A Brønsted base-promoted diastereoselective dimerization of azlactones

• Danielle L. J. Pinheiro,
• Gabriel M. F. Batista,
• Pedro P. de Castro,
• Leonã S. Flores,
• Gustavo F. S. Andrade and
• Giovanni W. Amarante

Beilstein J. Org. Chem. 2017, 13, 2663–2670, doi:10.3762/bjoc.13.264

• dimer was assigned as being trans, by X-ray crystallographic analysis. The kinetic reaction profile was determined by using 1H NMR reaction monitoring and revealed a second order overall kinetic profile. Furthermore, by employing this methodology, a diastereoselective total synthesis of a functionalized

• azlactone dimer, which is a versatile heterocycle containing two stereogenic centers (Figure 1). Kobayashi and co-workers demonstrated the rich reactivity of azlactones conducting the dimerization reaction using strong bases as catalysts; however, higher temperatures and long reaction times were required

• diastereomer was assigned by X-ray analysis. Finally, one of the products was selectively reduced to provide a functionalized analogue of streptopyrrolidine, a marine natural product isolated from Streptomyces sp. As shown in Table 1, our studies started with the synthesis of dimer 2a using azlactone 1a in the

Regioselective decarboxylative addition of malonic acid and its mono(thio)esters to 4-trifluoromethylpyrimidin-2(1H)-ones

• Sergii V. Melnykov,
• Andrii S. Pataman,
• Yurii V. Dmytriv,
• Svitlana V. Shishkina,
• Mykhailo V. Vovk and
• Volodymyr A. Sukach

Beilstein J. Org. Chem. 2017, 13, 2617–2625, doi:10.3762/bjoc.13.259

• heterochiral dimer in the crystal state. Intermolecular hydrogen bonds in the dimer are shown as dashed lines. Thermal ellipsoids are defined at 50% probability. Hydrogenation of compounds 4–6 and preparation of N1(3)-unsubstituted compounds 9–11d. Screening of the reaction conditions for organic base

What contributes to an effective mannose recognition domain?

• Christoph P. Sager,
• Deniz Eriş,
• Martin Smieško,
• Rachel Hevey and
• Beat Ernst

Beilstein J. Org. Chem. 2017, 13, 2584–2595, doi:10.3762/bjoc.13.255

• for the formation of a homodimer of A (Figure 8B) [40]. It is believed that this dimer enables transport of the lectin from the Golgi apparatus to cell membranes [73]. Due to a dislocated glutamate in the side chain of the homodimer (Figure 8B), the affinity for calcium binding and therefore also

Pyrene–nucleobase conjugates: synthesis, oligonucleotide binding and confocal bioimaging studies

• Artur Jabłoński,
• Yannic Fritz,
• Hans-Achim Wagenknecht,
• Rafał Czerwieniec,
• Tytus Bernaś,
• Damian Trzybiński,
• Krzysztof Woźniak and
• Konrad Kowalski

Beilstein J. Org. Chem. 2017, 13, 2521–2534, doi:10.3762/bjoc.13.249

• observed in the molecular structures of the metallocene–nucleobase derivatives [24][29]. In addition, each molecule of 2 in the dimer is further involved in a Cl···O halogen bond with an adjacent molecule of chloroform (Figure 3). Further details of intermolecular interactions present in the crystal

Synthesis and supramolecular properties of regioisomers of mononaphthylallyl derivatives of γ-cyclodextrin

• Markéta Bláhová,
• Sergey K. Filippov,
• Lubomír Kováčik,
• Jiří Horský,
• Simona Hybelbauerová,
• Zdenka Syrová,
• Tomáš Křížek and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2017, 13, 2509–2520, doi:10.3762/bjoc.13.248

• concentrations of 100, 10, and 1 mM. 1H NMR spectra of 3-O-derivative 2b in D2O at concentrations of 100, 10, and 1 mM. Putative objects and interactions in naphthylallyl-γ-CD solution, depicted schematically for 6I-O-naphthylallyl-γ-CD (2c). (a) Cyclic supramolecular dimer based on inclusion complexation. (b

Solvent-free copper-catalyzed click chemistry for the synthesis of N-heterocyclic hybrids based on quinoline and 1,2,3-triazole

• Martina Tireli,
• Silvija Maračić,
• Stipe Lukin,
• Marina Juribašić Kulcsár,
• Dijana Žilić,
• Mario Cetina,
• Ivan Halasz,
• Silvana Raić-Malić and
• Krunoslav Užarević

Beilstein J. Org. Chem. 2017, 13, 2352–2363, doi:10.3762/bjoc.13.232

• molecules (Figure 5b and Supporting Information File 1, section 7). Compound 5 may serve as a model for the crystal structure description. The molecules of 5 are linked by one C–H∙∙∙N hydrogen bond, so forming a dimer via eighteen-membered ring (e.g., see Figure 5c for 5) which can be described by graph-set

• gray. c) Capped-stick representation of 5, showing the dimer formed by C–H∙∙∙N hydrogen bond (orange stippled lines). Synthetic procedures for preparation of p-halogen-substituted and non-substituted phenyl-1,2,3-triazole 6-phenyl-2-(trifluoromethyl)quinolines. Reaction conditions and yields for the

One-pot syntheses of blue-luminescent 4-aryl-1H-benzo[f]isoindole-1,3(2H)-diones by T3P^® activation of 3-arylpropiolic acids

• Melanie Denißen,
• Alexander Kraus,
• Guido J. Reiss and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2017, 13, 2340–2351, doi:10.3762/bjoc.13.231

• 5 (left) and a centrosymmetric dimer formation by π–π interactions (right) (ellipsoids are drawn at the 40% probability level). The ORTEP-type plot of the asymmetric unit of the crystal structure 6 (top) and π-stacking interactions (bottom) (ellipsoids are drawn at the 40% probability level

Synthesis and application of trifluoroethoxy-substituted phthalocyanines and subphthalocyanines

• Satoru Mori and
• Norio Shibata

Beilstein J. Org. Chem. 2017, 13, 2273–2296, doi:10.3762/bjoc.13.224

• phthalocyanine. Furthermore, it is known that iron phthalocyanines easily form a μ-oxo dimer [53] that is connected face-to-face via oxygen, but a spectroscopic investigation revealed that it is difficult to form when using TFEO-FePc. This remarkable stability of TFEO-FePc is due to the low energy of the highest

• compared with mononuclear phthalocyanines by chemically modifying each unit unsymmetrically caused by an electronic interaction between each unit [68]. In addition, since it is possible to separate charges in dimer-type phthalocyanines, they are expected to be applied to new electron or energy transfer

• systems [69] such as solar cell materials as well as photocatalysts for organic reactions. A phthalocyanine dimer in which TFEO-Pcs are directly linked by C–C bonds has been reported (Scheme 4) [70][71]. This homodimer was synthesized by a palladium-catalyzed homo-coupling reaction of two A3B type

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