Stabilization of nanosized titanium dioxide by cyclodextrin polymers and its photocatalytic effect on the degradation of wastewater pollutants

• Tamás Zoltán Agócs,
• István Puskás,
• Erzsébet Varga,
• Mónika Molnár and
• Éva Fenyvesi

Beilstein J. Org. Chem. 2016, 12, 2873–2882, doi:10.3762/bjoc.12.286

• solution the rate of decomposition was lower partly attributed to adsorption of chloride on TiO2 surface. There might be a competition between dyes and anions for the adsorption sites and the anions may modify the superficial properties of TiO2 [44]. The total concentration of inorganic ions in tap water

New approaches to organocatalysis based on C–H and C–X bonding for electrophilic substrate activation

• Pavel Nagorny and
• Zhankui Sun

Beilstein J. Org. Chem. 2016, 12, 2834–2848, doi:10.3762/bjoc.12.283

• established that the C–H moiety can serve as a hydrogen bond donor and form hydrogen bonds with oxygen, nitrogen or halogens of neutral molecules or anions [17]. However, such interactions have been considered negligible in comparison to much stronger A–H···A hydrogen bonds (A = N, O, F). While Glasstone

• (Figure 1) have been utilized to enhance the electrophilicity of organic molecules. Recent spectroscopic and computational studies provided evidence that arenes might form strong hydrogen bonds between aryl C–H groups and anions (Cl−, NO3−, ClO4−, etc.) in the gas phase [28]. In addition, the introduction

• supramolecular complexes with anions [32][33][34]. The stability of such complexes correlated with the number of C–H bonds that could be formed by the receptor, and strong binding comparable to the more traditional X–H bonding based hydrogen bond donors was observed for the receptors forming 5–9 hydrogen bonds

Electron-transfer-initiated benzoin- and Stetter-like reactions in packed-bed reactors for process intensification

• Anna Zaghi,
• Daniele Ragno,
• Graziano Di Carmine,
• Carmela De Risi,
• Olga Bortolini,
• Pier Paolo Giovannini,
• Giancarlo Fantin and
• Alessandro Massi

Beilstein J. Org. Chem. 2016, 12, 2719–2730, doi:10.3762/bjoc.12.268

• . Moreover, the disclosed flow procedure constituted an equally effective (complete chemoselectivity) and environmentally benign alternative to the analogous batch process towards benzoin- and Stetter-type products mediated by toxic cyanide anions [29][30]. Results and Discussion The possibility of

From betaines to anionic N-heterocyclic carbenes. Borane, gold, rhodium, and nickel complexes starting from an imidazoliumphenolate and its carbene tautomer

• Ming Liu,
• Jan C. Namyslo,
• Martin Nieger,
• Mika Polamo and
• Andreas Schmidt

Beilstein J. Org. Chem. 2016, 12, 2673–2681, doi:10.3762/bjoc.12.264

• storage form of otherwise unstable species [26][27], but proved also to be suitable starting materials for the generation of anionic NHCs by deprotonation. As examples of the latter mentioned species, sydnone anions 1 [28], imidazole-2-ylidene-4-olate 2 [29] as well as its 4-aminide derivatives [30] have

• anions (4:1). The bond length between the gold atom and the carbene carbon atom (crystallographic numbering: Au1–C2) was found to be 202.11(15) pm and this value corresponds to the distances in other NHC gold complexes [36][37]. The coordination about the Au(I) center is almost linear, as a C2–Au(1)–C2A

Inhibition of peptide aggregation by means of enzymatic phosphorylation

• Kristin Folmert,
• Malgorzata Broncel,
• Hans v. Berlepsch,
• Christopher H. Ullrich,
• Mary-Ann Siegert and
• Beate Koksch

Beilstein J. Org. Chem. 2016, 12, 2462–2470, doi:10.3762/bjoc.12.240

• organic anions were found to enhance the formation of amyloid fibrils [16]. When, after a five minute incubation time of KFM6 with ATP, PKA is added, the concentration of β-sheets decreases and the minimum at 200 nm for random structures strongly increases (Figure 4b). This conformational transition shows

