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Search for "B" in Full Text gives 3144 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.

Electrochemical radical cation aza-Wacker cyclizations

  • Sota Adachi and
  • Yohei Okada

Beilstein J. Org. Chem. 2024, 20, 1900–1905, doi:10.3762/bjoc.20.165

Graphical Abstract
  • mmol), Bu4NOTf (0.1 M), TFA (1 equiv), CH3CN (0.4 mL), and 1,2-DCE (3.6 mL). Yields reported here are isolated yields. Mechanistic studies of aza-Wacker cyclization. A: Electrochemical (Bu4NOTf in CH3CN/1,2-DCE), B: non-electrochemical (LiClO4 in CH3NO2). Control studies for electrochemical aza-Wacker
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Published 05 Aug 2024

Access to 2-oxoazetidine-3-carboxylic acid derivatives via thermal microwave-assisted Wolff rearrangement of 3-diazotetramic acids in the presence of nucleophiles

  • Ivan Lyutin,
  • Vasilisa Krivovicheva,
  • Grigory Kantin and
  • Dmitry Dar’in

Beilstein J. Org. Chem. 2024, 20, 1894–1899, doi:10.3762/bjoc.20.164

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  • converted into the corresponding acids 4a,b by hydrogenolysis under mild conditions, which proceeded in quantitative yields (Scheme 4). It should be noted that this method of preparing β-lactam acids compares favorably with the alkaline hydrolysis of their methyl and ethyl esters, which does not always give
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Published 05 Aug 2024

2-Heteroarylethylamines in medicinal chemistry: a review of 2-phenethylamine satellite chemical space

  • Carlos Nieto,
  • Alejandro Manchado,
  • Ángel García-González,
  • David Díez and
  • Narciso M. Garrido

Beilstein J. Org. Chem. 2024, 20, 1880–1893, doi:10.3762/bjoc.20.163

Graphical Abstract
  • -hydroxytryptamine (a MAO-A substrate), in a molecular docking experiment tested against serotonin (Scheme 3). A similar class of benzofuran systems with attractive binding properties are those represented by 4-amino-3-(benzo[b]furan-2-yl)butanoic acids, baclofen analogs, elaborated to elucidate the structural
  • requirements for access to γ-aminobutyric receptor type B (GABAB) [18]. Amino acids 10–12 were demonstrated [19][20][21] to act as substrates of GABAB (Scheme 3), key metabotropic receptors from the G-protein-coupled receptor superfamily responsible for CNS inhibitory synapses [22]. The authors concluded that
  • decarboxylase (Scheme 8) [45][46][47]. Histamine is commonly degradated by two enzymes: diamine oxidase (DAO) to produce (imidazol-4-yl)acetic acid (44), or histamine N-methyltransferase (HMT) to N-methylhistamine 45. Monoamine oxidase B (MAO-B) transforms N-methylhistamine into (N-methylimidazol-4-yl)acetic
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Published 02 Aug 2024

The Groebke–Blackburn–Bienaymé reaction in its maturity: innovation and improvements since its 21st birthday (2019–2023)

  • Cristina Martini,
  • Muhammad Idham Darussalam Mardjan and
  • Andrea Basso

Beilstein J. Org. Chem. 2024, 20, 1839–1879, doi:10.3762/bjoc.20.162

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  • synthesis (DOS) where a single methodology should generate diverse scaffolds. This comprehensive review focuses on all these aspects, and has been divided into five chapters, describing, respectively: a) efforts to develop new and milder reaction conditions; b) the use of new building blocks; c) the
  • et al. reported the first biocatalytic GBB reaction using lipase [21]. The model reaction depicted in Scheme 2 (R = t-Bu) was tested in ethanol at room temperature with various enzymes, where Candida antarctica lipase B (CALB) and Aspergillus niger gave best results, affording 3 in 63% and 64% yields
  • into pentacycles 67. The same products were obtained when CoBr2 was used as external oxidant in the one-pot cascade reaction (Scheme 24, conditions b). No substantial improvement in the yields of 67 and 69 was observed when the synthesis was carried out in two steps, performing the GBB reaction under
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Published 01 Aug 2024

A facile three-component route to powerful 5-aryldeazaalloxazine photocatalysts

  • Ivana Weisheitelová,
  • Radek Cibulka,
  • Marek Sikorski and
  • Tetiana Pavlovska

