A combinatorial approach to improving the performance of azoarene photoswitches

• Joaquin Calbo,
• Aditya R. Thawani,
• Rosina S. L. Gibson,
• Andrew J. P. White and
• Matthew J. Fuchter

Beilstein J. Org. Chem. 2019, 15, 2753–2764, doi:10.3762/bjoc.15.266

• crystal structure). We attribute this to a packing effect in the solid state. To the best of our knowledge, an E-isomer azo photoswitch with this type of solid state packing is unprecedented and may open new possibilities in solid state photoswitchable materials applications. The benzene ring in 4pzH-F2

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

• -dimethylaminophenyl substituent furnishes α-pyrone 6g (Table 4, entry 13). For synthesizing 1H-pyridine derivatives 8 with an electron-donating group we employed the isolated dimer 7 and were able to isolate 1H-pyridines 8 in 52 and 34% yield (Scheme 10). Crystal structure of 1H-pyridine 5a The structure of 1H

Nanangenines: drimane sesquiterpenoids as the dominant metabolite cohort of a novel Australian fungus, Aspergillus nanangensis

• Heather J. Lacey,
• Cameron L. M. Gilchrist,
• Andrew Crombie,
• John A. Kalaitzis,
• Daniel Vuong,
• Peter J. Rutledge,
• Peter Turner,
• John I. Pitt,
• Ernest Lacey,
• Yit-Heng Chooi and
• Andrew M. Piggott

Beilstein J. Org. Chem. 2019, 15, 2631–2643, doi:10.3762/bjoc.15.256

• absolute structures, however their anomalous dispersion statistics indicate that the assignments are very likely to be correct. The crystal structure of 1 has four crystallographically-independent molecules, while the structures of 2b and 3b have two crystallographically-independent molecules, and the

• File 565: Details of cultivation media, fractionation schemes, NMR spectra and tabulated 2D NMR data for all compounds, detailed X-ray crystallographic details and CCDC deposition numbers, bioassay procedures and genomic data. Supporting Information File 566: Crystal structure information files for

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

• broad O–H absorption bands in their IR spectra (≈3400–3500 cm−1) and the presence of hydrogen-bonded water molecules in the crystal structure of E-3e (vide infra) indicate. The formation of betaines 3 includes the elimination of the N-phenyltriflamide anion, which is known as an excellent leaving group

• Information Supporting Information File 640: Experimental procedures, characterization data, NMR spectra (1H, 13C, 31P, 19F) and IR spectra for the synthesized compounds, and data for the X-ray crystal structure determinations.

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.

Anion-driven encapsulation of cationic guests inside pyridine[4]arene dimers

• Anniina Kiesilä,
• Jani O. Moilanen,
• Anneli Kruve,
• Christoph A. Schalley,
• Perdita Barran and
• Elina Kalenius

Beilstein J. Org. Chem. 2019, 15, 2486–2492, doi:10.3762/bjoc.15.241

• similar affinity towards the Me4N+ cation as 2. Also, all our attempts to obtain a solid-state single crystal structure of 1 with a cationic guest were unsuccessful. It is possible that the observation of such complexes requires special conditions present in the ESI source. To obtain more detailed

Photochromic diarylethene ligands featuring 2-(imidazol-2-yl)pyridine coordination site and their iron(II) complexes

• Andrey G. Lvov,
• Max Mörtel,
• Anton V. Yadykov,
• Frank W. Heinemann,
• Valerii Z. Shirinian and
• Marat M. Khusniyarov

Beilstein J. Org. Chem. 2019, 15, 2428–2437, doi:10.3762/bjoc.15.235

• ). Apparently, this product is the result of destruction of bis(pyrazolyl)borate moieties of complex 8 by methanol. Species 9 crystallizes as red, block-shaped crystals in the triclinic P−1 space group with one molecule in the unit cell. The crystal structure reveals two pairs of differently substituted iron

Effect of ring size on photoisomerization properties of stiff stilbene macrocycles

• Sandra Olsson,
• Óscar Benito Pérez,
• Magnus Blom and
• Adolf Gogoll

Beilstein J. Org. Chem. 2019, 15, 2408–2418, doi:10.3762/bjoc.15.233

• macrocyclic diethers 1a–d, all Z-isomers have a dihedral angle of 12–14°, roughly similar to the one in the crystal structure of (Z)-7. The deviation of this angle from 0° is due to steric interaction between two aromatic protons in position 4 (Figure 9). In the E-isomers, an increasing distortion of the

