Fritsch–Buttenberg–Wiechell rearrangement of magnesium alkylidene carbenoids leading to the formation of alkynes

• Tsutomu Kimura,
• Koto Sekiguchi,
• Akane Ando and
• Aki Imafuji

Beilstein J. Org. Chem. 2021, 17, 1352–1359, doi:10.3762/bjoc.17.94

• magnesium alkylidene carbenoids was studied by using 13C-labeled sulfoxides and by using DFT calculations. Keywords: alkyne; 1-chlorovinyl p-tolyl sulfoxide; DFT calculation; Fritsch–Buttenberg–Wiechell rearrangement; magnesium alkylidene carbenoid; Introduction Alkynes are important compounds in organic

• rearrangement of magnesium alkylidene carbenoids 3 by using 13C-labeled sulfoxides and by using DFT calculations is also described. Results and Discussion Synthesis of 1-heteroatom-substituted vinyl p-tolyl sulfoxides As magnesium alkylidene carbenoid precursors, a series of 1-heteroatom-substituted vinyl p

• (Scheme 3a). The 2,2-unsymmetrically substituted sulfoxides 2d–g were obtained as mixtures of geometric isomers that were separated by column chromatography on silica gel. FBW rearrangement of magnesium alkylidene carbenoids Based on the results of DFT calculations, the degree of the vinylidene character

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

• Guido Gambacorta,
• James S. Sharley and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90

• a factor of 5 and increasing proportionally the flow rate a theoretical throughput of 1.75 kg h−1 of 78 would be possible. Although such calculations can be made implementing the necessary changes are not as linearly scalable or simple as implied due to change in the mixing efficiency of the reactor

Structural effects of meso-halogenation on porphyrins

• Keith J. Flanagan,
• Maximilian Paradiz Dominguez,
• Zoi Melissari,
• Hans-Georg Eckhardt,
• René M. Williams,
• Dáire Gibbons,
• Caroline Prior,
• Gemma M. Locke,
• Alina Meindl,
• Aoife A. Ryan and
• Mathias O. Senge

Beilstein J. Org. Chem. 2021, 17, 1149–1170, doi:10.3762/bjoc.17.88

• . Additionally, we have used density functional theory calculations to determine the structure of several halogenated porphyrins. This contrasts conformational analysis with existing X-ray structures and gives a method to characterize samples that are difficult to crystallize. By using the methods outlined above

• need of crystallization, using DFT calculations with a high degree of accuracy. Keywords: conformational analysis; crystal engineering; halogenation; macrocycles; porphyrins; Introduction Crystal engineering using porphyrins as a scaffolding unit has been a topic of increasing interest over the past

• formation of the crystal networks. This is complemented with the use of density functional theory (DFT) calculation of structures that have currently not been determined due to difficulties of obtained crystals of sufficient quality for X-ray determination. Additionally, DFT calculations were conducted for

N-tert-Butanesulfinyl imines in the asymmetric synthesis of nitrogen-containing heterocycles

• Joseane A. Mendes,
• Paulo R. R. Costa,
• Miguel Yus,
• Francisco Foubelo and
• Camilla D. Buarque

Beilstein J. Org. Chem. 2021, 17, 1096–1140, doi:10.3762/bjoc.17.86

• %) from allylic sulfonamides 40 and Togni’s reagent (41). The reaction mechanism is proposed based on DFT calculations. In this study, they observed an intramolecularly intermediate Cu(III) species, and the sulfinamide acts as a direction group and nucleophile [75] (Scheme 14). Asymmetric synthesis of

• proceeded with high levels of diastereocontrol. The resulting sulfonamide derivatives 95 were transformed into the target spiro compound 97 by performing successive desulfinylation and intramolecular palladium-catalyzed N-arylation. To rationalize the stereochemical course of the addition, DFT calculations

Recent advances in palladium-catalysed asymmetric 1,4–additions of arylboronic acids to conjugated enones and chromones

• Jan Bartáček,
• Jan Svoboda,
• Martin Kocúrik,
• Jaroslav Pochobradský,
• Alexander Čegan,
• Miloš Sedlák and
• Jiří Váňa

