A chiral self-sorting photoresponsive coordination cage based on overcrowded alkenes

• Constantin Stuckhardt,
• Diederik Roke,
• Wojciech Danowski,
• Edwin Otten,
• Sander J. Wezenberg and
• Ben L. Feringa

Beilstein J. Org. Chem. 2019, 15, 2767–2773, doi:10.3762/bjoc.15.268

• structure determination [13][14] and stabilization of reactive species [15][16][17]. The use of reversible metal–ligand coordination bonds gives rise to systems that allow for adaption to external stimuli such as pH, anions, electric potential, concentration and light [4][8][18][19][20][21]. Using light to

• crystal of Pd2(stable E-1)4 formed from a racemic mixture of ligand E-1 suitable for X-ray structure determination was grown by vapor diffusion of a 1:1 mixture of benzene and diethyl ether into a solution of the cage in a 1:1 mixture of acetonitrile and chloroform. The crystal structure shows cage

Emission solvatochromic, solid-state and aggregation-induced emissive α-pyrones and emission-tuneable 1H-pyridines by Michael addition–cyclocondensation sequences

• Natascha Breuer,
• Irina Gruber,
• Christoph Janiak and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2019, 15, 2684–2703, doi:10.3762/bjoc.15.262

• -pyridines 5 was further corroborated by a single crystal X-ray structure determination of compound 5a (Figure 1) [35]. In the single crystal the carboxyl ester group is oriented to the N–H and via a hydrogen bond. Solid-state torsional/dihedral angles between the 4- and 6-positioned aryl rings differ

1,5-Phosphonium betaines from N-triflylpropiolamides, triphenylphosphane, and active methylene compounds

• Vito A. Fiore,
• Chiara Freisler and
• Gerhard Maas

Beilstein J. Org. Chem. 2019, 15, 2603–2611, doi:10.3762/bjoc.15.253

• fractionating crystallization. Structure determination by X-ray diffraction analysis revealed marked conformational differences around the CH–C(O–) single bond of E and Z-isomers and extended charge delocalization in the anionic part. Keywords: betaines; multi-component reactions; N-triflylamides; phospha

Formation of alkyne-bridged ferrocenophanes using ring-closing alkyne metathesis on 1,1’-diacetylenic ferrocenes

• Celine Bittner,
• Dirk Bockfeld and
• Matthias Tamm

Beilstein J. Org. Chem. 2019, 15, 2534–2543, doi:10.3762/bjoc.15.246

• characterisation, crystallographic data. Acknowledgements The authors wish to thank Dr. Holger Ott from Bruker AXS Inc., Karlsruhe, for the crystal structure determination of compound 4.

Isolation and biosynthesis of an unsaturated fatty acid with unusual methylation pattern from a coral-associated bacterium Microbulbifer sp.

• Amit Raj Sharma,
• Enjuro Harunari,
• Tao Zhou,
• Agus Trianto and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2019, 15, 2327–2332, doi:10.3762/bjoc.15.225

• biosynthetically unique: it has an uncommon methylation pattern in its carbon chain, derived from the C-methylation with ʟ-methionine at a carbon originated from a carbonyl carbon of acetate. In this paper, we report the isolation and structure determination of 1 and its biosynthetic origin proven by the feeding

1,2,3,4-Tetrahydro-1,4,5,8-tetraazaanthracene revisited: properties and structural evidence of aromaticity loss

• Arnault Heynderickx,
• Sébastien Nénon,
• Olivier Siri,
• Vladimir Lokshin and
• Vladimir Khodorkovsky

Beilstein J. Org. Chem. 2019, 15, 2059–2068, doi:10.3762/bjoc.15.203

• chemistry also reproduce the distortion, albeit to a smaller extent: 1.07 and 0.2 degrees. The frequency calculation reproduces the experimental IR spectrum reasonably well (Supporting Information File 1, Figure S1). The X-ray structure determination of 6a confirms that the protonation occurs at 5,8

• brownish yellow crystals in 50% yield. The bright yellow crystals of 3 used for recording the UV–vis absorption spectra and X-ray structure determination can be obtained only by sublimation. 1H NMR (DMSO-d6) δ 3.28 (s, 4H), 6.67 (br s, 2H), 6.68 (s, 2H), 8.17 (s, 2H); 13C NMR (DMF-d7) δ 39.84 (CH2), 104.88

Tautomerism as primary signaling mechanism in metal sensing: the case of amide group

