1-Imidoalkylphosphonium salts with modulated C_α–P⁺ bond strength: synthesis and application as new active α-imidoalkylating agents

• Jakub Adamek,
• Roman Mazurkiewicz,
• Anna Węgrzyk and
• Karol Erfurt

Beilstein J. Org. Chem. 2017, 13, 1446–1455, doi:10.3762/bjoc.13.142

• properties of the obtained 1-imidoalkylphosphonium salts were tested in the Tscherniac–Einhorn-type reaction with aromatic hydrocarbons as a model reaction. The generation of 1-imidocarbenium cations through the thermal splitting of the Cα–P+ bond seems to be the crucial step in the imidoalkylation of

• relatively reactive hydrogen carbons such as anisole or 1,3-dimethoxybenzene. Reactions with imidoalkylphosphonium salts that generate more stable carbenium cations, e.g., benzyl-type carbenium cations, started at a considerably lower temperature. The Cα–P+ bond strength can be considerably reduced and

• consequently the generation of the corresponding 1-imidocarbenium cations can be markedly facilitated using 1-imidoalkylphosphonium salts derived from triarylphosphines with electron-withdrawing substituents such as tris(m-chorophenyl)phosphine, tris(p-chlorophenyl)phosphine and tris[p-(trifluoromethyl)phenyl

An improved preparation of phorbol from croton oil

• Alberto Pagani,
• Simone Gaeta,
• Andrei I. Savchenko,
• Craig M. Williams and
• Giovanni Appendino

Beilstein J. Org. Chem. 2017, 13, 1361–1367, doi:10.3762/bjoc.13.133

• unclear. The use of THF was inspired by the work of Seebach on the solubility of peptides in ether-type organic solvents in the presence of certain alkaline cations [20], and it is not unconceivable that the interaction with sodium ions substantially diversifies the relative polarity of glycerol and

Strategies toward protecting group-free glycosylation through selective activation of the anomeric center

• A. Michael Downey and
• Michal Hocek

Beilstein J. Org. Chem. 2017, 13, 1239–1279, doi:10.3762/bjoc.13.123

• the pyranose was observed in any instance. In a 2007 follow-up study, Plusquellec and colleagues optimized a Lewis-acid-directed glycosylation approach in the presence of divalent cations to synthesize galactosyl furanosides using the same thioimidoyl-activating group. The optimized conditions (Table

Metal-free hydroarylation of the side chain carbon–carbon double bond of 5-(2-arylethenyl)-3-aryl-1,2,4-oxadiazoles in triflic acid

• Anna S. Zalivatskaya,
• Dmitry S. Ryabukhin,
• Marina V. Tarasenko,
• Alexander Yu. Ivanov,
• Irina A. Boyarskaya,
• Elena V. Grinenko,
• Ludmila V. Osetrova,
• Eugeniy R. Kofanov and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2017, 13, 883–894, doi:10.3762/bjoc.13.89

• protonation at N2, there should not be any correlation between the proton attached to N2 and Hα. The assignment of all signals in the 1H and 13C NMR spectra of cations Ca and Cm was undertaken on the basis of 1H–13C HSQC and 1H–15N HSQC spectra (see spectra in Supporting Information File 1). According to the

• groups. Selected 1H, 13C, 15N NMR data for cations Ca and Cm generated by protonation of oxadiazoles 1a and 1m at the N4 nitrogen (FSO3H, −80 °C for Ca, and −60 °C for Cm, with CH2Cl2 as internal standard). X-ray crystal structures of compounds 2a (left) (CCDC 1526767) and 2m (right) (CCDC 1526105

• ); ellipsoid contours of probability levels are 50%. The hydroarylation of 5-(2-arylethenyl)-3-aryl-1,2,4-oxadiazoles 1 under superelectrophilic activation leading to compounds 2. Selected electronic characteristics for cations A–F calculated by DFT from protonation of oxadiazole 1a. Hydroarylation of

