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

• solutions are required to overcome the chemical inertness for, and the thermodynamic limitations of the reversal of each polymer. Indeed, the ease (and outcome) of chain scission does not depend on the origin of the polymer but on its chemical structure [74][75]. For instance, plastics derived from biomass

Metal-free visible-light-enabled vicinal trifluoromethyl dithiolation of unactivated alkenes

• Xiaojuan Li,
• Qiang Zhang,
• Weigang Zhang,
• Jinzhu Ma,
• Yi Wang and
• Yi Pan

Beilstein J. Org. Chem. 2021, 17, 551–557, doi:10.3762/bjoc.17.49

• terminal olefins. Origin of the reaction design. Substrate scope of disulfides. Substrate scope of unactivated alkenes. Control experiments. Proposed mechanism. Optimization of the reaction conditions.a Supporting Information Supporting Information File 84: Full experimental details, compound

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

• reaction medium by centrifugation and washed several times with acetonitrile. Thus, the catalyst could be recovered and reused in three consecutive cycles, showing no loss of activity, but a drop in selectivity after the first cycle (selectivity/conversion for each cycle: 94/99.5; 78/99; 77/99). The origin

The synthesis of chiral β-naphthyl-β-sulfanyl ketones via enantioselective sulfa-Michael reaction in the presence of a bifunctional cinchona/sulfonamide organocatalyst

• Deniz Tözendemir and
• Cihangir Tanyeli

Beilstein J. Org. Chem. 2021, 17, 494–503, doi:10.3762/bjoc.17.43

• transition state model to explain the origin of the stereoinduction was proposed (Scheme 2), according to the Houk’s Brønsted acid hydrogen bonding model. Guo’s computational work in 2017 on the sulfa-Michael addition of thiols to enones in the presence of cinchona alkaloid-type organocatalysts showed that

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

• reactivity of proline at the P-site to a level comparable to that of other coded amino acids (Figure 11) [57]. The enhancement of the translation velocity was also observed for Dfp. For S-Flp, however, the reaction was substantially slowed down even compared to the native substrate proline. The origin of

• test sequence (formyl-Met-Lys-Lys-Lys-Xaa-Asp-Tyr-Lys-Asp-Asp-Asp-Asp-Lys-OH, Xaa = proline analogue) was expressed in an in vitro system. It was found that the yield of the target peptide increases in the order Pro ≈ R-Flp < S-Flp ≈ Dfp [86]. The origin of the effect is unclear. Nonetheless, these

Identification of volatiles from six marine Celeribacter strains

• Anuj Kumar Chhalodia,
• Jan Rinkel,
• Dorota Konvalinkova,
• Jörn Petersen and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2021, 17, 420–430, doi:10.3762/bjoc.17.38

• into dimethyl trisulfide and S-methyl methanethiosulfonate, and revealed the origin of the methylsulfanyl group of 2-(methyldisulfanyl)benzothiazole from methionine or DMSP, while the biosynthetic origin of the benzothiazol-2-ylsulfanyl portion could not be traced. The heterocyclic moiety of this

• compound is likely of anthropogenic origin, because 2-mercaptobenzothiazole is used in the sulfur vulcanization of rubber. Also in none of the feeding experiments incorporation into ethyl (E)-3-(methylsulfanyl)acrylate could be observed, questioning its bacterial origin. Our results demonstrate that the

• that some of the detected sulfur compounds are not or only partly of bacterial origin. Results and Discussion Headspace analysis The volatiles released by six marine Celeribacter type strains, including C. marinus DSM 100036T, C. neptunius DSM 26471T, C. manganoxidans DSM 27541T, C. baekdonensis DSM

Synthesis of legonmycins A and B, C(7a)-hydroxylated bacterial pyrrolizidines

• Wilfred J. M. Lewis,
• David M. Shaw and
• Jeremy Robertson

Beilstein J. Org. Chem. 2021, 17, 334–342, doi:10.3762/bjoc.17.31

• . These species include both Gram-positive and Gram-negative bacteria, indicating that pyrrolizidines are potential secondary metabolites of a variety of bacterial genera. The most recent addition to the bacterial pyrrolizidine literature also concerns their biosynthesis and addresses the origin of the

