Easy, efficient and versatile one-pot synthesis of Janus-type-substituted fullerenols

• Marius Kunkel and
• Sebastian Polarz

Beilstein J. Org. Chem. 2019, 15, 901–905, doi:10.3762/bjoc.15.87

• formula of the compound is identified by electrospray ionization mass spectrometry (ESIMS). The degree of polyhydroxylation and the number of substituents is determined and confirmed with thermogravimetric analysis (TGA) and the nature of oxygen moieties as well as the substituents attached are evaluated

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

• = Zn (5), Cd (6), Ni (7); L' = azo-CO2Me, M = Cd (8), Ni (9)), and characterized by elemental analysis, electrospray ionization mass spectrometry (ESIMS), IR, UV–vis and NMR spectroscopy (for diamagnetic Zn and Cd complexes) and X-ray single crystal structure analysis. The crystal structures of 3' and

Catalyst-free assembly of giant tris(heteroaryl)methanes: synthesis of novel pharmacophoric triads and model sterically crowded tris(heteroaryl/aryl)methyl cation salts

• Rodrigo Abonia,
• Luisa F. Gutiérrez,
• Braulio Insuasty,
• Jairo Quiroga,
• Kenneth K. Laali,
• Chunqing Zhao,
• Gabriela L. Borosky,
• Samantha M. Horwitz and
• Scott D. Bunge

Beilstein J. Org. Chem. 2019, 15, 642–654, doi:10.3762/bjoc.15.60

• and 9, respectively, packed with up to three different pharmacophors in a single molecule. The ability to perform these reactions in ethanol and even in water, with no catalysts is noteworthy. Representative methylium salts generated by ionization with DDQ/HPF6 exhibited 1H NMR signal broadening

Design, synthesis and spectroscopic properties of crown ether-capped dibenzotetraaza[14]annulenes

• Krzysztof M. Zwoliński and
• Julita Eilmes

Beilstein J. Org. Chem. 2019, 15, 617–622, doi:10.3762/bjoc.15.57

• been fully characterized by FTIR-ATR, 1H and 13C NMR spectroscopy, high-resolution electrospray ionization mass spectrometry (HR-ESIMS) and elemental analysis, and the results are in agreement with expected structures (vide infra). Both the crown ether-capped compounds 3a and 3b are highly symmetrical

Cyclopropene derivatives of aminosugars for metabolic glycoengineering

• Jessica Hassenrück and
• Valentin Wittmann

Beilstein J. Org. Chem. 2019, 15, 584–601, doi:10.3762/bjoc.15.54

• negative mode. The ionization method was electrospray (ESI) and for detection the time of flight (TOF) method was used. Analysis of recorded mass spectra was performed using the software Xcalibur by Thermo Fischer Scientific. 2,5-Dioxopyrrolidin-1-yl 2-methylcyclopropane-1-carboxylate (3): N

Syntheses and chemical properties of β-nicotinamide riboside and its analogues and derivatives

• Mikhail V. Makarov and
• Marie E. Migaud

Beilstein J. Org. Chem. 2019, 15, 401–430, doi:10.3762/bjoc.15.36

• more concentrated alkaline conditions (5 N KOH) as a result of a pyridinium ring opening–closure process [57]. It was also shown that the ionization of a diol fragment of NAD+ under alkaline conditions plays a very important role in the dissociative cleavage of the glycosyl bond of the “northern

Synthesis of C₃-symmetric star-shaped molecules containing α-amino acids and dipeptides via Negishi coupling as a key step

• Sambasivarao Kotha and
• Saidulu Todeti

Beilstein J. Org. Chem. 2019, 15, 371–377, doi:10.3762/bjoc.15.33

• resonance (13C NMR, 100 MHz and 125 MHz) spectra were recorded on a Bruker spectrometer. The high-resolution mass measurements were carried out by using electrospray ionization (ESI) spectrometer. Melting points were recorded on a Veego melting point apparatus. Negishi coupling product 10 Zinc (Zn) dust was

Sigmatropic rearrangements of cyclopropenylcarbinol derivatives. Access to diversely substituted alkylidenecyclopropanes

• Guillaume Ernouf,
• Jean-Louis Brayer,
• Christophe Meyer and
• Janine Cossy

Beilstein J. Org. Chem. 2019, 15, 333–350, doi:10.3762/bjoc.15.29

• were converted into α-allenic tertiary alcohols 22a–c (30–61%) The formation of alcohols 22a–c was explained by a mechanism involving ionization of the C4–O bond in imidates 21a–c, followed by ring opening of the alkylidenecyclopropyl cationic intermediates 23a–c [52] and addition of water to the

Computational characterization of enzyme-bound thiamin diphosphate reveals a surprisingly stable tricyclic state: implications for catalysis