New approach toward the synthesis of deuterated pyrazolo[1,5-a]pyridines and 1,2,4-triazolo[1,5-a]pyridines

• Aleksey Yu. Vorob’ev,
• Vyacheslav I. Supranovich,
• Gennady I. Borodkin and
• Vyacheslav G. Shubin

Beilstein J. Org. Chem. 2017, 13, 800–805, doi:10.3762/bjoc.13.80

• An efficient and operationally simple synthesis of 7-deuteropyrazolo[1,5-a]pyridine and 7-deutero-1,2,4-triazolo[1,5-a]pyridine derivatives using α-H/D exchange of 1-aminopyridinium cations in basic D2O followed by a 1,3-cycloaddition of acetylenes and nitriles is presented. A high regioselectivity

• and a high degree of deuterium incorporation were achieved. The procedure was applied for several 4-R-1-aminopyridinium cations (R = H, Me, OMe). Keywords: deuteration; 1,3-dipolar cycloaddition; pyrazolo[1,5-a]pyridine; 1,2,4-triazolo[1,5-a]pyridine; Introduction Isotopically labeled compounds find

• -1,2,4-triazolo[1,5-a]pyridine derivatives by H/D exchange of 1-aminopyridinium cations followed by the reaction with acetylenes and nitriles. Results and Discussion N-Aminopyridinium salts are easily available via direct N-amination of parent pyridines. Salt 1a was prepared by N-amination of pyridine

Substitution of fluorine in M[C₆F₅BF₃] with organolithium compounds: distinctions between O- and N-nucleophiles

• Anton Yu. Shabalin,
• Nicolay Yu. Adonin and
• Vadim V. Bardin

Beilstein J. Org. Chem. 2017, 13, 703–713, doi:10.3762/bjoc.13.69

• BuLi and PhC≡CLi. Indeed, heating 1-K with LiHal (Hal = I, Br, or Cl) in DME at 55–70 °C leads to the formation of C6F5H. [Bu4N][C6F5BF3] reacts with LiI in diglyme in a similar way. Because the cations K+ or Bu4N+ are replaced with Li+ in all cases, the reactions proceed via the lithium salt. Actually

Fluorescent carbon dots from mono- and polysaccharides: synthesis, properties and applications

• Stephen Hill and
• M. Carmen Galan

Beilstein J. Org. Chem. 2017, 13, 675–693, doi:10.3762/bjoc.13.67

• had a very stable fluorescence output, which was unaffected by a wide-range of transition metal cations. The new CD’s fluorescence intensity was, however, sensitive to changes in both pH and temperature. The CDs were shown to aggregate and change emission from pH 3 to 9, which the authors attribute to

• , each CD sample was exposed to the same concentration (0.001 M) of divalent metal cations Cu2+, Cd2+, Sn2+ or Zn2+ in solution and the fluorescence response monitored. The starch-based S-CDs showed an interesting PL response, whereas the fluorescence output increased when in solution with all metal ions

Derivatives of the triaminoguanidinium ion, 5. Acylation of triaminoguanidines leading to symmetrical tris(acylamino)guanidines and mesoionic 1,2,4-triazolium-3-aminides

• Jan Szabo,
• Julian Greiner and
• Gerhard Maas

Beilstein J. Org. Chem. 2017, 13, 579–588, doi:10.3762/bjoc.13.57

• of 1,2,4-triazolium triflate 9b in the solid state (Figure 3) is similar to that of 8b. However, the uptake of one water molecule per formula unit has resulted in different hydrogen bond patterns. A centrosymmetric hydrogen-bonded dimer (CF3SO3·H2O)2 is present which is connected to two cations

Pd- and Cu-catalyzed approaches in the syntheses of new cholane aminoanthraquinone pincer-like ligands

• Nikolay V. Lukashev,
• Gennadii A. Grabovyi,
• Dmitry A. Erzunov,
• Alexey V. Kazantsev,
• Gennadij V. Latyshev,
• Alexei D. Averin and
• Irina P. Beletskaya.

