Main group mechanochemistry

• Agota A. Gečiauskaitė and
• Felipe García

Beilstein J. Org. Chem. 2017, 13, 2068–2077, doi:10.3762/bjoc.13.204

• ) directly from germanium metal or germanium dioxide (GeO2) was recently reported [87]. Milling of germanium powder or GeO2 with quinone or catechol, respectively, in the presence of a Lewis base under LAG conditions, produced a series of germanium complexes (see Scheme 5). These complexes are inherently

Complexation of molecular clips containing fragments of diphenylglycoluril and benzocrown ethers with paraquat and its derivatives

• Leonid S. Kikot',
• Catherine Yu. Kulygina,
• Alexander Yu. Lyapunov,
• Svetlana V. Shishkina,
• Roman I. Zubatyuk,
• Tatiana Yu. Bogaschenko and
• Tatiana I. Kirichenko

Beilstein J. Org. Chem. 2017, 13, 2056–2067, doi:10.3762/bjoc.13.203

• paraquat, the following moieties may be involved: the glycoluril fragment (hydrogen bonds involving the oxygen atoms of the carbonyl groups), the catechol part of the crown ether fragments (π–π stacking interactions) and the polyether chains of benzocrown ethers (C–H···О interactions). The first two

Block copolymers from ionic liquids for the preparation of thin carbonaceous shells

• Sadaf Hanif,
• Bernd Oschmann,
• Dmitri Spetter,
• Muhammad Nawaz Tahir,
• Wolfgang Tremel and
• Rudolf Zentel

Beilstein J. Org. Chem. 2017, 13, 1693–1701, doi:10.3762/bjoc.13.163

• addition, a macroscopic color change of the hybrid material can be observed. As-synthesized TiO2 nanoparticles coated with the block copolymer looks brown due to the bound catechol. However, the color turns black after the pyrolysis (Figure 4d) indicating the presence of carbon material. This was proven by

• , CTA dodecyl chain), 0.85 (t, dodecyl-CH3 of CTA); FTIR ν: 2969 (w), 2255 (w), 1691 (m), 1645 (m, C=O, amide of dopamine), 1553 (s), 1434 (m), 1160 (m), 1020 cm−1 (m); SEC (eluent: HFIP): 23 180 g mol−1, PDI = 1.22. Synthesis of in situ functionalized TiO2 nanoparticles: 400 mg of catechol containing

Synthesis and enzymatic ketonization of the 5-(halo)-2-hydroxymuconates and 5-(halo)-2-hydroxy-2,4-pentadienoates

• Tyler M. M. Stack,
• William H. Johnson Jr. and
• Christian P. Whitman

Beilstein J. Org. Chem. 2017, 13, 1022–1031, doi:10.3762/bjoc.13.101

• monocyclic aromatic compounds (e.g., benzene, toluene, and alkyl-substituted derivatives) have been extensively studied for more than 60 years. Initially, the aromatic compound is converted to catechol or a catechol derivative. Subsequently, the resulting species undergoes meta-fission where this term refers

• to the position of the ring fission (shown on 1 in Scheme 1). An extradiol dioxygenase processes catechol 1 to 2-hydroxymuconate semialdehyde 2, which is oxidized by an NAD+-dependent dehydrogenase to yield 2-hydroxymuconate (3a) [6][7]. Ketonization of 3a to 2-oxo-3-hexenedioate (4a) is catalyzed by

Chemical probes for competitive profiling of the quorum sensing signal synthase PqsD of Pseudomonas aeruginosa

• Michaela Prothiwa,
• Dávid Szamosvári,
• Sandra Glasmacher and
• Thomas Böttcher

Beilstein J. Org. Chem. 2016, 12, 2784–2792, doi:10.3762/bjoc.12.277

• modelling and chemical lead optimization. Examples of successful inhibitors are represented by the scaffolds of various 2-benzamidobenzoic acids [11][25][26], 2-nitrophenyl derivatives [27][28][29], ureidothiophene-2-carboxylic acids [24][30], and catechol-based compounds [31]. Many promising in vitro