Beilstein J. Org. Chem. 2024, 20, 1831–1838, doi:10.3762/bjoc.20.161

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  • Discussion Regarding the synthesis of 5-aryldeazaalloxazines 2 (5-arylpyrimido[4,5-b]quinoline-2,4(1H,3H)-diones), the data in the literature are quite limited, and the known methodology describes the dehydrogenation of initially formed 5,10-dihydro analogues (5-aryl-5,10-dihydropyrimido[4,5-b]quinoline-2,4
  • (1H,3H)-dione) by refluxing with thionyl chloride [20][23]. However, the preparation of partially hydrogenated 5,10-dihydropyrimido[4,5-b]quinolinediones has been repeatedly reported by one-pot condensation of substituted anilines, aldehydes and barbituric acids, usually in protic solvents (alcohols
  • , water), which has become a common method for the synthesis of these derivatives [3][22][25][30][31][32][33]. In our previous studies [14][15][16][17][18][19] we have shown that the 5-aryl and 7,8-substitutients of the pyrimido[4,5-b]quinoline core have a significant effect on the photocatalytic activity
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Published 31 Jul 2024

Hetero-polycyclic aromatic systems: A data-driven investigation of structure–property relationships

  • Sabyasachi Chakraborty,
  • Eduardo Mayo Yanes and
  • Renana Gershoni-Poranne

Beilstein J. Org. Chem. 2024, 20, 1817–1830, doi:10.3762/bjoc.20.160

Graphical Abstract
  • constructing the COMPAS-2 dataset, we opted to maintain equal percentages of the different types of heterocycles (~10% of each type). This was done to avoid biasing the construction of molecules towards specific motifs. However, because there are multiple types of B-containing and N-containing heterocycles
  • number of heteroatoms of a certain type (section 2 of Supporting Information File 1). These plots (Figure S6 in Supporting Information File 1) made it readily apparent that the B atoms unsurprisingly accumulate in the regions of lower LUMO value and, to a lesser extent, higher HOMO values. The N, O, and
  • across the HOMO range, while it decreases for N and increases for B as the HOMO values rise. The trends are more pronounced for the LUMO: the B atoms are clearly most prevalent at the lower LUMO levels and steadily decrease towards the higher LUMO levels, concurrent with a steady rise in the likelihood
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Published 31 Jul 2024

Discovery of antimicrobial peptides clostrisin and cellulosin from Clostridium: insights into their structures, co-localized biosynthetic gene clusters, and antibiotic activity

  • Moisés Alejandro Alejo Hernandez,
  • Katia Pamela Villavicencio Sánchez,
  • Rosendo Sánchez Morales,
  • Karla Georgina Hernández-Magro Gil,
  • David Silverio Moreno-Gutiérrez,
  • Eddie Guillermo Sanchez-Rueda,
  • Yanet Teresa-Cruz,
  • Brian Choi,
  • Armando Hernández Garcia,
  • Alba Romero-Rodríguez,
  • Oscar Juárez,
  • Siseth Martínez-Caballero,
  • Mario Figueroa and
  • Corina-Diana Ceapă

Beilstein J. Org. Chem. 2024, 20, 1800–1816, doi:10.3762/bjoc.20.159

Graphical Abstract
  • represents the precursor peptides identified in this work. Each line represents a minimum of 27% of sequence identity (EFI – enzyme similarity tool [51]). B. Alignment of clostrisin with FlvA.2g [43], enterocin Wβ [44], plantaricin Wβ [45], and thusin α [46]. C. Alignment of cellulosin with lichenicidin A1
  • the samples. A. Precursor peptide for CloA1 and clostrisin and B. precursor peptide for CloA2 and cellulosin with the bacteria: 1. S. epidermidis MIQ43 and the 2. P. aeruginosa ATCC PA14 and 3. P. aeruginosa MIQPA25. Tests were performed in sterile polystyrene 96-well flat-bottom-shaped microtiter
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Published 30 Jul 2024

Oxidative fluorination with Selectfluor: A convenient procedure for preparing hypervalent iodine(V) fluorides

  • Samuel M. G. Dearman,
  • Xiang Li,
  • Yang Li,
  • Kuldip Singh and
  • Alison M. Stuart