Beilstein J. Org. Chem. 2021, 17, 1048–1085, doi:10.3762/bjoc.17.84

• catalytically relevant species is monomeric Pd–PyOx. This was further supported by a mass spectrometric study [52]. The catalytic cycle was also suggested in accordance with DFT calculations and mechanistic studies (Scheme 13) [48][49]. The key step for both, the enantioselectivity and turnover, is the

Metal-free glycosylation with glycosyl fluorides in liquid SO₂

• Krista Gulbe,
• Jevgeņija Lugiņina,
• Edijs Jansons,
• Artis Kinens and
• Māris Turks

Beilstein J. Org. Chem. 2021, 17, 964–976, doi:10.3762/bjoc.17.78

• of an ammonium salt. The 19F NMR spectra of the water-soluble components was than compared to the standard obtained from the reaction between TBAF and SO2. The peak that corresponds to the FSO2− anion was observed at 38.34 ppm (TFA as an external standard, −76.55 ppm) [77]. Also DFT calculations were

• the glycosylation in liquid SO2 was proved by employing 19F NMR spectroscopy and DFT calculations. Finally, a more conventional experimental procedure has been provided for the application of saturated SO2 solution in DCM or toluene. This protocol does not require specific equipment and the reactions

• ; reaction optimization data; reactivity of other glycosyl donors; proposed structures of side-products; detailed description of 19F NMR studies; stability tests for various glycosyl donors. Supporting Information File 145: Copies of NMR spectra. Supporting Information File 146: DFT calculations. Funding

Prins cyclization-mediated stereoselective synthesis of tetrahydropyrans and dihydropyrans: an inspection of twenty years

• Asha Budakoti,
• Pradip Kumar Mondal,
• Prachi Verma and
• Jagadish Khamrai

Beilstein J. Org. Chem. 2021, 17, 932–963, doi:10.3762/bjoc.17.77

• cyclization and minimizes the competitive 2-oxonia-[3,3]-sigmatropic rearrangement pathway. The reaction was highly stereoselective and afforded the cis-2,6-dihydropyran in the presence of Lewis acid FeCl3. From DFT calculations, the authors concluded that the Prins product is formed more rapidly than the α

• -trimethylsilylalkenyl cation 242 formed by the Grob-type fragmentation (Scheme 57), which was trapped by the subsequent attack of the halide anion, leading to the formation of Prins product 244. On the basis of theoretical calculations, the authors could conclude factors controlling the alkyne Prins cyclization over

• based on DFT calculations. A different [2 + 2]-cycloaddition process was suggested to rationalize the observed OH-selectivity. In 2015, Padrón and co-workers also reported the Prins cyclization catalyzed by a Fe(III) and trimethylsilyl halide system for the synthesis of all-cis-2,4,6-trisubstituted THP

Synthetic reactions driven by electron-donor–acceptor (EDA) complexes

• Zhonglie Yang,
• Yutong Liu,
• Kun Cao,
• Xiaobin Zhang,
• Hezhong Jiang and
• Jiahong Li

Beilstein J. Org. Chem. 2021, 17, 771–799, doi:10.3762/bjoc.17.67

• between radicals was carried out, affording thioether derivative 132 (Scheme 46). It has been proved by UV–vis spectroscopy and TDDFT calculations that the EDA complex was formed between an electron-rich mercaptan anion and electron-deficient aryl halides. Most importantly, this approach can be

• solvent (Scheme 57). The complex is bound together by weak halogen bonds, in which phosphorus lone-pair electrons interact with σ* orbitals of C–I bonds. A variety of arylphosphonates can be directly afforded by the simple combination of diaryliodonium salts and phosphite esters. In addition, calculations

Synthesis, structural characterization, and optical properties of benzo[f]naphtho[2,3-b]phosphoindoles

• Mio Matsumura,
• Takahiro Teramoto,
• Masato Kawakubo,
• Masatoshi Kawahata,
• Yuki Murata,
• Kentaro Yamaguchi,
• Masanobu Uchiyama and
• Shuji Yasuike

Beilstein J. Org. Chem. 2021, 17, 671–677, doi:10.3762/bjoc.17.56

• (DFT) calculations [27] were performed at the B3LYP/LanL2DZ level of theory to gain additional understanding of the electronic structures. The HOMO and LUMO energies of the selected compounds are listed in Table 3. The DFT calculations showed that these compounds have HOMO–LUMO gaps of 3.60–3.96 eV

