Applications of microscopy and small angle scattering techniques for the characterisation of supramolecular gels

• Connor R. M. MacDonald and
• Emily R. Draper

Beilstein J. Org. Chem. 2024, 20, 2608–2634, doi:10.3762/bjoc.20.220

Anion-dependent ion-pairing assemblies of triazatriangulenium cation that interferes with stacking structures

• Yohei Haketa,
• Takuma Matsuda and
• Hiromitsu Maeda

Beilstein J. Org. Chem. 2024, 20, 2567–2576, doi:10.3762/bjoc.20.215

• introduction of N-aryl units during the synthesis is rendered difficult owing to steric hindrances. For example, N-phenyl-substituted TATA+ cation 1b+ (Figure 1) [26] exhibited slightly red-shifted absorption and emission, with a higher quantum efficiency compared to those of N-alkyl-substituted TATA+ cations

• , 0.209 mmol, 19%) as a red solid. Rf 0.33 (MeOH/EtOAc/CH2Cl2 1:2:8); 1H NMR (600 MHz, CDCl3, 20 °C) δ (ppm) 7.68 (t, J = 8.4 Hz, 3H, TATA-H), 7.51 (t, J = 7.8 Hz, 3H, Ar-H), 7.44 (d, J = 7.8 Hz, 6H, Ar-H), 6.37 (d, J = 8.4 Hz, 6H, TATA-H), 2.10 (s, 18H, CH3); 13C NMR (151 MHz, CDCl3, 20 °C) δ (ppm

• % MeOH/CH2Cl2) and was recrystallized from CH2Cl2/n-hexane to afford 2+-PF6− (3.68 mg, 5.0 μmol, 68%) as a red solid. Rf 0.40 (5% MeOH/CH2Cl2); 1H NMR (600 MHz, CDCl3, 20 °C) δ (ppm) 7.63 (t, J = 8.4 Hz, 3H, TATA-H), 7.50 (t, J = 7.8 Hz, 3H, Ar-H), 7.43 (d, J = 7.8 Hz, 6H, Ar-H), 6.35 (d, J = 8.4 Hz, 6H

Synthesis and conformational analysis of pyran inter-halide analogues of ᴅ-talose

• Olivier Lessard,
• Mathilde Grosset-Magagne,
• Paul A. Johnson and
• Denis Giguère

Beilstein J. Org. Chem. 2024, 20, 2442–2454, doi:10.3762/bjoc.20.208

• , 17, and α-ᴅ-talose 18. ORTEP diagram showing 50% thermal ellipsoid probability (except for 18): carbon (gray), oxygen (red), fluorine (green), chlorine (orange), bromine (dark red), iodine (purple), and hydrogen (white). Packing arrangement of compound compound 15; a) View down the b axis; b

• ) proposed intermolecular interactions involving halogens. ORTEP diagram showing 50% thermal ellipsoid probability: carbon (gray), oxygen (red), fluorine (green), iodine (purple), and hydrogen (white). Synthesis of halogenated talopyranose analogues 13–15, and 17 that include a 2,3-cis, 3,4-cis relationship

Homogeneous continuous flow nitration of O-methylisouronium sulfate and its optimization by kinetic modeling

• Jiapeng Guo,
• Weike Su and
• An Su

Beilstein J. Org. Chem. 2024, 20, 2408–2420, doi:10.3762/bjoc.20.205

• experimental results. The red dots show the experimental values for a sulfuric acid mass fraction of 94% and the black dots show the experimental values for a sulfuric acid mass fraction of 98%. Nitration of IO with mixed acid. Values of k for different H2SO4 mass fractions and at different temperatures

Evaluating the halogen bonding strength of a iodoloisoxazolium(III) salt

• Dominik L. Reinhard,
• Anna Schmidt,
• Marc Sons,
• Julian Wolf,
• Elric Engelage and
• Stefan M. Huber

