Mechanochemical green synthesis of hyper-crosslinked cyclodextrin polymers

• Alberto Rubin Pedrazzo,
• Fabrizio Caldera,
• Marco Zanetti,
• Silvia Lucia Appleton,
• Nilesh Kumar Dhakar and
• Francesco Trotta

Beilstein J. Org. Chem. 2020, 16, 1554–1563, doi:10.3762/bjoc.16.127

• was as follows: 3.00 g of α-cyclodextrin, 3.33 g of β-cyclodextrins and 4.05 g of γ-cyclodextrins (3.30 mmol) were dissolved in 10 mL of DMF (in three different round-bottomed flasks). After complete dissolution of the cyclodextrins, 2.00 g (13 mmol) of CDI as cross linker were added to each batch

Heterogeneous photocatalysis in flow chemical reactors

• Christopher G. Thomson,
• Ai-Lan Lee and
• Filipe Vilela

Beilstein J. Org. Chem. 2020, 16, 1495–1549, doi:10.3762/bjoc.16.125

A smart deoxyribozyme-based fluorescent sensor for in vitro detection of androgen receptor mRNA

• Ekaterina A. Bryushkova,
• Erik R. Gandalipov and
• Julia V. Nuzhina

Beilstein J. Org. Chem. 2020, 16, 1135–1141, doi:10.3762/bjoc.16.100

• biological material. SDFS main components and its work model. A) Schematic representation of the SDFS structure. Dotted lines indicate hexaethylene glycol linkers in T1 and T4, and polythymidines linker in T2 and T3; Dz1 and Dz2 – deoxyribozyme sequences. B) The detailed structure of the Dz catalytic core

Bipyrrole boomerangs via Pd-mediated tandem cyclization–oxygenation. Controlling reaction selectivity and electronic properties

• Liliia Moshniaha,
• Marika Żyła-Karwowska,
• Joanna Cybińska,
• Piotr J. Chmielewski,
• Ludovic Favereau and
• Marcin Stępień

Beilstein J. Org. Chem. 2020, 16, 895–903, doi:10.3762/bjoc.16.81

• endocyclic CH2 moiety yielded a pair of very broad peaks at ca. 4.8–3.4 ppm. This splitting, which was also observed for cNDA2O, is consistent with slow inversion of helicity occurring at the ethylene bridge. In the 1H NMR spectrum of cNMI2H, the linker CH2 moiety and the 2,6-diisopropylphenyl (dipp) CH unit

• DFT calculations (Figure 1 and Supporting Information File 1). The length of the linker (n) in cNDAnX and cNMInX controls the in- and out-of-plane geometry of the chromophore. The observed changes can be expressed in terms of two parameters: α, the angle between the monopyrrole axis and the N–N vector

• . ΔE values for lactams cRnO are relatively insensitive to the length of the alkylene linker n, in spite of the large changes of the inter-subunit torsion (θ, Supporting Information File 1, Table S1) caused by the increase of n. In line with the absorption spectroscopy data, the ΔE gap is reduced in

Towards triptycene functionalization and triptycene-linked porphyrin arrays

• Gemma M. Locke,
• Keith J. Flanagan and
• Mathias O. Senge

Beilstein J. Org. Chem. 2020, 16, 763–777, doi:10.3762/bjoc.16.70

• evident linearity in these systems. Moreover, initial UV–vis and fluorescence studies show the promise of triptycene as a linker for electron transfer studies, showcasing its isolating nature. Keywords: BODIPY; Pd-catalyzed cross-coupling; porphyrins; Sonogashira cross-coupling; triptycene; Introduction

• topic [33]. Results and Discussion Synthesis of triptycene precursors Initially, to synthesize linearly linked triptycene porphyrin dimers, the attachment of various linker groups at the triptycene bridgehead carbon atoms was investigated. The initial strategy was to functionalize 9,10-dibromotriptycene

• bridgehead positions of triptycenes in 5 (Scheme 1) and 12 (Scheme 2), efforts were made to attach various chromophores in order to investigate the effects of triptycene as a linker for electron transfer properties. With the goal of synthesizing various new triptycene-linked porphyrin and BODIPY dimers

A systematic review on silica-, carbon-, and magnetic materials-supported copper species as efficient heterogeneous nanocatalysts in “click” reactions

