Halogen-bonding-induced diverse aggregation of 4,5-diiodo-1,2,3-triazolium salts with different anions

• Xingyu Xu,
• Shiqing Huang,
• Zengyu Zhang,
• Lei Cao and
• Xiaoyu Yan

Beilstein J. Org. Chem. 2020, 16, 78–87, doi:10.3762/bjoc.16.10

• triclinic space group . The single crystal of 2-OAc crystallizes in the monoclinic space group P21/c. The package diagram shows a dimer which is almost a rectangle (Figure 4). As shown in Table 1, The C–I···O distances are 2.547(2) Å and 2.582(2) Å. The C–I···O angles are 174.60(7)° and 170.38(7)°. The RXB

• -triazolium salts with different anions. When the anion is chloride, bromide or iodide, the crystal is a tetramer. Strong XB was observed in these forms. When the anion is changed to tetrafluoroborate, it takes Chinese lantern shape as a trimer. Triazolium trifluoroacetate and acetate exist as a dimer, while

Photocontrolled DNA minor groove interactions of imidazole/pyrrole polyamides

• Sabrina Müller,
• Jannik Paulus,
• Jochen Mattay,
• Heiko Ihmels,
• Veronica I. Dodero and
• Norbert Sewald

Beilstein J. Org. Chem. 2020, 16, 60–70, doi:10.3762/bjoc.16.8

• -protected photoswitchable ω-amino acid 1 (Scheme 2A) was performed based on a procedure by Aemissegger et al. [35]. The ω-amino acid 1 was subsequently used in the solid-phase synthesis or for the synthesis of the dimer 7 in solution (Scheme 2B). The incorporation of β-alanine as a 'molecular spring' was

• –Im–OH dimer 5 was obtained [42][43]. Owing to the poor coupling results of Fmoc–Py–OH to the amino function of a terminal Im moiety, the Fmoc–Azo–Im–OH dimer 7 was synthesized in 73% yield by coupling to the amine 4, as shown in Scheme 2B. HBTU as a coupling reagent and DIPEA as a base were employed

• monomers 2–4, and Fmoc–Py–Im–OH 5. B) Synthesis of the dimer Fmoc–Azo–Im–OH 7: a) DCC, THF, rt, 5 min, then 4, rt, 15 h, 41%; b) BF3∙Et2O, dichloromethane, 0 °C→rt, 12 h, 73%. Binding constants and melting temperatures of the interaction of the polyamides with dsDNA obtained by circular dichroism

Pigmentosins from Gibellula sp. as antibiofilm agents and a new glycosylated asperfuran from Cordyceps javanica

• Soleiman E. Helaly,
• Wilawan Kuephadungphan,
• Patima Phainuphong,
• Mahmoud A. A. Ibrahim,
• Kanoksri Tasanathai,
• Suchada Mongkolsamrit,
• Janet Jennifer Luangsa-ard,
• Souwalak Phongpaichit,
• Vatcharin Rukachaisirikul and
• Marc Stadler

Beilstein J. Org. Chem. 2019, 15, 2968–2981, doi:10.3762/bjoc.15.293

• with pigmentosin A, a 3,4-dihydro-α-naphthopyrone dimer with a 7,7′-dimethoxy pattern, by comparing its spectroscopic data with the published data for pigmentosin A [12]. Nevertheless, the chirality of the stereogenic centers C-3/C-3′ as well as the atropisomerism at the 6,6′ axis of pigmentosin A (1

• side of the dimer (Figure 3). Thus, compound 2 was determined to be a new asymmetrical dimer of 3,4-dihydro-α-naphthopyrone and 3-(propan-2-ol)-3,4-dihydro-α-naphthopyrone, a new member of the bis(naphtho-α-pyrone) group [12][13], for which we propose the trivial name pigmentosin B. To determine the

Emission solvatochromic, solid-state and aggregation-induced emissive α-pyrones and emission-tuneable 1H-pyridines by Michael addition–cyclocondensation sequences

• Natascha Breuer,
• Irina Gruber,
• Christoph Janiak and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2019, 15, 2684–2703, doi:10.3762/bjoc.15.262