• delocalized in the lone-pair orbitals on the sulfur atom, resulting in considerable destabilization and significantly small HOMO–LUMO gap compared to those of other phospholes 2, 3, 5, and 6. This result is similar to the reduction potentials of compounds 2 and 6. According to time-dependent DFT calculations

• plots of the HOMO−3 to LUMO of compounds 3 and 4. The calculations were performed at the level of B3LYP/LanL2DZ. Synthesis of benzo[f]naphtho[2,3-b]phosphoindoles. Selected bond lengths and angles. Absorption and emissions spectroscopy data.a Cyclic voltammetric dataa (E vs Ag/AgCl) and calculated HOMO

[2 + 1] Cycloaddition reactions of fullerene C₆₀ based on diazo compounds

• Yuliya N. Biglova

Beilstein J. Org. Chem. 2021, 17, 630–670, doi:10.3762/bjoc.17.55

• these isomers [77][78]. It has been shown by calculations that two of the four possible structures mentioned above are thermodynamically stable: [6,6]-isomers of methanofullerenes, which are characterized by a closed transannular bond (π-homoaromatic structure), as well as [5,6]-isomers, which have an

Amino- and polyaminophthalazin-1(2H)-ones: synthesis, coordination properties, and biological activity

• Zbigniew Malinowski,
• Emilia Fornal,
• Agata Sumara,
• Renata Kontek,
• Karol Bukowski,
• Beata Pasternak,
• Dariusz Sroczyński,
• Joachim Kusz,
• Magdalena Małecka and
• Monika Nowak

Beilstein J. Org. Chem. 2021, 17, 558–568, doi:10.3762/bjoc.17.50

• the coordination of copper(II) through nitrogen atoms of the pyridin-2-yl substituent, the pyridazin-3-one moiety, and the 2-(dimethylamino)ethyl group. In the vis–NIR spectrum recorded in methanol, based on TD-DFT calculations, the d–d, metal–ligand charge transfer (MLCT), ligand–metal charge

Menthyl esterification allows chiral resolution for the synthesis of artificial glutamate analogs

• Kenji Morokuma,
• Shuntaro Tsukamoto,
• Kyosuke Mori,
• Kei Miyako,
• Ryuichi Sakai,
• Raku Irie and
• Masato Oikawa

Beilstein J. Org. Chem. 2021, 17, 540–550, doi:10.3762/bjoc.17.48

• ) [10][11][12]. Since 10 was obtained as crystals, the configurational analysis was thereafter confirmed by single-crystal X-ray analysis, as shown in Figure 4. The conformational differences for 10 between the results of the calculations and the analysis of the NMR data compared to the situation in the

• crystal are arising from the four contiguous single bonds between the heterocycle and the menthyl group. These take a stable extended conformation in the calculations and in the NMR experiment, whereas a rather folded conformation is taken in the crystals. Such a discrepancy is often observed and reported

• not consistent well. Due to the conformational flexibility of the (2S)-isomer thus presumed, the de novo configurational characterization by spectroscopic analysis, in combination with conformational calculations, was unsuccessful to conclude that 10* is the (2S)-isomer, separately. With 10* (2S) in

Mesoionic tetrazolium-5-aminides: Synthesis, molecular and crystal structures, UV–vis spectra, and DFT calculations

• Vladislav A. Budevich,
• Sergei V. Voitekhovich,
• Alexander V. Zuraev,
• Vadim E. Matulis,
• Vitaly E. Matulis,
• Alexander S. Lyakhov,
• Ludmila S. Ivashkevich and
• Oleg A. Ivashkevich

Beilstein J. Org. Chem. 2021, 17, 385–395, doi:10.3762/bjoc.17.34

• -butyltetrazolium-5-aminide, its N,N’-ethylene-bridged bis-derivative and (1,3-di-tert-butyl-1H-tetrazol-3-ium-5-yl)(1-phenyl-1H-tetrazol-5-yl)amide by single crystal X-ray analysis. The structural and spectral features of the tetrazolium-5-aminides are discussed by using quantum-chemical calculations. Keywords