• Vera Deneva,
• Georgi Dobrikov,
• Aurelien Crochet,
• Daniela Nedeltcheva,
• Katharina M. Fromm and
• Liudmil Antonov

Beilstein J. Org. Chem. 2019, 15, 1898–1906, doi:10.3762/bjoc.15.185

• using Least Squares minimization. Crystal structure determination of 6 Crystal data for C20H19N3O2 (M =333.38 g/mol): monoclinic, space group P21/c (no. 14), a = 5.5438(8) Å, b = 17.850(2) Å, c = 17.184(3) Å, β = 91.719(12)°, V = 1699.7(4) Å3, Z = 4, T = 250(2) K, μ(Cu Kα) = 0.691 mm−1, dcalc = 1.303 g

Inherent atomic mobility changes in carbocation intermediates during the sesterterpene cyclization cascade

• Hajime Sato,
• Takaaki Mitsuhashi,
• Mami Yamazaki,
• Ikuro Abe and
• Masanobu Uchiyama

Beilstein J. Org. Chem. 2019, 15, 1890–1897, doi:10.3762/bjoc.15.184

• terpene cyclase active site [3][5][6]. Although many terpene cyclases are known [6][7][8][9][10], it is still challenging to identify the precise initial conformation of the oligoprenyl diphosphate substrate in the active site, even by X-ray crystal structure determination. This is because the substrate

Coordination chemistry and photoswitching of dinuclear macrocyclic cadmium-, nickel-, and zinc complexes containing azobenzene carboxylato co-ligands

• Jennifer Klose,
• Tobias Severin,
• Peter Hahn,
• Alexander Jeremies,
• Jens Bergmann,
• Daniel Fuhrmann,
• Jan Griebel,
• Bernd Abel and
• Berthold Kersting

Beilstein J. Org. Chem. 2019, 15, 840–851, doi:10.3762/bjoc.15.81

• π–π stacking occurs in this structure. [Cd2L(μ-azo-CO2Me)]BPh4.MeCN (8·MeCN): The crystal structure determination of 8·MeCN confirms that azo-CO2Me is also attached in the bridging mode. Figure 9 shows an ORTEP representation of the structure of the [Cd2L(μ-azo-CO2Me)]+ cation in 8. The [Cd2L]2

Efficient catalytic alkyne metathesis with a fluoroalkoxy-supported ditungsten(III) complex

• Henrike Ehrhorn,
• Janin Schlösser,
• Dirk Bockfeld and
• Matthias Tamm

Beilstein J. Org. Chem. 2018, 14, 2425–2434, doi:10.3762/bjoc.14.220

• and terminal alkynes and diynes”). The authors wish to thank Dr. M. Freytag for the crystal structure determination of W2F3·(NHMe2).

Determining the predominant tautomeric structure of iodine-based group-transfer reagents by ¹⁷O NMR spectroscopy

• Nico Santschi,
• Cody Ross Pitts,
• Benson J. Jelier and
• René Verel

Beilstein J. Org. Chem. 2018, 14, 2289–2294, doi:10.3762/bjoc.14.203

• over 50 kcal/mol, a high kinetic barrier suppresses the [a → b] isomerization (Figure 1) [5][6]. With SCF3 reagent 5a/5b, structure determination was notably challenging and solely provides a solid-state structural perspective. Thus, we wondered whether a correct structural assignment of reagent 5a/b

• would have been feasible without having to resort to the preparation of crystalline congeners and/or the preparation of 5b@MOF. Importantly, establishing a reliable way to differentiate cyclic (a) from acyclic (b) isomers in solution would facilitate future structure determination of similar iodine

• 17O NMR shift alone may be misleading in structure determination. For instance, the experimental value of 59 ppm for the known cyclic fluoroiodinane 3a is closer to the observed values of acyclic 1 (67 ppm) and 5b (32 ppm) than it is to cyclic 2a and 4a. However, assessment of the DFT-calculated

Synthesis of 1,4-imino-L-lyxitols modified at C-5 and their evaluation as inhibitors of GH38 α-mannosidases

• Maroš Bella,
• Sergej Šesták,
• Ján Moncoľ,
• Miroslav Koóš and
• Monika Poláková

Beilstein J. Org. Chem. 2018, 14, 2156–2162, doi:10.3762/bjoc.14.189

• & Development Operational Program funded by the ERDF. The crystal structure determination was made with the support of the project "University Science Park of STU Bratislava", ITMS 26240220084, supported by the Research & Development Operational Program funded by the ERDF.

