Iron-catalyzed domino coupling reactions of π-systems

• Austin Pounder and
• William Tam

Beilstein J. Org. Chem. 2021, 17, 2848–2893, doi:10.3762/bjoc.17.196

• a four-component radical dual difunctionalization and ordered assembly of two chemically distinct alkenes 114/115, aldehyde 65, and tert-butyl peroxide (Scheme 23) [108]. In order to selectively couple one alkene to another, without the formation of oligomers, the authors utilized the different

Adjusting the length of supramolecular polymer bottlebrushes by top-down approaches

• Tobias Klein,
• Franka V. Gruschwitz,
• Maren T. Kuchenbrod,
• Ivo Nischang,
• Stephanie Hoeppener and
• Johannes C. Brendel

Beilstein J. Org. Chem. 2021, 17, 2621–2628, doi:10.3762/bjoc.17.175

• min of centrifugation, no further change could be observed since the peak at this low elution time already corresponded to very small oligomers (Figure 3A). For BTP, a stronger downward shift of the peak maximum from 70 to 45 min could be observed after 1 min of mixing. Similar to BTU, the increase in

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

• polysaccharides longer than hexasaccharides. Shorter oligomers are discussed when they represent a key step towards the synthesis of the corresponding polysaccharide. Polymers based on a sugar backbone connected via glycosidic linkages are analyzed, excluding glycopolymers and other mimetics. Extraction

• better understanding of cellulose’s properties are hindered by its poor solubility in most solvents. Relatively short oligomers with DPs of 6–10 tend to aggregate and precipitate out of solution [54], making isolation of pure samples troublesome. Much effort has been put to tune the synthetic conditions

• developments of synthetic cellulose until the year 2005 were discussed in a previous review [58], therefore we will focus only on recent reports. A detailed discussion on the synthesis of cellulose oligomers by enzymatic depolymerization [59] and phosphorylase [60] can be found elsewhere. The first successful

Cationic oligonucleotide derivatives and conjugates: A favorable approach for enhanced DNA and RNA targeting oligonucleotides

• Mathias B. Danielsen and
• Jesper Wengel

Beilstein J. Org. Chem. 2021, 17, 1828–1848, doi:10.3762/bjoc.17.125

• , and examining the future design for ASOs. Keywords: antisense oligonucleotides; backbone modifications; cations; nucleobase modifications; sugar modifications; Introduction Antisense oligonucleotides (ASOs) are single-stranded (ss) oligomers composed of typically 10–25 nucleotides linked by

• the ON synthesis [28][29][30]. The corresponding modified ONs could be converted in a versatile manner to oligomers carrying the desired amine-functionalized groups at the 5-position on the pyrimidine nucleobase [28][29][30]. Similarly, the more reactive 5-cyanomethoxycarbonylmethyl-2’-deoxyuridine

• carrying the dimethylamino groups had a higher effect on the cellular uptake for 5’-FAM-labelled ASOs relative to the oligomers carrying BCNS being primary amines. However, both modifications demonstrated an improved cellular uptake relative to the unmodified 5’-end FAM-labelled 2’-OMe ASO [115]. Another

Chemical approaches to discover the full potential of peptide nucleic acids in biomedical applications

• Nikita Brodyagin,
• Martins Katkevics,
• Venubabu Kotikam,
• Christopher A. Ryan and
• Eriks Rozners

Beilstein J. Org. Chem. 2021, 17, 1641–1688, doi:10.3762/bjoc.17.116

Recent advances in the application of isoindigo derivatives in materials chemistry

• Andrei V. Bogdanov and
• Vladimir F. Mironov

Beilstein J. Org. Chem. 2021, 17, 1533–1564, doi:10.3762/bjoc.17.111

• a diketopyrrolopyrrole fragment in a mixture with PC71BM showed a record efficiency of 5.86% among oligomeric isoindigo [17]. At the same time, similarly constructed (D–A–D–A) oligomers 6 in the composition with PC71BM showed an efficiency of 1.3–1.4% [18]. Another way to design isoindigoid OSCs is

