A novel application of 2-silylated 1,3-dithiolanes for the synthesis of aryl/hetaryl-substituted ethenes and dibenzofulvenes

• Grzegorz Mlostoń,
• Paulina Pipiak,
• Róża Hamera-Fałdyga and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2017, 13, 1900–1906, doi:10.3762/bjoc.13.185

• ]. For example, in contrast to thiobenzophenone (1a), phenyl selenophen-2-yl thioketone (1b) does not form the corresponding 2,5-dihydro-1,3,4-thiadiazole of type 2, and even at −70 °C spontaneous elimination of N2 was observed. As products of this reaction, dimer 4 of the intermediate thiocarbonyl S

Pd(OAc)₂/Ph₃P-catalyzed dimerization of isoprene and synthesis of monoterpenic heterocycles

• Dominik Kellner,
• Maximilian Weger,
• Andrea Gini and
• Olga García Mancheño

Beilstein J. Org. Chem. 2017, 13, 1807–1815, doi:10.3762/bjoc.13.175

• procedure towards the tail-to-tail dimer using readily available Pd(OAc)2 and inexpensive triphenylphosphine as ligand. Furthermore, simple screw cap vials are employed, allowing carrying out the reaction at low pressure. In addition, the potential of the dimer as a chemical platform for the preparation of

• , titanium-, zirconium-, iron-, cobalt-, vanadium- or aluminum-based Ziegler-type catalysts lead mostly to the linear tail-to-head 2-TH dimer 2,6-dimethyl-1,3,6-octatriene (alloocimene) [27], and the use of nickel catalysts allows the preparation of the tail-to-tail dimer 2-TT (2,7-dimethyl-1,3,7-octatriene

• the tail-to-tail linkage [15][29]. Moreover, the naturally occurring head-to-tail 2-HT dimers, myrcene and ocimene, can be obtained in allylic alcohol when employing Pd(NO3)2/Ph3P/KOPh as catalytic system [30]. The head-to-head 2-HH dimer could also be prepared as major isomer under catalysis with the

18-Hydroxydolabella-3,7-diene synthase – a diterpene synthase from Chitinophaga pinensis

• Jeroen S. Dickschat,
• Jan Rinkel,
• Patrick Rabe,
• Arman Beyraghdar Kashkooli and
• Harro J. Bouwmeester

Beilstein J. Org. Chem. 2017, 13, 1770–1780, doi:10.3762/bjoc.13.171

• diphosphate and the pyrophosphate sensor, a highly conserved arginine located 43 amino acids upstream of the NSE triad, and the RY dimer, a highly conserved motif at the C-terminus. The substrate is ionised by extrusion of diphosphate, yielding a highly reactive allyl cation that can react in a cyclisation

The chemistry and biology of mycolactones

• Matthias Gehringer and
• Karl-Heinz Altmann

Beilstein J. Org. Chem. 2017, 13, 1596–1660, doi:10.3762/bjoc.13.159

New electroactive asymmetrical chalcones and therefrom derived 2-amino- / 2-(1H-pyrrol-1-yl)pyrimidines, containing an N-[ω-(4-methoxyphenoxy)alkyl]carbazole fragment: synthesis, optical and electrochemical properties

• Daria G. Selivanova,
• Alexei A. Gorbunov,
• Olga A. Mayorova,
• Alexander N. Vasyanin,
• Igor V. Lunegov,
• Elena V. Shklyaeva and
• Georgii G. Abashev

Beilstein J. Org. Chem. 2017, 13, 1583–1595, doi:10.3762/bjoc.13.158

• )alkyl]-9H-carbazole-3-carbaldehydes 2a,b CV curves has shown two oxidation waves with potential peak values at 1.39 V (Eox1) and 1.81 V (Eox2) (Figure 7a). These peaks correspond to the formation of cation radical (Eox1) and dication (Eox2); the last one loses two protons and forms a dimer structure

• ) and dication (Eox2) of a generated dimer. A similar picture was also observed for oxidation processes taking place in the solutions of 1-({5-{9-[6-(4-methoxyphenoxy)hexyl]-9H-carbazolyl}thiophen-2-yl})ethanone (5b) and 2b (Figure 7). The CV curves of the first potential scan obtained in the process of