Beilstein J. Org. Chem. 2024, 20, 2401–2407, doi:10.3762/bjoc.20.204

• ). Halogen bonding dimer found in the crystal structure of 7Br. Ellipsoids are shown at 50% probability (carbon: grey, nitrogen: blue, oxygen: red, bromine: orange, iodine: purple) and hydrogen atoms are shown in standard ball-and-stick model (white). Halogen and hydrogen bonding is indicated dashed. 1H NMR

Hydrogen-bond activation enables aziridination of unactivated olefins with simple iminoiodinanes

• Phong Thai,
• Lauv Patel,
• Diyasha Manna and
• David C. Powers

Beilstein J. Org. Chem. 2024, 20, 2305–2312, doi:10.3762/bjoc.20.197

• (red line). b) Cyclic voltammogram of iminoiodinane 2c (8.0 mM) with varying amounts of HFIP in 5.0 mL solution of MeCN (0.10 M TBABF4) under N2 atmosphere: 2c with no HFIP (black line); 2c with 5, 10, 15 µL HFIP (grey line); 2c with 25 µL HFIP (red line); only 25 µL (blue line). c) Diastereomeric

Catalysing (organo-)catalysis: Trends in the application of machine learning to enantioselective organocatalysis

• Stefan P. Schmid,
• Leon Schlosser,
• Frank Glorius and
• Kjell Jorner

Beilstein J. Org. Chem. 2024, 20, 2280–2304, doi:10.3762/bjoc.20.196

Synthesis and reactivity of the di(9-anthryl)methyl radical

• Tomohiko Nishiuchi,
• Kazuma Takahashi,
• Yuta Makihara and
• Takashi Kubo

Beilstein J. Org. Chem. 2024, 20, 2254–2260, doi:10.3762/bjoc.20.193

• structure of DAntM radical (left) and its spin delocalization on two anthryl units. (b) Plausible head-to-head σ-dimerization of the DAntM radical. (a) ESR spectrum of the DAntM radical (black line, Exp.) and its simulated pattern (red line, Sim.). (b) Hyperfine coupling constant of the DAntM radical. (a

• ) ESR spectrum of anthroxyl radical 5 (black line, Exp.) and its simulated pattern (red line, Sim.). (b) Hyperfine coupling constant of 5. (c) X-ray structure of 5. Hydrogen atoms are omitted for clarity. Cyclic voltammogram (CV) of DAntM cation. (a) CV measured with scan rate at 3.0 V s−1. (b) Scan

• rate dependency (0.1, 0.5, 1.0, 2.0, and 3.0 V s−1) of the redox wave. Measurement conditions: 100 mM n-Bu4NPF6 and 1 mM DAntM cation in CH2Cl2. Red arrows indicate the sweep direction. UV–vis–NIR spectra of (a) DAntM radical in toluene, (b) DAntM cation in TFA. Synthetic route to the DAntM radical

Metal-free double azide addition to strained alkynes of an octadehydrodibenzo[12]annulene derivative with electron-withdrawing substituents

• Naoki Takeda,
• Shuichi Akasaka,
• Susumu Kawauchi and
• Tsuyoshi Michinobu

Beilstein J. Org. Chem. 2024, 20, 2234–2241, doi:10.3762/bjoc.20.191

• profiles (ΔG298 in kJ mol−1) calculated at the ωB97X-D/6-31G(d,p)/PCM (in CH2Cl2). Absorption (blue) and fluorescence (red) spectra of 6a (2 × 10−5 M) in CH2Cl2. (a) Crosslinking reaction of PVC-N3 (x = 0.11) with compound 5. (b,c) Strain-stress curves of PVC-N3 before (blue) and after (red) crosslinking

Novel truxene-based dipyrromethanes (DPMs): synthesis, spectroscopic characterization and photophysical properties

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2024, 20, 2163–2170, doi:10.3762/bjoc.20.186

• different equivalents (2 equiv for 12, 6 equiv for 15 and 9 equiv for 17) at 0 °C under N2 atmosphere. The red reaction mixture was stirred for 30 min at 0 °C, and further stirred at room temperature for 1 to 6 hours. After the reaction completion (TLC monitoring), the mixture was poured gradually into