• substituent in the 3-position [29]. Most syntheses generating 1H-pyridines make use of ethyl cyanoactate as a starting material. It can react with itself and forms a dimer by selfcondensation, catalyzed by transition metals [30][31]. Intrigued by the unusual pseudo-four-component AMAC synthesis we

• conditions as for the 1H-pyridine from alkynone 3a was conducted, but only starting material could be isolated. Another option for the formation of the 1H-pyridine 5a was envisioned by an in situ generation of a dimer of ethyl cyanoacetate (4). The dimer 7 can be synthesized by iridium catalysis [30]. With

• dimer 7 in hand, we performed the reaction at 75 °C for 16 h, but we only could isolate 1H-pyridine 8a, which still contains an ester group (Scheme 8). Therefore, the in situ formation of the dimer starting from the alkynone 3a and ethyl cyanoacetate (4) was excluded for the formation of the 1H-pyridine

Formation of alkyne-bridged ferrocenophanes using ring-closing alkyne metathesis on 1,1’-diacetylenic ferrocenes

• Celine Bittner,
• Dirk Bockfeld and
• Matthias Tamm

Beilstein J. Org. Chem. 2019, 15, 2534–2543, doi:10.3762/bjoc.15.246

• performed RCAM with a higher substrate concentration of 1a of 21 mM. When further increasing the concentration of 1a to 125 mM a product mixture of the monomeric ferrocenophane 2a, the fully ring-closed dimeric compound as well as the open dimer can be identified with the help of mass spectrometry (see also

• analogue of the formula [Fe{C5H4COO(CH2)3 C≡}2]2 in a ratio of approximately 4:1. Related NMR spectra can be found in Supporting Information File 1 (Figures S9 and S10). Separation of the monomer 2b could be achieved with column chromatography on silica gel with a yield of 53%. The ring-closed dimer

Anion-driven encapsulation of cationic guests inside pyridine[4]arene dimers

• Anniina Kiesilä,
• Jani O. Moilanen,
• Anneli Kruve,
• Christoph A. Schalley,
• Perdita Barran and
• Elina Kalenius

Beilstein J. Org. Chem. 2019, 15, 2486–2492, doi:10.3762/bjoc.15.241

• to the electron-poor nature of the pyridine ring. Herein, we demonstrate the encapsulation of Me4N+ cations inside a dimeric hydrogen-bonded pyridine[4]arene capsule, which contradicts with earlier assumptions. The complexation of a cationic guest inside the pyridine[4]arene dimer has been detected

• could not be verified and the anions were assumed to interact with the pyridinearene cavity. Inclusion complexes of anions within pyridinearene dimers were also theoretically studied by DFT calculations, but using a truncated pyridinearene dimer model [8]. However, previous studies have also shown that

• -rim alkyl chains [11]. A PF6− anion was bound to the lower rim of the pyridine[4]arene dimer via CH–anion and CH–F interactions, while the neutral guest was hosted inside the dimer. Calculated electrostatic potential (ESP) surfaces revealed that the cavity does not possess any significant partial

Combining the Ugi-azide multicomponent reaction and rhodium(III)-catalyzed annulation for the synthesis of tetrazole-isoquinolone/pyridone hybrids

• Gerardo M. Ojeda,
• Prabhat Ranjan,
• Pavel Fedoseev,
• Lisandra Amable,
• Upendra K. Sharma,
• Daniel G. Rivera and
• Erik V. Van der Eycken

Beilstein J. Org. Chem. 2019, 15, 2447–2457, doi:10.3762/bjoc.15.237

• the relatively cheap complex (p-cymene)ruthenium(II) chloride dimer, in the presence of copper(II) acetate as oxidant under conventional heating. Despite all effort put in this attempt, the isolated yields were in the range of 14–62%, with the highest yield achieved after 24 h of reaction using 10 mol

• use of pentamethylcyclopentadienylrhodium(III) chloride dimer, [Cp*RhCl2]2, allowed reducing both the loading to 5 mol % and the reaction time to 12 h (Table 1). The addition of cesium acetate appeared to be required, probably to convert the pre-catalyst into the active catalyst. After some additional

