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Search for "air" in Full Text gives 716 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.

N-Glycosides of indigo, indirubin, and isoindigo: blue, red, and yellow sugars and their cancerostatic activity

  • Peter Langer

Beilstein J. Org. Chem. 2024, 20, 2840–2869, doi:10.3762/bjoc.20.240

Graphical Abstract
  • be selectively removed under slightly basic and reductive conditions (Na2SO3, dioxane, H2O) to give the desired free indoxyl-N-glycoside. Due to its instability in the presence of air, the crude material was directly used for the reaction with isatin to give the desired indirubin-N-rhamnoside β-30a
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Published 08 Nov 2024

Transition-metal-free decarbonylation–oxidation of 3-arylbenzofuran-2(3H)-ones: access to 2-hydroxybenzophenones

  • Bhaskar B. Dhotare,
  • Seema V. Kanojia,
  • Chahna K. Sakhiya,
  • Amey Wadawale and
  • Dibakar Goswami

Beilstein J. Org. Chem. 2024, 20, 2655–2667, doi:10.3762/bjoc.20.223

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  • tends to form explosive compounds upon heating in open air atmosphere. Although the hydroperoxide formed during the heating immediately reacts with the substrates, and no accumulation of hydroperoxide has been observed, these reactions must be done under a fume hood, and the THF volume should be
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Published 21 Oct 2024

The scent gland composition of the Mangshan pit viper, Protobothrops mangshanensis

  • Jonas Holste,
  • Paul Weldon,
  • Donald Boyer and
  • Stefan Schulz

Beilstein J. Org. Chem. 2024, 20, 2644–2654, doi:10.3762/bjoc.20.222

Graphical Abstract
  • distilled before use. All other chemicals were used without purification unless otherwise stated. Air- and H2O-sensitive reactions were performed under N2. ASAP-APCI-MS was performed on an Expression MS (Advion) mass spectrometer equipped with an APCI ionization source operated in positive mode. The
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Published 18 Oct 2024

Applications of microscopy and small angle scattering techniques for the characterisation of supramolecular gels

  • Connor R. M. MacDonald and
  • Emily R. Draper

Beilstein J. Org. Chem. 2024, 20, 2608–2634, doi:10.3762/bjoc.20.220

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  • the range of hierarchical assemblies [32]. Another significant concern posed by blotting is the brief introduction of an air–water interface which can lead to preferential organisation of particles, as well as unpredictable changes in local concentration on the TEM grid [41]. To overcome such
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Published 16 Oct 2024

Efficient modification of peroxydisulfate oxidation reactions of nitrogen-containing heterocycles 6-methyluracil and pyridine

  • Alfiya R. Gimadieva,
  • Yuliya Z. Khazimullina,
  • Aigiza A. Gilimkhanova and
  • Akhat G. Mustafin

Beilstein J. Org. Chem. 2024, 20, 2599–2607, doi:10.3762/bjoc.20.219

Graphical Abstract
  • mixture to room temperature, concentrated H2SO4 was slowly added until pH 6–7 according to litmus paper and left standing for 12 h. The precipitated white crystals were filtered off, washed with water, and dried in air. Compound 2 yields are given in [13] and compound 5 yields are given in Table 1. b
  • temperature, concentrated H2SO4 was slowly added until pH 6–7 according to litmus paper and left standing overnight (12 h). The precipitated crystals were filtered off, washed with water, acetone, and dried in air. The crude product was recrystallized from water with activated carbon. The yield of compound 2
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Published 16 Oct 2024

Synthesis and cytotoxicity studies of novel N-arylbenzo[h]quinazolin-2-amines

  • Battini Veeraiah,
  • Kishore Ramineni,
  • Dabbugoddu Brahmaiah,
  • Nangunoori Sampath Kumar,
  • Hélène Solhi,
  • Rémy Le Guevel,
  • Chada Raji Reddy,
  • Frédéric Justaud and
  • René Grée

