Synthesis of new asparagine-based glycopeptides for future scanning tunneling microscopy investigations

• Laura Sršan and
• Thomas Ziegler

Beilstein J. Org. Chem. 2020, 16, 888–894, doi:10.3762/bjoc.16.80

• comparison with naturally occurring amino acids [14]. Thus, there is still a great effort in finding new potential drugs derived from glycopeptides [4][15]. By using preparative mass spectrometry (pMS) combined with STM on submolecular-resolution peptides and carbohydrates can be investigated regarding their

One-pot synthesis of dicyclopenta-fused peropyrene via a fourfold alkyne annulation

• Ji Ma,
• Yubin Fu,
• Junzhi Liu and
• Xinliang Feng

Beilstein J. Org. Chem. 2020, 16, 791–797, doi:10.3762/bjoc.16.72

• -fused PAHs in large π-systems. High-resolution MALDI-TOF mass spectrum of 1. Inset: isotopic distribution compared to mass spectrum simulated for C84H50. Single-crystal X-ray structure of 1. (a) Top view and (b) side view of the (P,P) isomer. c) Crystal packing of the enantiomer pairs (P,P and M,M) of 1

Efficient synthesis of dipeptide analogues of α-fluorinated β-aminophosphonates

• Marcin Kaźmierczak and
• Henryk Koroniak

Beilstein J. Org. Chem. 2020, 16, 756–762, doi:10.3762/bjoc.16.69

• parts per million upfield from CFCl3 as an internal standard (δ = 0) in CDCl3 or CD3CN. 31P NMR Chemical shifts were expressed in parts per million in CDCl3 or CD3CN. High-resolution mass spectra were recorded by electron spray (ESIMS) techniques using a QToF Impact HD Bruker spectrometer. Reagent grade

Synthesis of C₇₀-fragment buckybowls bearing alkoxy substituents

• Yumi Yakiyama,
• Shota Hishikawa and
• Hidehiro Sakurai

Beilstein J. Org. Chem. 2020, 16, 681–690, doi:10.3762/bjoc.16.66

• used as a solvent and the residual solvent peaks were used as an internal standard (1H NMR: CDCl3 7.26 ppm; 13C NMR: CDCl3 77.00 ppm). High-resolution fast atom bombardment (FAB) mass spectra were measured on a JEOL JMS-700 spectrometer. TLC analysis was performed using Merck silica gel 60 F254, and

Design and synthesis of diazine-based panobinostat analogues for HDAC8 inhibition

• Sivaraman Balasubramaniam,
• Sajith Vijayan,
• Liam V. Goldman,
• Xavier A. May,
• Kyra Dodson,
• Sweta Adhikari,
• Fatima Rivas,
• Davita L. Watkins and
• Shana V. Stoddard

Beilstein J. Org. Chem. 2020, 16, 628–637, doi:10.3762/bjoc.16.59

• residual peak (CHCl3: 7.26 ppm for 1H, 77.2 ppm for 13C). Data are reported as follows: chemical shifts, multiplicity (s = singlet, d = doublet, t = triplet, q = quartet, quint = quintet, m = multiplet, br = broad), coupling constant J (Hz), and integration. High-resolution mass spectra were recorded using

Direct borylation of terrylene and quaterrylene

• Haruka Kano,
• Keiji Uehara,
• Kyohei Matsuo,
• Hironobu Hayashi,
• Hiroko Yamada and
• Naoki Aratani

Beilstein J. Org. Chem. 2020, 16, 621–627, doi:10.3762/bjoc.16.58

• 2,5,10,13-tetramesitylterrylene (TM4) in 58% yield. TM4 was successfully isolated through a silica gel pad and by reprecipitation. The structure of TM4 was characterized by mass spectrometry and 1H and 13C NMR spectroscopy. High-resolution MALDI mass spectrometry detected the parent ion peak at m/z

• many uses in organic devices. Experimental 1H NMR (500 MHz) and 13C NMR (126 MHz) spectra were recorded with a JEOL JNM-ECX500 spectrometer at 20 °C by using tetramethylsilane as an internal standard. High-resolution mass spectra (HRMS) were measured with the matrix-assisted laser desorption/ionization

Regioselectively α- and β-alkynylated BODIPY dyes via gold(I)-catalyzed direct C–H functionalization and their photophysical properties

• Takahide Shimada,
• Shigeki Mori,
• Masatoshi Ishida and
• Hiroyuki Furuta

Beilstein J. Org. Chem. 2020, 16, 587–595, doi:10.3762/bjoc.16.53

• of TIPS-ethynyl-substituted BODIPY derivatives 3–6 were characterized by 1H and 19F NMR spectroscopy, high-resolution mass spectrometry, and X-ray crystallographic analysis. The solid-state structures of the diethynyl-substituted BODIPYs were unambiguously elucidated by X-ray diffraction analysis (3a

