Progress and challenges in the synthesis of sequence controlled polysaccharides

• Giulio Fittolani,
• Theodore Tyrikos-Ergas,
• Denisa Vargová,
• Manishkumar A. Chaube and
• Martina Delbianco

Beilstein J. Org. Chem. 2021, 17, 1981–2025, doi:10.3762/bjoc.17.129

• ]. They participate in the formation of the cell-wall by interacting with cellulose microfibrils [191], however, these interactions lack a molecular description [192]. Some evidences suggest that the xylan–cellulose interaction depends on the xylan substitution pattern [193]. Natural xylans contain β(1–4

• the resulting polymers. Linear xylan precipitated with a MW of 9.2 kDa. Arabinofuranosyl xylans substituted at the C-2 or C-3 position of every third residue, formed crystalline aggregates. The authors speculated that a threefold helical screw conformation might enable the regular interaction of

• individual chains. The arabinose pattern also played a role in the interaction with cellulose, with the crystalline compound 62c that did not adsorb to cellulose, in contrast to 62b, which adsorbed irreversibly. The high adsorption of 62b was associated with its twofold helical screw conformation, only

Asymmetric organocatalyzed synthesis of coumarin derivatives

• Natália M. Moreira,
• Lorena S. R. Martelli and
• Arlene G. Corrêa

Beilstein J. Org. Chem. 2021, 17, 1952–1980, doi:10.3762/bjoc.17.128

• deprotonated by a base, affording an ammonium ylide/enolate. Meanwhile, the Re-face attack is favored after interaction of squaramide portion of the catalyst with coumarin. Then, a Michael addition followed by intramolecular cyclization affords the desired product 75, as shown in Scheme 23. An enantioselective

On the application of 3d metals for C–H activation toward bioactive compounds: The key step for the synthesis of silver bullets

• Renato L. Carvalho,
• Amanda S. de Miranda,
• Mateus P. Nunes,
• Roberto S. Gomes,
• Guilherme A. M. Jardim and
• Eufrânio N. da Silva Júnior

Beilstein J. Org. Chem. 2021, 17, 1849–1938, doi:10.3762/bjoc.17.126

Development of N-F fluorinating agents and their fluorinations: Historical perspective

• Teruo Umemoto,
• Yuhao Yang and
• Gerald B. Hammond

Beilstein J. Org. Chem. 2021, 17, 1752–1813, doi:10.3762/bjoc.17.123

• shown in Scheme 40, the 18-2 pyridinium series proved to be effective fluorinating agents for a wide range of substrates. Moreover, an extremely high ortho-selectivity was observed in the fluorination of phenol. This could be attributed to a hydrogen-bonding interaction between the sulfonate anion and

Cerium-photocatalyzed aerobic oxidation of benzylic alcohols to aldehydes and ketones

• Girish Suresh Yedase,
• Sumit Kumar,
• Jessica Stahl,
• Burkhard König and
• Veera Reddy Yatham

Beilstein J. Org. Chem. 2021, 17, 1727–1732, doi:10.3762/bjoc.17.121

• inhibition of the catalytic cycle upon the addition of TEMPO revealed that the reaction proceeds through radical intermediates. Next, we carried out UV–vis monitoring experiments in order to verify whether the interaction with the substituted benzyl alcohols and CeIV could lead to a ligand-to-metal charge

A systems-based framework to computationally describe putative transcription factors and signaling pathways regulating glycan biosynthesis

• Theodore Groth,
• Rudiyanto Gunawan and
• Sriram Neelamegham

Beilstein J. Org. Chem. 2021, 17, 1712–1724, doi:10.3762/bjoc.17.119

• their tissue-specific expression, DNA binding domains, and nucleosome interaction sequences [3]. Additional factors regulating transcriptional activity include: i) cofactors and small molecules that enable TF-DNA recognition and RNA polymerase recruitment [3]; ii) chromatin modifications, such as

• analysis of studies that link TFs to glycosylation pathways and glycan structures. Results TF–glycogene interaction map and relation to cell signaling pathways The article follows a workflow shown in Figure 2. It mines TF–glycosylation pathway relationships from the Cistrome Cancer DB [14], which involves

• signaling pathways contribute to altered glycan structures in diseases such as diabetes and cancer. Thus, this work represents a rich starting point for wet-lab validation and glycoinformatics DB construction. Visualizing TF–glycogene interaction networks revealed communities of glycogenes in each cancer

Breaking paracyclophane: the unexpected formation of non-symmetric disubstituted nitro[2.2]metaparacyclophanes