Beilstein J. Org. Chem. 2024, 20, 1785–1793, doi:10.3762/bjoc.20.157

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  • difluoroiodanes 7a and 7b containing the amide sidearms would have an even more acute N–I–N bond angle (156.6–156.9 °). Furthermore, the internal chelate NCC bond angle in 7a/b (111.7°) was calculated to be bigger than the corresponding OCC angle (108.3(5)° to 109.2(5)°) in 6 due to the sp2-hybridised carbon in
  • 7a/b and an sp3-hybridised carbon in 6. This NCC bond angle (111.7°) would certainly increase the angle strain in 7a/b and this, combined with the acute N–I–N bond angle (156.6–156.9°) caused by these two five-membered rings, could be the reason that we could not prepare these compounds. Stability
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Published 29 Jul 2024

Ugi bisamides based on pyrrolyl-β-chlorovinylaldehyde and their unusual transformations

  • Alexander V. Tsygankov,
  • Vladyslav O. Vereshchak,
  • Tetiana O. Savluk,
  • Serhiy M. Desenko,
  • Valeriia V. Ananieva,
  • Oleksandr V. Buravov,
  • Yana I. Sakhno,
  • Svitlana V. Shishkina and
  • Valentyn A. Chebanov

Beilstein J. Org. Chem. 2024, 20, 1773–1784, doi:10.3762/bjoc.20.156

Graphical Abstract
  • to drive the process towards the desired hydrolysis of the secondary amide group, we performed the post-Ugi transformation under MW activation in ethanol or acetonitrile (Scheme 3, conditions B or C). However, the application of MW irradiation did not change the course of the reaction, and as under
  • ) and p-anisidine (2a), the product that precipitated first from the reaction mixture was 2-oxo-4-(1H-pyrrol-3-yl)but-3-enoic acid amide 10b (Scheme 4; Table 1, footnote b). Pure Ugi bisamide 6a could only be obtained when the reaction was carried out in MeCN or EtOH. The same was observed in the case
  • Ugi bisamide 5d in the presence of HCl. Conditions: (A) 5 equiv HCl, MeOH, 80 °C, 3 h; (B) 5 equiv HCl, EtOH, MW 120 °C, 15 min; (C) 5 equiv HCl, MeCN, MW 100 °C, 20 min. The Ugi-4CR with the participation of p-anisidine and benzyl isocyanide. Successful attempt at tandem one-pot coupling of the Ugi
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Published 26 Jul 2024

Synthesis and characterization of 1,2,3,4-naphthalene and anthracene diimides

  • Adam D. Bass,
  • Daniela Castellanos,
  • Xavier A. Calicdan and
  • Dennis D. Cao

Beilstein J. Org. Chem. 2024, 20, 1767–1772, doi:10.3762/bjoc.20.155

Graphical Abstract
  • analogous to that observed for 7-Ph (Figure 2c). These pairs, however, are then infinitely packed such that adjacent 8-Ph molecules are aligned in the same direction to create an AA–BB stacking pattern, unlike the more common A–B–A–B stacking pattern found for 7-Ph. Additionally, it is worth observing that
  • 1,2,3,4-naphthalene and -anthracene diimide motifs as productive building blocks in imide-based organic materials. a) Structures of previously reported naphthalene and anthracene diimide isomers. b) The novel 1,2,3,4-naphthalene and -anthracene diimides reported here. Superstructures for a) 7-Ph and b) 8
  • = green, N = blue, and O = red. a) Absorption and b) emission spectra of the compounds dissolved in CH2Cl2. Cyclic voltammograms of the compounds collected on ca. 1 mM solutions of the analyte in CH2Cl2 with 0.1 M Bu4NPF6 as electrolyte. The major y-axis tick mark spacing corresponds to 5 μA. Structural
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Published 25 Jul 2024

Harnessing unprotected deactivated amines and arylglyoxals in the Ugi reaction for the synthesis of fused complex nitrogen heterocycles

  • Javier Gómez-Ayuso,
  • Pablo Pertejo,
  • Tomás Hermosilla,
  • Israel Carreira-Barral,
  • Roberto Quesada and
  • María García-Valverde

Beilstein J. Org. Chem. 2024, 20, 1758–1766, doi:10.3762/bjoc.20.154

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  • characterisation. Funding Funding from MCIN/AEI/10.13039/501100011033 [grant PID2020-117610RB-I00] is gratefully acknowledged. J. G.-A. and I. C.-B. thank Consejería de Educación de la Junta de Castilla y León, European Social Fund (ESF) and ERDF for their predoctoral (J. G.-A.) and post-doctoral (I. C.-B
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Published 25 Jul 2024