• Ferran Planas,
• Michael J. McLeish and
• Fahmi Himo

Beilstein J. Org. Chem. 2019, 15, 145–159, doi:10.3762/bjoc.15.15

• structure of ThDP and its related intermediates and ionization states have undergone intensive investigation (summarized in references [2][52]). Most of these investigations have focused on the structure and properties of the covalently modified ThDP intermediates of diverse ThDP-dependent enzymes. Less

• attention has been paid to the variety of states the cofactor itself can adopt on the enzyme. As shown in Scheme 1, when various tautomers and ionization states are included, ThDP can adopt at least seven forms on any given ThDP-dependent enzyme. This is prior to any reaction taking place. Most of these are

Mechanistic studies of an L-proline-catalyzed pyridazine formation involving a Diels–Alder reaction with inverse electron demand

• Anne Schnell,
• J. Alexander Willms,
• S. Nozinovic and
• Marianne Engeser

Beilstein J. Org. Chem. 2019, 15, 30–43, doi:10.3762/bjoc.15.3

• -substituted tetrazines via a Diels–Alder reaction with inverse electron demand has been studied with NMR and with electrospray ionization mass spectrometry. A catalytic cycle with three intermediates has been proposed. An enamine derived from L-proline and acetone acts as an electron-rich dienophile in a [4

• intermediates mimic single steps of the proposed catalytic cycle in the gas phase. Thus, the charge-tagged catalyst proved one more time its superior effectiveness for the detection and study of reactive intermediates at low concentrations. Keywords: charge-tag; electrospray ionization; enamine organocatalysis

• ; L-proline; reaction mechanism; Introduction Electrospray (ESI) mass spectrometry (MS) [1] is well suited for studying reaction mechanisms as it is a soft ionization method leaving most species intact [1][2][3]. In addition, it is a fast analytical method [3] making it possible to study transient

A simple and effective preparation of quercetin pentamethyl ether from quercetin

• Jin Tatsuzaki,
• Tomohiko Ohwada,
• Yuko Otani,
• Reiko Inagi and
• Tsutomu Ishikawa

Beilstein J. Org. Chem. 2018, 14, 3112–3121, doi:10.3762/bjoc.14.291

• '-tetramethylquercetin (4, conformation 4A). Conformation 4A has a structure in which the phenyl group is rotated due to the OMe group at the 3 position (the biaryl dihedral angle is +28.2°), and upon ionization of the OH at 5 position to the oxyanion, the planarity was not significantly restored. This may increase the

• the solvent peak for the 1H and 13C NMR spectra. The following abbreviations are used: s = singlet, d = doublet, t = triplet, q = quartet, dd = double doublet. Electron spray ionization time-of-flight mass spectra (ESI–TOF MS) were recorded on a Bruker micrOTOF-05 to give high-resolution mass spectra

Thermophilic phosphoribosyltransferases Thermus thermophilus HB27 in nucleotide synthesis

• Ilja V. Fateev,
• Ekaterina V. Sinitsina,
• Aiguzel U. Bikanasova,
• Maria A. Kostromina,
• Elena S. Tuzova,
• Larisa V. Esipova,
• Tatiana I. Muravyova,
• Alexei L. Kayushin,
• Irina D. Konstantinova and
• Roman S. Esipov

Beilstein J. Org. Chem. 2018, 14, 3098–3105, doi:10.3762/bjoc.14.289

• sequence). Mass spectra were measured on an Agilent 6224, ESI-TOF, LC/MS (USA) in positive ion mode (ESI), LCQ Fleet ion trap mass spectrometer (Thermo Electron, USA) and Agilent 1100 LC/MSD VL (Agilent Technologies) equipped an APCI and ESI source (positive and negative mode of ionization), 1100 DAD and

Organometallic vs organic photoredox catalysts for photocuring reactions in the visible region

• Aude-Héloise Bonardi,
• Frédéric Dumur,
• Guillaume Noirbent,
• Jacques Lalevée and
• Didier Gigmes

Beilstein J. Org. Chem. 2018, 14, 3025–3046, doi:10.3762/bjoc.14.282

• also produced and able to initiate the free radical polymerization. Concerning the cationic polymerization, initiating cations are also produced in the three systems proposed, e.g., in the catalytic cycle (Figure 5A). Thanks to the low ionization potential of the silyl radicals (TMS)3Si•, the

N-Acylated amino acid methyl esters from marine Roseobacter group bacteria

• Hilke Bruns,
• Lisa Ziesche,
• Nargis Khakin Taniwal,
• Laura Wolter,
• Thorsten Brinkhoff,
• Jennifer Herrmann,
• Rolf Müller and
• Stefan Schulz