Protonated paramagnetic redox forms of di-o-quinone bridged with p-phenylene-extended TTF: A EPR spectroscopy study

• Nikolay O. Chalkov,
• Vladimir K. Cherkasov,
• Gleb A. Abakumov,
• Andrey G. Starikov and
• Viacheslav A. Kuropatov

Beilstein J. Org. Chem. 2016, 12, 2450–2456, doi:10.3762/bjoc.12.238

• protic solvents were studied by EPR spectroscopy. The formation of relatively stable paramagnetic protonated redox forms of the parent triad was very surprising. The character of spin-density distribution in the semiquinone–quinone and semiquinone–catechol redox forms indicates that the p-phenylene

• argument in favor of a similar geometry of the ligand in these derivatives. At the same time, when comparing (1·)H and (1·)H3, it is obvious that the presence of the catechol terminus in (1·)H3 leads to a decrease in the acceptor ability of the whole ligand, and, in turn, results in smaller HFC constant

• values of the p-phenylene protons. The value of the hyperfine coupling constant of the catechol hydroxy protons (0.09 G) was estimated by means of a computer simulation of an experimental EPR spectrum, once the other hyperfine coupling constants had been identified. The spin-density distribution in the

Rearrangements of organic peroxides and related processes

• Ivan A. Yaremenko,
• Vera A. Vil’,
• Dmitry V. Demchuk and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2016, 12, 1647–1748, doi:10.3762/bjoc.12.162

Cupreines and cupreidines: an established class of bifunctional cinchona organocatalysts

• Laura A. Bryant,
• Rossana Fanelli and
• Alexander J. A. Cobb

Beilstein J. Org. Chem. 2016, 12, 429–443, doi:10.3762/bjoc.12.46

• synthesis of buphanidrine (104) and powelline (105) led to the bespoke development of another cupreidine catalyst CPN-107. Unfortunately, although the resulting adduct 108 (after alkylation of the catechol) was produced in a 70% enantiomeric excess (Scheme 24b), subsequent steps that had worked with the

Scope and limitations of the dual-gold-catalysed hydrophenoxylation of alkynes

• Adrián Gómez-Suárez,
• Yoshihiro Oonishi,
• Anthony R. Martin and
• Steven P. Nolan

Beilstein J. Org. Chem. 2016, 12, 172–178, doi:10.3762/bjoc.12.19

• , we explored the reaction using polyphenols as substrates (Scheme 3). Interestingly, we were able to selectively functionalize one (3ap) or both (4ap) hydroxy groups of catechol (2p) by using one or two equiv of 1a, respectively. Unfortunately, for the other polyphenol derivatives only the

Biocatalysis for the application of CO₂ as a chemical feedstock

• Apostolos Alissandratos and
• Christopher J. Easton

Beilstein J. Org. Chem. 2015, 11, 2370–2387, doi:10.3762/bjoc.11.259

• drive the equilibrium toward carboxylation, such as high CO2 concentration. Successful examples include the carboxylation of phenol and hydroxystyrene derivatives including catechol [102], guaiacol [110], indole [101] and pyrrole [100] (Scheme 7). Isocitrate dehydrogenase As discussed above, as part of

2-Hetaryl-1,3-tropolones based on five-membered nitrogen heterocycles: synthesis, structure and properties

• Yury A. Sayapin,
• Inna O. Tupaeva,
• Alexandra A. Kolodina,
• Eugeny A. Gusakov,
• Vitaly N. Komissarov,
• Igor V. Dorogan,
• Nadezhda I. Makarova,
• Anatoly V. Metelitsa,
• Valery V. Tkachev,
• Sergey M. Aldoshin and
• Vladimir I. Minkin

Beilstein J. Org. Chem. 2015, 11, 2179–2188, doi:10.3762/bjoc.11.236

• of catechol-O-methyltransferase [11], matrix metalloproteinases, carboxy-peptidase A, collagenase and thermolysin [12]. The biological activity of derivatives of 1,2-tropolone was the impetus for the rapid development of various methods for the synthesis and study of biological activity of these