Molecular recognition of N-acetyltryptophan enantiomers by β-cyclodextrin

• Spyros D. Chatziefthimiou,
• Mario Inclán,
• Petros Giastas,
• Athanasios Papakyriakou,
• Konstantina Yannakopoulou and
• Irene M. Mavridis

Beilstein J. Org. Chem. 2017, 13, 1572–1582, doi:10.3762/bjoc.13.157

• stronger H-bonding of the carboxyl group, as well as more favorable methyl–phenyl interactions inside the cavity. In contrast, no discrimination is shown by β-CD for (R)- and (S)-flurbiprofen [11], since the crystals grown from the racemic mixture have both enantiomers enclosed (as a head-to-head dimer) in

• a β-CD dimer. In the case of substituted CDs, 2,3,6-tri-O-methyl-α-CD discriminates between (R)- and (S)-mandelic acid [12] as it forms very different crystals from a racemic mixture. The same host crystallizes exclusively with (R)-(−)-1,7-dioxaspiro[5.5]undecane, the Dacus Oleae pheromone, from an

• percentage cannot be excluded. X-ray crystallography studies In the crystalline state, the structure of the inclusion complex of L-NAcTrp in β-CD comprises dimers. The asymmetric unit of the complex contains two crystallographically independent β-CD hosts (A and B) forming a dimer (Figure 2), in which two

A speedy route to sterically encumbered, benzene-fused derivatives of privileged, naturally occurring hexahydropyrrolo[1,2-b]isoquinoline

• Olga Bakulina,
• Alexander Ivanov,
• Vitalii Suslonov,
• Dmitry Dar’in and
• Mikhail Krasavin

Beilstein J. Org. Chem. 2017, 13, 1413–1424, doi:10.3762/bjoc.13.138

• formation of HPA dimer 11 and product of its decarboxylation 12 (Scheme 1). The formation of these two products (observed by 1H NMR) was recently reported by Knapp et al. [35] as a result from the treatment of HPA with a strong base (which was absent in our case). The failure to activate sterically hindered

Towards open-ended evolution in self-replicating molecular systems

• Herman Duim and
• Sijbren Otto

Beilstein J. Org. Chem. 2017, 13, 1189–1203, doi:10.3762/bjoc.13.118

• to the reaction mixture. Kinetic analysis revealed that the system exhibits parabolic replication (p = 1/2). Exponential growth in this system is not obtained due to the high thermodynamic stability of the [T∙T] dimer, leading to product inhibition. Although the efficiency of the reported

Interactions between shape-persistent macromolecules as probed by AFM

• Johanna Blass,
• Jessica Brunke,
• Franziska Emmerich,
• Cédric Przybylski,
• Vasil M. Garamus,
• Artem Feoktystov,
• Roland Bennewitz,
• Gerhard Wenz and
• Marcel Albrecht

Beilstein J. Org. Chem. 2017, 13, 938–951, doi:10.3762/bjoc.13.95

• matrix (HABA/TMG2) [55]. A representative MALDI spectrum, shown in Figure 4, exhibits a wide range of broad signals starting from the signal of the dimer at m/z 2,621.33 Da detected as [M + Na]+ and ending at the 38mer at m/z 48,196.23 Da for a S/N ratio ≥3, with an average 1297.4 mass units shift

Conformational study of L-methionine and L-cysteine derivatives through quantum chemical calculations and ³J_HH coupling constant analyses

• Weslley G. D. P. Silva,
• Carolyne B. Braga and
• Roberto Rittner

Beilstein J. Org. Chem. 2017, 13, 925–937, doi:10.3762/bjoc.13.94

• observed for this compound. The study of 2 through NMR spectroscopy was not carried out in the present work because it was not possible to obtain the corresponding free amino acid derivative. When in solution, cysteine forms a dimer through disulfide bonds between the –SH groups and thus, it cannot be