Stereo- and regioselectivity of the hetero-Diels–Alder reaction of nitroso derivatives with conjugated dienes

• Lucie Brulíková,
• Aidan Harrison,
• Marvin J. Miller and
• Jan Hlaváč

Beilstein J. Org. Chem. 2016, 12, 1949–1980, doi:10.3762/bjoc.12.184

• Scheme 5). More recently, the method was extended to the mild copper-catalyzed aerobic oxidation of hydroxylamines [48][49][50]. In 2014, the Lykakis group reported the selective oxidation of various arylamines into the corresponding nitrosoarenes through polyoxometalate anions supported on mesoporous

Ionic liquids as transesterification catalysts: applications for the synthesis of linear and cyclic organic carbonates

• Maurizio Selva,
• Alvise Perosa,
• Sandro Guidi and
• Lisa Cattelan

Beilstein J. Org. Chem. 2016, 12, 1911–1924, doi:10.3762/bjoc.12.181

• be recovered and reused to allow quantitative conversions even after several recycles. Moreover, the study highlighted that the catalytic activity increased with increasing acidity of the ILs and particularly with cations bearing SO3H anions (Scheme 5: ILs I, II, III, and IV). The same imidazolium

• dependence of the catalytic activity on the structure of IL cations and anions for the synthesis of DMC through the transesterification of EC with methanol [73]. They achieved the best results using a halogen and metal-free IL such as 1,3-dimethylimidazolium-2-carboxylate (DMIM-2-CO2), which was easily

Potent triazine-based dehydrocondensing reagents substituted by an amido group

• Munetaka Kunishima,
• Daiki Kato,
• Nobu Kimura,
• Masanori Kitamura,
• Kohei Yamada and
• Kazuhito Hioki

Beilstein J. Org. Chem. 2016, 12, 1897–1903, doi:10.3762/bjoc.12.179

• amide-type I and II using the same method resulted in low yields mainly because of the substitution of the methoxy group of 6 by amido anions (Supporting Information File 1). Thus, these compounds were successfully synthesized using an alternative method starting from cyanuric chloride via an

A chiral analog of the bicyclic guanidine TBD: synthesis, structure and Brønsted base catalysis

• Mariano Goldberg,
• Denis Sartakov,
• Jan W. Bats,
• Michael Bolte and
• Michael W. Göbel

Beilstein J. Org. Chem. 2016, 12, 1870–1876, doi:10.3762/bjoc.12.176

• contains two cations, two benzoate anions and ethyl acetate as a solvate molecule. Each cation is connected by two N–H···O hydrogen bonds to benzoate ions. The rings of cation 10 adopt a conformation close to an envelope with the phenyl substituents in pseudo-axial positions. The ion pairs and the solvate

Cross-linked cyclodextrin-based material for treatment of metals and organic substances present in industrial discharge waters

• Élise Euvrard,
• Nadia Morin-Crini,
• Coline Druart,
• Justine Bugnet,
• Bernard Martel,
• Cesare Cosentino,
• Virginie Moutarlier and
• Grégorio Crini

Beilstein J. Org. Chem. 2016, 12, 1826–1838, doi:10.3762/bjoc.12.172

• by means of organic resins to remove inorganic pollutants (e.g., metals and anions such as fluorides). Charles et al. [2] recently reported that this type of sequence is acknowledged for its efficiency. However, it is an approach to water treatment that combines two methods of separation using two

• anions and salts, sometimes exceeding one gram per liter [21]. In this study, calcium and chlorides were present in the DWs at concentrations of 500 and 3 000 mg·L−1, respectively. In fact, a large amount of these other inorganic elements could interact with the polymer, notably Ca2+, which was retained

Three-component synthesis of highly functionalized aziridines containing a peptide side chain and their one-step transformation into β-functionalized α-ketoamides

• Lena Huck,
• Juan F. González,
• Elena de la Cuesta and
• J. Carlos Menéndez

Beilstein J. Org. Chem. 2016, 12, 1772–1777, doi:10.3762/bjoc.12.166

• ][29] there is little precedent of their opening with weak nucleophiles such as carboxylate anions [30]. However, we expected that the presence of the 2-methoxy substituent would facilitate the desired transformation. The initial study was carried out on compound 2e, but we found that a variety of