Photochromic diarylethene ligands featuring 2-(imidazol-2-yl)pyridine coordination site and their iron(II) complexes

• Andrey G. Lvov,
• Max Mörtel,
• Anton V. Yadykov,
• Frank W. Heinemann,
• Valerii Z. Shirinian and
• Marat M. Khusniyarov

Beilstein J. Org. Chem. 2019, 15, 2428–2437, doi:10.3762/bjoc.15.235

• that bond. Two iron(II) centers are 8.057 Å apart in the dimer. The ligand 6 appears in the open-ring form and the parallel conformation [8], with the α-methyl groups pointing in similar directions. While still appearing in a distorted half-chair conformation, the phenyl substituent of the

• 2.1190(19) Å. The pyridine and imidazole Fe–N bond distances are 2.2467(19) Å and 2.1793(18) Å, which are very similar to those found for the dimer 8. On the contrary, the Fe–O bond distances to the β-keto ester moiety differ much less with 2.0812(15) Å and 2.0098(15) Å. The iron–donor bond distances are

Reversible switching of arylazopyrazole within a metal–organic cage

• Anton I. Hanopolskyi,
• Soumen De,
• Michał J. Białek,
• Yael Diskin-Posner,
• Liat Avram,
• Moran Feller and
• Rafal Klajn

Beilstein J. Org. Chem. 2019, 15, 2398–2407, doi:10.3762/bjoc.15.232

• release of "high-energy" water molecules from the cavity of 2 [50][51]. Determining the X-ray structure was challenging; the difficulty lies in the fact that both the cage and the encapsulated guest dimer exist in the form of two different conformations. Figure 3 shows (E-1)22 that features the main

• with any of the three methyl groups. Furthermore, we note that the resonance due to Hb – very broad in complex (E-1)22 as a consequence of dimer formation – becomes as sharp as those of the other protons after UV irradiation (compare spectra i and ii in Figure S23, Supporting Information File 1). Taken

Current understanding and biotechnological application of the bacterial diterpene synthase CotB2

• Ronja Driller,
• Daniel Garbe,
• Norbert Mehlmer,
• Monika Fuchs,
• Keren Raz,
• Dan Thomas Major,
• Thomas Brück and
• Bernhard Loll

Beilstein J. Org. Chem. 2019, 15, 2355–2368, doi:10.3762/bjoc.15.228

• ). CotB2 is arranged as a homo-dimer in crystallo [36][38] and it was demonstrated that CotB2 exists as a homo-dimer in solution as well [38]. The two active sites of CotB2 are arranged in an antiparallel fashion, resembling the arrangement initially observed for the monoterpene (+)-bornyl diphosphate

• synthase [47] and the sesquiterpene trichodiene synthase [48], but is in contrast to the parallel dimer as described for farnesyl diphosphate synthase [49]. Structurally, CotB2 is most closely related to the fungal monoterpene synthase aristolochene (PDB-ID 2OA6; [50]), and epi-isozizaene synthase (PDB-ID

Fluorescent phosphorus dendrimers excited by two photons: synthesis, two-photon absorption properties and biological uses

• Anne-Marie Caminade,
• Artem Zibarov,
• Eduardo Cueto Diaz,
• Aurélien Hameau,
• Maxime Klausen,
• Kathleen Moineau-Chane Ching,
• Jean-Pierre Majoral,
• Jean-Baptiste Verlhac,
• Olivier Mongin and
• Mireille Blanchard-Desce

Beilstein J. Org. Chem. 2019, 15, 2287–2303, doi:10.3762/bjoc.15.221

• derivatives grafted on the surface of phosphorhydrazone dendrimers. In this case, a β-diketone functionalized by a phenol was first grafted on the surface of the dendrimer [47], then BF3 was added to obtain the dioxaborines (Scheme 3). Monomer, dimer, and all generations of the dendrimer from zero (6 terminal

• dimer and 33% for the G1 dendrimer, but a 15% decrease of the TPA response was measured for the G2 dendrimer [53]. In addition, in that case, also the fluorescence quantum yield was found to decrease dramatically with an increasing number of fluorophores. TPA fluorophore as core of dendrimers None of