Beilstein J. Org. Chem. 2017, 13, 564–570, doi:10.3762/bjoc.13.55

• )anthraquinones with a series of cations demonstrated their high binding affinity to Cu2+, Al3+, and Cr3+. Keywords: amination; aminocholanes; bile acids; cation complexation; Cu-catalysis; diaminoanthraquinone; Pd-catalysis; Introduction Bile acids are known to ensure vital processes in vertebrate organisms

• groups. In contrast the presence of the diaminoanthraquinone scaffold allows for easy detection of ion binding due to the high sensitivity of an intensive absorption band at 550 nm to the strength of intermolecular NH···O hydrogen bonds [44]. We studied the influence of the various cations (Al3+, Mn2

• +, Fe2+, Co2+, Ni2+, Zn2+, Cu2+, Ag+, Pb2+, Hg2+, Cr3+, Ga3+, Y3+, In3+) on the UV spectrum of 5c (Figure 2). The qualitative selectivity test by stepwise addition of 1, 2, 3, and 5 equiv of metal perchlorates in MeCN to the solution of 5c in MeCN revealed that the majority of cations did not influence

Contribution of microreactor technology and flow chemistry to the development of green and sustainable synthesis

• Flavio Fanelli,
• Giovanna Parisi,
• Leonardo Degennaro and
• Renzo Luisi

Beilstein J. Org. Chem. 2017, 13, 520–542, doi:10.3762/bjoc.13.51

• Ar–Csp3, Ar–Csp2 and Ar–Csp bond-forming reactions. The use of a photochemical flow reactor, consisting of a polyfluorinated tube reactor wrapped around a 500 W Hg lamp, allowed to overcome batch limitations paving the way for metal-free arylation reactions via phenyl cations. Derivatives 14a–g were

Adsorption of RNA on mineral surfaces and mineral precipitates

• Elisa Biondi,
• Yoshihiro Furukawa,
• Jun Kawai and
• Steven A. Benner

Beilstein J. Org. Chem. 2017, 13, 393–404, doi:10.3762/bjoc.13.42

• . Further, we speculate that these trends can be accounted for by the changing size of the mineral lattice resulting from different ionic radii of different elements in a Periodic Table series. Results Carbonates We examined first various binary carbonate minerals with Group II (alkaline earth) cations

• trend should exist. For example, one might speculate that RNA would adsorb better onto a surface if the pattern of anion and cation sites on that surface matches more closely the distances of the anionic sites (phosphates) on the RNA molecule. While one might expect different cations in a mineral would

• more than either resembles calcite. Together, these results suggest, at least at the level of hypothesis, that the molecular structure of RNA is more compatible with the surface of an orthorhombic carbonate crystal (the “aragonite group”) having cations arranged with pseudo-hexagonal symmetry, than

Spectral and DFT studies of anion bound organic receptors: Time dependent studies and logic gate applications

• Srikala Pangannaya,
• Neethu Padinchare Purayil,
• Shweta Dabhi,
• Venu Mankad,
• Prafulla K. Jha,
• Satyam Shinde and
• Darshak R. Trivedi

Beilstein J. Org. Chem. 2017, 13, 222–238, doi:10.3762/bjoc.13.25

• receptors could further allow their use for detecting cations. This dual ion sensing property is expected to play a role in the study of logical interpretations at the arithmetic level. Results and Discussion UV–vis spectrophotometric studies Receptors R1and R2 vary in the substituent groups attached to the

• receptors R1 and R2 (4.5 × 10−5 M in DMSO) towards the cations Na+, K+, Ca2+, Mg2+, Al3+, Co2+, Ni2+, Cu2+, Zn2+, Pb2+, Cd2+ and Hg2+ that were used as nitrate salts at a concentration of 10−3 M in distilled water. A strong colorimetric response of receptor R1 towards Hg2+ cations resulting in a color