• confirm this assumption, we calculated the UV–vis spectra of 8a in different solvents for the model structures shown in Figure 4. The model structures in Figure 4b and Figure 4c were built based on the results of our calculations of NPA charges and the molecular electrostatic potential (MESP, Figure 5

• -butyltetrazolium-5-aminide, its N,N’-ethylene-bridged bis-derivative and (1,3-di-tert-butyl-1H-tetrazol-3-ium-5-yl)(1-phenyl-1H-tetrazol-5-yl)amide by single crystal X-ray analysis. The structural and spectral features of the tetrazolium-5-aminides were discussed by using quantum-chemical calculations

CF₃-substituted carbocations: underexploited intermediates with great potential in modern synthetic chemistry

• Anthony J. Fernandes,
• Armen Panossian,
• Bastien Michelet,
• Agnès Martin-Mingot,
• Frédéric R. Leroux and
• Sébastien Thibaudeau

Beilstein J. Org. Chem. 2021, 17, 343–378, doi:10.3762/bjoc.17.32

• certain extent upon the electron demand in the system to which it is attached”. Thus, despite the strong intrinsic electron-withdrawing character, the trifluoromethyl group was shown to modestly act as a π-electron donor when substituting a carbenium ion. Ab initio calculations were performed to account

• Letcka et al., which can be seen as a strong nF→2pC interaction (Wiberg bond order of 0.53 for each C–F bond), gave additional credit to these calculations (Figure 1, bottom) [26][27][28]. The thermochemical data can also provide information on the effect of the CF3 group on the stability of the

• carbenium ions. Calculations of the isodesmic reactions (1), (2), and (3) demonstrate the overall destabilizing effect of CF3 compared to H or CH3 when directly attached to a carbenium ion (i.e., α position, Scheme 1) [5][29]. Even an oxonium ion appears to be significantly destabilized by the presence of

Diels–Alder reaction of β-fluoro-β-nitrostyrenes with cyclic dienes

• Savva A. Ponomarev,
• Roman V. Larkovich,
• Alexander S. Aldoshin,
• Andrey A. Tabolin,
• Sema L. Ioffe,
• Jonathan Groß,
• Till Opatz and
• Valentine G. Nenajdenko

Beilstein J. Org. Chem. 2021, 17, 283–292, doi:10.3762/bjoc.17.27

• of CPD with the model nitrostyrene 1h was simulated in silico to predict the reaction pathway, the reaction rate constants, and the activation enthalpies. Density functional theory calculations were conducted for the reactants, products, and transition states using the B3LYP [64][65][66] and M062X

• File 206: Copies of spectra, experimental section, and computational details of DFT calculations. Acknowledgements The authors acknowledge the partial support in measuring of NMR spectra from the M. V. Lomonosov Moscow State University Program of Development. We thank Jan Brauer and Paul Eckhardt for

• their assistance with the computational calculations and evaluations. Parts of this research were conducted using the supercomputer MOGON and/or advisory services offered by the Johannes Gutenberg University Mainz (hpc.uni-mainz.de), which is a member of the AHRP (Alliance for High Performance Computing

Exploring the possibility of using fluorine-involved non-conjugated electron-withdrawing groups for thermally activated delayed fluorescence emitters by TD-DFT calculation

• Dongyang Chen and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2021, 17, 210–223, doi:10.3762/bjoc.17.21

• -dependent density functional theory calculations indicate that when only two ortho-disposed carbazole donors are used (Type I molecules), the lowest-lying triplet state possesses locally excited (LE) character while the lowest-lying singlet state possesses charge-transfer character. When five carbazole

• presence of these states helped to explain the short τd of 3.7 μs and the high EQEmax of 17% and good device stability with a T50 of 176 hours for the OLED [CIE coordinate (0.22, 0.40)] [23]. In an analogous manner, TD-DFT calculations predicted 5CzTRZ to possess a small ΔEST (0.02 eV) as well as a small

• calculated in gas phase in this work), which was reported as deep blue emitter with λEL = 418 nm and CIE coordinate of (0.15, 0.05) when doped in DPEPO [21]. DFT calculations for 5CzOCF3, 5CzSCF3, and 5CzSF5 predicted dense populations of excited states between T1 and S1, which should assist in rISC process