Six-fold C–H borylation of hexa-peri-hexabenzocoronene

• Mai Nagase,
• Kenta Kato,
• Akiko Yagi,
• Yasutomo Segawa and
• Kenichiro Itami

Beilstein J. Org. Chem. 2020, 16, 391–397, doi:10.3762/bjoc.16.37

• permeation chromatography (GPC) was performed with a JAI LaboACE LC-5060 instrument equipped with JAIGEL-2H columns using chloroform as an eluent. Retsch MM400, zirconia milling jars and zirconia balls were used for pulverizing at 30 Hz and 60 min. The high-resolution mass spectrum (HRMS) was obtained from a

• ≤ 55.862°), 2594 unique (Rint = 0.0529). Goodness-of-fit on F2: 1.093. R1 = 0.0733, wR2 = 0.2041 (I > 2σ(I)) and R1 = 0.1252, wR2 = 0.2378 (all data). Photophysical measurements UV–vis absorption spectra were recorded on a Shimadzu UV-3510 spectrometer with a resolution of 0.5 nm. The emission spectrum was

• measured on a Shimadzu RF-6000 spectrometer with a resolution of 0.5 nm. Absolute fluorescence quantum yield (ΦF) was determined on a Shimadzu RF-6000 spectrometer using a calibrated integrating sphere system upon excitation at 340 nm. For FL lifetime measurement, a Hamamatsu Photonics Quantaurus-Tau

Architecture and synthesis of P,N-heterocyclic phosphine ligands

• Wisdom A. Munzeiwa,
• Bernard Omondi and
• Vincent O. Nyamori

Beilstein J. Org. Chem. 2020, 16, 362–383, doi:10.3762/bjoc.16.35

• . Finally, the desired ligands were obtained by palladium-catalyzed phosphorylation with triphenylphosphine in DMF [92]. Resolution with palladium amine complexes and subsequent crystallization resulted in the enantiomerically pure ligands 95. C2-Symmetric atropisomeric diphosphines are among a diverse

p-Pyridinyl oxime carbamates: synthesis, DNA binding, DNA photocleaving activity and theoretical photodegradation studies

• Panagiotis S. Gritzapis,
• Panayiotis C. Varras,
• Nikolaos-Panagiotis Andreou,
• Katerina R. Katsani,
• Konstantinos Dafnopoulos,
• George Psomas,
• Zisis V. Peitsinis,
• Alexandros E. Koumbis and
• Konstantina C. Fylaktakidou

Beilstein J. Org. Chem. 2020, 16, 337–350, doi:10.3762/bjoc.16.33

• from Sigma–Aldrich Co. CT DNA stock solution was prepared according to standard procedures [84]. The CT DNA concentration was determined by the UV absorbance at 260 nm after 1:20 dilution using ε = 6600 M–1cm–1 [85]. High-resolution mass spectra (HRMS) were recorded on micrOTOF GC–MS QP 5050 Shimadzu

Synthesis and circularly polarized luminescence properties of BINOL-derived bisbenzofuro[2,3-b:3’,2’-e]pyridines (BBZFPys)

• Ryo Takishima,
• Yuji Nishii,
• Tomoaki Hinoue,
• Yoshitane Imai and
• Masahiro Miura

Beilstein J. Org. Chem. 2020, 16, 325–336, doi:10.3762/bjoc.16.32

• Mettler Toledo MP90. High-resolution mass spectra (HRMS) were recorded by APCI-TOF or EI. Preparative gel permeation chromatography (GPC) was conducted with a YMC GPC-T2000 column eluting with CHCl3. Absorption spectra were recorded with JASCO V-750 spectrometer. Photoluminescence spectra were recorded

Formal preparation of regioregular and alternating thiophene–thiophene copolymers bearing different substituents

• Atsunori Mori,
• Keisuke Fujita,
• Chihiro Kubota,
• Toyoko Suzuki,
• Kentaro Okano,
• Takuya Matsumoto,
• Takashi Nishino and
• Masaki Horie

Beilstein J. Org. Chem. 2020, 16, 317–324, doi:10.3762/bjoc.16.31

• spectra were recorded on Bruker Alpha spectrometer with an ATR attachment (Ge). High-resolution mass spectra (HRMS) were measured using a JEOL JMS-T100LP AccuTOF LC-Plus apparatus (ESI) with a JEOL MS-5414DART attachment. For thin-layer chromatography (TLC) analyses throughout this work, Merck precoated

Synthesis of 4-(2-fluorophenyl)-7-methoxycoumarin: experimental and computational evidence for intramolecular and intermolecular C–F···H–C bonds