Synthesis of polycyclic aromatic quinones by continuous flow electrochemical oxidation: anodic methoxylation of polycyclic aromatic phenols (PAPs)

  • Hiwot M. Tiruye,
  • Solon Economopoulos and
  • Kåre B. Jørgensen

Beilstein J. Org. Chem. 2024, 20, 1746–1757, doi:10.3762/bjoc.20.153

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  • Hiwot M. Tiruye Solon Economopoulos Kare B. Jorgensen Department of Chemistry, Bioscience and Environmental Engineering, Faculty of Science and Technology, University of Stavanger, P.O Box 8600 Forus, N-4036 Stavanger, Norway Advanced Optoelectronic Nanomaterials Research Unit, Department of
  • after removal of solvents from the reaction mixture. Thus, Et4NOTs can easily be recycled and reused for a greener reaction. Voltammetric studies To investigate their redox behaviour, PAPs 1a,b (Figure 1A), 3a–c (Figure 1C), and 6a–c (Figure 1E) were scanned between +2.2 V and −1.5 V. All compounds
  • structure B, which is further destabilized by the neighbouring ketone. A similar resonance hybrid will be formed for molecules substituted in the 4-position, like 6b, explaining the selectivity towards p-quinones. Abstraction of a proton rearomatizes the molecule before another cation is formed in the
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Published 24 Jul 2024

Syntheses and medicinal chemistry of spiro heterocyclic steroids

  • Laura L. Romero-Hernández,
  • Ana Isabel Ahuja-Casarín,
  • Penélope Merino-Montiel,
  • Sara Montiel-Smith,
  • José Luis Vega-Báez and
  • Jesús Sandoval-Ramírez

Beilstein J. Org. Chem. 2024, 20, 1713–1745, doi:10.3762/bjoc.20.152

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  • of a set of azomethine ylides and the 16-arylidene steroids 48a,b. Ylides were generated in situ by the nitrogen attack of the thiazolidine ring from 1,3-thiazolidine-4-carboxylic acid to a carbonyl group of acenaphthenequinone. The resulting reaction produced an iminium group, which promoted the
  • decarboxylation of the carboxylic residue when heated at reflux of methanol. After the regioselective cycloadditions, spiro compounds 49a,b were obtained in yields ranging from 75% to 91% (Scheme 15). Related derivatives have similarly been achieved in good to excellent yields [32][33]. Recently, López et al
  • starting material (35%). 16-Spiropyrazoline steroids In 2009 Mernyák et al. described the synthesis of 16-spiropyrazolines from 16-methylene-13α-estrone derivatives via a 1,3-dipolar cycloaddition reaction between the methylene of α,β-unsaturated ketones 53a,b and the ylide produced from the
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Published 24 Jul 2024

Chemo-enzymatic total synthesis: current approaches toward the integration of chemical and enzymatic transformations

  • Ryo Tanifuji and
  • Hiroki Oguri

Beilstein J. Org. Chem. 2024, 20, 1693–1712, doi:10.3762/bjoc.20.151

Graphical Abstract
  • through directed evolution [11]. P450 catalysis during the oxidation phase enabled the total synthesis of mitrephorone A [12], chevalone A [13], polysin [14], excolide B [15], and gedunin [16]. Fe(II)/2OG-dependent dioxygenases, such as FtmOx1, were employed as versatile catalysts in the synthesis of 13
  • of scaffold 6 yield a series of intermediates and natural products, including cotylenol (1) and brassicicenes I and B (9 and 10), as well as brassicicene O (12), which possesses a distinct scaffold resulting from a skeletal rearrangement. To the core scaffold 6, the P450 enzymes, BscB and BscC
  • ]. The P450 enzyme BscF is responsible for regioselective abstraction of a hydrogen at C12 and subsequent diastereoselective hydroxylation of the radical intermediate B to produce brassicicene B (10). Meanwhile, further single-electron oxidation of the intermediate B would trigger a Wagner–Meerwein-type
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Published 23 Jul 2024

