalag and
• Daniel B. Werz

Beilstein J. Org. Chem. 2016, 12, 2739–2747, doi:10.3762/bjoc.12.270

• a Wittig salt with a longer alkyl chain the synthesis of the fatty acid 11d with a chain of 21 carbon atoms in addition to the BTD unit was equally feasible. Spectroscopic properties and quantum chemical calculations If one follows the oligoene chain and includes the two s-cis-shaped double bonds of

Combined experimental and theoretical studies of regio- and stereoselectivity in reactions of β-isoxazolyl- and β-imidazolyl enamines with nitrile oxides

• Ilya V. Efimov,
• Marsel Z. Shafikov,
• Nikolai A. Beliaev,
• Natalia N. Volkova,
• Tetyana V. Beryozkina,
• Wim Dehaen,
• Zhijin Fan,
• Viktoria V. Grishko,
• Gert Lubec,
• Pavel A. Slepukhin and
• Vasiliy A. Bakulev

Beilstein J. Org. Chem. 2016, 12, 2390–2401, doi:10.3762/bjoc.12.233

• with inverse electron demand, similarly to the reaction of enamines with azides [37]. To gain deeper insights into the mechanism of the cycloaddition between nitrile oxides and enamines, quantum chemical calculations were carried out using the Gaussian 09 [38] programs package at B3LYP/def2-TZVP [39

Organometallic chemistry

• Bernd F. Straub,
• Rolf Gleiter,
• Claudia Meier and
• Lutz H. Gade

Beilstein J. Org. Chem. 2016, 12, 2216–2221, doi:10.3762/bjoc.12.213

• improved understanding of this industrially important process was achieved by a combination of ligand design for the rhodium catalysts, kinetic studies, and high-level quantum-chemical calculations [126][135][142][145][146][152][155]. In 2006, he initiated the foundation of the “Catalysis Research

Superelectrophilic activation of 5-hydroxymethylfurfural and 2,5-diformylfuran: organic synthesis based on biomass-derived products

• Dmitry S. Ryabukhin,
• Dmitry N. Zakusilo,
• Mikhail O. Kompanets,
• Anton A.Tarakanov,
• Irina A. Boyarskaya,
• Tatiana O. Artamonova,
• Mikhail A. Khohodorkovskiy,
• Iosyp O. Opeida and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2016, 12, 2125–2135, doi:10.3762/bjoc.12.202

• (Scheme 1). All species A, B, C, and D may play a role as reactive intermediates derived from 1a and 2 in superacids. To estimate the electrophilic properties of cations A, B, C, and D we performed quantum chemical calculations by the DFT method (Table 1). HOMO and LUMO energies, global electrophilicity

Experimental and theoretical insights in the alkene–arene intramolecular π-stacking interaction

• Valeria Corne,
• Ariel M. Sarotti,
• Carmen Ramirez de Arellano,
• Rolando A. Spanevello and
• Alejandra G. Suárez

Beilstein J. Org. Chem. 2016, 12, 1616–1623, doi:10.3762/bjoc.12.158

• , Universidad de Valencia, Valencia 46100, Spain 10.3762/bjoc.12.158 Abstract Chiral acrylic esters derived from biomass were developed as models to have a better insight in the aryl–vinyl π-stacking interactions. Quantum chemical calculations, NMR studies and experimental evidences demonstrated the presence

Synthesis of 2,1-benzisoxazole-3(1H)-ones by base-mediated photochemical N–O bond-forming cyclization of 2-azidobenzoic acids

• Daria Yu. Dzhons and
• Andrei V. Budruev

Beilstein J. Org. Chem. 2016, 12, 874–881, doi:10.3762/bjoc.12.86

• to quantum-chemical calculations, the energy barrier of this rearrangement is approximately 40 kJ mol−1 [51], with the limiting step being the formation of B. Therefore, the direction of this reaction solely depends on the conversion of A and formation of C. Dyall et al. [52][53] have proposed a