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

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

• -phosphate backbone relative to native phosphodiester oligomers. This N-type sugar puckering and increased hydration of the sugar phosphate backbone could also account for the triplex-favoring properties of this modification [72]. Amide While many amide backbone oligonucleotide variants exist, the focus of

• [54][100]. DNA oligomers containing GNA residues have been shown to form duplexes with DNA and RNA and to display self-pairing, whereby duplex formation was accompanied by hypochromicity [97][99]. In terms of stability, a single substitution from DNA to either (S)-GNA or (R)-GNA results in a decrease

• modified with 4'-fluoro modifications have more labile glycosidic linkages under similar conditions [203][204]. Rosenberg attributed this contrast to the electronegativity differences between the groups and the effect this would have on the stabilization of the resulting oxocarbenium ion [202]. Oligomers

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

• building blocks, including monomers, oligomers or added-value chemicals, is an attractive tool for the recycling and valorisation of these materials. The present manuscript shortly reviews the most significant contributions that appeared in the field within the period January 2010–January 2020 describing

• decomposition of the polymeric chain, monomers or oligomers, depending on the waste polymer and the process. The as-obtained compounds can be reused as raw materials for the process industry (hence the term feedstock) to produce chemicals, fuels or other polymers. Thermochemical processes include pyrolysis [55

• ]. The tar obtained may be used for road construction [66]. The present paper shortly reviews the most significant contributions that appeared in the literature, from January 2010 to January 2020, in the field of metal-catalysed selective depolymerisation of plastics to reusable monomers, oligomers or

¹⁹F NMR as a tool in chemical biology

• Diana Gimenez,
• Aoife Phelan,
• Cormac D. Murphy and
• Steven L. Cobb

Beilstein J. Org. Chem. 2021, 17, 293–318, doi:10.3762/bjoc.17.28

• ionization and ion mobility), CD spectroscopy and atomic force microscopy, the authors were able to obtain detailed information about the size and secondary structure associated with some of the soluble intermediates. These included: large β-sheet oligomers formed immediately after solubilization (oligomer

• O1); a small oligomer that forms transiently during the early stages of the lag phase (oligomer O2) and 4 spectroscopically distinct forms of oligomers that appear during the later stages of aggregation and apparently coexist with the proto-fibrillar species (oligomers O3–O6, Figure 10). It is worth

Supramolecular polymers with reversed viscosity/temperature profile for application in motor oils

• Jan-Erik Ostwaldt,
• Christoph Hirschhäuser,
• Stefan K. Maier,
• Carsten Schmuck and
• Jochen Niemeyer

Beilstein J. Org. Chem. 2021, 17, 105–114, doi:10.3762/bjoc.17.11

• 60 °C/100 °C). Here we assume the formation of a mixture of differently sized cyclic structures, that are represented by the signal at 10–40 nm. Elevating the temperature leads to the formation of oligomers and polymers that possess larger hydrodynamic radii. Interestingly, the peak representing the

Molecular basis for protein–protein interactions

• Brandon Charles Seychell and
• Tobias Beck

Beilstein J. Org. Chem. 2021, 17, 1–10, doi:10.3762/bjoc.17.1

• because the methods normally neglect self-interactions. The advantages of homooligomeric complexes over monomer proteins include an increase in the diversity of the functions [61], allosteric regulation [62], protection against denaturation [63], and the oligomers being able to form without increasing the

Ultrasound-assisted Strecker synthesis of novel 2-(hetero)aryl-2-(arylamino)acetonitrile derivatives

• Emese Gal,
• Luiza Gaina,
• Hermina Petkes,
• Alexandra Pop,
• Castelia Cristea,
• Gabriel Barta,
• Dan Cristian Vodnar and
• Luminiţa Silaghi-Dumitrescu

Beilstein J. Org. Chem. 2020, 16, 2929–2936, doi:10.3762/bjoc.16.242

• using “green” solvents, for example, low vapor pressure solvents such as ionic liquids [3], low volatile solvents such as glycerol, ethylene glycol and its oligomers, or nontoxic water solvent, as well as in heterogeneous media under solvent-free conditions [4]. Other advantages induced by sonication