One-pot synthesis of 4′-alkyl-4-cyanobiaryls on the basis of the terephthalonitrile dianion and neutral aromatic nitrile cross-coupling

• Roman Yu. Peshkov,
• Elena V. Panteleeva,
• Wang Chunyan,
• Evgeny V. Tretyakov and
• Vitalij D. Shteingarts

Beilstein J. Org. Chem. 2016, 12, 1577–1584, doi:10.3762/bjoc.12.153

• orientation is in agreement with the electronic structure of anion 3, which is characterized by HOMO localization predominantly at the ipso position to the cyano group [24]. This type of HOMO is typical for cyclohexadienyl anions generated from monocyanoarenes [42][43]. The highest yield of 5 (5ab, 70%) was

• ), as well as 4'-methyl-2-cyanobiphenyl (2h). In addition, two new neutral carbonitriles – 2,6-difluorobenzonitrile (2g) and 1-cyanonaphthalene (2i) – were tested as cross-coupling participants and found to react with dianion 12−. Alkylation of intermediate anions 3b–i in all these reactions was

• mechanisms within cross-coupling: heterolytic addition of dianion 12− (SNH) to nitrile 2, and/or electron transfer from 12− to 2 followed by recombination or relaxation in the primary pair of radical anions 1·− and 2·− (Scheme 2). These probable reaction mechanisms were studied in [23][24] and are beyond

Biosynthesis of oxygen and nitrogen-containing heterocycles in polyketides

• Franziska Hemmerling and
• Frank Hahn

Beilstein J. Org. Chem. 2016, 12, 1512–1550, doi:10.3762/bjoc.12.148

• polyketides, they mostly appear in form of 3-acyltetronates and it was proposed that this structural motif is able to mimic corresponding anions of acidic functional groups like phosphates, sulphates or carboxylates. In fact, tetronates often act by inhibiting enzymes that process the respective functional

From N-vinylpyrrolidone anions to modified paraffin-like oligomers via double alkylation with 1,8-dibromooctane: access to covalent networks and oligomeric amines for dye attachment

• Daniela Obels,
• Melanie Lievenbrück and
• Helmut Ritter

Beilstein J. Org. Chem. 2016, 12, 1395–1400, doi:10.3762/bjoc.12.133

Molecular weight control in organochromium olefin polymerization catalysis by hemilabile ligand–metal interactions

• Stefan Mark,
• Hubert Wadepohl and
• Markus Enders

Beilstein J. Org. Chem. 2016, 12, 1372–1379, doi:10.3762/bjoc.12.131

• [8][9][10][11][12]. Examples are the switching from polymerization to trimerization selectivity [13] or the suppression of chain termination by weak interactions with fluorine substituents [14][15][16][17]. The interaction with fluorine atoms from fluorinated borate anions have also shown to play a

NeoPHOX – a structurally tunable ligand system for asymmetric catalysis

• Jaroslav Padevět,
• Marcus G. Schrems,
• Robin Scheil and
• Andreas Pfaltz

Beilstein J. Org. Chem. 2016, 12, 1185–1195, doi:10.3762/bjoc.12.114

• anions were omitted for clarity. Retrosynthetic analysis for NeoPHOX ligands. Synthesis of 1st generation NeoPHOX Ir-complexes [19]. Synthesis of a C(5)-disubstituted NeoPHOX-Ir complex. Revisited synthetic strategy for the preparation of a threonine-based NeoPHOX ligand. Undesired β-lactam formation

Cationic Pd(II)-catalyzed C–H activation/cross-coupling reactions at room temperature: synthetic and mechanistic studies

• Takashi Nishikata,
• Alexander R. Abela,
• Shenlin Huang and
• Bruce H. Lipshutz

Beilstein J. Org. Chem. 2016, 12, 1040–1064, doi:10.3762/bjoc.12.99

• examined. A cationic palladium-catalyzed electrophilic aromatic C–H substitution without basic anions [137][138][139][140][141][142] would hold considerable promise as an alternative and potentially milder approach to achieving valued C–H activation/coupling reactions. While several cationic palladium