• Vuyisa Mzozoyana,
• Fanie R. van Heerden and
• Craig Grimmer

Beilstein J. Org. Chem. 2020, 16, 190–199, doi:10.3762/bjoc.16.22

• equipped with a 5 mm BBOZ probe at frequencies of 400 MHz, 100 MHz, and 376 MHz for 1H, 13C, and 19F, respectively. High-resolution mass spectrometry (HRMS) was performed on a Waters LCT Premier time-of-flight mass spectrometer. Synthesis of methyl 2-fluorobenzoylacetate (3): To a stirred mixture of MgCl2

The use of isoxazoline and isoxazole scaffolding in the design of novel thiourea and amide liquid-crystalline compounds

• Itamar L. Gonçalves,
• Rafaela R. da Rosa,
• Vera L. Eifler-Lima and
• Aloir A. Merlo

Beilstein J. Org. Chem. 2020, 16, 175–184, doi:10.3762/bjoc.16.20

• , intensity, resolution and peaks of some phase transitions are lost. Considering that molecules self-organize upon cooling, first by hydrogen bonds followed by π-stacking and van der Waals forces, DSC scanning at 10 °C/min is too fast to allow the molecules to self-assemble in a perfect 3D matrix. Even with

• plots of compounds. Acknowledgements Thanks to Dr. Rômulo Faria Santos Canto of the Universidade Federal de Ciências da Saúde de Porto Alegre for the analyses of high-resolution mass spectrometry. Funding The authors wish to thank the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil

Halogen-bonding-induced diverse aggregation of 4,5-diiodo-1,2,3-triazolium salts with different anions

• Xingyu Xu,
• Shiqing Huang,
• Zengyu Zhang,
• Lei Cao and
• Xiaoyu Yan

Beilstein J. Org. Chem. 2020, 16, 78–87, doi:10.3762/bjoc.16.10

• good yield (Scheme 1). The product 2-I was characterized by 1H NMR, 13C NMR, and high-resolution mass spectrometry. 2-I has a poor solubility in most organic solvents such as dichloromethane, trichloromethane, tetrahydrofuran, and ethanol. A single crystal of 2-I was obtained by slow diffusion of ether

• of dry nitrogen or in a glovebox. At the same time, the syntheses were performed under a standard Schlenk vacuum line. 1H NMR spectra were recorded on a Bruker Avance 400 MHz spectrometer. High-resolution mass spectra (HRMS) were acquired with a Thermo Scientific (Q-Exactive) instrument using

Understanding the role of active site residues in CotB2 catalysis using a cluster model

• Keren Raz,
• Ronja Driller,
• Thomas Brück,
• Bernhard Loll and
• Dan T. Major

Beilstein J. Org. Chem. 2020, 16, 50–59, doi:10.3762/bjoc.16.7

• reactivity of the isolated species and provided crucial mechanistic insights, the biorelevant mechanism cannot be fully understood without taking into account the enzyme–solvent environment. A common problem when studying these enzymes is the lack of high-resolution crystal structures that are biologically

• reaction. The coordinates of the amino acids and the substrate GGPP were taken from the corresponding X-ray structure, with a resolution of 1.8 Å [42]. In this approach, geometry optimizations with the “Modredundant” keyword were performed, and the active site residues, diphosphate moiety, and magnesium

Light-controllable dithienylethene-modified cyclic peptides: photoswitching the in vivo toxicity in zebrafish embryos

• Sergii Afonin,
• Oleg Babii,
• Aline Reuter,
• Volker Middel,
• Masanari Takamiya,
• Uwe Strähle,
• Igor V. Komarov and
• Anne S. Ulrich

Beilstein J. Org. Chem. 2020, 16, 39–49, doi:10.3762/bjoc.16.6

• (converted to the ON photoform) by applying light of a specific wavelength, precisely at the desired site of action. Spatiotemporal resolution of such light-mediated drug delivery is limited mainly by the technical characteristics of the medical devices used for light application and by the light propagation

Starazo triple switches – synthesis of unsymmetrical 1,3,5-tris(arylazo)benzenes

• Andreas H. Heindl and
• Hermann A. Wegner

Beilstein J. Org. Chem. 2020, 16, 22–31, doi:10.3762/bjoc.16.4

• only E- and Z-configuration of the AB, but also different configurations of the Boc groups. However, the coupling products could be unequivocally identified by high-resolution mass spectrometry. Next, 16a/16b were coupled with N-Boc-N-phenylhydrazine to afford the corresponding tris(arylazo)benzene

Synthesis of C-glycosyl phosphonate derivatives of 4-amino-4-deoxy-α-ʟ-arabinose

• Lukáš Kerner and
• Paul Kosma

Beilstein J. Org. Chem. 2020, 16, 9–14, doi:10.3762/bjoc.16.2

• ]. Under basic conditions, such as by treatment of 9 with 1 M NaOH in MeOH, the exo double bond of compound 9 could be shifted to produce the corresponding endo-glycal 10 in 80% yield. The m/z value of the high-resolution mass spectrum indicated that 10 was an isomer of 9. In the 1H NMR (600 MHz) spectrum