• Pezhman Shiri and
• Jasem Aboonajmi

Beilstein J. Org. Chem. 2020, 16, 551–586, doi:10.3762/bjoc.16.52

• 10 cycles. A mixture of GO, 1-vinylimidazole (98), and cross-linker 99 in ethanol was sonicated for 20 min [85]. Afterwards, the mixture was deoxygenated in an Ar atmosphere for 20 min. In the next step, polymerization was generated by adding AIBN (3 wt %). This was then heated at 70 °C for 24 h

Synthesis and circularly polarized luminescence properties of BINOL-derived bisbenzofuro[2,3-b:3’,2’-e]pyridines (BBZFPys)

• Ryo Takishima,
• Yuji Nishii,
• Tomoaki Hinoue,
• Yoshitane Imai and
• Masahiro Miura

Beilstein J. Org. Chem. 2020, 16, 325–336, doi:10.3762/bjoc.16.32

• condensed (hetero)acenes from rather simple polyarenes, in which several aromatic units are connected with each other through appropriate linker units [2][3][4][5][6][7][8][9][10][11]. Recently, we reported the synthesis and optical properties of a series of furan-fused aromatics via the formal

• dehydrogenative coupling adopting oxygen atom as the linker [12][13][14][15][16][17]. In particular, bisbenzofuro[2,3-b:3′,2′-e]pyridines (BBZFPys) were found to exhibit intense photoluminescence with relatively high quantum efficiency (Φflu up to 0.70), indicating that the BBFZPy scaffold may serve as a key

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

• )phenyl)azophenylacetic acid, as the linker between two Im/Py polyamide strands. Only the (Z)-azobenzene-containing polyamides bound to the minor groove of double-stranded DNA hairpins. Photoisomerization was exemplarily evaluated by 1H NMR experiments, while minor groove binding of the (Z)-azobenzene

• tethering of two antiparallel polyamide segments increases the sequence specificity and the affinity of the polyamides to their cognate dsDNA. Different linker strategies were used, with γ-aminobutyric acid (γ) being the most successful representative. The resulting hairpin polyamides bound with 100-fold

• replacement of the γ-aminobutyric acid linker between the two hairpin strands by a photoswitchable azobenzene motif. As the azobenzene moiety undergoes a considerable steric reorganization upon isomerization from the E- to the Z-configuration, the end-to-end distance in a 4,4'-disubstituted azobenzene changes

Automated glycan assembly of arabinomannan oligosaccharides from Mycobacterium tuberculosis

• Alonso Pardo-Vargas,
• Priya Bharate,
• Martina Delbianco and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2019, 15, 2936–2940, doi:10.3762/bjoc.15.288

• linker as solid support [25]. A typical AGA cycle consisted of three modules. The acidic wash module prepared the resin for glycosylation by quenching any remaining base from a previous cycle. In the glycosylation module, the thioglycoside donor was coupled to the resin upon activation with NIS and TfOH

Carbazole-functionalized hyper-cross-linked polymers for CO₂ uptake based on Friedel–Crafts polymerization on 9-phenylcarbazole

• Dandan Fang,
• Xiaodong Li,
• Meishuai Zou,
• Xiaoyan Guo and
• Aijuan Zhang

Beilstein J. Org. Chem. 2019, 15, 2856–2863, doi:10.3762/bjoc.15.279

• polymers (HCPs), a series of 9-phenylcarbazole (9-PCz) HCPs (P1–P11) has been made by changing the molar ratio of cross-linker to monomer, the reaction temperature T1, the used amount of catalyst and the concentration of reactants. Fourier transform infrared spectroscopy was utilized to characterize the

• structure of the obtained polymers. The TG analysis of the HCPs showed good thermal stability. More importantly, a comparative study on the porosity revealed that: the molar ratio of cross-linker to monomer was the main influence factor of the BET specific surface area. Increasing the reaction temperature

• HCPs include solvent knitting methods [10], Scholl coupling reaction [11], the knitting method with formaldehyde dimethyl acetal (FDA) [12], functional group reactions [2][13] and so on. Among these methods, the knitting method with FDA as external cross-linker is the most time-efficient approach [14

Chemical synthesis of the pentasaccharide repeating unit of the O-specific polysaccharide from Escherichia coli O132 in the form of its 2-aminoethyl glycoside

