Synthesis of acremines A, B and F and studies on the bisacremines

• Nils Winter and
• Dirk Trauner

Beilstein J. Org. Chem. 2019, 15, 2271–2276, doi:10.3762/bjoc.15.219

• not affect any reaction. Next, we tried to enhance the possibility for productive reactivity by tethering two units of 5 and therefore executed the reaction in an intramolecular way (Scheme 5). Unfortunately, treatment of 23 with various redox catalysts led either to decomposition or recovery of the

Recent advances in transition-metal-catalyzed incorporation of fluorine-containing groups

• Xiaowei Li,
• Xiaolin Shi,
• Xiangqian Li and
• Dayong Shi

Beilstein J. Org. Chem. 2019, 15, 2213–2270, doi:10.3762/bjoc.15.218

• orchestrated redox process, an alkoxyl radical-guided strategy for the site-selective fluorination of unactivated methylene and methine C–H bonds was published by Liu and co-workers in 2018 (Scheme 44) [91]. The fluorination of various primary, secondary, and tertiary hydroperoxides was achieved in moderate to

1,2,3-Triazolium macrocycles in supramolecular chemistry

• Mastaneh Safarnejad Shad,
• Pulikkal Veettil Santhini and
• Wim Dehaen

Beilstein J. Org. Chem. 2019, 15, 2142–2155, doi:10.3762/bjoc.15.211

• and imidazolium which can recognize different anions, have been reported in the literature. As a matter of fact, porphyrin macrocycles are used for sensing of anionic compounds by a measurable physical response due to their intrinsic optical and redox properties [38]. Beer and co-workers have

• association constant of macrocycle 3 in the more competitive 15% water/acetone medium, still demonstrating a high binding affinity for sulfate anion (Ka = 2.5 × 105 M−1) while the cage 3 did not show any binding toward the other tested anions in the more aqueous solvent mixture. 2.3. Redox-active 1,2,3

• charge-assisted C–H···anion interactions. According to the cyclic voltammetry analysis, the redox-active macrocycle was able to recognize chloride, causing a cathodic shift of the Epa wave of the ferrocene/ferrocenium redox couple. However, a quick disappearance of the redox signal was observed when the

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

• moieties allows further modifications at these units to achieve fine-tuning of the light absorption and redox properties. In the course of this study, we also expected that these derivatives could serve as interesting components of supramolecular structures that can assemble in a predictable way owing to

Naphthalene diimides with improved solubility for visible light photoredox catalysis

• Barbara Reiß and
• Hans-Achim Wagenknecht

Beilstein J. Org. Chem. 2019, 15, 2043–2051, doi:10.3762/bjoc.15.201

• catalysis is mainly [Ru(bpy)3]2+ [21], due to its strong MLCT (metal-to-ligand charge transfer) absorption, the excellent yield of its triplet state and the long lifetime, the versatile redox behavior (Ru3+ vs Ru+) in quenching processes and the chemical and photochemical robustness. Despite their positive

• easily incorporated into the core structure in order to tune optical and redox properties. Naphthalene diimides (NDIs) as the smallest possible rylene dyes are such an important class of organic dyes. In contrast to their bigger homologs perylene diimides which were rarely used for photoredox catalysis

• order to tune their optical and redox properties as mentioned above [39][40][52]. The common synthetic approach for core-substituted NDIs (cNDIs) makes tailor-made dyes rather easily accessible. With respect to these unique properties, NDIs should also be explored for photoredox catalysis. We present

Synthesis and anion binding properties of phthalimide-containing corona[6]arenes

• Meng-Di Gu,
• Yao Lu and
• Mei-Xiang Wang

Beilstein J. Org. Chem. 2019, 15, 1976–1983, doi:10.3762/bjoc.15.193

• redox properties of phthalimide-bearing O6-corona[3]arene[3]tetrazines, a cyclic voltammogram (CV) and a differential pulse voltammogram of 3a were recorded. As depicted in Figure 3, macrocycle 3a undergoes a reversible sequential one-electron redox process at −811, −883, −1871, and −2367 mV. The