Recent advances in transition-metal-catalyzed incorporation of fluorine-containing groups

• Xiaowei Li,
• Xiaolin Shi,
• Xiangqian Li and
• Dayong Shi

Beilstein J. Org. Chem. 2019, 15, 2213–2270, doi:10.3762/bjoc.15.218

• Scheme 45a. Cyclooctadiene iridium chloride dimer, [IrCl(COD)]2, was an effective catalyst to promote this fluorination with Et3N·3HF, forming allylic fluorides in moderate to good yields. This facile method shows a good regioselectivity to gain the branched isomer within 1 h. Later in 2017, they

1,2,3-Triazolium macrocycles in supramolecular chemistry

• Mastaneh Safarnejad Shad,
• Pulikkal Veettil Santhini and
• Wim Dehaen

Beilstein J. Org. Chem. 2019, 15, 2142–2155, doi:10.3762/bjoc.15.211

• [TCNQ]−· radical anion, dragging the second [TCNQ]− near to the cavity by the help of the electrostatic stabilization supplied by the 1,2,3-triazolium cations, coupling of the two [TCNQ]−· anion radicals in the cavity and rapid formation of the sigma-connected dimer, reduction of the photogenerated

• porphyrin cation by the iodide counterions of the triazolium macrocycle, either before or after the constraining of the second [TCNQ]−· anion radical, finally, the dimer is either ejected from the host or is displaced by the [TCNQ]−· anion radical. It was clearly shown that the macrocycle 15 acts as a

• compound 8. Chemical structures of compound 9. Chemical structures of compound 10, 11 and 12. Chemical structure of compound 13. Chemical structure of compound 15 including the sigma-connected TCNQ dimer. Chemical structure of compound 16 for the kinetic resolution of epoxides. Chemical structure of

Genome mining in Trichoderma viride J1-030: discovery and identification of novel sesquiterpene synthase and its products

• Xiang Sun,
• You-Sheng Cai,
• Yujie Yuan,
• Guangkai Bian,
• Ziling Ye,
• Zixin Deng and
• Tiangang Liu

Beilstein J. Org. Chem. 2019, 15, 2052–2058, doi:10.3762/bjoc.15.202

• aspartate-rich motif, 276NSE/DTE triad, 366RY dimer and 230R monomer (Figure S1, Supporting Information File 1) [29][30][31]. Furthermore, in a phylogenetic analysis (Figure 2), Tvi09626 belonged to Clade V of Class I terpene synthases. In previous studies, terpene synthases have been studied in the genus

Attempted synthesis of a meta-metalated calix[4]arene

• Christopher D. Jurisch and
• Gareth E. Arnott

Beilstein J. Org. Chem. 2019, 15, 1996–2002, doi:10.3762/bjoc.15.195

• be formed. However, the 1H NMR spectroscopic evidence for this was speculative at best and would suggest a very small quantity of the desired product (see Supporting Information File 1, Figure S34). Another main contaminant was the dichloro(p-cymene)ruthenium(II) dimer, which we could not eliminate

• dichloro(p-cymene)ruthenium(II) dimer or the triazolium chloride salt already observed. As a last attempt to find evidence for the ruthenacycle, a high-resolution mass spectrum was acquired directly after the reaction was completed. The most important isotopic distribution detected was at 984.4283 Da

Identification of optimal fluorescent probes for G-quadruplex nucleic acids through systematic exploration of mono- and distyryl dye libraries

• Xiao Xie,
• Michela Zuffo,
• Marie-Paule Teulade-Fichou and
• Anton Granzhan

Beilstein J. Org. Chem. 2019, 15, 1872–1889, doi:10.3762/bjoc.15.183

• and RNA structures The fluorimetric response of the dye library was investigated against a set of 14 diverse nucleic acid structures (Table 2), including ten G4-DNA structures of different topologies (parallel G4: c-kit2, 25CEB, c-kit87up, c-myc, c-src1; parallel dimer G4: c-myb; hybrid G4: 22AG, 46AG

Water inside β-cyclodextrin cavity: amount, stability and mechanism of binding

• Stiliyana Pereva,
• Valya Nikolova,
• Silvia Angelova,
• Tony Spassov and
• Todor Dudev