Tuning the solid-state emission of liquid crystalline nitro-cyanostilbene by halogen bonding

• Subrata Nath,
• Alexander Kappelt,
• Matthias Spengler,
• Bibhisan Roy,
• Jens Voskuhl and
• Michael Giese

Beilstein J. Org. Chem. 2021, 17, 124–131, doi:10.3762/bjoc.17.13

• induces the formation of nematic mesophases with broad temperature ranges, the temperature range of the mesophase of the azobenzene-based assemblies is significant narrower. Theoretical calculations and the modular use of halogen bond donors with changing fluorination degree reveal that at least three

Direct synthesis of anomeric tetrazolyl iminosugars from sugar-derived lactams

• Michał M. Więcław and
• Bartłomiej Furman

Beilstein J. Org. Chem. 2021, 17, 115–123, doi:10.3762/bjoc.17.12

• calculations were performed on a simplified model to provisionally validate this proposed mechanism. The geometry of the intermediate species were optimized with Gaussian 09 software [44], using the B3LYP/LANL2DZ theory level for Zr and B3LYP/6-31G(d,p) for other atoms, with GD3 empirical dispersion correction

• requires protic conditions, in opposition to what is generally agreed upon for these type of reactions. An alternative reaction mechanism is proposed and provisionally confirmed with DFT calculations. Moreover, selected α-tetrazolyl-iminosugars were subjected to further transformations, yielding new

• Information File 98: Experimental procedures, characterization data, ECD analyses for 5a and 2-epi-5a, calculations of appropriate ECD and UV spectra, crystallographic data for 3a and 3e, atomic coordinates, energies, and number of imaginary frequencies for computed stationary points, and copies of 1H and 13C

Supramolecular polymers with reversed viscosity/temperature profile for application in motor oils

• Jan-Erik Ostwaldt,
• Christoph Hirschhäuser,
• Stefan K. Maier,
• Carsten Schmuck and
• Jochen Niemeyer

Beilstein J. Org. Chem. 2021, 17, 105–114, doi:10.3762/bjoc.17.11

• BUs via the amino group should result in the necessary concave prearrangement [28]. Force field calculations, carried out in order to determine the optimal distance between LU and BU (see Supporting Information File 1, chapter 8), show that a propionamide is the shortest linker that allows for

Molecular basis for protein–protein interactions

• Brandon Charles Seychell and
• Tobias Beck

Beilstein J. Org. Chem. 2021, 17, 1–10, doi:10.3762/bjoc.17.1

• perfect geometry to form the capsid irreversibly [80]. However, this approach is too simplistic and does not take into consideration kinetic traps where capsid formation cannot be completed due to a lack of assembly units. As a result, the use of assembly simulations and mathematical calculations shows

• initial capsid formation is limited due to the time required for an intermediate steady state for the consequent assembly. These mathematical calculations and generalisations, however, do not take into consideration biological scaffolds, such as nucleic acids, which can facilitate or disrupt the capsid

Pentannulation of N-heterocycles by a tandem gold-catalyzed [3,3]-rearrangement/Nazarov reaction of propargyl ester derivatives: a computational study on the crucial role of the nitrogen atom

• Giovanna Zanella,
• Martina Petrović,
• Dina Scarpi,
• Ernesto G. Occhiato and
• Enrique Gómez-Bengoa

Beilstein J. Org. Chem. 2020, 16, 3059–3068, doi:10.3762/bjoc.16.255

• theoretical calculations predict that the position of the propargylic acetate substituent has a great impact on the reactivity. In contrast to our previous successful cyclization of the 2-substituted substrates, where the nitrogen favors the formation of the cyclized final product, the substitution at

• position 3 was computed to have a deleterious effect on the electronic properties of the molecules, increasing the activation barriers of the Nazarov reaction. The sluggish reactivity of 3-substituted piperidines predicted by the calculations was further confirmed by the results obtained with some designed

• substrates. Keywords: DFT calculations; gold catalysis; Nazarov reaction; N-heterocycles; Introduction In the development of new and effective catalysts, step economy is surely one of the major goals. A reduction of the number of steps in the synthesis of complex compounds can be attained by cascade