• electrochemical result indicated the occurrence of electronic communication between aromatic rings. The potential for the first redox process (−811 mV) obtained from CV and DPV revealed the electron deficiency of the macrocycle. The resulting electron-deficient O6-corona[3]arene[3]tetrazines prompted us to

Morphology-tunable and pH-responsive supramolecular self-assemblies based on AB₂-type host–guest-conjugated amphiphilic molecules for controlled drug delivery

• Yang Bai,
• Cai-ping Liu,
• Di Chen,
• Long-hai Zhuo,
• Huai-tian Bu and
• Wei Tian

Beilstein J. Org. Chem. 2019, 15, 1925–1932, doi:10.3762/bjoc.15.188

• stimuli-responsive supramolecular self-assemblies with regulated self-assembly morphologies due to their response to various external stimuli, such as temperature [12], light [13][14][15], redox [16][17][18], and pH [19][20]. In addition, β-cyclodextrin (β-CD), pillararene and cucurbituril have been

• utilized as host units to construct these stimuli-responsive supramolecular self-assemblies [21][22][23][24][25][26][27]. For example, β-CD can form inclusion complexes with guests such as azobenzene [28][29], ferrocene [30][31] and benzimidazole [32][33][34] to construct light-, redox-, and pH-responsive

Identification of optimal fluorescent probes for G-quadruplex nucleic acids through systematic exploration of mono- and distyryl dye libraries

• Xiao Xie,
• Michela Zuffo,
• Marie-Paule Teulade-Fichou and
• Anton Granzhan

Beilstein J. Org. Chem. 2019, 15, 1872–1889, doi:10.3762/bjoc.15.183

• governing their interaction with DNA and sensing capabilities. In fact, although it is known in broad terms that some molecular features (e.g., size and shape of the aromatic scaffold, charge, redox potential) influence the interaction of dyes with G4-DNA, a thorough assessment of such phenomena by

• potential of dyes, rendering the photoinduced electron-transfer reaction with guanine residues in DNA energetically disfavored and resulting in higher fluorescence quantum yields. However, in the absence of redox potential data, this assumption could not be experimentally verified. Finally, we showed that

Metal-free mechanochemical oxidations in Ertalyte^® jars

• Andrea Porcheddu,
• Francesco Delogu,
• Lidia De Luca,
• Claudia Fattuoni and
• Evelina Colacino

Beilstein J. Org. Chem. 2019, 15, 1786–1794, doi:10.3762/bjoc.15.172

• successfully used to induce mechanochemical oxidative processes on several structurally different primary and secondary alcohols. The proposed redox process is safe, inexpensive and performing effectively, especially on the macroscale. Herein, an Ertalyte® jar has been successfully used, for the first time, in

• the atom efficiency [4][5]. The discovery of (2,2,6,6-tetramethylpiperidin-1-yl)oxyl, commonly known as TEMPO by Lebedev and Kazarnowskii in 1960 has been hailed as a significant breakthrough in the field of redox reactions, allowing the fast and selective oxidation of alcohols to the related carbonyl

• , especially in redox processes conducted in no-metal reactors, could prevent excessive heating of the jar, avoid the decomposition of starting materials and therefore, limit the formation of byproducts [40]. Following our interest in mechanochemistry and the design of new cost-effective oxidation procedures

Functional panchromatic BODIPY dyes with near-infrared absorption: design, synthesis, characterization and use in dye-sensitized solar cells

• Quentin Huaulmé,
• Cyril Aumaitre,
• Outi Vilhelmiina Kontkanen,
• David Beljonne,
• Alexandra Sutter,
• Gilles Ulrich,
• Renaud Demadrille and
• Nicolas Leclerc