Reversible switching of arylazopyrazole within a metal–organic cage

• Anton I. Hanopolskyi,
• Soumen De,
• Michał J. Białek,
• Yael Diskin-Posner,
• Liat Avram,
• Moran Feller and
• Rafal Klajn

Beilstein J. Org. Chem. 2019, 15, 2398–2407, doi:10.3762/bjoc.15.232

• , Supporting Information File 1). Front view (a) and side view (b) of the X-ray crystal structure of (E-1)22 (major conformations of 1 and 2; see also Supporting Information File 1, Figures S15 and S16). The horizontal plane (pink) denotes the positions of eight equatorial imidazole groups; four axial

In water multicomponent synthesis of low-molecular-mass 4,7-dihydrotetrazolo[1,5-a]pyrimidines

• Irina G. Tkachenko,
• Sergey A. Komykhov,
• Vladimir I. Musatov,
• Svitlana V. Shishkina,
• Viktoriya V. Dyakonenko,
• Vladimir N. Shvets,
• Mikhail V. Diachkov,
• Valentyn A. Chebanov and
• Sergey M. Desenko

Beilstein J. Org. Chem. 2019, 15, 2390–2397, doi:10.3762/bjoc.15.231

• . Crystal data: The crystal structure of compound 9a was measured on an Xcalibur-3 diffractometer (graphite monochromated Mo Kα radiation, CCD detector, ω-scanning). The structure was solved by the direct method using the SHELXTL package [34][35]. Full-matrix least-squares refinement against F2 in

Current understanding and biotechnological application of the bacterial diterpene synthase CotB2

• Ronja Driller,
• Daniel Garbe,
• Norbert Mehlmer,
• Monika Fuchs,
• Keren Raz,
• Dan Thomas Major,
• Thomas Brück and
• Bernhard Loll

Beilstein J. Org. Chem. 2019, 15, 2355–2368, doi:10.3762/bjoc.15.228

• mutagenesis have exciting applications for the sustainable production of high value bioactive substances. Keywords: biotechnology; CotB2; crystal structure; cyclooctatin; diterpene; reaction mechanism; terpene synthase; Introduction Terpenes represent one of the most diverse groups of natural biomolecules

• subsequent cyclization unlikely. Crystal structure of CotB2wt·Mg2+3·F-Dola resembles the closed, active conformation The structure of CotB2wt·Mg2+3·F-Dola has been obtained by co-crystallization of CotB2wt and FGGDP (PDB-ID 6GGI; [37]), representing the closed, active conformation. Fluorinated substrates

• -crystallized with AHD, a compound that mimics the diphosphate group of GGDP and acts as a suicide inhibitor. The crystal structure of CotB2wt·Mg2+3·AHD (PDB-ID 6GGJ; [37]) confirmed the active site architecture as observed in the structure of CotB2wt·Mg2+3·F-Dola and more importantly, that the folding of the C

Small anion-assisted electrochemical potential splitting in a new series of bistriarylamine derivatives: organic mixed valency across a urea bridge and zwitterionization

• Keishiro Tahara,
• Tetsufumi Nakakita,
• Alyona A. Starikova,
• Takashi Ikeda,
• Masaaki Abe and
• Jun-ichi Kikuchi

Beilstein J. Org. Chem. 2019, 15, 2277–2286, doi:10.3762/bjoc.15.220

• . Such N–H···F hydrogen-bond formation was also reported for other urea derivatives with PF6− as counteranion in the solid state [54][55]. The N···F distance of 2.85 Å in 1b+–PF6− is slightly longer than that observed in the crystal structure of a silver complex having a pyridyl urea ligand (2.67 and

Characterization of two new degradation products of atorvastatin calcium formed upon treatment with strong acids

• Jürgen Krauß,
• Monika Klimt,
• Markus Luber,
• Peter Mayer and
• Franz Bracher

Beilstein J. Org. Chem. 2019, 15, 2085–2091, doi:10.3762/bjoc.15.206

• NMR spectroscopy, HRMS data and X-ray crystal structure analysis. Keywords: atorvastatin; crystal structure; cyclization; degradation products; fragmentation; stress test; Introduction Over the past decades, the general trend toward globalization of the supply chains for active pharmaceutical

• isopropyl residue, originally located at C-2 of the pyrrole, is shifted to C-3, rendering the annulated, tetrasubstituted pyrrole 6. The structure of 6 was confirmed by X-ray crystal structure analysis. However, most likely cleavage of the carboxanilide moiety (compare formation of 7 from atorvastatin with

• elucidated by NMR and crystal structure analysis. The bridged tricyclic product 6 was formed with concentrated hydrochloric acid, whereas lactone 7 resulted from treatment with concentrated sulfuric acid. We propose mechanisms for the formation of the novel artefacts 6 and 7 here. But it has to be mentioned