Synthesis of tetrasubstituted pyrazoles containing pyridinyl substituents

• Josef Jansa,
• Ramona Schmidt,
• Ashenafi Damtew Mamuye,
• Laura Castoldi,
• Alexander Roller,
• Vittorio Pace and
• Wolfgang Holzer

Beilstein J. Org. Chem. 2017, 13, 895–902, doi:10.3762/bjoc.13.90

• the main product, but also containing biphenyl, traces of the desired product 6a, the homocoupling dimer 7a as well as a compound 8, obviously resulting from attack of PhLi to the pyridine system attached to pyrazole N-1 (Scheme 4). Negishi cross-couplings with 4-iodopyrazoles 3a–d The Negishi cross

Expression, purification and structural analysis of functional GABA transporter 1 using the baculovirus expression system

• Jing Hu,
• Chris Weise,
• Christoph Böttcher,
• Hua Fan and
• Jian Yin

Beilstein J. Org. Chem. 2017, 13, 874–882, doi:10.3762/bjoc.13.88

• independently [33][34]. A similar example is the bacteria homologue LeuT, which was also crystallized as a dimer [13], however, each monomer has its own binding pocket, indicating that the monomers are the functional units. Therefore, a GAT1/GFP fusion protein monomer could be suitable for further structural

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

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

• ) 176(2)°; N4–H···Cl, N4···Cl 3.320(2) Å, NH···Cl 2.53(2) Å, <(N4–H···Cl) 148(2)°. Left: solid-state structure of 9b·H2O (ORTEP plot). Right: centrosymmetric hydrogen-bonded dimer of (CF3SO3)−·H2O (Mercury plot); the substituents at the triazole ring are not complete. Selected bond lengths (Å): C1–N1

Synthesis of 1-indanones with a broad range of biological activity

• Marika Turek,
• Dorota Szczęsna,
• Marek Koprowski and
• Piotr Bałczewski

Beilstein J. Org. Chem. 2017, 13, 451–494, doi:10.3762/bjoc.13.48

• 90, it has been proved that this reaction proceeds with participation of Ni-complex 91 isolated in 83% yield which next was converted to 1-indanone 90a via the monomeric complex 92 or its dimer. o-Bromobenzaldehyde 93, in the presence of a palladium catalyst, underwent intermolecular carbopalladation

• of Ni-complex-catalyzed [2 + 2 + 2] cyclotrimerization proceeding via the intermediate 283 [110] (Scheme 79). The dimer 284 of the starting dialkyne has also been obtained. 2.3 From o-bis(dibromomethyl)benzene Erenler et al. have utilized o-bis(dibromomethyl)benzene (286) and cyclopentenone 239 to

Dimerization reactions of aryl selenophen-2-yl-substituted thiocarbonyl S-methanides as diradical processes: a computational study

• Michael L. McKee,
• Grzegorz Mlostoń,
• Katarzyna Urbaniak and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2017, 13, 410–416, doi:10.3762/bjoc.13.44

• already at −70 °C. The structure of the dimer of phenyl selenophen-2-yl thiocarbonyl S-methanide (8) was determined as the unusual macroheterocycle 9 [13] (Scheme 2). Further, the study showed that the presence of the selenophenyl substituent is essential for this type of dimerization. In addition

• , substituents located in 4-position of the phenyl ring influence the yield of 9 formed in a competitive reaction with the formal [2 + 3]-cycloaddition of 8 with the starting thioketone 10 leading to the sterically crowded 1,3-dithiolane 11. The structure of the dimer 9, confirmed by an X-ray analysis [13

• pathway via a diradical intermediate leading to the formation of the unusual macrocyclic dimer 9 by computational methods. First calculations were made for phenyl selenophen-2-yl thiocarbonyl S-methanide (8A), which can undergo a 1,3-dipolar electrocyclization (1,3-ring closure) to form the thiirane 3a

Continuous N-alkylation reactions of amino alcohols using γ-Al₂O₃ and supercritical CO₂: unexpected formation of cyclic ureas and urethanes by reaction with CO₂