Beilstein J. Org. Chem. 2019, 15, 1758–1768, doi:10.3762/bjoc.15.169

• conduction band (CB) of the metal oxide and the redox potential of the electrolyte. Abundant literature on BODIPY derivatives allowed us to identify a chemical approach to fulfill those criteria, i.e., the introduction of an electron rich unit at the 3rd and 5th positions of the BODIPY core via a vinyl

• its reversible redox properties and high electron-donating strength (see Figure 1) [26]. In order to promote the delocalization from the electron-donating unit to the electron-withdrawing and anchoring group located on its 8 position, a 2,3,5,6-tetramethyl-BODIPY derivative has been designed (see

• well as to determine the energy levels of their highest occupied molecular orbital (HOMO) and lower unoccupied molecular orbital (LUMO). All the redox potentials were calibrated with respect to Ferrocene (Fc), assuming that E(Fc/Fc+) = 0.40 V with respect to SCE (see experimental details). The low

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

• ][60]. They have been employed for a number of organic reactions viz., hydrosilylation of aldehydes and ketones, acetylation reactions, redox reactions, oxidative esterification, etc. [61][62][63]. Thus, in concern with increasing demand for sustainable development, a growing number of catalytic

Reversible end-to-end assembly of selectively functionalized gold nanorods by light-responsive arylazopyrazole–cyclodextrin interaction

• Maximilian Niehues,
• Patricia Tegeder and
• Bart Jan Ravoo

Beilstein J. Org. Chem. 2019, 15, 1407–1415, doi:10.3762/bjoc.15.140

• nanoparticle systems [18][19][20][21][22][23][24]. The host–guest interaction can be responsive to external stimuli such as redox, pH or light, with the latter being the most desirable for assembling nanoparticles by virtue of its noninvasive nature [25]. Prominent light-responsive guest molecules are

Complexation of a guanidinium-modified calixarene with diverse dyes and investigation of the corresponding photophysical response

• Yu-Ying Wang,
• Yong Kong,
• Zhe Zheng,
• Wen-Chao Geng,
• Zi-Yi Zhao,
• Hongwei Sun and
• Dong-Sheng Guo

Beilstein J. Org. Chem. 2019, 15, 1394–1406, doi:10.3762/bjoc.15.139

• excited-state photophysics, redox behavior and utilizable luminescence properties [60][61]. These Ru complexes exhibit transitions involving charge transfer from the metal-centered d orbital to the ligand p orbital, commonly known as metal-to-ligand charge transfer (MLCT). Upon excitation, the excited

Selenophene-containing heterotriacenes by a C–Se coupling/cyclization reaction

• Pierre-Olivier Schwartz,
• Sebastian Förtsch,
• Astrid Vogt,
• Elena Mena-Osteritz and
• Peter Bäuerle

Beilstein J. Org. Chem. 2019, 15, 1379–1393, doi:10.3762/bjoc.15.138

• 3/DSS 4 (28,400 to 20,830 L mol−1 cm−1). No fluorescence was observed for each of the four heteroacenes DTT 1 to DSS 4 neither in DCM nor in THF. Electrochemical properties and electropolymerization The redox properties of the heterotriacenes 1–4 were investigated by means of cyclic voltammetry in

• as electrolyte and the redox and optical properties of the obtained films were determined. Electropolymer P(DTT) P1 has already been reported in literature and the findings agree well with our results [46][51]. In Figure 8, exemplarily the electropolymerization of heterotriacene DST 2 (left) and

• P1–P4 in a monomer-free electrolyte showed broad and unstructured redox waves typical for conducting polymers reflecting the inhomogeneity of the material containing various electrophoric moieties due to variations in the (conjugated) chain length and conformational issues [52]. As well the

Robust perfluorophenylboronic acid-catalyzed stereoselective synthesis of 2,3-unsaturated O-, C-, N- and S-linked glycosides