• Suraj Patel,
• Tyson N. Dais,
• Paul G. Plieger and
• Gareth J. Rowlands

Beilstein J. Org. Chem. 2021, 17, 1518–1526, doi:10.3762/bjoc.17.109

• archetypal cyclophane, with a strong interaction between the two aromatic rings, but it is readily available, being a ‘dimer’ for the polymer parylene [6][7]. Over the last twenty years, there has been a resurgence in interest in this compound as a scaffold for the synthesis of asymmetric catalysts, energy

• materials, and as the basis of the study of through-space conjugation [2][8][9][10][11][12][13][14][15][16]. There are fewer studies of [2.2]metacyclophane (2) and its derivatives. This is probably related to a lack availability as well as the reduced interaction between the aromatic rings [17]. But the odd

Double-headed nucleosides: Synthesis and applications

• Vineet Verma,
• Jyotirmoy Maity,
• Vipin K. Maikhuri,
• Ritika Sharma,
• Himal K. Ganguly and
• Ashok K. Prasad

Beilstein J. Org. Chem. 2021, 17, 1392–1439, doi:10.3762/bjoc.17.98

• followed by their duplex formation studies against complimentary oligonucleotide strands had described a very selective zipper-interaction [35], whereas a relative stabilization was observed due to stacking of these additional nucleobases across the minor groove [31]. The biological activity of the acyclic

Antiviral therapy in shrimp through plant virus VLP containing VP28 dsRNA against WSSV

• Santiago Ramos-Carreño,
• Ivone Giffard-Mena,
• Jose N. Zamudio-Ocadiz,
• Alfredo Nuñez-Rivera,
• Ricardo Valencia-Yañez,
• Jaime Ruiz-Garcia,
• Maria Teresa Viana and
• Ruben D. Cadena-Nava

Beilstein J. Org. Chem. 2021, 17, 1360–1373, doi:10.3762/bjoc.17.95

• ] that could be favorable for tube formation. The interaction of a rigid and quasi-long dsRNA molecule with the capsid protein dimers enables the elongated tubular structure formation under these experimental conditions [59]. The spherical VLPs have an average diameter of 25.8 nm corresponding to capsids

A new glance at the chemosphere of macroalgal–bacterial interactions: In situ profiling of metabolites in symbiosis by mass spectrometry

• Marine Vallet,
• Filip Kaftan,
• Veit Grabe,
• Fatemeh Ghaderiardakani,
• Simona Fenizia,
• Aleš Svatoš,
• Georg Pohnert and
• Thomas Wichard

Beilstein J. Org. Chem. 2021, 17, 1313–1322, doi:10.3762/bjoc.17.91

• spp. [13]. The Roseovarius-factor that promotes cell division is still unknown [3][8]. Algal substances are released into the surrounding environment to attract epiphytic bacteria and initiate the cross-kingdom interaction [14][15]. Ulva attracts Roseovarius sp. MS2 through the sulphur-containing

• using mass spectrometry-based methods. For example, stable sulphur isotope (34S) labelled DMSP was used to track DMSP uptake and degradation by marine bacteria, and secondary ion mass spectrometry was applied to visualise it at the single-cell level [16]. The interaction between epibiotic bacteria on

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

• Guido Gambacorta,
• James S. Sharley and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90

• interaction with the reagents. As a result, several hollow fibres-immobilised catalysts have been prepared and applied in flow scenarios [112]. A titania-, zirconia- and silica-implanted polyamide-imide (PAI) hollow fibre was grafted with aminosilane functional groups in order to create a bifunctional

Structural effects of meso-halogenation on porphyrins

• Keith J. Flanagan,
• Maximilian Paradiz Dominguez,
• Zoi Melissari,
• Hans-Georg Eckhardt,
• René M. Williams,
• Dáire Gibbons,
• Caroline Prior,
• Gemma M. Locke,
• Alina Meindl,
• Aoife A. Ryan and
• Mathias O. Senge

Beilstein J. Org. Chem. 2021, 17, 1149–1170, doi:10.3762/bjoc.17.88

• affected by both halogen type and metal insertion. In compound 1 the main motifs seen are the face-to-face stacking at 3.326(4) Å (Figure 2A) and the tilted edge-on interaction (≈64°) (Figure 2B). The other motif seen is the inline interactions where layers of porphyrins are lined up with the bromine atoms

• motif of bromine atoms pointing towards the phenyl rings is visible in this structure and seems to be a staple of this series (Figure 3B). Secondly, the edge-on interaction in this structure has changed, where the pyrrole moiety is pointing towards the face of the porphyrin macrocycle as seen in Figure

• packing like the one observed in compound 1 (Supporting Information File 1, Figure S4) with the same stacking, edge-on interaction and layers of porphyrin with ↑↓↑↓ repeating pattern (Figure 8). This is also reflected in the NSD where the largest contribution is seen in the B1u OOP mode, but it is not