• change from pale yellow to colorless occurred together with a decrease in the absorption band centered at 395 nm. The binding of cations to receptor R1 follows the hard soft acid base concept. Further a charge transition from the ligand to the metal allows the selective binding of Hg2+ ion accompanied by

Poly(ethylene glycol)s as grinding additives in the mechanochemical preparation of highly functionalized 3,5-disubstituted hydantoins

• Andrea Mascitti,
• Massimiliano Lupacchini,
• Ruben Guerra,
• Ilya Taydakov,
• Lucia Tonucci,
• Nicola d’Alessandro,
• Frederic Lamaty,
• Jean Martinez and
• Evelina Colacino

Beilstein J. Org. Chem. 2017, 13, 19–25, doi:10.3762/bjoc.13.3

• reaction of the corresponding ureido derivative B-Leu was slowed down and the methyl ester moiety was partially hydrolysed. Indeed, the base activity was increased due to the presence of water in PEG as well as by the PEG crown-ether-like effect [1], chelating the potassium cations. It is worth noticing

A versatile route to polythiophenes with functional pendant groups using alkyne chemistry

• Xiao Huang,
• Li Yang,
• Rikard Emanuelsson,
• Jonas Bergquist,
• Maria Strømme,
• Martin Sjödin and
• Adolf Gogoll

Beilstein J. Org. Chem. 2016, 12, 2682–2688, doi:10.3762/bjoc.12.265

• phthalimide-EDOT derivative 13 failed to polymerize. A plausible reason could be an interference of the electron rich aromatic moieties with the thiophene radical cations formed during polymerization, in analogy to previous suggestions from Bäuerle et al. for triazolomethyl-substituted EDOT. Post

Interactions between cyclodextrins and cellular components: Towards greener medical applications?

• Loïc Leclercq

Beilstein J. Org. Chem. 2016, 12, 2644–2662, doi:10.3762/bjoc.12.261

Construction of bis-, tris- and tetrahydrazones by addition of azoalkenes to amines and ammonia

• Artem N. Semakin,
• Aleksandr O. Kokuev,
• Yulia V. Nelyubina,
• Alexey Yu. Sukhorukov,
• Petr A. Zhmurov,
• Sema L. Ioffe and
• Vladimir A. Tartakovsky

Beilstein J. Org. Chem. 2016, 12, 2471–2477, doi:10.3762/bjoc.12.241

• modulation of the molecular geometry, for example through coordination with metal cations, hydrogen bond formation or irradiation. These unique structural features of the hydrazone fragment have been successfully exploited in the design of various molecular switches, fluorophores and machines. Bis- and

A direct method for the N-tetraalkylation of azamacrocycles

• Andrew J. Counsell,
• Angus T. Jones,
• Matthew H. Todd and
• Peter J. Rutledge

Beilstein J. Org. Chem. 2016, 12, 2457–2461, doi:10.3762/bjoc.12.239

• ]. This is due in part to the versatility of these macrocycles towards N-functionalisation, in part to the tendency of functionalised cyclams and cyclens to coordinate selectively a wide range of metal cations, and in part to the diverse and interesting physical and chemical behaviour displayed by the

Superelectrophilic activation of 5-hydroxymethylfurfural and 2,5-diformylfuran: organic synthesis based on biomass-derived products

• Dmitry S. Ryabukhin,
• Dmitry N. Zakusilo,
• Mikhail O. Kompanets,
• Anton A.Tarakanov,
• Irina A. Boyarskaya,
• Tatiana O. Artamonova,
• Mikhail A. Khohodorkovskiy,
• Iosyp O. Opeida and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2016, 12, 2125–2135, doi:10.3762/bjoc.12.202

• (Scheme 1). All species A, B, C, and D may play a role as reactive intermediates derived from 1a and 2 in superacids. To estimate the electrophilic properties of cations A, B, C, and D we performed quantum chemical calculations by the DFT method (Table 1). HOMO and LUMO energies, global electrophilicity