• Madhu Babu Tatina,
• Xia Mengxin,
• Rao Peilin and
• Zaher M. A. Judeh

Beilstein J. Org. Chem. 2019, 15, 1275–1280, doi:10.3762/bjoc.15.125

• ][17][18][19], redox reagents [20] and metal catalysts [21][22][23]. However, many of these catalysts have limited substrate scope, give variable selectivities and yields, require harsh reaction conditions and an excess amount of catalysts that are typically expensive, toxic and moisture/air sensitive

Diaminoterephthalate–α-lipoic acid conjugates with fluorinated residues

• Leon Buschbeck,
• Aleksandra Markovic,
• Gunther Wittstock and
• Jens Christoffers

Beilstein J. Org. Chem. 2019, 15, 981–991, doi:10.3762/bjoc.15.96

• molecular reactions (cleavage, anchoring) in monolayers after their assembly on surfaces. In the course of our project on surface modifications by redox-active SAMs, we envisioned a bifunctionalized DAT as suitable building block. Surface binding to a metal support, e.g., gold, should be accomplished by an

Photochemical generation of the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radical from caged nitroxides by near-infrared two-photon irradiation and its cytocidal effect on lung cancer cells

• Ayato Yamada,
• Manabu Abe,
• Yoshinobu Nishimura,
• Shoji Ishizaka,
• Masashi Namba,
• Taku Nakashima,
• Kiyofumi Shimoji and
• Noboru Hattori

Beilstein J. Org. Chem. 2019, 15, 863–873, doi:10.3762/bjoc.15.84

• addition to their ease of handling, nitroxides are highly sensitive to electron paramagnetic resonance (EPR) spectroscopy and redox reactions. Therefore, nitroxides have been developed and utilized in diverse and crucial applications, not only in chemistry, but also in biology, physiology, and energy

• approach for investigating the role of redox-active nitroxides in mediating oxidative stress in organisms [27][28][29][30][31][32]. In 1997, Scaiano and co-workers reported the triplet-xanthone sensitized generation of the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radical from alkoxyamine 1 under

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

• redox potential [6]. The facile formation of such compounds and their unusual properties led us to synthesize derivatives bearing azobenzene carboxylates as bridging co-ligands. A series of mixed-ligand complexes of the type [M2L(μ-L')]+, where M = Zn(II), Ni(II), or Cd(II), L' = p-azobenzene

A diastereoselective approach to axially chiral biaryls via electrochemically enabled cyclization cascade

• Hong Yan,
• Zhong-Yi Mao,
• Zhong-Wei Hou,
• Jinshuai Song and
• Hai-Chao Xu

Beilstein J. Org. Chem. 2019, 15, 795–800, doi:10.3762/bjoc.15.76

• electrochemistry is a powerful tool for adding or taking electrons from organic molecules to promote redox reactions because of its reagent-free feature and the tunability of electric current and potential [20][21][22][23][24][25][26][27][28][29][30]. We [31][32][33][34] and others [35][36][37][38][39][40][41

• previously established conditions employing a three-necked round-bottomed flask as the cell, a reticulated vitreous carbon (RVC) anode and a platinum plate cathode [31]. The reaction was carried in refluxing MeCN/H2O (9:1) with tetraarylhydrazine 1 as the redox catalyst, NaHCO3 (2 equiv) as an additive, and

• reaction. A mechanism for the electrochemical synthesis was proposed based on the results from our previous work [31] and of this work (Scheme 3). The redox catalyst 1 is oxidized at the anode to give radical cation I. In the meanwhile, H2O is reduced at the cathode to afford HO− and H2. The base generated

The LANCA three-component reaction to highly substituted β-ketoenamides – versatile intermediates for the synthesis of functionalized pyridine, pyrimidine, oxazole and quinoxaline derivatives

• Tilman Lechel,
• Roopender Kumar,
• Mrinal K. Bera,
• Reinhold Zimmer and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2019, 15, 655–678, doi:10.3762/bjoc.15.61

• acetic anhydride at 90 °C furnished the expected pyrimidine derivative PM61 in 69% yield [32] showing that this transformation involves an internal redox reaction. However, the mechanism of this rearrangement is still under discussion [56][57] and side-products such as PM62 having a 4-ethyl group (3