Beilstein J. Org. Chem. 2018, 14, 2964–2973, doi:10.3762/bjoc.14.276

• the three strains. Mass spectrometry The analysis of the mass spectra of NAMEs, NABMEs, NAVMEs, and NAGMEs revealed the typical fragmentation of N-acylated amino acid methyl esters under both EI (Figure 7) and ESI ionization (Figure 8). Detailed structural information can be obtained by EI-MS. A

Copolymerization of epoxides with cyclic anhydrides catalyzed by dinuclear cobalt complexes

• Yo Hiranoi and
• Koji Nakano

Beilstein J. Org. Chem. 2018, 14, 2779–2788, doi:10.3762/bjoc.14.255

• initiated by monofunctional pentafluorobenzoate from (R,R,S,S)-1 and [PPN][OCOC6F5] [19]. The formation of the alternating copolymers initiated by monofunctional pentafluorobenzoate and the bifunctional chain-transfer agents was confirmed by matrix-assisted laser desorption/ionization time-of-flight mass

• atmospheric pressure chemical ionization–time-of-flight (APCI–TOF) method. Size-exclusion-chromatography (SEC) analyses for evaluating molecular weights were carried with two columns (Shodex KF-804L) using chloroform as an eluent at 40 °C at 1 mL/min. The molecular weight was calibrated against standard

Novel solid-phase strategy for the synthesis of ligand-targeted fluorescent-labelled chelating peptide conjugates as a theranostic tool for cancer

• Sagnik Sengupta,
• Mena Asha Krishnan,
• Premansh Dudhe,
• Ramesh B. Reddy,
• Bishnubasu Giri,
• Sudeshna Chattopadhyay and
• Venkatesh Chelvam

Beilstein J. Org. Chem. 2018, 14, 2665–2679, doi:10.3762/bjoc.14.244

• peptide coupling procedures. 1H and 13C NMR data were recorded using a Bruker AV 400 MHz NMR spectrometer with TMS (tetramethylsilane) as internal reference. Mass spectra were recorded on a Brukermicro TOF-Q II spectrometer in positive mode and negative mode electrospray ionization methods. Reactions were

• Supporting Information File 208: NMR and HRMS spectra of compounds 3, 4 and analytical HPLC spectra of purified (λ at 254 nm and 225 nm) as well as crude (λ at 225 nm), electrospray ionization mass spectra and high-resolution mass spectra for bioconjugates 13 and 17. Acknowledgements The authors are

A novel and practical asymmetric synthesis of eptazocine hydrobromide

• Ruipeng Li,
• Zhenren Liu,
• Liang Chen,
• Jing Pan,
• Kuaile Lin and
• Weicheng Zhou

Beilstein J. Org. Chem. 2018, 14, 2340–2347, doi:10.3762/bjoc.14.209

• Bruker 400 MHz spectrometer with TMS as an internal standard. Mass spectra were recorded with a Q-TOF mass spectrometer using electrospray positive ionization (ESI+). Enantiomeric ratios were determined by HPLC using a chiral column (Chiralpak AY-H) with hexane/isopropyl alcohol 50:50 as eluents

Novel photochemical reactions of carbocyclic diazodiketones without elimination of nitrogen – a suitable way to N-hydrazonation of C–H-bonds

• Liudmila L. Rodina,
• Xenia V. Azarova,
• Jury J. Medvedev,
• Dmitrij V. Semenok and
• Valerij A. Nikolaev

Beilstein J. Org. Chem. 2018, 14, 2250–2258, doi:10.3762/bjoc.14.200

• electrospray ionization (ESI-QTOF). Chemical shifts are reported in ppm, and coupling constants are given in hertz (Hz). All signals in NMR spectra were normalized relative to signals of CНCl3 (δ = 7.26 ppm in 1H NMR) and CDCl3 (δ = 77.0 in 13C NMR spectra). For single crystal X-ray diffraction experiments of

Coordination-driven self-assembly of discrete Ru₆–Pt₆ prismatic cages

• Aderonke Ajibola Adeyemo and
• Partha Sarathi Mukherjee

Beilstein J. Org. Chem. 2018, 14, 2242–2249, doi:10.3762/bjoc.14.199

• heterometallic prismatic cages 3a and 3b obtained from the reaction of two arene–ruthenium(II) clips 1a and 1b and tritopic platinum(II) metalloligand 2 in methanol/chloroform mixture in 3:2 ratio (Scheme 1). Both cages were fully characterized by 1H, 31P, 195Pt, 1H,1H COSY, DOSY NMR, electrospray ionization

• acetonitrile. The 1H, 31P, 195Pt and 13C NMR experiments (Supporting Information File 1, Figures S9–S12) and electrospray ionization mass spectrometry (ESIMS, Supporting Information File 1, Figure S13) of metalloligand 2 evidenced the formation of a pure compound. The 1H NMR spectrum of 2 revealed two doublets