Computational toolbox for the analysis of protein–glycan interactions

• Ferran Nieto-Fabregat,
• Maria Pia Lenza,
• Angela Marseglia,
• Cristina Di Carluccio,
• Antonio Molinaro,
• Alba Silipo and
• Roberta Marchetti

Beilstein J. Org. Chem. 2024, 20, 2084–2107, doi:10.3762/bjoc.20.180

• involving unusual ligands, useful tools can be employed to provide the parameters needed for running MD simulations. Charge calculations and electron density computations for glycan units can be performed using tools like the online RED Server [70]. Although information on force fields is usually available

Regioselective alkylation of a versatile indazole: Electrophile scope and mechanistic insights from density functional theory calculations

• Pengcheng Lu,
• Luis Juarez,
• Paul A. Wiget,
• Weihe Zhang,
• Krishnan Raman and
• Pravin L. Kotian

Beilstein J. Org. Chem. 2024, 20, 1940–1954, doi:10.3762/bjoc.20.170

• N1- and N2-transition states with favorable NCIs shown as red dashed lines. Reaction of 18 under conditions A and B (top), and proposed chelation/coordination pathways to account for regioselectivity (bottom); black two-headed curved arrows indicate the observed NOEs of the major product; adetermined

• and N2 transition states with favorable NCIs shown as red dashed lines. DFT-calculated transition-state structures and energies of 21 under conditions A (top) and conditions B (bottom). NMR, NOE, and yield data of compounds 8 and 9. Synthesis of compounds P1 and P2. Reaction of 21 under conditions A

A new platform for the synthesis of diketopyrrolopyrrole derivatives via nucleophilic aromatic substitution reactions

• Vitor A. S. Almodovar and
• Augusto C. Tomé

Beilstein J. Org. Chem. 2024, 20, 1933–1939, doi:10.3762/bjoc.20.169

• -di(het)aryl groups via Suzuki–Miyaura [26][27][28] or Sonogashira [29][30][31] reactions. In this study, we report a straightforward method to obtain a diverse array of N-substituted DPP derivatives through a two-step process. Firstly, the N-alkylation of Pigment Red 254 (DPP 1) is achieved using

• reagents used in this work were purchased from Merck Life Science (Algés, Portugal) or TCI Europe N.V. (Belgium) and were used as received. Pigment Red 254 was purchased from TCI Europe N.V. The solvents were used as received or distilled and dried by standard procedures. Analytical thin-layer

Negishi-coupling-enabled synthesis of α-heteroaryl-α-amino acid building blocks for DNA-encoded chemical library applications

• Matteo Gasparetto,
• Balázs Fődi and
• Gellért Sipos

Beilstein J. Org. Chem. 2024, 20, 1922–1932, doi:10.3762/bjoc.20.168

• results, thiazole 2b, benzothiazole 2i and benzimidazole 2t react very well with sodium nitrite in an acidic environment (Scheme 6, red section). Among the various subclasses of compounds, pyrazole 2l exhibited a high reactivity using t-BuONO and EtONa in ethanol (Scheme 6, red section). On the other hand

Novel oxidative routes to N-arylpyridoindazolium salts

• Oleg A. Levitskiy,
• Yuri K. Grishin and
• Tatiana V. Magdesieva

Beilstein J. Org. Chem. 2024, 20, 1906–1913, doi:10.3762/bjoc.20.166

• amine A1 without the lutidine additive (black curve) and after addition of 2 equiv (red curve). DMF, 0.1 M NaOTs, 0.1 V/s, Pt disc electrode, vs Ag/AgCl, KCl(sat.) Semi-differential CV curves for the mediators (TEMPO, bis(4-tert-butylphenyl)nitroxide and tris(4-bromphenyl)amine) and amine A3 in DMF

The Groebke–Blackburn–Bienaymé reaction in its maturity: innovation and improvements since its 21st birthday (2019–2023)