Pyridinoacridine alkaloids of marine origin: NMR and MS spectral data, synthesis, biosynthesis and biological activity

• Louis P. Sandjo,
• Victor Kuete and
• Maique W. Biavatti

Beilstein J. Org. Chem. 2015, 11, 1667–1699, doi:10.3762/bjoc.11.183

• , threonine, glycine or γ-aminobutyric acid gave different types of these marine alkaloids. Previously, Gellerman demonstrated (Figure 7) that catechol (64) and kynuramine (65) could be potential precursors in the eilatin (58) (or other pyridoacridines) biosynthesis [75]. The feeding experiments with labelled

• produced by the EIMS of subarine (37) [40]. Biosynthesis pathway I [74]. Reaction illustrating catechol and kynuramine as possible biosynthetic precursors [75]. Biosynthesis pathway B deduced from the feeding experiment A using labelled precursors [76]. Proposed biosynthesis pathway [47]. 4H-Pyrido[2,3,4

Tetrathiafulvalene-based azine ligands for anion and metal cation coordination

• Awatef Ayadi,
• Aziz El Alamy,
• Olivier Alévêque,
• Magali Allain,
• Nabil Zouari,
• Mohammed Bouachrine and
• Abdelkrim El-Ghayoury

Beilstein J. Org. Chem. 2015, 11, 1379–1391, doi:10.3762/bjoc.11.149

• ) as it was previously observed within a catechol-appended TTF derivative [51]. Adjacent dimers interact through hydrogen bonding interaction C–H···O (H···O 2.70(2) Å) formed between the NO2 group and an aromatic C–H that results in the establishment of R22(10) cyclic motifs (blue filling in Figure 11

Adsorption mechanism and valency of catechol-functionalized hyperbranched polyglycerols

• Stefanie Krysiak,
• Qiang Wei,
• Klaus Rischka,
• Andreas Hartwig,
• Rainer Haag and
• Thorsten Hugel

Beilstein J. Org. Chem. 2015, 11, 828–836, doi:10.3762/bjoc.11.92

• adhesives are promising candidates. Understanding the mechanism of the extraordinarily strong adhesive bonds of the catechol group will likely aid in the development of adhesives. With this aim, we study the adhesion of catechol-based adhesives to metal oxides on the molecular level using atomic force

• concluded that hyperbranched polyglycerols with added catechol end groups are promising candidates for durable surface coatings. Keywords: adhesion; atomic force microscopy; catechol; hyperbranched polyglycerols; valency; Introduction While underwater glues are still a challenge for industrial adhesive

• hyperbranched polyglycerol as a hydrophilic core with numerous DOPA (catechol) groups attached. A similar system has already proven to be advantageous for an antifouling coating on titanium oxide surfaces [21][22]. An added benefit of this system is that the oxidation of catechol to quinones makes crosslinking

Discrete multiporphyrin pseudorotaxane assemblies from di- and tetravalent porphyrin building blocks

• Mirko Lohse,
• Larissa K. S. von Krbek,
• Sebastian Radunz,
• Suresh Moorthy,
• Christoph A. Schalley and
• Stefan Hecht

Beilstein J. Org. Chem. 2015, 11, 748–762, doi:10.3762/bjoc.11.85

• association strongly, no selective deprotonation of the porphyrin core has been attempted. The preparation of the corresponding crown ether hosts (Scheme 2) involved an initial Williamson ether synthesis in which catechol (17) was first extended with 2-[2-(2-chloroethoxy)ethoxy]ethanol to diol 18, which was

Synthesis of tripodal catecholates and their immobilization on zinc oxide nanoparticles

• Franziska Klitsche,
• Julian Ramcke,
• Julia Migenda,
• Andreas Hensel,
• Tobias Vossmeyer,
• Horst Weller,
• Silvia Gross and
• Wolfgang Maison