Beilstein J. Org. Chem. 2024, 20, 2592–2598, doi:10.3762/bjoc.20.218

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  • in heat gun-dried round-bottomed flasks under a dry argon or nitrogen atmosphere. Air and moisture-sensitive compounds were introduced via syringes or cannula, using standard inert atmosphere techniques. In addition, the gas stream was passed through glass cylinder filled with P2O5 to remove any
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Published 14 Oct 2024

Transition-metal-free synthesis of arylboronates via thermal generation of aryl radicals from triarylbismuthines in air

  • Yuki Yamamoto,
  • Yuki Konakazawa,
  • Kohsuke Fujiwara and
  • Akiya Ogawa

Beilstein J. Org. Chem. 2024, 20, 2577–2584, doi:10.3762/bjoc.20.216

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  • under transition-metal-free and open-air conditions. Conventional methods required photoirradiation or electrolysis to generate aryl radicals from triarylbismuthines. In this study, it was found that simply heating the solution of triarylbismuthines in benzotrifluoride (BTF) in air successfully led to
  • investigated various transition-metal-free methods for the generation of aryl radicals from shelf-stable aryl compounds (Scheme 1b). For example, the heating of arylhydrazine hydrochlorides (ArNHNH2·HCl) in the presence of base under open-air conditions successfully led to the generation of aryl radicals and
  • the subsequent trapping with E–E compounds (E = S, Se, Te, Br, and I) successfully formed new C–E bonds (Scheme 1b) [51][52][53][54][55][56][57][58]. We also demonstrated that the photoirradiation (λ > 300 nm) of the triarylbismuthines in air successfully allowed the generation of the corresponding
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Published 11 Oct 2024

A review of recent advances in electrochemical and photoelectrochemical late-stage functionalization classified by anodic oxidation, cathodic reduction, and paired electrolysis

  • Nian Li,
  • Ruzal Sitdikov,
  • Ajit Prabhakar Kale,
  • Joost Steverlynck,
  • Bo Li and
  • Magnus Rueping

Beilstein J. Org. Chem. 2024, 20, 2500–2566, doi:10.3762/bjoc.20.214

Graphical Abstract
  • − is protonated to produce DDQH2. The anodic oxidation of DDQH2 regenerates DDQ, which re-enters the catalytic cycle (Scheme 29). Furthermore, Qiu and coworkers disclosed a metal-free electrochemical dihydroxylation of unactivated alkenes using water as the hydroxy source under air conditions [40
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Published 09 Oct 2024

Facile preparation of fluorine-containing 2,3-epoxypropanoates and their epoxy ring-opening reactions with various nucleophiles

  • Yutaro Miyashita,
  • Sae Someya,
  • Tomoko Kawasaki-Takasuka,
  • Tomohiro Agou and
  • Takashi Yamazaki

Beilstein J. Org. Chem. 2024, 20, 2421–2433, doi:10.3762/bjoc.20.206

Graphical Abstract
  • the resultant mixture was stirred at 50 °C for 19 h under the open air. After quenching the reaction with 1 M HCl aq., the mixture was extracted with AcOEt three times and the combined organic phase was washed with brine. Evaporation of the volatiles furnished crude materials which were recrystallized
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Published 25 Sep 2024

Asymmetric organocatalytic synthesis of chiral homoallylic amines

  • Nikolay S. Kondratyev and
  • Andrei V. Malkov

Beilstein J. Org. Chem. 2024, 20, 2349–2377, doi:10.3762/bjoc.20.201

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  • synthetic utilisation [3]. Both, nature and humanity utilise ammonia as the central precursor to introduce nitrogen into organic compounds. Nature achieves this through enzymatic processes, sourcing ammonia from geological origins or directly from the air [4], while humanity relies on the Haber–Bosch
  • 24, which supported the hypotheses regarding the selectivity-determining transition states arrangement. It is important to note, that boronic acids 14 are highly sensitive to oxidation by air and could only be purified in air-free conditions and stored in airtight containers. Additionally
  • molecule. The BINOL catalyst 39 forming arylboronate species, enables the shift to occur asymmetrically. In the second step, the hydrolysis of unreactive diaminonaphthalene derivative 42 gives the poorly reactive and highly air-sensitive trifluoromethylallylboronic acid 43, but after the dehydration forms
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Published 16 Sep 2024