Synthesis of 4-substituted azopyridine-functionalized Ni(II)-porphyrins as molecular spin switches

• Jannis Ludwig,
• Tobias Moje,
• Fynn Röhricht and
• Rainer Herges

Beilstein J. Org. Chem. 2020, 16, 2589–2597, doi:10.3762/bjoc.16.210

• only the cis isomer coordinates to the Ni(II) for steric reasons and 3. intermolecular coordination. At higher concentrations dimer formation or coordination oligomers between trans record player molecules occurs [35]. To compare the new molecules (1f–j) with previous systems (1a–d), the switching

Naphthalene diimide bis-guanidinio-carbonyl-pyrrole as a pH-switchable threading DNA intercalator

• Poulami Jana,
• Filip Šupljika,
• Carsten Schmuck and
• Ivo Piantanida

Beilstein J. Org. Chem. 2020, 16, 2201–2211, doi:10.3762/bjoc.16.185

• GCP moiety by itself does not interact with DNA/RNA but, if combined with oligomers [15][16] or attached to the aryl moiety containing at least two aromatic rings [17], it will ensure efficient DNA/RNA binding. Moreover, due to the weakly acidic pKa = 6 of GCP, interactions and consequently

Automated high-content imaging for cellular uptake, from the Schmuck cation to the latest cyclic oligochalcogenides

• Rémi Martinent,
• Javier López-Andarias,
• Dimitri Moreau,
• Yangyang Cheng,
• Naomi Sakai and
• Stefan Matile

Beilstein J. Org. Chem. 2020, 16, 2007–2016, doi:10.3762/bjoc.16.167

• acidification process) was observed, which further supports the endosomal uptake mechanism. Except for this small peptide, GCP was also integrated into larger peptides, including branched [29], three-armed [30][31], dendritic [32], and self-assembled oligomers [33][34] for gene delivery and transfection based

Three new O-isocrotonyl-3-hydroxybutyric acid congeners produced by a sea anemone-derived marine bacterium of the genus Vibrio

• Dandan Li,
• Enjuro Harunari,
• Tao Zhou,
• Naoya Oku and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2020, 16, 1869–1874, doi:10.3762/bjoc.16.154

• , Tenacibaculum maritimum NBRC16015. Structural similarities among 1–4, the O-isocrotonylated 3-hydroxybutyrate oligomers 5, and microbial biopolymer polyhydroxyalkanoates (PHA) suggest the presence of a common biosynthetic machinery, and hence a possible dehydrative modification at the hydroxy terminus of PHA

• bacteria, Vibrio sp. SI9, isolated from the sea anemone Radianthus crispus, was found to produce a known ester 4 and its new congeners 1–3 (Figure 1). Compound 4 is the shortest among the five oligomers of O-isocrotonyl-oligo(3-hydroxybutyrate) (5) previously discovered from Vibrio [9]. In this study, we

Synthesis of new fluorescent molecules having an aggregation-induced emission property derived from 4-fluoroisoxazoles

• Kazuyuki Sato,
• Akira Kawasaki,
• Yukiko Karuo,
• Atsushi Tarui,
• Kentaro Kawai and
• Masaaki Omote

Beilstein J. Org. Chem. 2020, 16, 1411–1417, doi:10.3762/bjoc.16.117

• bioprobes [9][10][11][12][13][14]. For example, it is presumed that prion disease, which is caused by the accumulation of prion protein aggregates in the brain, plays an important role in the pathophysiological mechanism of prion protein-polymerized oligomers. However, since prion protein oligomers cannot

Disposable cartridge concept for the on-demand synthesis of turbo Grignards, Knochel–Hauser amides, and magnesium alkoxides

• Mateo Berton,
• Kevin Sheehan,
• Andrea Adamo and
• D. Tyler McQuade

Beilstein J. Org. Chem. 2020, 16, 1343–1356, doi:10.3762/bjoc.16.115

• , most probably due to the disaggregation of oligomers [43][44]. We used this approach to overcome the solubility issue under continuous conditions. First, we verified that similar results are achieved in presence and absence of LiCl in solution for the EtMgBr formation (Section 2.2, Supporting