• no stoichiometric quantities of competing acetate anions, additional acid is not needed to produce and maintain active catalyst. Proposed mechanisms Our results have demonstrated that a dicationic palladium complex effectively catalyzes C–H activation of arylureas at room temperature. Based on these

1H-Imidazol-4(5H)-ones and thiazol-4(5H)-ones as emerging pronucleophiles in asymmetric catalysis

• Antonia Mielgo and
• Claudio Palomo

Beilstein J. Org. Chem. 2016, 12, 918–936, doi:10.3762/bjoc.12.90

• -catalyzed allylation substitution reaction of oxazol-4(5H)-ones and thiazol-4(5H)-ones to afford enantioenriched tertiary alcohols and thioethers (Scheme 19) [42]. In this case the diastereoselectivity is controlled by cations, in contrast to most of the described protocols wherein it is modulated by anions

Synthesis of 2,1-benzisoxazole-3(1H)-ones by base-mediated photochemical N–O bond-forming cyclization of 2-azidobenzoic acids

• Daria Yu. Dzhons and
• Andrei V. Budruev

Beilstein J. Org. Chem. 2016, 12, 874–881, doi:10.3762/bjoc.12.86

• 2,1-benzisoxazole-3(1H)-ones is reported. The optimization and scope of this cyclization reaction is discussed. It is shown that an essential step of the ring closure of 2-azidobenzoic acids is the formation and photolysis of 2-azidobenzoate anions. Keywords: aryl azides; azepinones; 2,1

• increase in the yield of 3a. In our opinion, this effect of the solvent or base on the yield of 2a may be explained by the formation of 2a through a heterocyclization of 2-azidobenzoate anions. Therefore, the role of the base in the reaction is the in situ generation of the 2-azidobenzoate anion and the

Bi- and trinuclear copper(I) complexes of 1,2,3-triazole-tethered NHC ligands: synthesis, structure, and catalytic properties

• Shaojin Gu,
• Jiehao Du,
• Jingjing Huang,
• Huan Xia,
• Ling Yang,
• Weilin Xu and
• Chunxin Lu

Beilstein J. Org. Chem. 2016, 12, 863–873, doi:10.3762/bjoc.12.85

• , which are comparable to the known Cu(I)–NHC complexes [36][37][38][39]. The Cu1–Cu2 separation is 2.7867(7) Å, showing a weak metal−metal interaction. The molecular structure of complex 4 is depicted in Figure 3. Complex 4 consists of the cation unit [Cu2(L3)2]2+ and two hexafluorophosphate anions

• anions have been removed for clarity. Selected bond distances (Å) and angles (°): Cu2-C5 1.896(3), Cu2-N14 1.911(3), Cu2-N1 2.362(3), Cu2-Cu1 2.7867(7), Cu1-C26 1.898(3), Cu1-N7 1.915(3), Cu1-N8 2.340(3); C5-Cu2-N14 173.37(13), C5-Cu2-N1 77.64(13), N14-Cu2-N1 108.15(12), C5-Cu2-Cu1 69.80(9), N14-Cu2-Cu1

• 111.70(8), N1-Cu2-Cu1 98.90(7), C26-Cu1-N7 167.08(15), C26-Cu1-N8 78.22(13), N7-Cu1-N8 111.77(13), C26-Cu1-Cu2 73.57(9). ORTEP drawing of [Cu2(L3)2](PF6)2 (4). Thermal ellipsoids are drawn at the 30% probability level. Hydrogen atoms and anions have been removed for clarity. Selected bond distances (Å

Strecker degradation of amino acids promoted by a camphor-derived sulfonamide

• M. Fernanda N. N. Carvalho,
• M. João Ferreira,
• Ana S. O. Knittel,
• Maria da Conceição Oliveira,
• João Costa Pessoa,
• Rudolf Herrmann and
• Gabriele Wagner

Beilstein J. Org. Chem. 2016, 12, 732–744, doi:10.3762/bjoc.12.73

• types of reactions include the alkylation of the imine nitrogen atom followed by ring annulation [6], cleavage of the sulfonimine [7][8] or camphor [9] rings, reduction of the CO or CN double bonds [10], addition of acetylide anions to form dialkynes that can undergo complex skeletal rearrangements and