Beilstein J. Org. Chem. 2019, 15, 1592–1600, doi:10.3762/bjoc.15.163

• rim is the preferred mode of coordination (n = 2; Figure 2, structure a). In this construct the water dimer not only connects two oppositely located OH groups from the rim, but additionally interacts with four other OH groups and forms an elaborate hydrogen-bond network that almost occludes the

• against experimental data (dissociation energy, D0, in the gas phase) on water dimer. Frequency calculations for each M062X/6-31G(d,p) optimized construct were performed at the same level of theory. No imaginary frequency was found for the lowest energy configurations of any of the optimized structures

Synthesis of 9-O-arylated berberines via copper-catalyzed C_Ar–O coupling reactions

• Qiaoqiao Teng,
• Xinhui Zhu,
• Qianqian Guo,
• Weihua Jiang,
• Jiang Liu and
• Qi Meng

Beilstein J. Org. Chem. 2019, 15, 1575–1580, doi:10.3762/bjoc.15.161

• 9-O-phenylene-bridged berberine dimer (5) was synthesized by copper-catalyzed cross-coupling of tetrahydroberberrubine and aryl iodides, followed by oxidation with I2. Keywords: arylation; berberines; cross-coupling; copper; lipophilicity; structural modification; Introduction Berberine (BBR) is a

• were subsequently converted back to the respective 9-O-arylated berberines and 9-O-phenylene-bridged berberine dimer. Oxidation with DMSO-d6 was first attempted with 2a. It showed good stability at ambient temperature and only 16% conversion to the 9-O-Ph berberine 3a was noted after 72 h of heating at

• backbone was observed as with Br2 [5]. This makes I2 a better oxidant for the oxidation of tetrahydroberberines. Compounds 3a–o are yellow solids, which are soluble in CH2Cl2, CH3CN, DMSO and MeOH. In contrast, the phenylene-bridged dimer 5 is only sparingly soluble in DMSO and MeOH. The formation of the

2,3-Dibutoxynaphthalene-based tetralactam macrocycles for recognizing precious metal chloride complexes

• Li-Li Wang,
• Yi-Kuan Tu,
• Huan Yao and
• Wei Jiang

Beilstein J. Org. Chem. 2019, 15, 1460–1467, doi:10.3762/bjoc.15.146

• values for (TBA)2[PtCl4] and (TBA)2[PdCl4] were 189 ± 36 M−1 and 198 ± 15 M−1, respectively. It should be noted that PdCl42− is relatively labile at high concentrations and is in equilibrium with the palladate dimer (Pd2Cl62−) and chloride ions [32][39]. The formation of Pd2Cl62− was supported by an ESI

Introduction of an isoxazoline unit to the β-position of porphyrin via regioselective 1,3-dipolar cycloaddition reaction

• Xiujun Liu,
• Xiang Ma and
• Yaqing Feng

Beilstein J. Org. Chem. 2019, 15, 1434–1440, doi:10.3762/bjoc.15.143

• longer than the distance when MeOH coordinated to the Zn2+ ions [49]. This may attribute to the larger volume of the C6H4CO2Me group than MeOH when closing to the Zn2+ center. In the dimer structure, two planes defined by porphyrin macrocycles are parallel with a distance of 7.11 Å. The bulky substituent

• trimethylphenyl group) in CDCl3 (500 MHz, 25 °C). The representative dimeric structure of 3a according to the crystal structure (a) and enantiomeric dimer structure in crystal (b–d, the phenyl group at meso-positions and 2,6-dichlorophenyl group were omitted for the sake of clarity). The distances of Zn–O (c) and

Borylation and rearrangement of alkynyloxiranes: a stereospecific route to substituted α-enynes

• Ruben Pomar Fuentespina,
• José Angel Garcia de la Cruz,
• Gabriel Durin,
• Victor Mamane,
• Jean-Marc Weibel and
• Patrick Pale

Beilstein J. Org. Chem. 2019, 15, 1416–1424, doi:10.3762/bjoc.15.141

• occurred upon oxygen-directed metalation. The resulting oxiranyllithium probably exists as a dimer in solution, as it has been nicely evidenced by structural characterization and NMR studies of the lithiated o-trifluoromethylstyrene oxide [37]. Such dimerization obviously stabilizes the oxiranyllithium