• Cristina Martini,
• Muhammad Idham Darussalam Mardjan and
• Andrea Basso

Beilstein J. Org. Chem. 2024, 20, 1839–1879, doi:10.3762/bjoc.20.162

Oxidative fluorination with Selectfluor: A convenient procedure for preparing hypervalent iodine(V) fluorides

• Samuel M. G. Dearman,
• Xiang Li,
• Yang Li,
• Kuldip Singh and
• Alison M. Stuart

Beilstein J. Org. Chem. 2024, 20, 1785–1793, doi:10.3762/bjoc.20.157

• days, but it decomposed completely to iodosyl 9 after just 48 hours in dry chloroform-d1 in air (red line in Figure 3). The difference in the stability of difluoroiodane 6 in CDCl3 and CD3CN was attributed to the ability of acetonitrile to coordinate to the iodine(V) centre. Stabilisation via halogen

• (blue line), dry CDCl3 with 2.4 equivalents of dry pyridine (green line), and dry CDCl3 (red line). Order of hydrolytic stability for the four hypervalent iodine(V) fluorides. Examples of fluorination using hypervalent iodine(III) reagents 1 and 2. Preparations and reactions of hypervalent iodine(V

Synthesis and characterization of 1,2,3,4-naphthalene and anthracene diimides

• Adam D. Bass,
• Daniela Castellanos,
• Xavier A. Calicdan and
• Dennis D. Cao

Beilstein J. Org. Chem. 2024, 20, 1767–1772, doi:10.3762/bjoc.20.155

• = green, N = blue, and O = red. a) Absorption and b) emission spectra of the compounds dissolved in CH2Cl2. Cyclic voltammograms of the compounds collected on ca. 1 mM solutions of the analyte in CH2Cl2 with 0.1 M Bu4NPF6 as electrolyte. The major y-axis tick mark spacing corresponds to 5 μA. Structural

Chemo-enzymatic total synthesis: current approaches toward the integration of chemical and enzymatic transformations

• Ryo Tanifuji and
• Hiroki Oguri

Beilstein J. Org. Chem. 2024, 20, 1693–1712, doi:10.3762/bjoc.20.151

• . Subsequently, the downstream HR-iPKS module, SorbB, catalyzes both the extension of polyketide chain from 30 using two additional malonyl-CoAs and C-methylations exploiting two units of SAM (S-adenosyl methionine) to generate thioester 31 on the ACP domain. Then, the reduction (Red) domain located at the C

• ][98][99]. The reduction (Red) domain at the C-terminus of SfmC reduces the thioester 87 to release aldehyde 88 from SfmB, while the adenylation (A) domain activates 86 and loads it onto the PCP domain of SfmC. The Pictet–Spengler (PS) domain then catalyzes the first diastereoselective PS cyclization

• to form bicyclic thioester 89 with incorporation of a stereogenic center at C1. The Red domain liberates bicyclic aldehyde 90 by reducing the resulting thioester 89, while the A domain again activates another molecule of tyrosine derivative 86, facilitating its loading onto the PCP domain. In the

Oxidation of benzylic alcohols to carbonyls using N-heterocyclic stabilized λ³-iodanes

• Thomas J. Kuczmera,
• Pim Puylaert and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2024, 20, 1677–1683, doi:10.3762/bjoc.20.149

• was added, no significant shifts in the NMR spectral signals were detected, probably due to the poor solubility of the iodane. Conversely, with the addition of the red tetrazine salt 1c, a significant downfield shift was observed for the alpha-carbon protons from 3.51 ppm to 4.55 ppm, as illustrated

• formation of a) an alkoxy-NHI which is causing a significant downfield shift of the protons in alpha-position (orange) compared to the free alcohol 2 (blue) and b) oxidation of p-tolylmethanol (3a, blue) to the aldehyde 4a (green) and carboxylic acid 4a’ (red). Reaction conditions: An equimolar mixture of

Methyltransferases from RiPP pathways: shaping the landscape of natural product chemistry