• compounds as well as carboxylate anions. This is different in the ninhydrin reaction where the corresponding anions lose CO2 upon attempted geometry optimization. Decarboxylation of the imines of the oxoimine 1 only occurs when a zwitterion is formed by proton transfer to one of the two nitrogen atoms. This

• done with the program PCGamess (version 7.1) [40][41], using B3LYP/6-31G** for neutral compounds and B3LYP/6-31++G** for anions. Zero-point energies and basis set superposition errors were not included since no high precision numerical results were needed. Data analysis and visualization was done with

From steroids to aqueous supramolecular chemistry: an autobiographical career review

• Bruce C. Gibb

Beilstein J. Org. Chem. 2016, 12, 684–701, doi:10.3762/bjoc.12.69

• in useful yields. The highly defined nature of the intermediate lithiate anions is important to the control of these reactions. Thus, much wider ranges of products are observed if direct electrophilic substitution is used as an alternative strategy of host functionalization [24]. As well as proving

• sulfate increased guest association, whilst salting-in sodium perchlorate weakened binding considerably. The surprise was that the root cause of the latter was competitive binding of the anions to the hydrophobic pocket of our anionic host. A follow-on full paper expanded in these results considerably and

Creating molecular macrocycles for anion recognition

• Amar H. Flood

Beilstein J. Org. Chem. 2016, 12, 611–627, doi:10.3762/bjoc.12.60

• Amar H. Flood Department of Chemistry, Indiana University, Bloomington, IN 47405, USA 10.3762/bjoc.12.60 Abstract The creation and functionality of new classes of macrocycles that are shape persistent and can bind anions is described. The genesis of triazolophane macrocycles emerges out of

• upon in the creation of two new macrocycles. First, cyanostars are larger and like to capture large anions. Second is tricarb, which also favors large anions but shows a propensity to self-assemble in an orderly and stable manner, laying a foundation for future designs of hierarchical nanostructures

• geometrically appealing to work with. In our stables we have triangles, squares and pentagons represented by triacarb, triazolophane and cyanostar macrocycles. The analogy to donut shapes is obvious and the hole in their middles can be both filled with anions and observed using real-space scanning tunneling

Recent advances in N-heterocyclic carbene (NHC)-catalysed benzoin reactions

• Rajeev S. Menon,
• Akkattu T. Biju and
• Vijay Nair

Beilstein J. Org. Chem. 2016, 12, 444–461, doi:10.3762/bjoc.12.47

• yields and enantioselectivity (Scheme 17). It is noteworthy that the catalytically generated Breslow intermediates undergo selective 1,2-addition with ynones and the competing Stetter-type reactivity was not observed [33]. Aza-benzoin reactions In aza-benzoin reactions, the acyl anions generated from

• aldehydes react with an aza electrophile. Imines possessing an electron-withdrawing N-substituent constitute the most commonly used aza electrophile and the reaction affords an α-aminocarbonyl compound as the product. The NHC-mediated addition of aldehyde-derived acyl anions to nitroso compounds leading to

• the electrophilic component in a few reactions of NHC-bound aldehydes. The addition of acyl anions occur at the nitrogen atom of the nitroso compound. A NHC-catalysed cascade reaction of o-vinylarylaldehydes with nitrosoarenes afforded functionalised 2,3-benzoxazin-4-ones 45 [44]. The initial

Tandem processes promoted by a hydrogen shift in 6-arylfulvenes bearing acetalic units at ortho position: a combined experimental and computational study

• Mateo Alajarin,
• Marta Marin-Luna,
• Pilar Sanchez-Andrada and
• Angel Vidal

Beilstein J. Org. Chem. 2016, 12, 260–270, doi:10.3762/bjoc.12.28

• activation of the benzylidenemalonate fragment by scandium(III) triflate as the catalyst (Scheme 1) [27]. Because fulvenes are widely used as the direct precursors of cyclopentadienyl anions following the addition of nucleophiles, including the hydride anion, to its exocyclic sp2 carbon atom [28][29], we