Secondary metabolites of Bacillus subtilis impact the assembly of soil-derived semisynthetic bacterial communities

• Heiko T. Kiesewalter,
• Carlos N. Lozano-Andrade,
• Mikael L. Strube and
• Ákos T. Kovács

Beilstein J. Org. Chem. 2020, 16, 2983–2998, doi:10.3762/bjoc.16.248

• this genus, bacillaene had the lowest impact. However, these results must be interpreted with caution and need further investigations since Viridibacillus was one of the lowest abundant genera in the mock communities, and abundance calculations are sensitive to the depth of sequencing. Besides the

• ratio calculations. Rarefaction curves of the samples were calculated and visualised with the R package ranacapa [77]. Diversity analyses of the B. subtilis-treated and untreated samples were performed with ASV counts multiplied by factor 100,000 and transformed into integer proportions. The alpha

Naphthalonitriles featuring efficient emission in solution and in the solid state

• Sidharth Thulaseedharan Nair Sailaja,
• Iván Maisuls,
• Jutta Kösters,
• Alexander Hepp,
• Andreas Faust,
• Jens Voskuhl and
• Cristian A. Strassert

Beilstein J. Org. Chem. 2020, 16, 2960–2970, doi:10.3762/bjoc.16.246

• calculations are needed in order to confirm this hypothesis, which is object of ongoing studies. Nonetheless, due to the fact that a vibrational progression is not observed at 77 K, TICT would only account to a minor extent. All the emission spectra and time-resolved photoluminescence decay curves are

UV resonance Raman spectroscopy of the supramolecular ligand guanidiniocarbonyl indole (GCI) with 244 nm laser excitation

• Tim Holtum,
• Vikas Kumar,
• Daniel Sebena,
• Jens Voskuhl and
• Sebastian Schlücker

Beilstein J. Org. Chem. 2020, 16, 2911–2919, doi:10.3762/bjoc.16.240

• the results from density functional theory (DFT) calculations. Keywords: GCI; GCP; guanidiniocarbonyl indole; guanidiniocarbonyl pyrrole; UVRR; Raman spectroscopy; resonance Raman; Introduction Supramolecular ligands are capable to selectively bind to peptides and proteins via reversible non

• –1800 cm−1. Peaks appearing within the 900–1100 cm−1 region cover various pyrrole ring deformation modes while the peak at 1400 cm−1 belongs to a symmetrical half-ring vibration of pyrrole [13]. Based on the results from DFT calculations [13], the peaks around 1470 cm−1 are assigned to N–H bending and C

• the results from density functional theory (DFT) calculations. The assignment of the peaks detectable in the experimental UVRR spectrum is mainly based on the experimental wavenumber position (peak position). Only normal modes with non-vanishing Raman activities were considered. One cannot expect an

Fluorine effect in nucleophilic fluorination at C4 of 1,6-anhydro-2,3-dideoxy-2,3-difluoro-β-D-hexopyranose

• Danny Lainé,
• Vincent Denavit,
• Olivier Lessard,
• Laurie Carrier,
• Charles-Émile Fecteau,
• Paul A. Johnson and
• Denis Giguère

Beilstein J. Org. Chem. 2020, 16, 2880–2887, doi:10.3762/bjoc.16.237

• density functional theory (DFT) calculations). Finally, we wish to report the preparation of novel multi-vicinal fluorinated alditol analogues using a simple reduction protocol. Results and Discussion We initially supposed that DAST, a commonly used reagent to install fluorine atoms on the carbohydrate

• , DFT calculations were performed with Gaussian 09, revision E.01 [44] to evaluate the hypothesis for the formation of oxiranium ion A. Calculations were performed with the CAM-B3LYP functional [45][46][47] using Grimme’s D3 dispersion correction [48] and the 6-31+G(d,p) basis set. The results of our

• modeling calculations showed a distance of 1.52 Å between the endocyclic oxygen and C4. With the optimisation of the C4 deoxyfluorination successfully completed, and as a demonstration of the usefulness of our strategy, we completed the synthesis of two fluorinated alditol analogues (Scheme 1). We first