• Maria-Paula Schröder,
• Isabel P.-M. Pfeiffer and
• Silja Mordhorst

Beilstein J. Org. Chem. 2024, 20, 1652–1670, doi:10.3762/bjoc.20.147

• . There are several options for chemical methylation (see text), but only one example is shown. Enzymatic synthesis is highlighted in red as this is the focus of this highlight. PURE = protein synthesis using recombinant elements, MT = methyltransferase. Biological methylation. A) Methyl donors from

• , PDB ID: 6UAK (https://doi.org/10.2210/pdb6UAK/pdb), [72]. The residues involved in SAH binding are depicted in red. Reaction scheme of the PAMT´s catalysis, leading to the enzymatic conversion of aspartate to aspartyl-O-methyl ester, followed by a two-step non-enzymatic conversion via succinimide

Polymer degrading marine Microbulbifer bacteria: an un(der)utilized source of chemical and biocatalytic novelty

• Weimao Zhong and
• Vinayak Agarwal

Beilstein J. Org. Chem. 2024, 20, 1635–1651, doi:10.3762/bjoc.20.146

• from Microbulbifer Agarases Agarose is a natural polymer consisting of a linear chain of alternating residues of 3-O-linked β-ᴅ-galactopyranose and 4-O-linked 3,6-anhydro-α-ʟ-galactose. Agarose is a major component of agar, a polysaccharide present in the cell walls of some red algae [101]. Agarases

Supramolecular assemblies of amphiphilic donor–acceptor Stenhouse adducts as macroscopic soft scaffolds

• Ka-Lung Hung,
• Leong-Hung Cheung,
• Yikun Ren,
• Ming-Hin Chau,
• Yan-Yi Lam,
• Takashi Kajitani and
• Franco King-Chi Leung

Beilstein J. Org. Chem. 2024, 20, 1590–1603, doi:10.3762/bjoc.20.142

• supramolecular structural transformations [37]. The large-aspect-ratio DA nanostructures assembled into macroscopic soft scaffolds, for which the disassembly process on a macroscopic length scale was controlled by white light. Furthermore, the red-light-responsiveness of the DAs could be regained in aqueous

• (Figure 1a). Upon 625 nm red-light irradiation for 60 s at 20 °C to reach the photostationary state (PSS), the strong absorption band at 470–685 nm was diminished, with a clear isosbestic point at 259 nm (Figure 1a, red line), which indicates a selective photoisomerization process from the open-isomer O

• -DA11 (Figure 1a, black line and Figure 1b blue line) to the cyclized-isomer C-DA11 (Figure 1a, red line). The resulting solution continued to be irradiate with 625 nm red light for 60 s at 20 °C and subsequently stored in the dark at 20 °C for 60 min for the thermal back reaction to occur to test the

Mining raw plant transcriptomic data for new cyclopeptide alkaloids

• Draco Kriger,
• Michael A. Pasquale,
• Brigitte G. Ampolini and
• Jonathan R. Chekan

Beilstein J. Org. Chem. 2024, 20, 1548–1559, doi:10.3762/bjoc.20.138

• fluorescein sample was adjusted to 6.30 min to correct for run to run drifts in retention time. Biosynthetic scheme for the formation of burpitides using a split (top) or fused (bottom) pathway. RS is recognition sequence. Peptide modifications are shown in red. Cladogram made from 647 plant species surveyed

• color-coded to show localization of various molecules. Molecules in red are new to this study and predicted by MS/MS fragmentation. Ceanothine B was isolated and its structure confirmed by 1D and 2D NMR. Correlations are indicated as follows: red lines – COSY, green lines – TOCSY, pink arrows – NOSEY

Benzylic C(sp³)–H fluorination

• Alexander P. Atkins,
• Alice C. Dean and
• Alastair J. J. Lennox

Beilstein J. Org. Chem. 2024, 20, 1527–1547, doi:10.3762/bjoc.20.137

• -catalysed bidentate-directed benzylic C(sp3)–H fluorination. Palladium-catalysed benzylic fluorination using a transient directing group approach. Ratio refers to fluorination (red) vs oxygenation (blue) product. Outline for benzylic C(sp3)–H fluorination via radical intermediates. Iron(II)-catalysed