A fiber-optic spectroscopic setup for isomerization quantum yield determination

  • Anouk Volker,
  • Jorn D. Steen and
  • Stefano Crespi

Beilstein J. Org. Chem. 2024, 20, 1684–1692, doi:10.3762/bjoc.20.150

Graphical Abstract
  • molecular photoswitch generally has a stable state A and a metastable state B, which would be the trans- and cis-isomers, respectively, for azobenzene. The rate equations of the isomerization can be described in terms of the quantum yields and the molar absorption coefficients. It is possible to show that
  • the change in the concentration of A is given by Equation 2 [47]: The first term gives the photochemical reaction from A to B, which is governed by the number of photons absorbed at a given wavelength, qA, as well as the quantum yield ΦA→B for this reaction. NA is Avogadro’s number, V is the total
  • law, the light absorbed by the sample, Abstot, in a setup with a given path length l can be expressed as the sum of the absorbances of the single species A and B and consequently in terms of the concentrations of A and B and their respective molar absorption coefficients (εA and εB): For absorbances
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Published 22 Jul 2024

Oxidation of benzylic alcohols to carbonyls using N-heterocyclic stabilized λ3-iodanes

  • Thomas J. Kuczmera,
  • Pim Puylaert and
  • Boris J. Nachtsheim

Beilstein J. Org. Chem. 2024, 20, 1677–1683, doi:10.3762/bjoc.20.149

Graphical Abstract
  • optimized conditions, revealing the tetrazole-substituted iodane 1a to be the best oxidant for this reaction (Table 2). The two suitable methods (A: HCl in EtOAc; B: TBACl in MeCN) were then applied to a variety of activated alcohols. The best option is shown in Figure 5. Model substrate 4a could be
  • decomposition for thiophenylmethanol 3y. Regarding the reaction mechanism, two plausible pathways can be discussed based on literature examples (Scheme 1, path a [17] and path b [33]). In either path, initial ligand exchange to the hydroxy(chloro)iodane I-OH is proposed. For getting an indication of a chloride
  • the alkyl hypochlorite IIa. The second mechanism (path b) requires a direct ligand exchange of I-OH with the alcohol and subsequent β-elimination of the alkoxy(hydroxy)iodane IIb to form the desired aldehyde 4. Conclusion In conclusion, this study has successfully introduced N-heterocycle-stabilized
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Published 19 Jul 2024

Ring opening of photogenerated azetidinols as a strategy for the synthesis of aminodioxolanes

  • Henning Maag,
  • Daniel J. Lemcke and
  • Johannes M. Wahl

Beilstein J. Org. Chem. 2024, 20, 1671–1676, doi:10.3762/bjoc.20.148

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  • . Build and release approach for the functionalization of simple precursors. a) General overview. b) Embedding azetidines into the general synthetic strategy. Modularity of the Norrish–Yang cyclization for the synthesis of azetidines. Ring-opening reactions using electron-deficient ketones and boronic
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Published 19 Jul 2024

Methyltransferases from RiPP pathways: shaping the landscape of natural product chemistry

  • Maria-Paula Schröder,
  • Isabel P.-M. Pfeiffer and
  • Silja Mordhorst

Beilstein J. Org. Chem. 2024, 20, 1652–1670, doi:10.3762/bjoc.20.147

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  • a carboxylic acid. SAM is used as a donor of the methyl group [67][68][69]. The linear cyanobactin aeruginosamide B, produced by Microcystis aeruginosa PCC 9432, was the first RiPP reported to be O-methylated at its C-terminus [70]. LahSB is a SAM-dependent MT encoded in the lah BGC of
  • demonstrated. OlvSA, an O-MT encoded in the olv cluster from Streptomyces olivaceus NRRL B-3009 (Figure 5), is involved in the biosynthesis of the class I lanthipeptide OlvA(BCSA). It catalyses the conversion of a highly conserved ʟ-aspartate to ʟ-isoaspartate by methylation of a side chain carboxylate group
  • isolated from Bacillus amyloliquefaciens FZB42 and it mainly exhibits bactericidal activity against Bacillus anthracis [94][95][96]. The dimethylation is essential for its bioactivity; desmethyl plantazolicin showed MIC values >128 µg/mL for B. anthracis, while the dimethyl species showed MIC values
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Published 18 Jul 2024

Polymer degrading marine Microbulbifer bacteria: an un(der)utilized source of chemical and biocatalytic novelty