Synthesis and reactivity of the di(9-anthryl)methyl radical

  • Tomohiko Nishiuchi,
  • Kazuma Takahashi,
  • Yuta Makihara and
  • Takashi Kubo

Beilstein J. Org. Chem. 2024, 20, 2254–2260, doi:10.3762/bjoc.20.193

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  • dimerization in solution, the radical still remains even at 190 K due to the bulky nature of the two anthryl groups. Interestingly, upon exposure to air, the purple color of the radical solution quickly fades to orange, resulting in decomposition to give 9-anthryl aldehyde and anthroxyl radical derivatives
  • aromatic hydrocarbon radicals, which can persist in air-saturated solutions for several days to months, have been synthesized by employing bulky substituents around the spin-localized carbon center [13][14][15]. These stable radicals have paved the way to elucidate the nature of radical species, advancing
  • from the basic skeleton of the highly reactive diphenylmethyl radical [26][27][28]. This spin delocalization is similar to that of the galvinoxyl radical, which shows high stability in air [29]. Thus, the DAntM radical would be a stable radical with a reactive site. Additionally, utilizing the reactive
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Published 05 Sep 2024

Selective hydrolysis of α-oxo ketene N,S-acetals in water: switchable aqueous synthesis of β-keto thioesters and β-keto amides

  • Haifeng Yu,
  • Wanting Zhang,
  • Xuejing Cui,
  • Zida Liu,
  • Xifu Zhang and
  • Xiaobo Zhao

Beilstein J. Org. Chem. 2024, 20, 2225–2233, doi:10.3762/bjoc.20.190

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  • thioesters 2 (2a as an example) A mixture of (E)-3-(ethylthio)-1-phenyl-3-(phenylamino)prop-2-en-1-one (1a, 70.8 mg, 0.25 mmol) and DBSA (87.9 mg, 0.25 mmol) in water (2 mL) was stirred at reflux in an oil bath under air for 5 h until 1a was completely consumed, as confirmed by TLC monitoring. Then, the pH
  • water (2 mL) was stirred at reflux in an oil bath under air for 24 h until 1a was completely consumed, as confirmed by TLC monitoring. Then, the pH value of the reaction mixture was adjusted to neutral using a 10% CH3COOH solution, and the reaction mixture was extracted with CH2Cl2 (3 × 20 mL). The
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Published 03 Sep 2024

Multicomponent syntheses of pyrazoles via (3 + 2)-cyclocondensation and (3 + 2)-cycloaddition key steps

  • Ignaz Betcke,
  • Alissa C. Götzinger,
  • Maryna M. Kornet and
  • Thomas J. J. Müller

Beilstein J. Org. Chem. 2024, 20, 2024–2077, doi:10.3762/bjoc.20.178

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  • al. used this for the regioselective one-pot synthesis of pyrazoles 175 by 1,3-dipolar cycloaddition with electron-deficient alkenes (Scheme 59) [177]. The reaction is carried out in air to oxidize an intermediary
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Published 16 Aug 2024

1,2-Difluoroethylene (HFO-1132): synthesis and chemistry

  • Liubov V. Sokolenko,
  • Taras M. Sokolenko and
  • Yurii L. Yagupolskii

Beilstein J. Org. Chem. 2024, 20, 1955–1966, doi:10.3762/bjoc.20.171

Graphical Abstract
  • introduced into commercial use [1][2][3]. Recently, these compounds and blends thereof have replaced HFCs in refrigerants and air-conditioning systems [1][2][3]. The commercial production of HFOs has made these compounds available for chemists to be used as important reagents in laboratories. For example
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Published 12 Aug 2024