Multiswitchable photoacid–hydroxyflavylium–polyelectrolyte nano-assemblies

• Alexander Zika and
• Franziska Gröhn

Beilstein J. Org. Chem. 2021, 17, 166–185, doi:10.3762/bjoc.17.17

• depicted in Figure 11. The highest percentage of reformed Flavy is found for l = 0.9, while the reversibility is less expressed with decreasing loading ratios for both cycles. Since it is independent on the cycle and dependent on the loading ratio the origin likely lies in the fact that with a decreasing

• MicroCal ITC data analysis software for Origin 7.0. Top: pelargonidin cation (Flavy) and network of chemical reactions; bottom: corresponding UV–vis spectra of the different states of Flavy. Characterization of Flavy: a) 1H NMR spectrum at pH 7.0 (form A) before and after irradiation; b) 13C NMR spectrum

Control over size, shape, and photonics of self-assembled organic nanocrystals

• Chen Shahar,
• Yaron Tidhar,
• Yunmin Jung,
• Haim Weissman,
• Sidney R. Cohen,
• Ronit Bitton,
• Iddo Pinkas,
• Gilad Haran and
• Boris Rybtchinski

Beilstein J. Org. Chem. 2021, 17, 42–51, doi:10.3762/bjoc.17.5

• ) and Origin 7.5 (OriginLab) softwares. Chemical structure of compound 1 and UV–vis spectra in an aggregating aqueous medium and in the disaggregating solvent THF. Transmission electron microscopy (TEM) images (left, zoomed-out and zoomed-in; 1 × 10−4 M solutions of 1 deposited on TEM grids) and crystal

Recent progress in the synthesis of homotropane alkaloids adaline, euphococcinine and N-methyleuphococcinine

• Dimas J. P. Lima,
• Antonio E. G. Santana,
• Michael A. Birkett and
• Ricardo S. Porto

Beilstein J. Org. Chem. 2021, 17, 28–41, doi:10.3762/bjoc.17.4

• majority of these alkaloids have an endogenous origin. In a dangerous situation or predator attack, the beetles can emit droplets of hemolymph. This substance comes from the tibiofemoral joints situated in their legs, a mechanism known as reflex bleeding. This situation brings the alkaloids to the surface

• this precursor in (−)-adaline, supporting fatty acid origin for this alkaloid. Reflex bleeding is costly due to energy expended in chemical synthesis and fluid loss. Therefore, it is only deployed when other strategies have failed, and the ladybird is in severe danger [35][36]. A massive discrepancy in

Nocarimidazoles C and D, antimicrobial alkanoylimidazoles from a coral-derived actinomycete Kocuria sp.: application of ¹J_C,H coupling constants for the unequivocal determination of substituted imidazoles and stereochemical diversity of anteisoalkyl chains in microbial metabolites

• Md. Rokon Ul Karim,
• Enjuro Harunari,
• Amit Raj Sharma,
• Naoya Oku,
• Kazuaki Akasaka,
• Daisuke Urabe,
• Mada Triandala Sibero and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2020, 16, 2719–2727, doi:10.3762/bjoc.16.222

• actinomycete origin. For example, salinosporamide A, an antitumor drug candidate in clinical trials, is a proteasome inhibitor with an unusual γ-lactam-β-lactone bicyclic core produced by marine Salinospora tropica [10]. Abyssomicin, another example of uncommon polycyclic frameworks, is an antibacterial

• members, nocarimidazoles C (1) and D (2), were obtained from a marine-derived actinomycete of the genus Kocuria. The exclusive origin of these metabolites from marine bacteria, as well as the distribution among phylogenetically distinct taxa imply their potential function in the adaptation of the

Asymmetric Mannich reactions of (S)-N-tert-butylsulfinyl-3,3,3-trifluoroacetaldimines with yne nucleophiles

• Ziyi Li,
• Li Wang,
• Yunqi Huang,
• Haibo Mei,
• Hiroyuki Konno,
• Hiroki Moriwaki,
• Vadim A. Soloshonok and
• Jianlin Han

Beilstein J. Org. Chem. 2020, 16, 2671–2678, doi:10.3762/bjoc.16.217

• sulfinyl oxygen and the oxygen electron lone pair. The latter presents a lesser steric obstacle rendering the corresponding nucleophilic attack the more probable event. These ever-unexpected results strongly suggest that the origin of the stereocontrol in the reactions of imine 1 is not just the bulk of