Extension of the 5-alkynyluridine side chain via C–C-bond formation in modified organometallic nucleosides using the Nicholas reaction

• Renata Kaczmarek,
• Dariusz Korczyński,
• James R. Green and
• Roman Dembinski

Beilstein J. Org. Chem. 2020, 16, 1–8, doi:10.3762/bjoc.16.1

• of alkynyl nucleosides 2 and 3 were confirmed by 1H and 13C NMR spectroscopy and high-resolution mass spectrometry [64][65]. The conversion of alkynyl nucleosides 2 and 3 into the corresponding dicobalt hexacarbonyl nucleosides complexes of 4 and 5 was accomplished at room temperature (Co2(CO)8, THF

• , 22 °C, 1 h) with 88–77% yield after silica gel column chromatography (Scheme 1). The structures of nucleosides 4 and 5 were confirmed by NMR and IR spectroscopy (for the synthesis of a related unprotected nucleoside, see [31]). The MS spectra of 4 and 5 exhibited appropriate high resolution molecular

Chemical synthesis of tripeptide thioesters for the biotechnological incorporation into the myxobacterial secondary metabolite argyrin via mutasynthesis

• David C. B. Siebert,
• Roman Sommer,
• Domen Pogorevc,
• Michael Hoffmann,
• Silke C. Wenzel,
• Rolf Müller and
• Alexander Titz

Beilstein J. Org. Chem. 2019, 15, 2922–2929, doi:10.3762/bjoc.15.286

• , encoded by the gene fusA1) as their target [11][12]. The co-crystal structure of argyrin B (2) and P. aeruginosa EF-G1 provides structural information of the complex at atomic resolution as basis for further structure-based optimization [11]. Jones and colleagues analyzed possible resistance mechanisms to

Palladium-catalyzed Sonogashira coupling reactions in γ-valerolactone-based ionic liquids

• László Orha,
• József M. Tukacs,
• László Kollár and
• László T. Mika

Beilstein J. Org. Chem. 2019, 15, 2907–2913, doi:10.3762/bjoc.15.284

• File 1. Exact mass measurements were performed on a high-resolution Q-Exactive Focus hybrid quadrupole-orbitrap mass spectrometer (Thermo Fisher Scientific, Bremen, Germany) equipped with a heated electrospray ionization (ESI) source. Samples were dissolved in acetonitrile/water 1:1 (v/v) solvent

Carbazole-functionalized hyper-cross-linked polymers for CO₂ uptake based on Friedel–Crafts polymerization on 9-phenylcarbazole

• Dandan Fang,
• Xiaodong Li,
• Meishuai Zou,
• Xiaoyan Guo and
• Aijuan Zhang

Beilstein J. Org. Chem. 2019, 15, 2856–2863, doi:10.3762/bjoc.15.279

• used without further purification. Characterization methods Fourier-transform infrared (FTIR) spectra of HCPs were obtained by using a Nicolet 6700 spectrometer over a wave number range of 4000–400 cm−1 by scanning 32 times at a resolution of 4 cm−1. TG analysis of the polymers were conducted with a

Photoreversible stretching of a BAPTA chelator marshalling Ca²⁺-binding in aqueous media

• Aurélien Ducrot,
• Arnaud Tron,
• Robin Bofinger,
• Ingrid Sanz Beguer,
• Jean-Luc Pozzo and
• Nathan D. McClenaghan

Beilstein J. Org. Chem. 2019, 15, 2801–2811, doi:10.3762/bjoc.15.273

• spectra were recorded in the positive mode. High-resolution mass spectrometry (HRMS) measurements were performed with an ESI source on a Q-TOF mass spectrometer with an accuracy tolerance of 2 ppm (Fédération de Recherche CBM/ICOA (FR2708) platform). The electrospray needle was maintained at 5000 V and

Diversity-oriented synthesis of spirothiazolidinediones and their biological evaluation

• Sambasivarao Kotha,
• Gaddamedi Sreevani,
• Lilya U. Dzhemileva,
• Milyausha M. Yunusbaeva,
• Usein M. Dzhemilev and
• Vladimir A. D’yakonov

Beilstein J. Org. Chem. 2019, 15, 2774–2781, doi:10.3762/bjoc.15.269

• 125 MHz spectrometers using tetramethylsilane (TMS) as an internal standard and chloroform-d as a solvent. High resolution mass spectrometry (HRMS) was performed using a Bruker (Maxis Impact) or a Micromass Q-ToF spectrometer. The melting points recorded are uncorrected. The microwave used here was a