Synthesis of benzo[d]imidazo[2,1-b]benzoselenoazoles: Cs₂CO₃-mediated cyclization of 1-(2-bromoaryl)benzimidazoles with selenium

• Mio Matsumura,
• Yuki Kitamura,
• Arisa Yamauchi,
• Yoshitaka Kanazawa,
• Yuki Murata,
• Tadashi Hyodo,
• Kentaro Yamaguchi and
• Shuji Yasuike

Beilstein J. Org. Chem. 2019, 15, 2029–2035, doi:10.3762/bjoc.15.199

• was fully characterized by 1H and 13C NMR spectroscopy and HRMS, and further confirmed by single-crystal X-ray diffraction (XRD) analysis. The ORTEP drawing and packing structure of 2a obtained from the single crystal XRD analysis are illustrated in Figure 1. The crystal structure contained two

• . Cyclization of 1-(2-bromophenyl)benzimidazoles with chalcogen elements.a Absorption spectroscopy dataa. Supporting Information Supporting Information File 401: Experimental details and analytical data, copies of absorption and NMR spectra. Supporting Information File 402: X-ray crystal structure of 2a

Fluorinated azobenzenes as supramolecular halogen-bonding building blocks

• Esther Nieland,
• Oliver Weingart and
• Bernd M. Schmidt

Beilstein J. Org. Chem. 2019, 15, 2013–2019, doi:10.3762/bjoc.15.197

• to facilitate readability. a) Space-filling model of U1···A2. The kinked alignment of both the lutidine units of U1 and the azobenzenes A2 can be seen. b) Part of the X-ray crystal structure showing the halogen bonding azobenzene A2 in detail. Selected bond lengths: N3–I1 2.7810(2), I2–N4 2.816(2) Å

Installation of -SO₂F groups onto primary amides

• Jing Liu,
• Shi-Meng Wang,
• Njud S. Alharbi and
• Hua-Li Qin

Beilstein J. Org. Chem. 2019, 15, 1907–1912, doi:10.3762/bjoc.15.186

• introduced into the stirred reaction mixture by slowly bubbling from a balloon, and the mixture was allowed to stir at 50 °C for 12 h. Isolated yields. a50 °C, 18 h. Amide resonance model and X-ray single crystal structure of 4e (CCDC 1906002). The proposed reaction mechanism. Optimization of the reaction

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

• stabilization in acetonitrile. The explanation for the sudden stabilization of 6K was found by X-ray measurements of its crystal, obtained in acetonitrile. The crystal structure of 6, shown in Figure 3, clearly indicates that the K form is stabilized through the formation of linear intermolecular associates. It

• exists exclusively as H-aggregates as in the crystal structure. The absorption spectra of 6 in acetonitrile upon addition of Mg(ClO4)2 are shown in Figure 4. A clear isosbestic point can be seen in the area where the enol tautomer does not absorb, indicating that the tautomeric equilibrium is shifted

• 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

Application of chiral 2-isoxazoline for the synthesis of syn-1,3-diol analogs

• Juanjuan Feng,
• Tianyu Li,
• Jiaxin Zhang and
• Peng Jiao

Beilstein J. Org. Chem. 2019, 15, 1840–1847, doi:10.3762/bjoc.15.179

• gave 16 in 87% yield [26][27]. The absolute stereochemistry of 16 was confirmed by crystal structure analysis [72] and the specific rotation [28] of 17. Centimeter-long prismatic single crystals of 17 were obtained by slow evaporation of a petroleum solution. Starting from 9, we tested several

Design, synthesis and biological evaluation of immunostimulating mannosylated desmuramyl peptides

• Rosana Ribić,
• Ranko Stojković,
• Lidija Milković,
• Mariastefania Antica,
• Marko Cigler and
• Srđanka Tomić

Beilstein J. Org. Chem. 2019, 15, 1805–1814, doi:10.3762/bjoc.15.174

• innate immunity through macrophage response as well as to more distally affect adaptive immunity through the production of antigen-specific T cells [5]. MDP binding to NOD2 has been confirmed [6] as well as the crystal structure of NOD2 in the inactive ADP-bound state [7]. MDP is the structural fragment

Complexation of 2,6-helic[6]arene and its derivatives with 1,1′-dimethyl-4,4′-bipyridinium salts and protonated 4,4'-bipyridinium salts: an acid–base controllable complexation