Water-soluble host–guest complexes between fullerenes and a sugar-functionalized tribenzotriquinacene assembling to microspheres

• Si-Yuan Liu,
• Xin-Rui Wang,
• Man-Ping Li,
• Wen-Rong Xu and
• Dietmar Kuck

Beilstein J. Org. Chem. 2020, 16, 2551–2561, doi:10.3762/bjoc.16.207

• 1505.9611 (Δ = + 5.2 ppm). The surprising presence of six equivalents of water points to the formation of strong hydrogen bonds between the sugar ester bonds of TBTQ-(OAcG)6 and the water molecules as guests. However, the origin of this intriguing observation associated with the attachment of just two

Styryl-based new organic chromophores bearing free amino and azomethine groups: synthesis, photophysical, NLO, and thermal properties

• Anka Utama Putra,
• Deniz Çakmaz,
• Nurgül Seferoğlu,
• Alberto Barsella and
• Zeynel Seferoğlu

Beilstein J. Org. Chem. 2020, 16, 2282–2296, doi:10.3762/bjoc.16.189

• Shimadzu 1800 UV–vis spectrophotometer in Britton–Robinson buffer solutions [63] with pH values ranging from 5.5 to 11 at room temperature (25 °C). The pKa values were obtained using the Origin software by recording the curve data. Computational methods The geometries of the dyes in their ground states

Tools for generating and analyzing glycan microarray data

• Akul Y. Mehta,
• Jamie Heimburg-Molinaro and
• Richard D. Cummings

Beilstein J. Org. Chem. 2020, 16, 2260–2271, doi:10.3762/bjoc.16.187

• aglycone (for example, a glycolipid obtained directly by extraction from a natural origin), an appropriate surface needs to be selected which is compatible with the glycoconjugate. Printing methods Once the decision about the surface to which they are to be attached is made, the glycans are dissolved in

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

• ). Origin 7.0 software, supplied by the manufacturer, was used for data analysis. During the titration of ct-DNA, d: poly(rA)–poly(rU), poly(dAdT)–poly(dAdT), and poly(dGdC)–poly(dGdC) with the compound 4, one aliquot of 2 μL and 27 aliquots of 10 μL of 4 (c = 1.0 × 10−4 M) were injected from rotating

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

• ]. This group is one of the most widespread bacterial genera of marine origin, cataloging 128 species at the time of writing [2], of which more than 12 are known to cause enteritis, marine food poisoning, bacteremia, septicemia, cellulitis, or other infectious diseases in human and aquatic animals [3][4

• -chain 3-hydroxy acids are the common building blocks with PHA, the microbial storage polymer. The structural similarities among 1–5 and PHA suggest a quite similar or even the same biosynthetic origin of these molecules, and hence a potential dehydrative modification at the hydroxy terminus of PHA. MS

Polarity effects in 4-fluoro- and 4-(trifluoromethyl)prolines

• Vladimir Kubyshkin

Beilstein J. Org. Chem. 2020, 16, 1837–1852, doi:10.3762/bjoc.16.151

• C4-exo conformation of the pyrrolidine ring. Keywords: amino acids; cis–trans isomerism; fluorine; polarity; proline; Introduction Polarity is among the key features essential for understanding the behavior of organic molecules of biological origin. In particular, there is a set of polarity-related

• hydrophobic, while the introduction of a polar or an ionizable group makes it hydrophilic. Two amino acids stand out from the dualistic hydrophilic/hydrophobic classification: glycine and proline (Figure 1A) [1]. The origin of their effect onto the structure polarity is not due to the presence of additional

• origin of the effect is orbital (the gauche-effect) rather than through space dipolar interaction (assuming that an interaction of dipoles would be attenuated in polar solvents, which was not observed). A stabilization of certain side-chain conformers was also observed in the trifluoromethylated

Models of necessity

• Timothy Clark and
• Martin G. Hicks

Beilstein J. Org. Chem. 2020, 16, 1649–1661, doi:10.3762/bjoc.16.137

• that in reality share a common origin. This common origin is the key to successful chemistry models. Conclusion Data infrastructures are evolving and growing in many areas without being interoperable, giving rise to a phase of creolization, in which many inefficiencies in working with data retard

