Ring-closing metathesis of prochiral oxaenediynes to racemic 4-alkenyl-2-alkynyl-3,6-dihydro-2H-pyrans

• Viola Kolaříková,
• Markéta Rybáčková,
• Martin Svoboda and
• Jaroslav Kvíčala

Beilstein J. Org. Chem. 2020, 16, 2757–2768, doi:10.3762/bjoc.16.226

• precatalysts [18][19][20] in the enantioselective RCM, however, the high air and moisture sensitivity makes their use less practical. The choice of the catalyst is one of the key elements in both cross and ring-closing enyne metathesis and the other is the substrate structure. Both of these factors determine

Selective recognition of ATP by multivalent nano-assemblies of bisimidazolium amphiphiles through “turn-on” fluorescence response

• Rakesh Biswas,
• Surya Ghosh,
• Shubhra Kanti Bhaumik and
• Supratim Banerjee

Beilstein J. Org. Chem. 2020, 16, 2728–2738, doi:10.3762/bjoc.16.223

• Aqueous buffer solutions of PBImNs (N = 10, 12 and 14) were first stabilized for 15 min and then 5 µL of these solutions were drop casted on glass cover slips. The samples were dried in air overnight and then under high vacuum for 8–10 hours. Finally, the morphologies of the samples were recorded in a

A heterobimetallic tetrahedron from a linear platinum(II)-bis(acetylide) metalloligand

• Matthias Hardy,
• Marianne Engeser and
• Arne Lützen

Beilstein J. Org. Chem. 2020, 16, 2701–2708, doi:10.3762/bjoc.16.220

• purple solution was stirred in an argon atmosphere for 16 hours at 50 °C. After cooling to room temperature, the solution was filtered and 3 mL of n-pentane were added to the filtrate. The resulting precipitate was collected, washed with n-pentane and diethyl ether and dried in a stream of air. The

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

• under air to form the disulfide. Investigation on the spin switching performance of the Ni(II)-porphyrins The spin switching performance of a record player molecule depends on different parameters: 1. the coordination strength of the axial ligand, 2. the effectivity of the cis–trans isomerization, since

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

• spectra were recorded on an inVia Reflex confocal Raman microscope (Renishaw plc, Wotton-under-Edge, UK) by dropping the sample solutions of TBTQ-(OG)6 and TBTQ-(OG)6 C60 onto a slide glass with subsequent air drying. C60 was tested in powder form on a slide glass. Ultrasonic mixing was performed with a

Dawn of a new era in industrial photochemistry: the scale-up of micro- and mesostructured photoreactors

• Emine Kayahan,
• Mathias Jacobs,
• Leen Braeken,
• Leen C.J. Thomassen,
• Simon Kuhn,
• Tom van Gerven and
• M. Enis Leblebici

Beilstein J. Org. Chem. 2020, 16, 2484–2504, doi:10.3762/bjoc.16.202

• metal cavity caused overheating. Therefore, a cooling jacket around the metal cavity was implemented in the design, along with a fan to blow air through the space between the lamp and the quartz photoreactor tubes. The design was called firefly reactor. Various [2 + 2] cycloadditions were performed in

• light path of the reactor. The major drawback of the aerosol photoreactor are safety issues, especially for organic oxidation reactions. Spraying organics into air or oxygen could lead to explosions. Therefore, the lower and upper explosion limits for the several organic photooxidation reactions should

A proposed sustainability index for synthesis plans based on input provenance and output fate: application to academic and industrial synthesis plans for vanillin as a case study

• John Andraos

Beilstein J. Org. Chem. 2020, 16, 2346–2362, doi:10.3762/bjoc.16.196

• air, water, soil, and sediment. Based on the definition of variables in Equations 1, 2, and 3 we can then define the following key parameters. The process mass intensity (PMI) [13] is defined according to Equation 4. The mass fractions of valorized inputs (FVI) and valorized waste outputs (FVO) are

• ] and other cellulosic biomass feedstocks, respectively. Isoeugenol and eugenol were chosen to originate from the natural product clover oil since 80% by weight of this essential oil is eugenol [48], and isoeugenol is directly obtained from eugenol by base-catalyzed isomerization. (5) Oxygen from air

Formation of an exceptionally stable ketene during phototransformations of bicyclo[2.2.2]oct-5-en-2-ones having mixed chromophores