• Emilia S. Streng,
• Darren S. Lee,
• Michael W. George and
• Martyn Poliakoff

Beilstein J. Org. Chem. 2017, 13, 329–337, doi:10.3762/bjoc.13.36

• observed as the major product (52%) together with 14, a dimer of the starting material 12 as the main byproduct (42%). Formation of 13 involves incorporation of the CO2 solvent into the product. Despite the very large number of reactions studied in scCO2, there are relatively few examples of incorporation

• of CO2 into the product. In this case, incorporation presumably occurs via the formation of a carbamate intermediate. This surprising formation of 13 suggests the incorporation of CO2 into 12 with the dimer formation as a competing reaction. In fact, when further conditions were studied, it became

• apparent that the dimer 14 could be formed from oxazolidinone 13 as increasing the residence time led to an increase in selectivity of 14 over 13 (Table 4, entry 2). Indeed, when 13 was used as the starting material, the major product that was isolated was 14; and this reactivity of 13 has been reported

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

• ] versus 1/[AcO−]2 confirming a 1:2 binding ratio between R1 and AcO− ion as represented in Figure 6. The necessity of two AcO― ions in the binding process could be justified by the fact that a formation of the dimer [(CH3COO)2H]− is more favored than the formation of CH3COOH alone. The UV–vis spectrum of

Dynamics and interactions of ibuprofen in cyclodextrin nanosponges by solid-state NMR spectroscopy

• Monica Ferro,
• Franca Castiglione,
• Nadia Pastori,
• Carlo Punta,
• Lucio Melone,
• Walter Panzeri,
• Barbara Rossi,
• Francesco Trotta and
• Andrea Mele

Beilstein J. Org. Chem. 2017, 13, 182–194, doi:10.3762/bjoc.13.21

• form IbuH after the lyophilisation of the hydrogels obtained by swelling CDNS(1:4) and CDNS(1:8) with aqueous IbuNa solutions. 2. 1H Fast MAS NMR spectra reveal that ibuprofen loaded in the CDNS polymeric scaffold does not form H-bonds with the polymer, but rather it crystallizes as a dimer. 3. 13C CP

• bonded dimer, sketched in the inset. 13C CP-MAS NMR spectra for samples of β-CD (top), CDNS(1:4) (middle) and CDNS(1:8) polymers (bottom). CL indicates the carbonyl group of the cross-linking agent. 13C CP-MAS NMR spectrum of: a) CDNS(1:4) polymer; b) CDNS(1:4)-IbuNa system; c) CDNS(1:8)-IbuNa system; d

The synthesis of α-aryl-α-aminophosphonates and α-aryl-α-aminophosphine oxides by the microwave-assisted Pudovik reaction

• Erika Bálint,
• Ádám Tajti,
• Anna Ádám,
• István Csontos,
• Konstantin Karaghiosoff,
• Mátyás Czugler,
• Péter Ábrányi-Balogh and
• György Keglevich

Beilstein J. Org. Chem. 2017, 13, 76–86, doi:10.3762/bjoc.13.10

• was evaluated by DFT calculations. Two α-aminophosphonates were subjected to an X-ray study revealing a racemic dimer formation made through a N–H···O=P intermolecular hydrogen bridges pair. Keywords: α-aryl-α-aminophosphine oxides; α-aryl-α-aminophosphonates; microwave; Pudovik reaction

• similar to the sample studied in the earlier work at room temperature [62]. Apart from the formation of the centrosymmetric dimer through a strong N–H···O=P hydrogen bridge (cf. Table 7), there is a C–H…O short contact to an ester oxygen atom of a next, translated and inverted 5b molecule, as well. In

• compound 5d, where all H···H contacts appear around or longer than the respective sums of van der Waals radii, and the only short attractive contact is in the H-bridge promoted dimer. Theoretical study on the addition of the >P(O)H species to N-benzylideneamines The calculations were carried out by the

Extrusion – back to the future: Using an established technique to reform automated chemical synthesis

• Deborah E. Crawford

Beilstein J. Org. Chem. 2017, 13, 65–75, doi:10.3762/bjoc.13.9

• by initially forming a dimer from multifunctional monomers, which then forms a trimer, then oligomer and finally a polymer (Figure 4) [24]. Kim and Hyun report the synthesis of polyurethane, discussing the associated numerical simulation they conducted to determine the dependency of shear rate on