N-tert-Butanesulfinyl imines in the asymmetric synthesis of nitrogen-containing heterocycles

• Joseane A. Mendes,
• Paulo R. R. Costa,
• Miguel Yus,
• Francisco Foubelo and
• Camilla D. Buarque

Beilstein J. Org. Chem. 2021, 17, 1096–1140, doi:10.3762/bjoc.17.86

• with InBr3 as Lewis acid, in dichloromethane at room temperature [106]. Under these reaction conditions, sulfinyl imine is formed first along with the boronate by interaction of the corresponding vinylboronic acid with the carboxylic group of the imino acid intermediate. The transfer of the vinyl unit

Synthetic accesses to biguanide compounds

• Oleksandr Grytsai,
• Cyril Ronco and
• Rachid Benhida

Beilstein J. Org. Chem. 2021, 17, 1001–1040, doi:10.3762/bjoc.17.82

• [1] such as antidiabetics, antimalaria, disinfectants, and antivirals. After a period of dormancy, the discovery of the anticancer activity of metformin has reignited a growing interest in biguanides. Indeed, in biological media, the biguanide group is highly prone to interaction with biomolecules

Metal-free glycosylation with glycosyl fluorides in liquid SO₂

• Krista Gulbe,
• Jevgeņija Lugiņina,
• Edijs Jansons,
• Artis Kinens and
• Māris Turks

Beilstein J. Org. Chem. 2021, 17, 964–976, doi:10.3762/bjoc.17.78

• mannose α-11. Glucosides 14 were isolated in a moderate yield, but without any α,β-selectivity due to the mismatched interaction between the anomeric effect and neighboring protecting group assistance. The diminished selectivity compared to the series of pivaloyl-protected glucosides 10 leads to the

Prins cyclization-mediated stereoselective synthesis of tetrahydropyrans and dihydropyrans: an inspection of twenty years

• Asha Budakoti,
• Pradip Kumar Mondal,
• Prachi Verma and
• Jagadish Khamrai

Beilstein J. Org. Chem. 2021, 17, 932–963, doi:10.3762/bjoc.17.77

• -orbital at C4. These orbital stabilizations, along with the lack of 1,3-diaxial interaction experienced by the incoming nucleophile (mostly halide) leads to the preferential equatorial attack over an axial attack by the nucleophile (Scheme 3) to give all-cis-2,4,6-trisubstituted THPs. In the absence of an

• to give oxocarbenium ion 15, wherefrom two competing transition states, 15a and 15b, can possibly form. In the 6-membered chair-like transition state 15a, there is a 1,3-diaxial interaction between “H” and the substituent R2, while for the other five-membered transition state 15b, there is no such

• 1,3-diaxial interaction, which favors the formation of tetrahydrofuran product 17 instead of the tetrahydropyran 16 (Scheme 4). Although the Prins cyclization is one of the powerful tools for the construction of 2,6-disubstituted THPs, there are some limitations that restrict a wide applicability. The

Beyond ribose and phosphate: Selected nucleic acid modifications for structure–function investigations and therapeutic applications

• Christopher Liczner,
• Kieran Duke,
• Gabrielle Juneau,
• Martin Egli and
• Christopher J. Wilds

Beilstein J. Org. Chem. 2021, 17, 908–931, doi:10.3762/bjoc.17.76

• was also believed to render AM1-RNA incompatible with siRNA therapeutic strategies, as there was crystallographic data [82] that showed the main interaction between the phosphates of the RNA duplex and the Ago2 protein is electrostatic in nature, this was, however, not the case, owing to the observed

• in the vicinity of a hydrophobic patch that is surrounded by lysine and arginine residues [15]. The latter generate an electric field that could polarize sulfur atoms (the PS2 group still carries a negative charge), thereby enhancing the interaction of the PS2 moiety with the edge of phenylalanine as

• well accommodated in the minor groove and making a stabilizing interaction with a trapped water molecule and the adjacent phosphate (Figure 6). It’s this pre-organization of the MOE groups, making the duplex more rigid, which is hypothesized to cause the increase in RNA binding affinity. Furthermore

Microwave-assisted multicomponent reactions in heterocyclic chemistry and mechanistic aspects

• Shivani Gulati,
• Stephy Elza John and
• Nagula Shankaraiah

Beilstein J. Org. Chem. 2021, 17, 819–865, doi:10.3762/bjoc.17.71

• electrostatic interaction between carboxylate and iminium moieties undergoes a nucleophilic attack by isocyanide to generate nitrilium ion B. The intramolecular acylation of B forms C followed by Mumm rearrangement results in the formation of the desired products 22. The intermediate D may exist in equilibrium