• Asitanga Ghosh

Beilstein J. Org. Chem. 2020, 16, 2297–2303, doi:10.3762/bjoc.16.190

• less congested one has been observed. The ketenes were exceptionally stable both in air and solution. Its stability studies in acetonitrile through time-dependent UV absorption spectra revealed that it remained almost unchanged at least for a couple of weeks. Keywords: α,β- and β,γ-enones; bridgehead

• 10a,b were exceptionally stable both in air and solution. Their stability studies in acetonitrile through time-dependent absorption spectra (Figure 3) revealed that they remained almost unchanged at least for six to eight weeks. Such photoinduced intramolecular 1,5-phenyl migration from carbon to

Photosensitized direct C–H fluorination and trifluoromethylation in organic synthesis

• Shahboz Yakubov and
• Joshua P. Barham

Beilstein J. Org. Chem. 2020, 16, 2151–2192, doi:10.3762/bjoc.16.183

Access to highly substituted oxazoles by the reaction of α-azidochalcone with potassium thiocyanate

• Mysore Bhyrappa Harisha,
• Pandi Dhanalakshmi,
• Rajendran Suresh,
• Raju Ranjith Kumar and
• Shanmugam Muthusubramanian

Beilstein J. Org. Chem. 2020, 16, 2108–2118, doi:10.3762/bjoc.16.178

• substituted oxazoles and 2-aminothiazoles from α-azidochalcones and potassium thiocyanate employing potassium persulfate and ferric nitrate, respectively. This new route gains a streamlined workup and the elimination of air-sensitive techniques to afford the product in good yield in a greener medium over a

Naphthalene diimide–amino acid conjugates as novel fluorimetric and CD probes for differentiation between ds-DNA and ds-RNA

• Annike Weißenstein,
• Myroslav O. Vysotsky,
• Ivo Piantanida and
• Frank Würthner

Beilstein J. Org. Chem. 2020, 16, 2032–2045, doi:10.3762/bjoc.16.170

• the heats of dilution of the compounds and the polynucleotides. All solutions used in the ITC experiments were degassed under vacuum prior to use to eliminate air bubbles. Structures of investigated compounds stressing steric differences in linker length attached to the NDI core. UV–vis absorption

Regiodivergent synthesis of functionalized pyrimidines and imidazoles through phenacyl azides in deep eutectic solvents

• Paola Vitale,
• Luciana Cicco,
• Ilaria Cellamare,
• Filippo M. Perna,
• Antonio Salomone and
• Vito Capriati

Beilstein J. Org. Chem. 2020, 16, 1915–1923, doi:10.3762/bjoc.16.158

• synthesis of 2-azido ketones 2d, 2e, 2f, 2k, 2l and 2m α-Haloketone 1 (1.5 mmol) and NaN3 (107 mg, 1.65 mmol) were sequentially added to the ChCl/Gly (1:2 mol/mol, 2.0 g) eutectic mixture. The reaction mixture was stirred at 25 °C under air for 3–12 h until complete consumption of the starting material

• azide (0.75 mmol) was added to a solution of 2-chloroacetophenone (1a, 0.5 mmol) in ChCl/Gly (1:2 mol/mol, 1.0 g) under air and with vigorous stirring. The mixture was then warmed to 80 °C. After 12 h, 10 mL of water were added and the solid 3a was recovered by decantation (or filtration) from the

• ) in ChCl/ urea (1:2 mol/mol, 0.5 g) eutectic mixture at 25 °C, under air and with vigorous stirring. The reaction was monitored by TLC (hexane/EtOAc 7:3). After 4 h, 5 mL of water were added and the reaction mixture was extracted with EtOAc (3 × 5 mL). The combined organic phases were dried over

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

• culture for 12 h at 37 °C in an atmosphere of 95% air and 5% CO2 saturated with H2O, the drug solutions were transferred into each cell culture to make up 200 μL of the culture. The highest concentration of the vehicle solvents (MeOH or DMSO) was set at 0.5 vol %, where the growth of the cells was not

When metal-catalyzed C–H functionalization meets visible-light photocatalysis

• Lucas Guillemard and
• Joanna Wencel-Delord

Beilstein J. Org. Chem. 2020, 16, 1754–1804, doi:10.3762/bjoc.16.147

• general strategy, in 2014, Rueping and co-workers reported the pioneering contribution concerning the synthesis of indoles via an intramolecular C–H/C–H oxidative coupling of N-arylenamines under air atmosphere. This procedure was based on dual catalysis involving a double C–H activation system and