Back to the future: Why we need enzymology to build a synthetic metabolism of the future

• Tobias J. Erb

Beilstein J. Org. Chem. 2019, 15, 551–557, doi:10.3762/bjoc.15.49

• require less energy (ATP, redox power and/or photons) and can be supposedly operated at higher catalytic rates compared to natural carbon fixation. Accordingly, the synthetic CO2-fixation cycles should be able to convert more carbon dioxide with less energy in a given time and hence succeed natural

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

• Mikhail V. Makarov Marie E. Migaud Mitchell Cancer Institute, University of South Alabama, 1660 Springhill Ave., Mobile, AL 36604, USA 10.3762/bjoc.15.36 Abstract The β-anomeric form of nicotinamide riboside (NR+) is a precursor for nicotinamide adenine dinucleotide (NAD+), a redox cofactor

• nicotinamide adenine dinucleotide (NAD+, Figure 1), an intracellular redox cofactor, central to all cells’ biochemistry. Unlike its phosphorylated and reduced forms, NAD+ is also a non-redox substrate for many intra- and extracellular enzymes, participating in cellular signaling pathways and regulating post

N-Arylphenothiazines as strong donors for photoredox catalysis – pushing the frontiers of nucleophilic addition of alcohols to alkenes

• Fabienne Speck,
• David Rombach and
• Hans-Achim Wagenknecht

Beilstein J. Org. Chem. 2019, 15, 52–59, doi:10.3762/bjoc.15.5

• after 20 h of irradiation. Keywords: addition; phenothiazine; photochemistry; photoredox catalysis; redox potential; Introduction Visible-light photoredox catalysis has become a precious tool in modern synthetic organic chemistry and experiences a continuously growing interest in industrial

• ][16] the interest of using this class of catalysts only gained limited interest during the last years. The advantage of using N-phenylphenothiazine catalysts in photoredox chemistry is attributed to their beneficial redox properties. Moreover, a modification of the core is rather simple and allows

• chemical redox dynamics between −2.1 V up to +2.1 V. One of the key problems in photochemistry, which was recently addressed by the development of the consecutive photoelectron transfer process (conPET) [5], is the need to push the frontiers by accessing high reduction potentials. While the classical

Mn-mediated sequential three-component domino Knoevenagel/cyclization/Michael addition/oxidative cyclization reaction towards annulated imidazo[1,2-a]pyridines

• Olga A. Storozhenko,
• Alexey A. Festa,
• Delphine R. Bella Ndoutoume,
• Alexander V. Aksenov,
• Alexey V. Varlamov and
• Leonid G. Voskressensky

Beilstein J. Org. Chem. 2018, 14, 3078–3087, doi:10.3762/bjoc.14.287

• the redox potentials of three or more reactants at a time and employment of a sequential one-pot strategy may become one of the reasonable solutions. The vast biological activity of the compounds, bearing the imidazo[1,2-a]pyridine scaffold makes this heterocycle of great importance to the fields of

Repurposing the anticancer drug cisplatin with the aim of developing novel Pseudomonas aeruginosa infection control agents

• Mingjun Yuan,
• Song Lin Chua,
• Yang Liu,
• Daniela I. Drautz-Moses,
• Joey Kuok Hoong Yam,
• Thet Tun Aung,
• Roger W. Beuerman,
• May Margarette Santillan Salido,
• Stephan C. Schuster,
• Choon-Hong Tan,
• Michael Givskov,
• Liang Yang and
• Thomas E. Nielsen

Beilstein J. Org. Chem. 2018, 14, 3059–3069, doi:10.3762/bjoc.14.284

• established biofilm [44]. In addition, the gold-containing drug, auranofin, was found to be a broad-spectrum bactericidal compound, that targets the thiol-redox homeostasis of a range of Gram-positive bacteria [45]. Further studies will be carried out to better understand the resistance mechanism and