• Debasish Pal and
• Balaram Mukhopadhyay

Beilstein J. Org. Chem. 2019, 15, 2563–2568, doi:10.3762/bjoc.15.249

• chemically synthesized oligosaccharides before [8][9][10]. The corresponding aminopropyl linker has also been used by others [11]. The chemically synthesized oligosaccharide structure will help to elucidate further biological implications of the O-antigen concerned and possible vaccine potential. Results and

Effect of ring size on photoisomerization properties of stiff stilbene macrocycles

• Sandra Olsson,
• Óscar Benito Pérez,
• Magnus Blom and
• Adolf Gogoll

Beilstein J. Org. Chem. 2019, 15, 2408–2418, doi:10.3762/bjoc.15.233

• units are then attached to an n-alkanediyl linker using a Williamson ether synthesis to yield the diethers 6a–d. Finally, the stiff stilbene unit is formed by an intramolecular McMurry reaction resulting in 1a–d [25][26]. The Z-isomer is formed in huge excess in these reactions and any trace amounts of

• ). Photoisomerization Photoisomerizing the (Z)-1a–d to the (E)-1a–d isomers requires to stretch the linker. The isomerization was achieved by irradiation of a degassed solution of (Z)-1a–d in chloroform or deuterated chloroform using either a 280 or 300 nm filter (Scheme 3). The conversion was followed by UV–vis or 1H

• the noncyclic reference is presented in Figure 2. As the linker chain gets shorter the E-isomer becomes less favored. What is particularly interesting is that even with the longest chain of twelve carbons a significantly lower amount of E-isomer as compared to the reference is obtained. Clearly even a

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

• having a longer linker between the fluorophore and the phenol (Scheme 5). Studies of both the dumbbell-like dendrimers of this new series with P(S)Cl2 and ammonium terminal functions revealed that the branches are less protective towards the solvents than in the previous case. Indeed, the type of solvent

Click chemistry towards thermally reversible photochromic 4,5-bisthiazolyl-1,2,3-triazoles

• Chenxia Zhang,
• Kaori Morinaka,
• Mahmut Kose,
• Takashi Ubukata and
• Yasushi Yokoyama

Beilstein J. Org. Chem. 2019, 15, 2161–2169, doi:10.3762/bjoc.15.213

• photochromic diarylethenes containing triazole groups have been reported [20][21][22][23][24][25][26][27][28][29][30][31], all of them use the triazole ring as the linker of the second functional molecule with the diarylethene core. To the best of our knowledge, no diarylethenes or terarylenes possessing the

• been used many times to connect two functional molecules. When the Ru(I)-catalyzed Huisgen reaction is employed to connect two functional molecules, the linker itself possesses the thermally reversible photochromic property. Thus, this work can open the door to the creation of promising new materials

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

• binaphthyl system and the Lewis acidic metal center facilitated the enantioselective synthesis of cyclic carbonates from epoxides. Various catalyst was screened by changing the linker length (n = 4 to 8) and nucleophilic counter anion (X = I, Cl, Br), and 16c was found to be the best catalyst for the

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

• detection of double-stranded DNA. Compounds 15a and 16a are homo-dimeric derivatives, featuring two distyryl moieties connected via a C3 (15a) or a C4 (16a) linker. In addition, we included 9 mono-styryl derivatives. Among these, compounds 17a and 18a are long-known [66][67]; however, to the best of our

Design, synthesis and biological evaluation of immunostimulating mannosylated desmuramyl peptides

• Rosana Ribić,
• Ranko Stojković,
• Lidija Milković,
• Mariastefania Antica,
• Marko Cigler and
• Srđanka Tomić

Beilstein J. Org. Chem. 2019, 15, 1805–1814, doi:10.3762/bjoc.15.174

• present the design, synthesis and biological evaluation of novel mannosylated desmuramyl peptide derivatives. Mannose was coupled to dipeptides containing a lipophilic adamantane on N- or C-terminus through a glycolyl or hydroxyisobutyryl linker. Adjuvant activities of synthesized compounds were

• synthesized and biologically evaluated [19][20][21]. The best adjuvant activity in experiments in vivo showed the ManAdTP derivative (Figure 2) which has a ᴅ-configuration at the (adamant-1-yl)glycine moiety and (R)-configuration at the hydroxyisobutyryl linker. Its activity was higher than PGM that was used