Beilstein J. Org. Chem. 2015, 11, 678–686, doi:10.3762/bjoc.11.77

• conditions, the catechol moieties were reasonably stable and only small amounts (5%) of the corresponding oxidized quinones were detectable by NMR in the solutions after 24 h. The ZnO NPs were treated with the buffered catecholate solutions for 12 h, isolated by centrifugation, washed with a small amount of

• comparably lower loss of catecholate loading confirms the ability of our triscatecholates to form stable layers on ZnO NPs and parallels our previous observations on TiO2 and stainless steel surfaces [31]. The observed difference in catechol loading has an impact on the stability of the ZnO NPs in water. The

• monochromator). A) Schematic drawing of a bifunctional anchor molecule and its immobilization on a nanoparticle (NP); B) tripodal catechol derivative, derived from the native bifunctional anchors dopamine and L-DOPA. Catecholates for the immobilization on ZnO NPs. A) XRD pattern of ZnO NPs obtained by the

Natural phenolic metabolites with anti-angiogenic properties – a review from the chemical point of view

• Qiu Sun,
• Jörg Heilmann and
• Burkhard König

Beilstein J. Org. Chem. 2015, 11, 249–264, doi:10.3762/bjoc.11.28

• the amino acid cysteine, producing aliphatic secondary metabolites with thiol functionalities instead of phenolic ones. Nevertheless, this class contains thio-analogs of the naturally occurring o-catechol substructure, and thus, it has been included in this review. Zhang and Xu et al. [51] have

Recent advances in the electrochemical construction of heterocycles

• Robert Francke

Beilstein J. Org. Chem. 2014, 10, 2858–2873, doi:10.3762/bjoc.10.303

• generated 1,2-benzoquinones via sequential Michael addition/ring closure An electrochemical method for the synthesis of benzofuran and indol derivatives is based on the oxidation of catechol in presence of 1,3-dicarbonyl compounds or analogous C,H-acidic compounds 62 (Scheme 24) [69][70][71][72]. The

• oxidation of catechol in the presence of 4-hydroxycoumarin was reported by Tabaković et al. (Scheme 25, left) [69]. Using an undivided cell, an aqueous sodium acetate electrolyte and a graphite anode, the product was obtained in 95% yield. In a similar fashion, benzofurans of type 68 and 69 were synthesized

• indole derivatives. Anodic anellation of catechol derivatives 66 with different 1,3-dicarbonyl compounds. Electrosynthesis of 1,2-fused indoles from catechol and ketene N,O-acetals. Reaction of N-acyliminium pools with olefins having a nucleophilic substituent. Synthesis of thiochromans using the cation

Boron-substituted 1,3-dienes and heterodienes as key elements in multicomponent processes

• Ludovic Eberlin,
• Fabien Tripoteau,
• François Carreaux,
• Andrew Whiting and
• Bertrand Carboni

Beilstein J. Org. Chem. 2014, 10, 237–250, doi:10.3762/bjoc.10.19

• . In the case of methyl acrylate or acrylonitrile, a mixture of cis diastereomers was obtained regioselectively at higher temperature, in a 1:1.6 to 1:1.8 ratio. By contrast, the [4 + 2]-cycloaddition proved to be completely regioselective when performed on the catechol derivative in the absence of

3-Pyridinols and 5-pyrimidinols: Tailor-made for use in synergistic radical-trapping co-antioxidant systems

• Luca Valgimigli,
• Daniele Bartolomei,
• Riccardo Amorati,
• Evan Haidasz,
• Jason J. Hanthorn,
• Susheel J. Nara,
• Johan Brinkhorst and
• Derek A. Pratt

Beilstein J. Org. Chem. 2013, 9, 2781–2792, doi:10.3762/bjoc.9.313

• has shown to equal the performance of the best co-antioxidant systems designed by nature, such as the tocopherol/ascorbate system [5] or the tocopherol/catechol system [8]. In general, the most effective individual antioxidants, e.g. the bicyclic pyridinols (9a–c), pyridinols (4b) and pyrimidinols (6d