First thia-Diels–Alder reactions of thiochalcones with 1,4-quinones

• Grzegorz Mlostoń,
• Katarzyna Urbaniak,
• Paweł Urbaniak,
• Anna Marko,
• Anthony Linden and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2018, 14, 1834–1839, doi:10.3762/bjoc.14.156

• of charge from the Cambridge Crystallographic Data Centre via http://www.ccdc.cam.ac.uk/structures. Supporting Information File 470: Experimental data for selected compounds 4, details of the crystal structure determination, and copies of 1H and 13C NMR spectra for all products. Acknowledgements

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

• 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

Synthesis and in vitro biochemical evaluation of oxime bond-linked daunorubicin–GnRH-III conjugates developed for targeted drug delivery

• Sabine Schuster,
• Beáta Biri-Kovács,
• Bálint Szeder,
• Viktor Farkas,
• László Buday,
• Zsuzsanna Szabó,
• Gábor Halmos and
• Gábor Mező

Beilstein J. Org. Chem. 2018, 14, 756–771, doi:10.3762/bjoc.14.64

• formaldehyde (e.g., from the softeners of the plastic tubes) not only during the reaction steps (cleavage, ligation) but also under the HPLC purification conditions which has a high impact on the yield [35]. Secondary structure determination by electronic circular dichroism spectroscopy ECD spectra of GnRH-III

Enhanced quantum yields by sterically demanding aryl-substituted β-diketonate ancillary ligands

• Rebecca Pittkowski and
• Thomas Strassner

Beilstein J. Org. Chem. 2018, 14, 664–671, doi:10.3762/bjoc.14.54

• 3 by a solid-state structure (Figure 1). Details of the structure determination are given in Supporting Information File 1, Table S1. The absorption spectra (Figure 2) were measured in dichloromethane solution at ambient temperature. The complexes show almost identical absorption behavior with only

• ). Supporting Information The Supporting Information contains NMR-spectra, additional figures, details of the solid state structure determination and computational details. CCDC 1823322 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge via http

• ://www.ccdc.cam.ac.uk/data_request/cif, or by emailing data_request@ccdc.cam.ac.uk, or by contacting The Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB21EZ, UK; fax: +44 1223 336033. Supporting Information File 67: NMR spectra, additional figures, details of the solid state structure determination

Sequential Ugi reaction/base-induced ring closing/IAAC protocol toward triazolobenzodiazepine-fused diketopiperazines and hydantoins

• Robby Vroemans,
• Fante Bamba,
• Jonas Winters,
• Joice Thomas,
• Jeroen Jacobs,
• Luc Van Meervelt,
• Jubi John and
• Wim Dehaen

Beilstein J. Org. Chem. 2018, 14, 626–633, doi:10.3762/bjoc.14.49

• . The structure of hydantoin-fused triazolobenzodiazepine was confirmed by a X-ray crystal structure determination of 10a (Figure 3). The three-step synthesis of heterocycle-fused triazolobenzodiazepines involves the well-known Ugi 4-CR as the first step and the IAAC as the last, the mechanisms of which

Regioselective decarboxylative addition of malonic acid and its mono(thio)esters to 4-trifluoromethylpyrimidin-2(1H)-ones

• Sergii V. Melnykov,
• Andrii S. Pataman,
• Yurii V. Dmytriv,
• Svitlana V. Shishkina,
• Mykhailo V. Vovk and
• Volodymyr A. Sukach

Beilstein J. Org. Chem. 2017, 13, 2617–2625, doi:10.3762/bjoc.13.259

• decarboxylative addition of malonic acid mono-4-methoxyphenyl thioester (1b) to 4-trifluoromethylpyrimidin-2(1H)-ones 2a–m. Supporting Information Supporting Information File 481: Experimental procedures, characterization data and X-ray structure determination for compound 11b. Supporting Information File 482

¹⁵N-Labelling and structure determination of adamantylated azolo-azines in solution

• Sergey L. Deev,
• Alexander S. Paramonov,
• Tatyana S. Shestakova,
• Igor A. Khalymbadzha,
• Oleg N. Chupakhin,
• Julia O. Subbotina,
• Oleg S. Eltsov,
• Pavel A. Slepukhin,
• Vladimir L. Rusinov,
• Alexander S. Arseniev and
• Zakhar O. Shenkarev