  • Weimao Zhong and
  • Vinayak Agarwal

Beilstein J. Org. Chem. 2024, 20, 1635–1651, doi:10.3762/bjoc.20.146

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  • and cloned from deep-sea-derived Microbulbifer sp. JAMB-A94 with pH and temperature optima being 7.0 and 55 °C, respectively [26]. The recombinant enzyme was likewise produced using a B. subtilis host. The crystal structure of the catalytic domain was determined to show a β-jelly roll fold with
  • 8.0 and 55 °C, respectively. The biocatalytic utility of the enzyme was also evaluated; it was used for neoagarooligosaccharide production in high yield [80]. Five additional GH-16 agarases AgaA3 produced in B. subtilis, ID2563 produced in E. coli, N3-1 produced in Pichia pastoris, AG1 produced in E
  • agarase was also reported from the same bacterium [27]. The recombinant enzyme (rAgaO) was expressed in B. subtilis cells to demonstrate that this enzyme was an endo-type β-agarase and degraded agarose to neoagarohexaose as the main product [27]. The enzyme rAgaO represents the first and only report on
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Published 17 Jul 2024

pKalculator: A pKa predictor for C–H bonds

  • Rasmus M. Borup,
  • Nicolai Ree and
  • Jan H. Jensen

Beilstein J. Org. Chem. 2024, 20, 1614–1622, doi:10.3762/bjoc.20.144

Graphical Abstract
  • assume a linear relationship between the experimental pKa values and as this assumption allows us to derive the empirical constants a and b and correct any systematic errors; see Equation 2, where ΔG° is replaced by . After retrieving the empirical constants a and b, we can determine the QM-computed pKa
  • , each ML model is trained on our original training set and tested against the held-out test set. Finally, we select the best-performing ML model. Results and Discussion Computing pKa values From section “The quantum chemistry-based workflow” above, we can determine the empirical values a and b in
  • reliable experimental pKa values and computed values. The values for the computed are then fitted against the experimental pKa values, leaving us with empirical constants a and b; see Figure 1. We now use the derived linear regression to convert all computed ΔG° values into QM-computed pKa values for our
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Published 16 Jul 2024

Generation of multimillion chemical space based on the parallel Groebke–Blackburn–Bienaymé reaction

  • Evgen V. Govor,
  • Vasyl Naumchyk,
  • Ihor Nestorak,
  • Dmytro S. Radchenko,
  • Dmytro Dudenko,
  • Yurii S. Moroz,
  • Olexiy D. Kachkovsky and
  • Oleksandr O. Grygorenko

Beilstein J. Org. Chem. 2024, 20, 1604–1613, doi:10.3762/bjoc.20.143

Graphical Abstract
  • yellow. Distribution of maximal values among pairwise-calculated Tanimoto similarities T (MFP2 fingerprints [46]) of extended Bemis–Murcko scaffolds for the generated chemical space members (5.60 Mln. scaffolds) to the extended Bemis–Murcko scaffolds of A) ChEMBL compounds (v. 33); B) PubChem compounds
  • ) comparative analysis of 50,000 randomly selected molecules picked from the generated chemical space and A) ChEMBL compounds; B) PubChem compounds; C) ZINC15 compounds; and D) enamine’s stock screening collection. Some biologically active representatives of the generated GBB chemical space found in the ChEMBL
  • database. Groebke–Blackburn–Bienaymé (GBB) reaction. A) Parallel GBB reaction and B) examples of library members 4 obtained (relative configurations are shown). Supporting Information The Supporting Information for this article contains structures of reactants 1–3, experimental details on the parallel
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Published 16 Jul 2024

Supramolecular assemblies of amphiphilic donor–acceptor Stenhouse adducts as macroscopic soft scaffolds

  • Ka-Lung Hung,
  • Leong-Hung Cheung,
  • Yikun Ren,
  • Ming-Hin Chau,
  • Yan-Yi Lam,
  • Takashi Kajitani and
  • Franco King-Chi Leung