Regioselective alkylation of a versatile indazole: Electrophile scope and mechanistic insights from density functional theory calculations

  • Pengcheng Lu,
  • Luis Juarez,
  • Paul A. Wiget,
  • Weihe Zhang,
  • Krishnan Raman and
  • Pravin L. Kotian

Beilstein J. Org. Chem. 2024, 20, 1940–1954, doi:10.3762/bjoc.20.170

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  • yields from the same carbon sources through reagent control. Experimental General methods All materials were obtained from commercial suppliers and used without further purification unless otherwise noted. Anhydrous solvents were obtained from Sigma-Aldrich and used directly. Reactions involving air- or
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Published 09 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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  • catalysts Noncovalent organocatalysts display a few advantages compared to the traditional metal Lewis acids, such as lower environmental impact, higher stability to air and moisture, easier removal from the GBB products. In this regard, Bolotin et al. in 2022 have reported the high catalytic activity of
  • conditions. The study was started by reacting 2-aminopyridines, indole-3-carbaldehyde 62 and ethyl isocyanoacetate (63) under open air in the presence of Yb(OTf)3 catalyst (Scheme 24, conditions a). The results showed that fused polycyclic indoles 67 were obtained (albeit in lower yields, 25%) instead of the
  • oxidized to the corresponding imine 94 by oxygen in the air (as the cyclization did not proceed when the reaction was conducted under nitrogen atmosphere). The activation of the triple bond by tetrabutylammonium bromide regioselectively induced the 6-endo-dig cyclization to furnish 95 in moderate yields
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Published 01 Aug 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
  • force microscopy The study employed atomic force microscopy (AFM) in air to observe the bacterial morphological changes on the surface of S. epidermidis triggered by the impact of lanthipeptides. The concentrations of peptides were estimated based on the SDS gel band intensity, and we expect there is
  • 0.1% w/v poly-ʟ-lysin solution in water (Sigma-Aldrich) and immediately deposited onto freshly cleaved mica to be incubated for 10 min at room temperature to allow adsorption. The surface was then rinsed using 600 µL of ultrapure 0.2 µm filtered water and slowly dried using compressed air. Imaging was
  • performed using a Digital Instruments NanoScope V, acquiring 1024 samples per line with silicon nitride cantilevers possessing a nominal spring constant of 0.32 Nm−1 and a 0.8–1.0 Hz scan rate. Imaging was conducted at room temperature using the ScanAsyst™ air mode. Images were processed using NanoScope
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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

Graphical Abstract
  • alternative approach, we reported the first application of using fluoroiodane 2 as a fluorinating reagent in 2013 [11]. The chelate sidearm makes 2 an air-stable, easy-to-handle solid with excellent fluorinating ability and it often exhibits different reactivity to that observed with fluoroaza reagents such
  • during the work-up procedure in air. When the reaction time was shortened to 24 hours, a complex reaction mixture was obtained (Table 1, entry 2). Reducing the amount of TCCA to 3 equivalents (Table 1, entry 3) delivered difluoroiodane 6 in the same 90% yield. Finally, we performed the reaction and work
  • the same experiment was repeated in air, iodine(V) fluorides 6, 21 and 22 decomposed to 55–65% remaining after 7 days presumably due to the moisture in the air, whereas trifluoroiodane 20 was less stable with only 37% remaining. Difluoroiodane 6 was also stable in dry chloroform-d1 under argon over 7
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Published 29 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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  • sodium hydride, yielding moderate yields (ranging from 23% to 68%). The cyclization initially formed the non-isolated intermediate i, which was oxidized by molecular oxygen from air, introducing the hydroxy group at the α-position of the cyano group. The protocol utilised mild conditions and short
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Published 24 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

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  • measurement altering the kinetics of isomerization, a known problem for similar setups [24]. The power readings from the thermal power sensor were recorded by using Thorlabs’ Optical Power Monitor (OPM) software. The resulting data showed some fluctuations depending on environment temperature and air movement
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Published 22 Jul 2024