Fluorohydration of alkynes via I(I)/I(III) catalysis

• Jessica Neufeld,
• Constantin G. Daniliuc and
• Ryan Gilmour

Beilstein J. Org. Chem. 2020, 16, 1627–1635, doi:10.3762/bjoc.16.135

• Hammett analyses, have identified key determinants that are essential for reaction efficiency. X-ray crystal structure analysis of ketone 2 reveals a dihedral angle of φO=C-C-F = −3.7°. Although the origin of this specificity requires clarification, this fluorohydration reaction constitutes a rare case of

Antibacterial scalarane from Doriprismatica stellata nudibranchs (Gastropoda, Nudibranchia), egg ribbons, and their dietary sponge Spongia cf. agaricina (Demospongiae, Dictyoceratida)

• Cora Hertzer,
• Stefan Kehraus,
• Nils Böhringer,
• Fontje Kaligis,
• Robert Bara,
• Dirk Erpenbeck,
• Gert Wörheide,
• Till F. Schäberle,
• Heike Wägele and
• Gabriele M. König

Beilstein J. Org. Chem. 2020, 16, 1596–1605, doi:10.3762/bjoc.16.132

• Doriprismatica (former Glossodoris or Casella) atromarginata [38][41][44][45][50], reported the isolation of scalaranes, homoscalaranes, norscalaranes, spongian diterpenoids and furanoditerpenoids. A dietary origin of these molecules was inferred and attributed to dictyoceratid sponges of the genera Hyrtios and

• [25]. Yet determining the origin and in vitro production of these metabolites is anything but trivial. Sponges are known to host complex symbiont communities, with up to 30–60% as microbial biomass [13][77]. These highly species-specific communities are most probably vertically transmitted [78] and

• for a wide chemodiversity of terpenoid natural products [14][81]. Besides, the marine fungi Penicillium spp. and Aspergillus spp. are often associated with sponge hosts and were found to produce various terpenoids as well [15][82][83]. Hence, if sponges are not the origin of these metabolites, it is

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

• with TiO2 as a model system for metal oxide and inorganic semiconductor HPCats. 2.1 Inorganic semiconductor photocatalysis Semiconductors are defined as materials that have a conductivity between that of an insulator and a conductor [77]. The origin of conductivity is based on the quantum states of

Highly selective Diels–Alder and Heck arylation reactions in a divergent synthesis of isoindolo- and pyrrolo-fused polycyclic indoles from 2-formylpyrrole

• Carlos H. Escalante,
• Eder I. Martínez-Mora,
• Carlos Espinoza-Hicks,
• Alejandro A. Camacho-Dávila,
• Fernando R. Ramos-Morales,
• Francisco Delgado and
• Joaquín Tamariz

Beilstein J. Org. Chem. 2020, 16, 1320–1334, doi:10.3762/bjoc.16.113

• endo selectivity in the Diels–Alder cycloadditions. Since experimental and theoretical results have demonstrated that the nature of the C–H···π interaction mainly depends on the dispersion interactions [64][67][77], these are probably not only at the origin of the endo stereoselectivity of the present

Development of fluorinated benzils and bisbenzils as room-temperature phosphorescent molecules

• Shigeyuki Yamada,
• Takuya Higashida,
• Yizhou Wang,
• Masato Morita,
• Takuya Hosokai,
• Kaveendra Maduwantha,
• Kaveenga Rasika Koswattage and
• Tsutomu Konno

Beilstein J. Org. Chem. 2020, 16, 1154–1162, doi:10.3762/bjoc.16.102

• low ΦPL of less than 0.02 (Table 1), meaning that most of the excited states of all samples deactivate nonradiatively. At the moment, we cannot certify the origin of the low ΦPL in terms of the molecular properties, for instance, the main pathway of nonradiative deactivation. Experiments are currently

Synthesis and properties of quinazoline-based versatile exciplex-forming compounds

• Rasa Keruckiene,
• Simona Vekteryte,
• Ervinas Urbonas,
• Matas Guzauskas,
• Eigirdas Skuodis,
• Dmytro Volyniuk and
• Juozas V. Grazulevicius

Beilstein J. Org. Chem. 2020, 16, 1142–1153, doi:10.3762/bjoc.16.101

• the solution in a polar solvent, apparently because of the high polarity of compound 1. Furthermore, the emission of the solid sample was more efficient than that of the solution, with a PLQY of up to 6%. In order to determine the origin of the emission, PL decay curves of the solid samples of