• described the combination of rhodium and photoredox catalysis for the direct C–H ortho-olefination of arylamides (Figure 7) [74]. The procedure was performed under air at 80 °C and turned out to be efficient using a low loading of a Ru-based photosensitizer. A broad range of DGs could be installed on the

• under air atmosphere and required harsh reaction conditions with temperatures of up to 120 °C. The substituents on both substrates had a minor impact on the reaction outcome and the coupling products were isolated in comparable yields. The applicability of the reaction was underlined by its tolerance

Et₃N/DMSO-supported one-pot synthesis of highly fluorescent β-carboline-linked benzothiophenones via sulfur insertion and estimation of the photophysical properties

• Dharmender Singh,
• Vipin Kumar and
• Virender Singh

Beilstein J. Org. Chem. 2020, 16, 1740–1753, doi:10.3762/bjoc.16.146

• synthesis of benzothiophenes, however, these methods rely on the use of organosulfur-based substrates [38][39][40][41]. Moreover, these methods are associated with some limitations such as using costly metal catalysts, air-sensitive starting materials, malodorous sulfides or thiols, low yields, and

Tuneable access to indole, indolone, and cinnoline derivatives from a common 1,4-diketone Michael acceptor

• Dalel El-Marrouki,
• Sabrina Touchet,
• Abderrahmen Abdelli,
• Hédi M’Rabet,
• Mohamed Lotfi Efrit and
• Philippe C. Gros

Beilstein J. Org. Chem. 2020, 16, 1722–1731, doi:10.3762/bjoc.16.144

• under air. Herein, we report our investigations on this reaction, and we have shown that it can be selectively directed towards the synthesis of indole, indolone, or cinnoline derivatives by just changing the substrates, substituents, or heating mode (Scheme 1). Results and Discussion The synthesis of

Clickable azide-functionalized bromoarylaldehydes – synthesis and photophysical characterization

• Dominik Göbel,
• Marius Friedrich,
• Enno Lork and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2020, 16, 1683–1692, doi:10.3762/bjoc.16.139

• rare [64][65][66][67][68][69]. Takeuchi et al. [28] reported a bromofluorenecarbaldehyde 2 which shows blue fluorescence in chloroform at 298 K under air and green phosphorescence under argon with a phosphorescence quantum yield of ΦP = 5.9% (Figure 1b). This observation is reasoned by a strong (π,π

Rearrangement of o-(pivaloylaminomethyl)benzaldehydes: an experimental and computational study

• Csilla Hargitai,
• Györgyi Koványi-Lax,
• Tamás Nagy,
• Péter Ábrányi-Balogh,
• András Dancsó,
• Gábor Tóth,
• Judit Halász,
• Angéla Pandur,
• Gyula Simig and
• Balázs Volk

Beilstein J. Org. Chem. 2020, 16, 1636–1648, doi:10.3762/bjoc.16.136

• Raney nickel (Ra-Ni), sometimes as the main product, depending on the activity of the catalyst [10] (Scheme 2). The oxidative dimerization of 1-phenylisoindole (6a) to compound 5a took place under various conditions: when refluxing in benzene in the presence of air [5][11], during an attempted

A dynamic combinatorial library for biomimetic recognition of dipeptides in water

• Florian Klepel and
• Bart Jan Ravoo

Beilstein J. Org. Chem. 2020, 16, 1588–1595, doi:10.3762/bjoc.16.131

• mL vial. Another 100 µL of a template stock solution (90 mM) was added. For a reference sample the template solution was substituted for buffer. Small magnetic stirring bars were added, and the vials were covered by a layer of perforated Parafilm to slow down drying due to fast air exchange. After

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

• some interesting reactor designs that could be implemented to enhance organic synthesis. Keywords: air purification; flow chemistry; heterogeneous photoredox catalysis; organic synthesis; reactor design; water purification; Review 1 Introduction 1.1 Scope of the review This review aims to be of

• transfer catalysis (EnT, Section 4.2). The final two subsections review the importance of HPCats in flow reactors for the photocatalytic remediation of wastewater (Section 4.3) and air pollution (Section 4.4), an increasingly significant area of research to prevent damage to the environment and human