Synthetic reactions driven by electron-donor–acceptor (EDA) complexes

• Zhonglie Yang,
• Yutong Liu,
• Kun Cao,
• Xiaobin Zhang,
• Hezhong Jiang and
• Jiahong Li

Beilstein J. Org. Chem. 2021, 17, 771–799, doi:10.3762/bjoc.17.67

• spectroscopy shows that phosphono radicals could proceed throughout the reaction. A halogen bond (XB) is a noncovalent interaction formed between a halogen atom and a neutral or negatively charged Lewis base. It is a kind of weak intermolecular interaction analogous to a hydrogen bond and basically can be

Synthesis of β-triazolylenones via metal-free desulfonylative alkylation of N-tosyl-1,2,3-triazoles

• Soumyaranjan Pati,
• Renata G. Almeida,
• Eufrânio N. da Silva Júnior and
• Irishi N. N. Namboothiri

Beilstein J. Org. Chem. 2021, 17, 762–770, doi:10.3762/bjoc.17.66

• ) bearing pseudoaxially oriented OTs group suffers from only limited steric crowding (1,3-diaxial interaction). In the case of dimedone 2d, the two bulky methyl groups impart greater steric hindrance (1,3-diaxial interaction) to the incoming nucleophile in the event of pseudoaxial approach leading to

DNA with zwitterionic and negatively charged phosphate modifications: Formation of DNA triplexes, duplexes and cell uptake studies

• Yongdong Su,
• Maitsetseg Bayarjargal,
• Tracy K. Hale and
• Vyacheslav V. Filichev

Beilstein J. Org. Chem. 2021, 17, 749–761, doi:10.3762/bjoc.17.65

• hydrophobicity of Ts results in less water molecules involved in the formation of hydrogen bonds with dsDNA. However, it does not improve the interaction between two DNA strands, possibly due to the large size of the Ts moiety. For duplexes of the N+ and Ts-ONs formed with complementary RNA, both ΔH and TΔS

Valorisation of plastic waste via metal-catalysed depolymerisation

• Francesca Liguori,
• Carmen Moreno-Marrodán and
• Pierluigi Barbaro

Beilstein J. Org. Chem. 2021, 17, 589–621, doi:10.3762/bjoc.17.53

• and the possible product contamination by homogeneous catalysts [199]. The conventional catalysts for this reaction are EG-soluble metal acetates, the activity of which showed a decrease in the order Zn2+ > Mn2+ > Co2+, which was attributed to the diverse interaction between the metal cation promoter

Breakdown of 3-(allylsulfonio)propanoates in bacteria from the Roseobacter group yields garlic oil constituents

• Anuj Kumar Chhalodia and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2021, 17, 569–580, doi:10.3762/bjoc.17.51

• preferred gas-phase reaction. The ecology of marine bacteria in their interaction with algae is particularly interesting in which the bacteria can promote the algal growth, but can also kill their host [10][11]. For both processes, the phytohormone indole-3-acetic acid is used as a messenger molecule [10

A new and efficient methodology for olefin epoxidation catalyzed by supported cobalt nanoparticles

• Lucía Rossi-Fernández,
• Viviana Dorn and
• Gabriel Radivoy

Beilstein J. Org. Chem. 2021, 17, 519–526, doi:10.3762/bjoc.17.46

• takes place to some extent, we assume that a competitive reaction pathway involving the participation of cobalt-superoxo active radicals (Co–O–O•) generated by interaction of the CoNPs with O2 [15] could not be disregarded. Conclusion To conclude, we have described a new and efficient heterogeneous

Biochemistry of fluoroprolines: the prospect of making fluorine a bioelement

• Vladimir Kubyshkin,
• Rebecca Davis and
• Nediljko Budisa

Beilstein J. Org. Chem. 2021, 17, 439–460, doi:10.3762/bjoc.17.40

• potential due to the hydrogen atoms at the exterior (Figure 4). This local charge plays an important role in the interaction of proline with the environment in a protein. For example, when a side chain of an aromatic residue docks onto the proline residue, they engage in a donor–acceptor interaction, while

• , while the remaining C–H bond in Flp acquires an enhanced positive charge due to the electron-withdrawing effect of fluorine. Based on these considerations, a fluoroproline–aromatic-system interaction has been previously utilized in the engineering of a few peptide therapeutics [44][45]. 2.3

• -Flp), 3) a lack of interaction with chaperones, 4) misfolding that leads to aggregation, 5) an inhibitory effect of the target protein on the cellular machinery and 6) misfolding that leads to rapid degradation of the protein, to name a few. A misfolding can occur for reasons such as an altered