Recent highlights in biosynthesis research using stable isotopes

• Jan Rinkel and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2015, 11, 2493–2508, doi:10.3762/bjoc.11.271

• subsequent 1,2-hydride migration to 63 followed by ring closure gives 64, which is deprotonated to give pentalenene (65). Quantum chemical calculations led to the suggestion of the protoilludyl cation 66 as central intermediate between 61 and 64 (pathway B), which is directly formed from 61 [72

Deproto-metallation of N-arylated pyrroles and indoles using a mixed lithium–zinc base and regioselectivity-computed CH acidity relationship

• Mohamed Yacine Ameur Messaoud,
• Ghenia Bentabed-Ababsa,
• Madani Hedidi,
• Aïcha Derdour,
• Floris Chevallier,
• Yury S. Halauko,
• Oleg A. Ivashkevich,
• Vadim E. Matulis,
• Laurent Picot,
• Valérie Thiéry,
• Thierry Roisnel,
• Vincent Dorcet and
• Florence Mongin

Beilstein J. Org. Chem. 2015, 11, 1475–1485, doi:10.3762/bjoc.11.160

• recently [42][52]. The results of quantum chemical calculations on CH acidity of the different N-arylated pyrroles 1 and indoles 2, obtained both for THF solution (Figure 5) and gas phase (see Supporting Information File 1), are presented in the current paper. A potential acidity of the methoxy groups in

Antioxidant potential of curcumin-related compounds studied by chemiluminescence kinetics, chain-breaking efficiencies, scavenging activity (ORAC) and DFT calculations

• Adriana K. Slavova-Kazakova,
• Silvia E. Angelova,
• Timur L. Veprintsev,
• Petko Denev,
• Davide Fabbri,
• Maria Antonietta Dettori,
• Maria Kratchanova,
• Vladimir V. Naumov,
• Aleksei V. Trofimov,
• Rostislav F. Vasil’ev,
• Giovanna Delogu and
• Vessela D. Kancheva

Beilstein J. Org. Chem. 2015, 11, 1398–1411, doi:10.3762/bjoc.11.151

• quantum chemical calculations (see section “Model 4: DFT calculations”) for BDE of 13 and studied compounds in water medium confirm our hypothesis. It is noteworthy that the literature data for individual phenolic compounds acquired with ORAC as a model system are rather poor in comparison with the data

• to act as chain-breaking antioxidants. The experimental results (models 1–3) obtained are qualitatively supported by quantum chemical calculations (model 4). Dimers showed higher activity than the corresponding monomers in the experiments in homogeneous solutions (models 1 and 2) and similar activity

On the strong difference in reactivity of acyclic and cyclic diazodiketones with thioketones: experimental results and quantum-chemical interpretation

• Andrey S. Mereshchenko,
• Alexey V. Ivanov,
• Viktor I. Baranovskii,
• Grzegorz Mloston,
• Ludmila L. Rodina and
• Valerij A. Nikolaev

Beilstein J. Org. Chem. 2015, 11, 504–513, doi:10.3762/bjoc.11.57

• -oxathiole 3 and alkene 5 (4:1) was formed, whereas at 80 °C, product 5 was formed exclusively (81%) [20]. In order to explain the obtained results and to elucidate the reaction pathway (which governs reactions of DDC 1 with aromatic and aliphatic thioketones 2), detailed quantum-chemical calculations of the

• transient thiirane S-sulfide 8’d (step d), it is most likely that it follows the pathway proposed for the spontaneous desulfurization of matrix-isolated oxathiiranes [32]. Conclusion The quantum-chemical calculations show that the initial step of the 1,3-dipolar cycloaddition of acyclic 2-diazo-1,3

• relative energy of the reagents, reaction intermediates, transition states, and reaction products on the potential energy surfaces were carried out. The results of the performed study are summarized and discussed in the present publication. Results and Discussion The subjects of the quantum-chemical