• recombination [154][155]. Suárez and co-workers used the photodeposition of platinum onto tungsten oxide (WO3) powder, before immobilising within a zeolite framework to produce visible light-active HPCats for the degradation of pollutants in air [156]. Scaiano and co-workers have also utilised photodeposition

An overview on disulfide-catalyzed and -cocatalyzed photoreactions

• Yeersen Patehebieke

Beilstein J. Org. Chem. 2020, 16, 1418–1435, doi:10.3762/bjoc.16.118

• attractive because the reagents involved in the reaction process are simple and inexpensive, plus they only require molecular oxygen or air. In addition, disulfide-catalyzed cyclization reactions are also very effective for the generation of five- and six-membered rings. The unique high selectivity and

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

• solids without clogging. More recently, we began to think about this combination for producing air- and water-sensitive reagents immediately prior to use. In particular, we were interested in addressing a dichotomy where discovery-scale (50–100 mL) organometallic reagents are used with uncertain

• with perfluorinated polymer film (PFA), and the bags are filled with the fluid to dispense. The pumping is accomplished by enclosing the bag in a metal clamshell, with contact surfaces made with an elastomer (Figure 3A). When compressed air is pumped in the clamshell, it squeezes the bag through the

• keep the back pressure and a constant flow rate is achieved by the tubing length and diameter downstream of the pump or by the fluidic network for more complex cases. The flow is pulseless as a result of the fact that it is driven by compressed air. On-demand reagent (ODR) system design: The ODR

Photocatalytic trifluoromethoxylation of arenes and heteroarenes in continuous-flow

• Alexander V. Nyuchev,
• Ting Wan,
• Borja Cendón,
• Carlo Sambiagio,
• Job J. C. Struijs,
• Michelle Ho,
• Moisés Gulías,
• Ying Wang and
• Timothy Noël

Beilstein J. Org. Chem. 2020, 16, 1305–1312, doi:10.3762/bjoc.16.111

• less side-products (derived from alternative radical formation from the other two reagents [23][25]) and tolerance towards water and air gives this reagent a certain advantage over the others [24]. To transfer the batch procedure into continuous-flow conditions, the concentration of 1 was initially

Oxime radicals: generation, properties and application in organic synthesis

• Igor B. Krylov,
• Stanislav A. Paveliev,
• Alexander S. Budnikov and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2020, 16, 1234–1276, doi:10.3762/bjoc.16.107

• either 1,2,4-oxadiazoles 72 or quinazolinones 73 (Scheme 26), depending on the reaction conditions. The 1,2,4-oxadiazole ring was selectively obtained in DMF at 60 °С under oxygen atmosphere (1 atm) in the presence of an excess of K3PO4, whereas in DMSO at 100 °С under air and in the presence of Cs2CO3

• (nmp)2) resulted in isoxazolines 110 with a hydroxylmethyl group or methylisoxazolines 111 (Scheme 35) [125]. The reaction in iPrOH under an oxygen atmosphere with the addition of 10 mol % of t-BuOOH (conditions A) produced hydroxymethylisoxazolines 110, and the reaction in toluene under air with the

• oxygen of air (Scheme 36) [126]. The peroxide initially formed in the reaction was reduced by treatment with a saturated Na2S2O4 solution. The formation of peroxide was confirmed by a control experiment in which the hydroperoxide 113b’ was isolated when the treatment of the reaction mixture with sodium

Activated carbon as catalyst support: precursors, preparation, modification and characterization

• Melanie Iwanow,
• Tobias Gärtner,
• Volker Sieber and
• Burkhard König

Beilstein J. Org. Chem. 2020, 16, 1188–1202, doi:10.3762/bjoc.16.104

• . After preparation of char by carbonization of the precursor materials for a certain time at a defined temperature under inert gas atmosphere, steam, air or CO2 activate the materials at higher temperatures (800–1000 °C) to form a porous structure according to the Equations 1–3 [81][85][86]. It is

• of oxygen-containing surface groups can be influenced by treatment with different oxidants such as H2O2, HNO3, oxygen/ air, ozone or NaOCl. Thereby, the acidic or basic behavior and the resulting surface chemistry of the activated carbons are determined. Jaramillo et al. investigated the influence of

• different oxidizing reagents on the activated carbon materials prepared from cherry stones. Different amounts of oxygen functional groups were found on the surface of the materials depending on the oxidizing agents used: HNO3 > O3 > H2O2 > O2 (air). Mostly carboxyl groups were formed by the oxidative