Room-temperature Pd/Ag direct arylation enabled by a radical pathway

• Amy L. Mayhugh and
• Christine K. Luscombe

Beilstein J. Org. Chem. 2020, 16, 384–390, doi:10.3762/bjoc.16.36

• . Results and Discussion Initial attempts to polymerize iodoindole monomer 1 using the reported conditions (Scheme 1) produced oligomers with an unanticipated coupling pattern in good yield (87%, Figure 1, Supporting Information File 1, Figure S3). The 1H NMR signals from the C2-H, C3-H on the pyrrole ring

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

• chemical synthesis of AM is an attractive alternative. AM polysaccharides as large as 92-mers as well as many shorter AM oligomers have been prepared by solution-phase synthesis [16][17][18][19][20]. These multi-step syntheses are challenging and time-consuming. AGA reduces time and effort to access

• procedure B. For detailed procedures, see Tables S10 and S11 in Supporting Information File 1. Schematic representation of LAM and AM oligomers obtained using AGA. Schematic representation of AGA for oligomannosides and oligoarabinomannosides using building blocks 1–3. AGA of arabinomannosides 4–9

In search of visible-light photoresponsive peptide nucleic acids (PNAs) for reversible control of DNA hybridization

• Lei Zhang,
• Greta Linden and
• Olalla Vázquez

Beilstein J. Org. Chem. 2019, 15, 2500–2508, doi:10.3762/bjoc.15.243

• base sensitive compounds, which undergo degradation under standard Fmoc deprotection conditions. As it is common for PNAs, our oligomers have an acetylated N-terminus and a C-terminal carboxamide group. After completion of the PNA sequences, the orthogonally protected backbone module [2-(N-Alloc

Sugar-derived oxazolone pseudotetrapeptide as γ-turn inducer and anion-selective transporter

• Sachin S. Burade,
• Sushil V. Pawar,
• Tanmoy Saha,
• Navanath Kumbhar,
• Amol S. Kotmale,
• Manzoor Ahmad,
• Pinaki Talukdar and
• Dilip D. Dhavale

Beilstein J. Org. Chem. 2019, 15, 2419–2427, doi:10.3762/bjoc.15.234

• stereochemically stable quaternary carbon center [1]. For example, TAA-derived peptides containing a cyclopropane ring and ʟ/ᴅ-dimethyl tartrate showed an α-turn and form 310-helical conformations in higher oligomers [2][3][4]. While, TAA-derived peptides having a tetrahydrofuran ring demonstrated a β-turn type

Morphology-tunable and pH-responsive supramolecular self-assemblies based on AB₂-type host–guest-conjugated amphiphilic molecules for controlled drug delivery

• Yang Bai,
• Cai-ping Liu,
• Di Chen,
• Long-hai Zhuo,
• Huai-tian Bu and
• Wei Tian

Beilstein J. Org. Chem. 2019, 15, 1925–1932, doi:10.3762/bjoc.15.188

• HGCMs containing one host and other guest moieties have been used to construct intramolecular complexes [36], cyclic oligomers [37], supramolecular polymers [23][38][39][40], gels [41][42], etc. However, AB-type HGCMs were still limited to obtain non-spherical stimuli-responsive supramolecular self

Host–guest interactions between p-sulfonatocalix[4]arene and p-sulfonatothiacalix[4]arene and group IA, IIA and f-block metal cations: a DFT/SMD study

• Valya K. Nikolova,
• Cristina V. Kirkova,
• Silvia E. Angelova and
• Todor M. Dudev

Beilstein J. Org. Chem. 2019, 15, 1321–1330, doi:10.3762/bjoc.15.131

• ., acetaldehyde – ethanal, CH3CHO) are required in condensation reactions with resorcinol and pyrogallol [1]. Thiacalixarenes are macrocycles (or cyclic oligomers) based on a condensation of the same phenol derivatives and sulfur [2]. They are characterized by a larger cavity size than the conventional