New triazinephosphonate dopants for Nafion proton exchange membranes (PEM)

  • Fátima C. Teixeira,
  • António P. S. Teixeira and
  • C. M. Rangel

Beilstein J. Org. Chem. 2024, 20, 1623–1634, doi:10.3762/bjoc.20.145

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  • were used as received, without further purification. Solvents and air-sensitive reagents were distilled under a dry nitrogen atmosphere. Dry THF was distilled from sodium benzophenone ketyl. A Nafion N115 film was acquired from FuelCell Store and a 20 wt % mixture in lower aliphatic alcohols and water
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Published 17 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

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  • ][40]. Photoresponsive supramolecular amphiphiles are responsive, complex, and adaptable in aqueous medium [41][42][43]. Supramolecular assemblies of photoresponsive molecular amphiphiles in aqueous medium can undergo transformation in solution or at the air–water interface and even sustained
  • conductive carbon adhesive tape and air-dried for 48 h before measurement. SLS The scattering intensity of the samples was determined by SLS measurements using a Wyatt Technology DynaPro NanoStar. The scattering intensity was recorded as a parameter signifying the assembly size since the objects in solution
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Published 15 Jul 2024

Domino reactions of chromones with activated carbonyl compounds

  • Peter Langer

Beilstein J. Org. Chem. 2024, 20, 1256–1269, doi:10.3762/bjoc.20.108

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  • . Conditions: i, 1) DBU (1.3 equiv), 1,4-dioxane, 20 °C, 12 h; 2) I2 (2 equiv), DBU (3 equiv), MeCN or DMF. Then aqueous work-up at the air. Synthesis of 39a–i. Conditions: i, method A: DBU (1.3 equiv), 1,4-dioxane, 20 °C; method B: K2CO3 (4 equiv), DMF, 20 °C. Synthesis of 40. Conditions: i, piperidine, MeOH
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Published 29 May 2024

Mechanistic investigations of polyaza[7]helicene in photoredox and energy transfer catalysis

  • Johannes Rocker,
  • Till J. B. Zähringer,
  • Matthias Schmitz,
  • Till Opatz and
  • Christoph Kerzig

Beilstein J. Org. Chem. 2024, 20, 1236–1245, doi:10.3762/bjoc.20.106

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  • bands peaking at 441 nm and 640 nm were observed that we assign to 3Aza-H. However, on longer time scales the shape of the spectrum changes significantly (Figure S4, Supporting Information File 1) indicating that more than one absorbing species is generated. Measurements on an air-saturated solution
  • transient species in Ar-saturated/air-saturated solution is also reflected in the kinetic traces at 440 nm and 640 nm (Figure 1B, inset). Following the decay of the transient triplet species (³Aza-H), essentially the same signal is reached irrespective of the presence of oxygen or argon in the solution. The
  • air-saturated solution (red spectrum) and used it to separate the signal that only stems from the oxidative quenching step (green spectrum). This correction likely overestimates the contribution of the two-photon process to the radical cation signal in the presence of 4CP, considering that quenching
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Published 28 May 2024

Competing electrophilic substitution and oxidative polymerization of arylamines with selenium dioxide

  • Vishnu Selladurai and
  • Selvakumar Karuthapandi

Beilstein J. Org. Chem. 2024, 20, 1221–1235, doi:10.3762/bjoc.20.105

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  • evaporation of solvent, polymer 1 was obtained as a black solid. The solid was vacuum-filtered using a Büchner funnel and washed with acetonitrile. The solid was air-dried to give 2.33 g of a black crystalline solid that was insoluble in ethyl acetate and barely soluble in methanol. The filtrate was collected
  • mmol, ≈1.66 g). The flask content was stirred under a nitrogen atmosphere at 80 °C for 3 h. Evaporation of the reaction mixture on a rotary evaporator gave a black crystalline solid. The resulting solid was vacuum-filtered, washed with acetonitrile, and air-dried to yield 2.36 g of polymer 2 as a black
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Published 27 May 2024
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