Selective formation of a zwitterion adduct and bicarbonate salt in the efficient CO₂ fixation by N-benzyl cyclic guanidine under dry and wet conditions

• Yoshiaki Yoshida,
• Naoto Aoyagi and
• Takeshi Endo

Beilstein J. Org. Chem. 2018, 14, 2204–2211, doi:10.3762/bjoc.14.194

• Sanso (Yamagata, Japan). The NMR spectra were obtained using a JEOL ECS-400 spectrometer operating at 400 MHz for 1H and 100 MHz for 13C. The elemental analyses were performed by a Perkin Elmer 2400II CHNS/O Analyzer. Mass spectroscopy was performed on a Shimadzu GCMS-QP2010SE in electron ionization (EI

A switchable [2]rotaxane with two active alkenyl groups

• Xiu-Li Zheng,
• Rong-Rong Tao,
• Rui-Rui Gu,
• Wen-Zhi Wang and
• Da-Hui Qu

Beilstein J. Org. Chem. 2018, 14, 2074–2081, doi:10.3762/bjoc.14.181

• spectroscopy and high-resolution electrospray ionization (HRESI) mass spectrometry. The HRESI mass spectra of [2]rotaxane R1 showed a major peak at m/z 2083.3862, corresponding to the species of R1 losing one PF6− anion, i.e., [M − PF6−]+. The 1H NMR spectrum also fitted the R1 structure well and reveals that

• construct stimuli-responsive polymers and smart materials. Experimental General and materials 1H NMR and 13C NMR spectra were measured on a Bruker AV-400 spectrometer. The electronic spray ionization (ESI) mass spectra were tested on a LCT Premier XE mass spectrometer. Chemicals were used as received from

Synthesis and supramolecular self-assembly of glutamic acid-based squaramides

• Juan V. Alegre-Requena,
• Marleen Häring,
• Isaac G. Sonsona,
• Alex Abramov,
• Eugenia Marqués-López,
• Raquel P. Herrera and
• David Díaz Díaz

Beilstein J. Org. Chem. 2018, 14, 2065–2073, doi:10.3762/bjoc.14.180

• 2.5 instrument. Specific rotation calculations were made in chloroform or acetone employing a Jasco P-1020 polarimeter. ESI ionization method and mass analyzer type MicroTof-Q were used for HRMS measurements. 1H NMR spectra and 13C APT-NMR spectra were recorded at 300 MHz and 75 MHz, respectively

Coordination-driven self-assembly vs dynamic covalent chemistry: versatile methods for the synthesis of molecular metallarectangles

• Li-Li Ma,
• Jia-Qin Han,
• Wei-Guo Jia and
• Ying-Feng Han

Beilstein J. Org. Chem. 2018, 14, 2027–2034, doi:10.3762/bjoc.14.178

• signals, consistent with the loss of electron density upon coordination of the nitrogen atom to the metal centers (Figure 1a,b). Analysis of the reaction solution using electrospray ionization mass spectrometry (ESIMS) showed a signal at m/z = 476.1010, corresponding to a tertracation species of complex

Efficient catenane synthesis by cucurbit[6]uril-mediated azide–alkyne cycloaddition

• Antony Wing Hung Ng,
• Chi-Chung Yee,
• Kai Wang and
• Ho Yu Au-Yeung

Beilstein J. Org. Chem. 2018, 14, 1846–1853, doi:10.3762/bjoc.14.158

• for support of the Electrospray Ionization Quadrupole Time-of-Flight Mass Spectrometry Facilities under support for Interdisciplinary Research in Chemical Science.

Synthesis and photophysical studies of a multivalent photoreactive Ru^II-calix[4]arene complex bearing RGD-containing cyclopentapeptides

• Sofia Kajouj,
• Lionel Marcelis,
• Alice Mattiuzzi,
• Adrien Grassin,
• Damien Dufour,
• Pierre Van Antwerpen,
• Didier Boturyn,
• Eric Defrancq,
• Mathieu Surin,
• Julien De Winter,
• Pascal Gerbaux,
• Ivan Jabin and
• Cécile Moucheron

Beilstein J. Org. Chem. 2018, 14, 1758–1768, doi:10.3762/bjoc.14.150

• (ATR) spectrometer. High-resolution mass spectra were obtained on a Waters Synapt G2-Si spectrometer (Waters, Manchester, UK) equipped with an electrospray ionization used in the positive ion mode. Source parameters were as follow: capillary voltage, 3.1 kV; sampling cone, 30 V; source Offset, 80 V

• ; source temperature, 150 °C and desolvation temperature, 200 °C. Matrix-assisted laser desorption/ionization time-of-flight (MALDI-ToF) mass spectra were recorded using a Waters QToF Premier mass spectrometer equipped with a Nd-YAG laser of 355 nm with a maximum pulse energy of 65 μJ delivered to the