• on atoms C2, C3, and Ofuran upon protonation of furans 1a and 2 reveal a significant positive charge delocalization into the furan ring in species A, B, C, and D. However, from these calculations no unambiguous answer could be obtained that reveals what cations in pairs A or B, and C or D may take

• . This means that dehydration of this group does not occur in TfOH and cation B is not formed. For comparison, chemical shifts of carbocationic centers in various benzyl cations (R2)ArC+ lie in a much more down-field range of ~182–270 ppm [50][51][52][53][54][55][56][57]. Comparison of 1H and 13C NMR

The direct oxidative diene cyclization and related reactions in natural product synthesis

• Juliane Adrian,
• Leona J. Gross and
• Christian B. W. Stark

Beilstein J. Org. Chem. 2016, 12, 2104–2123, doi:10.3762/bjoc.12.200

• for divalent cations. It is commonly used to both modify intracellular Ca2+ concentrations and to investigate Ca2+ transport across biological membranes [58]. In 2011, Kocienski and co-workers reported on a formal synthesis of ionomycin using an auxiliary-directed, diastereoselective permanganate

Thiophene-forming one-pot synthesis of three thienyl-bridged oligophenothiazines and their electronic properties

• Dominik Urselmann,
• Konstantin Deilhof,
• Bernhard Mayer and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2016, 12, 2055–2064, doi:10.3762/bjoc.12.194

• electronics [37][38][39][40]. In comparison to thiophene, phenothiazine, a tricyclic dibenzo-1,4-thiazine, possesses a significantly lower oxidation potential, similar to aniline. However, phenothiazine derivatives form stable deeply colored radical cations with perfect Nernstian reversibility [41][42][43][44

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

• as byproducts (Scheme 3, bottom). Seedon et al. reported another green protocol for the preparation of ILs. The authors described the synthesis of aqueous hydroxide solutions of organic cations, subsequently neutralized by simple acid–base reactions, giving access to ionic liquids that are difficult

• 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

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

• given in the Experimental section. In addition, it was observed that without Ca2+ cations the removal efficiency was above 99%, except for aluminum and chromium (Table 1). When expressing these results in mmol of total metal retained per gram of polymer, it can be noted that for the highest

• -linking agent BTCA was used, this compound presents four carboxylic functions and a previous study [18] showed that only two of its carboxylic groups reacted with the CD units to form the polymer network, the two remaining ones being available to react with cations through chemisorption (electrostatic

Synthesis and properties of fluorescent 4′-azulenyl-functionalized 2,2′:6′,2″-terpyridines

• Adrian E. Ion,
• Liliana Cristian,
• Mariana Voicescu,
• Masroor Bangesh,
• Augustin M. Madalan,
• Daniela Bala,
• Constantin Mihailciuc and
• Simona Nica

Beilstein J. Org. Chem. 2016, 12, 1812–1825, doi:10.3762/bjoc.12.171

• steps, which can only be explained on the basis of the redox behavior of the azulene unit. The ability of the 4′-azulenyl 2,2′:6′,2″-terpyridine to bind poisoning metal cations was studied by UV–vis titrations using aqueous solutions of Hg(II) and Cd(II) chlorides as illustrative examples. Keywords

• origin of the fluorescence emission will be also described by time-dependent density functional theory (TDDFT) calculations. The ability of the terpyridine compounds to bind poisoning metal cations was investigated by spectrophotometric titrations of methanolic 4′-azulenyl-substituted terpyridine

The EIMS fragmentation mechanisms of the sesquiterpenes corvol ethers A and B, epi-cubebol and isodauc-8-en-11-ol

• Patrick Rabe and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2016, 12, 1380–1394, doi:10.3762/bjoc.12.132

• +·, followed by an inductive cleavage with neutral loss of isobutyraldehyde to H2+·. This reactive intermediate can stabilise to the conjugated radical cations I2+· or J2+· by two alternative hydrogen rearrangements. PMA135 for the base peak ion m/z = 135 reveals that this fragment ion is produced from C1–C9