Advancements in the mechanistic understanding of the copper-catalyzed azide–alkyne cycloaddition

• Regina Berg and
• Bernd F. Straub

Beilstein J. Org. Chem. 2013, 9, 2715–2750, doi:10.3762/bjoc.9.308

Bidirectional cross metathesis and ring-closing metathesis/ring opening of a C₂-symmetric building block: a strategy for the synthesis of decanolide natural products

• Bernd Schmidt and
• Oliver Kunz

Beilstein J. Org. Chem. 2013, 9, 2544–2555, doi:10.3762/bjoc.9.289

• alkenes. With borane–THF at −50 °C the reduction proceeded to completion, but gave a 1:1 mixture of diastereomers (Table 3, entry 3). With catechol borane at −78 °C conversion was again complete, but the diastereoselectivity was far from being synthetically useful (Table 3, entry 4). Due to these rather

Crystal design using multipolar electrostatic interactions: A concept study for organic electronics

• Peer Kirsch,
• Qiong Tong and
• Harald Untenecker

Beilstein J. Org. Chem. 2013, 9, 2367–2373, doi:10.3762/bjoc.9.272

• study, with a predicted [15] HOMO energy of −5.64 eV and LUMO of −1.29 eV (Figure 2). Results and Discussion Synthesis and structural characterization The synthesis of model compound 1 is extremely simple: octafluoronaphthalene (2) [16][17][18] is reacted with catechol in the presence of potassium

• considered predominantly as a highly anisotropic 1D conductor for holes, but as a quite isotropic 3D conductor for electrons. Conclusion The fluorinated tetraoxatetrahydrohexacene derivative 1 was synthesized in an extremely simple, one-step procedure from octafluoronaphthalene and catechol. Due to the

• nitrogen atmosphere. X-ray diffraction measurements were carried out with a SuperNova (Agilent) diffractometer. Synthesis of 6,7,8,9,10,11-hexafluorobenzo[b]oxanthrene (3): A solution of octafluoronaphthalene (2, 340 mg, 1.2 mmol) in THF (10 mL) was added dropwise to the suspension of catechol (0.26 g, 2.4

Complete σ* intramolecular aromatic hydroxylation mechanism through O₂ activation by a Schiff base macrocyclic dicopper(I) complex

• Albert Poater and
• Miquel Solà

Beilstein J. Org. Chem. 2013, 9, 585–593, doi:10.3762/bjoc.9.63

• in mind the key role of dioxygen in biology, in particular toward Cu and Fe metal centers, being involved in the catalytic cycle of proteins, including dinuclear copper-active sites, such as hemocyanin, tyrosinase and catechol oxidases [1][2][3][4][5][6][7], either transporting or activating O2, its

Efficient electroorganic synthesis of 2,3,6,7,10,11-hexahydroxytriphenylene derivatives

• Carolin Regenbrecht and
• Siegfried R. Waldvogel

Beilstein J. Org. Chem. 2012, 8, 1721–1724, doi:10.3762/bjoc.8.196

• Carolin Regenbrecht Siegfried R. Waldvogel Institute for Organic Chemistry, Mainz University, Duesbergweg 10–14, 55128 Mainz, Germany 10.3762/bjoc.8.196 Abstract 2,3,6,7,10,11-Hexahydroxytriphenylene of good quality and purity can be obtained via anodic treatment of catechol ketals and subsequent

• . The shift of potentials is supported by cyclic voltammetry studies. Keywords: catechol; electrochemical oxidation; hexahydroxytriphenylene; ketals; propylene carbonate; Introduction The unique spectroscopic and geometric features of triphenylenes give rise to a variety of applications for this very

• [8][9]. Typically, the oxidative trimerization of catechol derivatives can be induced by metal salts in high oxidation states, for example by molybdenum pentachloride [4][10]. Electrochemical methods can be applied to realize the oxidative trimerization since the formation of metal waste is avoided