• Jing Li,
• Qiang Shi,
• Ying Han and
• Chuan-Feng Chen

Beilstein J. Org. Chem. 2019, 15, 1795–1804, doi:10.3762/bjoc.15.173

• G1, (c) free G1, (d) H4 with 1.0 equiv G1, (e) free H4. [H1]0 = [H4]0 = [G1]0 = 2.0 mM. Partial 1H NMR spectra (400 MHz, CD2Cl2, 298 K) of (a) free H1, (b) H1 with 1.0 equiv G4, (c) free G4, (d) H4 with 1.0 equiv G4, (e) free H4. [H1]0 = [H4]0 = [G4]0 = 2.0 mM. Crystal structure of complex H1·G1. (a

• ) Top view, (b) side view, and (c) packing viewed along c-axis. Blue lines denote the non-covalent interactions between H1 and G1. Solvent molecules and hydrogen atoms not involved in the non-covalent interactions were omitted for clarity. Crystal structure of complex H5·G1. (a) Top view, (b) side view

Synthesis of ([1,2,4]triazolo[4,3-a]pyridin-3-ylmethyl)phosphonates and their benzo derivatives via 5-exo-dig cyclization

• Aleksandr S. Krylov,
• Artem A. Petrosian,
• Julia L. Piterskaya,
• Nataly I. Svintsitskaya and
• Albina V. Dogadina

Beilstein J. Org. Chem. 2019, 15, 1563–1568, doi:10.3762/bjoc.15.159

• coupling constant of 2JНР ≈ 20 Hz. In the 13С NMR spectra, the methylene carbon resonated as a doublet at δ 23.5 ppm (JCP = 143 Hz). In addition, the structures of triazolopyridines 3–8 were unambiguously confirmed by the crystal structure of 5b. Remarkably, the presence of a nitro group in the pyridine

Molecular basis for the plasticity of aromatic prenyltransferases in hapalindole biosynthesis

• Takayoshi Awakawa and
• Ikuro Abe

Beilstein J. Org. Chem. 2019, 15, 1545–1551, doi:10.3762/bjoc.15.157

• AmbP1 and AmbP3 functions, elucidated through their X-ray crystal structures. The knowledge presented here will contribute to the understanding of aromatic PTase reactions and will enhance their uses as biocatalysts. Keywords: crystal structure; cyanobacteria; Friedel–Crafts reaction; hapalindole

• (Figure 2B). Remarkably, AmbP3 also accepts (10S)-hapalindole A (HA), and transfers the dimethylallyl group onto the C-2 carbon of hapalindole A in normal prenylation mode to yield compound 3 (Figure 2B). X-ray crystal structure analysis of AmbP1 To understand the effect of Mg2+ ions on the AmbP1 reaction

• PTases that utilize a Mg2+ ion to reorganise the active site cavity to control the regiospecificity of the prenylation reaction. X-ray crystal structure analysis of AmbP3 The crystal structures of AmbP3 complexed with DMSPP/hapalindole U (HU structure) and A (HA structure) were each solved at 2.00 Å [14

A heteroditopic macrocycle as organocatalytic nanoreactor for pyrroloacridinone synthesis in water

• Piyali Sarkar,
• Sayan Sarkar and
• Pradyut Ghosh

Beilstein J. Org. Chem. 2019, 15, 1505–1514, doi:10.3762/bjoc.15.152

• ) SEM image and (c) TEM image showing the nanoranged particle distribution of the macrocycle. Dependence of the yield of compound 4a on the reaction time using BATA-MC. Yields of product 4a at different catalyst loading. X-ray single crystal structure of 4d (CCDC 1898008). Representation of BATA-MC

2,3-Dibutoxynaphthalene-based tetralactam macrocycles for recognizing precious metal chloride complexes

• Li-Li Wang,
• Yi-Kuan Tu,
• Huan Yao and
• Wei Jiang

Beilstein J. Org. Chem. 2019, 15, 1460–1467, doi:10.3762/bjoc.15.146

• butyl methylene group next to the oxygen atoms. A single crystal (Figure 2) of 1, which was suitable for X-ray crystallography, was obtained by slow evaporation of its solution in CH3CN. The crystal structure clearly shows that 1 adopts a flattened chair conformation with the two naphthalenes in

• (500 MHz, CDCl3) of a) 1 at 298 K, b) 1 at 223 K, and c) 2 at 298 K. Two different views of the X-ray single crystal structure of 1 obtained from its CH3CN solution. Partial 1H NMR spectra (500 MHz, CDCl3, 0.5 mM, 298 K) of 1 and the equimolar mixture with TBA[AuCl4]. ESI mass spectrum of complex AuCl4