• which two series of compounds were prepared: (i) derivatives containing a glycolyl linker between mannose and dipeptide, and (ii) derivatives containing a parent (R)-hydroxyisobutyryl linker (Figure 3). In both series, positions of adamantane binding (to the N- or C-terminus) were altered in comparison

Synthesis and conformational preferences of short analogues of antifreeze glycopeptides (AFGP)

• Małgorzata Urbańczyk,
• Michał Jewgiński,
• Joanna Krzciuk-Gula,
• Jerzy Góra,
• Rafał Latajka and
• Norbert Sewald

Beilstein J. Org. Chem. 2019, 15, 1581–1591, doi:10.3762/bjoc.15.162

• the resin linker in an efficient four-step procedure compatible with Fmoc-based SPPS. In the first step the Fmoc group was cleaved by treatment with 20% piperidine in DMF giving the free amino function on the resin linker. Then the resin was washed with DCM, DMF and NMP. In the next step the free

• Fmoc-Sieber-PS resin was N-methylated. Firstly, the Fmoc group was cleaved with 20% piperidine in DMF from the resin linker (3 × 10 min shaking). After washing the resin three times with DCM, DMF and 1-methyl-2-pyrrolidone (NMP), the free amino groups of the resin were o-NBS protected. A mixture of 4

Diazocine-functionalized TATA platforms

• Roland Löw,
• Talina Rusch,
• Fynn Röhricht,
• Olaf Magnussen and
• Rainer Herges

Beilstein J. Org. Chem. 2019, 15, 1485–1490, doi:10.3762/bjoc.15.150

• coupling to a bulk gold surface via a conjugated linker over 11 bonds and 14 Å [11]. Thermal cis→trans isomerizations of azobenzenes are usually slow with half-lives of the trans-isomer within the range of hours to days at room temperature (parent azobenzene: 4–5 d at 25 °C) [12]. Rotation around the N=N

Reversible end-to-end assembly of selectively functionalized gold nanorods by light-responsive arylazopyrazole–cyclodextrin interaction

• Maximilian Niehues,
• Patricia Tegeder and
• Bart Jan Ravoo

Beilstein J. Org. Chem. 2019, 15, 1407–1415, doi:10.3762/bjoc.15.140

• assembly and disassembly of the AuNR could be induced by host–guest interaction of CD on the nanorods and a photoswitchable arylazopyrazole cross-linker in aqueous solution. The end-to-end assembly of AuNR could be effectively controlled by irradiation with UV and visible light, respectively, over four

• was only achieved when the CD ligand and the divalent azobenzene linker were premixed to generate the host–guest complex. This solution was then added to the AuNR leading to a ligand exchange preferentially at the ends and therefore to the linear arrangement of AuNR. If the AuNR were first end

• -functionalized with the CD, no assembly could be observed after addition of the divalent azobenzene linker. Moreover, the assemblies could only once be disassembled by the combination of UV irradiation and physical forces by sonication. The light-induced back-isomerization of azobenzenes did not form similar end

Synthesis of dipolar molecular rotors as linkers for metal-organic frameworks

• Sebastian Hamer,
• Fynn Röhricht,
• Marius Jakoby,
• Ian A. Howard,
• Xianghui Zhang,
• Christian Näther and
• Rainer Herges

Beilstein J. Org. Chem. 2019, 15, 1331–1338, doi:10.3762/bjoc.15.132

• dicarboxylic acid-substituted dipolar molecular rotors for the use as linker molecules in metal-organic frameworks (MOFs). The rotor molecules exhibit very low rotational barriers and decent to very high permanent, charge free dipole moments, as shown by density functional theory calculations on the isolated

• molecules. Four rotors are fluorescent in the visible region. The linker designs are based on push–pull-substituted phenylene cores with ethynyl spacers as rotational axes, functionalized with carboxylic acid groups for implementation in MOFs. The substituents at the phenylene core are chosen to be small to

• linkers in MOFs with potential applications as ferroelectric materials and for optical signal processing. Keywords: benzothiadiazole; dipolar rotor; fluorescence; large dipole moment; metal organic framework linker; Introduction Rotors are among the fundamental functional units in engineering in our