Beilstein J. Org. Chem. 2017, 13, 2535–2548, doi:10.3762/bjoc.13.250

• of the azolo-1,2,4-triazines. The combined analysis of the JHN and JCN couplings in 15N-labelled compounds provides an efficient method for the structure determination of N-alkylated azolo-azines even in the case of isomer formation. The isomerization of adamantylated tetrazolo[1,5-b][1,2,4]triazin-7

• , respectively. The obtained NMR assignments are collected in Table 1 (1H, 15N) and Table 2 (13C). 13C-15N couplings for the structure determination of N-adamantylated azoloazines. The incorporation of 15N labels into the synthesized compounds led to the appearance of 1H-15N and 13C-15N J-coupling constants (JCN

One-pot syntheses of blue-luminescent 4-aryl-1H-benzo[f]isoindole-1,3(2H)-diones by T3P^® activation of 3-arylpropiolic acids

• Melanie Denißen,
• Alexander Kraus,
• Guido J. Reiss and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2017, 13, 2340–2351, doi:10.3762/bjoc.13.231

• structure determination of compound 4b (Figure 1). The twist angle of the phenyl substituent (ring A) and the 1H-pyrrole-2,5-dionyl moiety is 51.37(7)°, whereas the p-anisyl substituent (ring B) is considerably twisted against the adjacent six-membered ring by 70.95(7)° (Figure 1) [50]. Upon slightly

Comparative profiling of well-defined copper reagents and precursors for the trifluoromethylation of aryl iodides

• Peter T. Kaplan,
• Jessica A. Lloyd,
• Mason T. Chin and
• David A. Vicic

Beilstein J. Org. Chem. 2017, 13, 2297–2303, doi:10.3762/bjoc.13.225

• methods including the reaction of [Cu(O-t-Bu)]4 with Me3SiCF3 and phen (B2, Scheme 1) [12] or by reaction of [(MeO)3BCF3] with CuI and phen (B3, Scheme 1) [8]. The compound [(PPh3)3CuCF3] has been for a long time [13], however, its trifluoromethylating ability and structure determination was not reported

Mechanochemical Knoevenagel condensation investigated in situ

• Sebastian Haferkamp,
• Franziska Fischer,
• Werner Kraus and
• Franziska Emmerling

Beilstein J. Org. Chem. 2017, 13, 2010–2014, doi:10.3762/bjoc.13.197

• grinding process, whereas p-nitrobenzaldehyde remains crystalline until the onset of the product formation. The crystalline product was of sufficient quality for single crystal X-ray structure determination. Results and Discussion Scheme 1 illustrates the investigated Knoevenagel condensation of p

Molecular recognition of N-acetyltryptophan enantiomers by β-cyclodextrin

• Spyros D. Chatziefthimiou,
• Mario Inclán,
• Petros Giastas,
• Athanasios Papakyriakou,
• Konstantina Yannakopoulou and
• Irene M. Mavridis

Beilstein J. Org. Chem. 2017, 13, 1572–1582, doi:10.3762/bjoc.13.157

• -CD (6 mΜ) at 50–60 °C, required a small quantity of ethanol in order to obtain a clear solution, from which crystals of hydrated native β-CD precipitated. This was proved from data collection from several crystals and structure determination based on isomorphous replacement using the coordinates of

• days, produced crystals that could not be refined by isomorphous replacement using the coordinates of hydrated β-CD or other isomorphous crystals, as above. Structure determination. Low temperature X-ray data were collected at synchrotron radiation light sources. A single crystal, covered with a drop

Glycoscience@Synchrotron: Synchrotron radiation applied to structural glycoscience

• Serge Pérez and
• Daniele de Sanctis

Beilstein J. Org. Chem. 2017, 13, 1145–1167, doi:10.3762/bjoc.13.114

• of polysaccharides. Insights into the kinetics of catalytic events observed in the crystalline state are also presented as well as some aspects of structure determination of protein in solution. Keywords: antibodies; carbohydrate binding domains; cellulose; glycosaminoglycans; glycolipids; glycosyl

• dramatic impact on the throughput and on the complexity of the structures determined. However, despite the development in nano-volume liquid handling for high-throughput screens, the crystallization of biological macromolecules still represents an important bottleneck in structure determination. Nanoliter

G-Protein coupled receptors: answers from simulations

• Timothy Clark

Beilstein J. Org. Chem. 2017, 13, 1071–1078, doi:10.3762/bjoc.13.106

• stable conformation. These techniques are discussed in far more detail in reference [6]. One further problem in GPCR structure determination is to obtain crystals in which the GPCR is in the active conformation. The active conformation could be stabilized at low pH with detergents for opsin/rhodopsin [15