Beilstein J. Org. Chem. 2024, 20, 1590–1603, doi:10.3762/bjoc.20.142

Graphical Abstract
  • solution (20 μM). (a) DA11, (c) DA7, (e) DA6 solutions in the beginning (black line), upon 625-nm irradiation over the course of 1 min (orange lines), and after irradiation to reach the PSS (red line). (b) DA11, (d) DA7, (f) DA6 upon thermal back reaction over the course of 60 min at 20 °C (cyan lines) and
  • 400–480 nm area), (b) DA7 (inset: enlarged 275–290 nm area), (c) DA6 (inset: enlarged 430–490 nm area) in the beginning (black line), upon white-light irradiation over the course of 60 min (orange lines), and after 60 min (red line). Irradiation was carried out at 20 °C using a light-guide-equipped
  • BBZM-I xenon light source (380–800 nm, 300 W) positioned at a distance of 1 cm from the sample. TEM images of freshly prepared aqueous solutions before irradiation of (a) DA11 (0.25 wt %, 4.1 mM), (c) DA7 (0.25 wt %, 4.5 mM), and (e) DA6 (0.25 wt %, 4.6 mM). The solutions of (b) DA11, (d) DA7, and (f
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Published 15 Jul 2024

Regio- and stereochemical stability induced by anomeric and gauche effects in difluorinated pyrrolidines

  • Ana Flávia Candida Silva,
  • Francisco A. Martins and
  • Matheus P. Freitas

Beilstein J. Org. Chem. 2024, 20, 1572–1579, doi:10.3762/bjoc.20.140

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  • Gaussian 16 package of software [24]. a) Pseudoequatorial and pseudoaxial conformations of pyrrolidine. b) Cis- and trans-isomers of 3-fluoropyrrolidine. Flat representations of 2,3-, 3,4-, and 2,4-difluoropyrrolidines. The potential effects resulting from the addition of a second 1,2- or 1,3-fluorine atom
  • the CCSD structure is 20.3316. “a” denotes DGTZVP and “b” denotes 6-311++G**. Exhaustive illustration of all conformational, configurational, and constitutional isomers of difluorinated pyrrolidine, illustrating the relative orientation of the C–F and N–H bonds used to build the input geometry for the
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Published 12 Jul 2024

Electrocatalytic hydrogenation of cyanoarenes, nitroarenes, quinolines, and pyridines under mild conditions with a proton-exchange membrane reactor

  • Koichi Mitsudo,
  • Atsushi Osaki,
  • Haruka Inoue,
  • Eisuke Sato,
  • Naoki Shida,
  • Mahito Atobe and
  • Seiji Suga

Beilstein J. Org. Chem. 2024, 20, 1560–1571, doi:10.3762/bjoc.20.139

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  • ) a PEM reactor and (b) MEA. Hypothesis of the trap of quinoline on membrane and tetrahydroquinoline and the effect of adding an acid. Recycled use of MEA for the electroreduction of 6a in the presence of PTSA (0.10 equiv). Reaction conditions: anode catalyst, Pt/C; cathode catalyst, Pt/C; 6a, 1.5
  • standard. b0.125 M. c0.25 M. d1,4-dioxane/H2O (7:1, 0.25 M). a) Large scale synthesis of 7a and b) electoreduction of 6a using H2SO4 as a proton source. Scope of the electroreduction of 6 in the presence of PTSA (1 equiv). Reaction conditions: anode catalyst, Pt/C; cathode catalyst, Pt/C; 8, 1.5 mmol
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Mining raw plant transcriptomic data for new cyclopeptide alkaloids

  • Draco Kriger,
  • Michael A. Pasquale,
  • Brigitte G. Ampolini and
  • Jonathan R. Chekan

Beilstein J. Org. Chem. 2024, 20, 1548–1559, doi:10.3762/bjoc.20.138

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  • alkaloids, containing both Ziziphus and Ceanothus genera. In addition to the subclass defining Tyr-phenol-O to carbon linkage, the cyclopeptide alkaloids of this family are typically oxidatively decarboxylated and N-methylated (Figure 1, adouetine X and Figure 3, ceanothine B) [19][20][21]. Our
  • (Figure 3 and Supporting Information File 2). Malvaceae family The Malvaceae family contains Hibiscus syriacus (Rose of Sharon), the only known producer of hibispeptin-type burpitides (Figure 3, hibispeptin B) [24][25]. These molecules contain a C–C linkage between the phenol derived from tyrosine and the
  • γ-carbon of isoleucine. As expected from previous genomic analysis [7], the transcriptome of H. syriacus contained precursor peptides corresponding to both hibispeptin A and B (Figure 3 and Supporting Information File 2). The closely related Hibiscus cannabinus possessed similar transcripts, while
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