Electrophilic oligodeoxynucleotide synthesis using dM-Dmoc for amino protection

• Shahien Shahsavari,
• Dhananjani N. A. M. Eriyagama,
• Bhaskar Halami,
• Vagarshak Begoyan,
• Marina Tanasova,
• Jinsen Chen and
• Shiyue Fang

Beilstein J. Org. Chem. 2019, 15, 1116–1128, doi:10.3762/bjoc.15.108

• removed with an acid in each synthetic cycle. The exo-amino groups of nucleosides dA, dC and dG are protected with acyl groups, the nascent ODN is anchored to a solid support via a base- or nucleophile-cleavable linker, and in the most widely used phosphoramidite technology the phosphate groups are

• protected with the 2-cyanoethyl group. These protecting groups and the linker have to be cleaved under strongly basic and nucleophilic conditions. As a result, many sensitive groups including acetal, hemiacetal, vinyl ethers, enol ethers, aldehydes, esters, activated esters, thioesters, aziridines, epoxides

• as linker to enable deprotection and cleavage under milder basic conditions [32]. The palladium-labile allyl groups were also used for amino protection [33][34]. The o-nitrobenzyl function was used as linker to enable photo cleavage [34]. However, these methods are still not ideal. The phenoxyacetyl

A chemically contiguous hapten approach for a heroin–fentanyl vaccine

• Yoshihiro Natori,
• Candy S. Hwang,
• Lucy Lin,
• Lauren C. Smith,
• Bin Zhou and
• Kim D. Janda

Beilstein J. Org. Chem. 2019, 15, 1020–1031, doi:10.3762/bjoc.15.100

• fentanyl-like domains. Analysis of the results obtained by SPR and ELISA revealed trends in antibody affinity and titers for heroin and fentanyl based on epitope size and linker location. In antinociception studies, the best performing vaccines offered comparable protection against heroin as our benchmark

• of chemically contiguous drug–hapten conjugates, we envisioned generating a series of structurally diverse heroin–fentanyl haptens with a focus on linker placement and bond distance between each drug’s chemical connections in order to probe the effect of the drug-epitope structure on eliciting an

• hoped to be silent spacers. In sum, the feasibility of a singular heroin–fentanyl vaccine would be evaluated through five spatial presentations, differentiated in Figure 2 by background color. The second consideration in our chemically contiguous hapten design was the location of the linker to the

Diaminoterephthalate–α-lipoic acid conjugates with fluorinated residues

• Leon Buschbeck,
• Aleksandra Markovic,
• Gunther Wittstock and
• Jens Christoffers

Beilstein J. Org. Chem. 2019, 15, 981–991, doi:10.3762/bjoc.15.96

• bathochromic shift is observed towards the absorption at 451–473 nm (514 nm for compound 7, which is exceptionally high) and emission at 547–567 nm. The quantum yields of compounds 1–4 range between 0.21 and 0.57, for compounds 5–8 with propylene linker, the quantum yields are between 0.04–0.13. Interestingly

• . Bifunctional DAT as a cross-linker for proteins. The compound is a turn-on-probe, i.e., the fluorescence quantum yield Φ = 2% increased upon reaction with the target to Φ = 41%. High-resolution XPS of SAM 3. High-resolution XPS of SAM 7. Preparation of DAT–ALA conjugate 3 with fluorinated benzyl residue

• . Preparation of conjugate 7 consisting of fluorinated DAT and ALA moieties with an additional propylene linker unit. Spectroscopic properties of diaminoterephthalates 1–8; solvent CH2Cl2. Binding energies of the C 1s, O 1s, S 2p, N 1s, and F 1s photoemission lines of SAM 3 and SAM 7. Supporting Information

New α- and β-cyclodextrin derivatives with cinchona alkaloids used in asymmetric organocatalytic reactions

• Iveta Chena Tichá,
• Simona Hybelbauerová and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2019, 15, 830–839, doi:10.3762/bjoc.15.80

• as the promoter (not in a catalytic amount) of a Henry reaction and obtained the product with 99% ee. Subsequently, Doyagüez et al. [17] attached L-proline to β-CD via different linkers (including a triazole linker) and used the resulting organocatalysts in an aldol reaction in water, albeit with a