• segments. Representative diagram explaining the process involved in step growth polymerisation, which involves the formation of a dimer, then trimer followed by oligomer synthesis. Taken from [24]. Comparison of choline chloride/D-fructose DES prepared via twin screw extrusion (left) and conventional

Diastereoselective anodic hetero- and homo-coupling of menthol-, 8-methylmenthol- and 8-phenylmenthol-2-alkylmalonates

• Matthias C. Letzel,
• Hans J. Schäfer and
• Roland Fröhlich

Beilstein J. Org. Chem. 2017, 13, 33–42, doi:10.3762/bjoc.13.5

• the electrode surface [22]. The generation of radicals in a thin reaction layer at the electrode surface leads to high radical concentrations that favor bimolecular radical coupling. Electrolysis of equal carboxylic acids leads to a symmetrical dimer by homo-coupling of the radicals. Coelectrolysis of

• intermediate radicals. An excess of one coacid leads to mainly two products: the unsymmetrical coupling product and the dimer of the coacid used in excess. The coelectrolysis (hetero-coupling) of carboxylic acids 13–17 with ten equivalents of 3,3-dimethylbutyric acid (20) afforded the hetero-coupling products

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

• -cyclooctadiene)rhodium(I) dimer, or with bis(triphenylphosphine)rhodium(I) carbonyl chloride in anhydrous toluene at reflux temperature, respectively. During these reactions, the water of crystallization of the starting material is – at least partially – removed by azeotropic distillation and Rh(I) is obviously

• ) = 2144, 2Θmax = 55.2°, 89393 reflections, of which 11117 were independent (Rint = 0.070), 625 parameters, 6 restraints, R1 = 0.038 (for 8729 I > 2σ(I)), wR2 = 0.095 (all data), S = 1.06, largest diff. peak/hole = 1.063/−0.370 e Å−3, dimer. CCDC 1489189 (8), 1489190 (9), 1489191 (11), and 1489192 (12

• -cyclooctadiene)rhodium(I) dimer and stirred under an inert atmosphere overnight at reflux temperature. The resulting colorless solid was filtered off, washed with THF and dried in vacuo. Yield: 0.09g (50%) of a yellow solid, mp: 280 °C. Method B: A solution of 0.16 g (0.72 mmol) of 2-(3-butyl-1H-imidazolium-1-yl

Radical polymerization by a supramolecular catalyst: cyclodextrin with a RAFT reagent

• Kohei Koyanagi,
• Yoshinori Takashima,
• Takashi Nakamura,
• Hiroyasu Yamaguchi and
• Akira Harada

Beilstein J. Org. Chem. 2016, 12, 2495–2502, doi:10.3762/bjoc.12.244

• in water was significantly low, leading to the formation of precipitates. β-CD-CTA forms a self-inclusion complex or a supramolecular dimer complex, which was characterized using 2D ROESY NMR (Supporting Information File 1, Figure S4). We focused on the polymerization activity of α-CD-CTA because the

A new protocol for the synthesis of 4,7,12,15-tetrachloro[2.2]paracyclophane

• Donghui Pan,
• Yanbin Wang and
• Guomin Xiao

Beilstein J. Org. Chem. 2016, 12, 2443–2449, doi:10.3762/bjoc.12.237

• hydroxide was formed and then decomposed in boiling toluene, resulting in a small amount of a dimer product 16 and a quantity of polymer byproduct (Table 3, entry 1). After the reaction, the polymer byproduct was removed by filtration, and the dimer product was obtained by concentrating the filtrate under

• reduced pressure. Thus, a chromatographic purification was not necessary in the improved dimerization protocol. To suppress the polymerization and to improve the yield of the dimer product, we attempted the addition of a polymerization inhibitor. As expected, the addition of 3 mol % phenothiazine

• significantly improved the yield of 16 to 25% (Table 3, entry 2). The addition of 2-chlorophenothiazine increased the yield to 35% (Table 3, entry 3), which was about three times than that without any inhibitor. In addition, the 35% yield of dimer product was about two times the yield (20%) when the protocol