• species. Applied to oxiranyllithium derived from cis or trans-alkynyloxiranes, such dimer may easily form from the cis-oxirane (Scheme 2, entry 4), but not from the trans-isomer, or at least the large steric constrain present in it may hamper its stability. Indeed, the long oxirane C–O bond adjacent to

• lithium observed by X-ray diffraction in the lithiated o-trifluoromethylstyrene oxide [37] may be further elongated due to hindrance introduced by the trans-substituent adjacent to the lithium atom of the second oxirane in the dimer (Scheme 2, entry 5). Such effect may facilitate the formation of the

Selenophene-containing heterotriacenes by a C–Se coupling/cyclization reaction

• Pierre-Olivier Schwartz,
• Sebastian Förtsch,
• Astrid Vogt,
• Elena Mena-Osteritz and
• Peter Bäuerle

Beilstein J. Org. Chem. 2019, 15, 1379–1393, doi:10.3762/bjoc.15.138

• formed dimers showed some differences: in DTT 1 the molecules overlap in a parallel orientation whereas in DST 3 an antiparallel orientation of the molecules in the dimer was found. The degree of overlap was determined to 73% and 64% for DTT 1 and DST 3, respectively. Less degree of overlap (43–53% and

Selective detection of DABCO using a supramolecular interconversion as fluorescence reporter

• Indrajit Paul,
• Debabrata Samanta,
• Sudhakar Gaikwad and
• Michael Schmittel

Beilstein J. Org. Chem. 2019, 15, 1371–1378, doi:10.3762/bjoc.15.137

• , 3, and 4 and of the resulting products, i.e., rectangle 5, sandwich 6 and rhodium porphyrin dimer 7. Comparison of partial 1H NMR spectra (400 MHz, CD2Cl2, 298 K) of (a) ligand 2; (b) ligand 1; (c) porphyrin 3; (d) complex 7 = [(3)2(4)]; (e) rectangle 5 = [Cu4(1)2(2)2]4+]; (f) sandwich complex 6

• ); (c) after addition of 4.0 equiv of rhodium porphyrin 3, leading to formation of rectangle 5 and rhodium porphyrin dimer 7. (d) Further addition of 2.0 equiv of DABCO furnishes state II; (e) finally, addition of 4.0 equiv of rhodium porphyrin 3 recovered rectangle 5 along with 4.0 equiv of complex 7

One-pot activation–alkynylation–cyclization synthesis of 1,5-diacyl-5-hydroxypyrazolines in a consecutive three-component fashion

• Christina Görgen,
• Katharina Boden,
• Guido J. Reiss,
• Walter Frank and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2019, 15, 1360–1370, doi:10.3762/bjoc.15.136

• dimer of compound 5r (thermal ellipsoids at 30% probability). Glyoxylation–alkynylation (GA) and activation–alkynylation (AA) synthesis of alkynediones in a one-pot fashion. Consecutive three-component synthesis to give 5-benzoyl-3-phenyl-1H-pyrazole (6a) after alkaline deacylation of intermediate 5a

Mechanochemical Friedel–Crafts acylations

• Mateja Đud,
• Anamarija Briš,
• Iva Jušinski,
• Davor Gracin and
• Davor Margetić

Beilstein J. Org. Chem. 2019, 15, 1313–1320, doi:10.3762/bjoc.15.130

• anthracene in 95% yield. This [4π + 4π] cycloreversion in mechanochemical conditions is analogous to previously described dissociation of labile anthracene/C60 cycloadduct [52]. When the reaction of 19 with 20 was carried out in solution (DCM, overnight), 60% of dimer was converted to anthracene, and traces

• ); aconversion from NMR analysis; bsolution reaction in flask, substrate/acylation reagent/AlCl3 ratio is 1:1:2.5; ball-milling details are given in Table 1. Scope of aromatic substrates in FCR under mechanochemical activation conditions. aIsolated yields. Mechanochemical regiodirected FCR of anthracene dimer