Catalytic trifluoromethylation of iodoarenes by use of 2-trifluoromethylated benzimidazoline as trifluoromethylating reagent

• Tatsuhiro Uchikura,
• Nanami Kamiyama,
• Taisuke Ishikawa and
• Takahiko Akiyama

Beilstein J. Org. Chem. 2020, 16, 2442–2447, doi:10.3762/bjoc.16.198

• synthesis. Experimental General procedure of trifluoromethylation: Aryl iodide 1 (0.1 mmol), 2 (56 mg, 0.2 mmol), CuI (3.8 mg, 0.02 mmol), 2,2’-bipyridyl (12.5 mg, 0.08 mmol), and potassium carbonate (55.6 mg, 0.4 mmol) were mixed in benzonitrile (1.0 mL), and the mixture heated to 90 °C. After 48 h

Design and synthesis of a bis-macrocyclic host and guests as building blocks for small molecular knots

• Elizabeth A. Margolis,
• Rebecca J. Keyes,
• Stephen D. Lockey IV and
• Edward E. Fenlon

Beilstein J. Org. Chem. 2020, 16, 2314–2321, doi:10.3762/bjoc.16.192

• bromide in 1-bromo-4-chlorobutane (16) with sodium azide to give azide 17 in 52% yield (Scheme 5). Treatment of 17 with potassium phthalimide and catalytic potassium iodide was followed by hydrazine unmasking to give the desired aminoazide 18 in 37% over the two steps. Reductive amination of 18 with dial

The B & B approach: Ball-milling conjugation of dextran with phenylboronic acid (PBA)-functionalized BODIPY

• Patrizia Andreozzi,
• Lorenza Tamberi,
• Elisamaria Tasca,
• Gina Elena Giacomazzo,
• Marta Martinez,
• Mirko Severi,
• Marco Marradi,
• Stefano Cicchi,
• Sergio Moya,
• Giacomo Biagiotti and
• Barbara Richichi

Beilstein J. Org. Chem. 2020, 16, 2272–2281, doi:10.3762/bjoc.16.188

• recorded on an Inova 400 instrument. Fourier transform infra red absorption spectroscopy (FTIR) was carried out with a Shimadzu IRAffinity-1S spectrometer. Potassium bromide (KBr) pellets were prepared using 100 mg of potassium bromide and 1.0 mg of sample. The spectra were recorded under inert atmosphere

• and a pure potassium bromide pellet was used as background. Inductively coupled plasma atomic emission spectroscopy (ICP-AES) was used to determine the boron (B) concentrations and was performed in triplicate using a Varian 720-ES Inductively Coupled Plasma Atomic Emission Spectrometer (ICP-AES). An

Synthetic approaches to bowl-shaped π-conjugated sumanene and its congeners

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 2212–2259, doi:10.3762/bjoc.16.186

• tripotassiumsumanenide [68]. As can be inspected from Scheme 36, this complex was prepared by treating the sumanene molecule with an excess of potassium metal. After stirring the reaction for 56 h, the suspension was filtered off and the filtrate was layered in hexanes at 10 °C to yield the beautiful dark-red blocks of

• generate the corresponding pyrazine-fused sumanene networks 169a–f and 170a–f in low-to-good yields (Scheme 44). As can be inspected from Scheme 45, oxidation of 155 and 160 with both oxone (potassium peroxymonosulfate) and H2O2 afforded the one-ring-opened product 177. Interestingly, when these compounds

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

• azidochalcones, when treated with potassium thiocyanate in the presence of potassium persulfate, lead to 2,4,5-trisubstituted oxazoles in good yields. Incidentally, 2-aminothiazoles are the products when ferric nitrate is employed instead of persulfate in the above reaction. Keywords: aminothiazole; oxazole

• ; potassium persulfate; thiazole; vinyl azide; Introduction Vinyl azide is one of the most versatile and potent building blocks explored in the synthesis of several heterocycles [1][2][3][4][5]. It can undergo photolysis or thermolysis to afford highly strained three-membered 2H-azirine, which can act as the

• substituted α-azidochalcones with potassium thiocyanate. Thiocyanate is a known ambident reagent with two potential sites of attack, enabling the selective and efficient construction of C–C and C–N bonds towards biologically important heterocyclic skeletons [62][63][64]. Results and Discussion Previously, we

Convenient access to pyrrolidin-3-ylphosphonic acids and tetrahydro-2H-pyran-3-ylphosphonates with multiple contiguous stereocenters from nonracemic adducts of a Ni(II)-catalyzed Michael reaction

• Alexander N. Reznikov,
• Dmitry S. Nikerov,
• Anastasiya E. Sibiryakova,
• Victor B. Rybakov,
• Evgeniy V. Golovin and
• Yuri N. Klimochkin

Beilstein J. Org. Chem. 2020, 16, 2073–2079, doi:10.3762/bjoc.16.174

• detected in the reaction even after 72 h in the presence of 1 equiv of potassium phosphate or carbonate with TEBAC (0.1 equiv, Table 1, entries 4 and 5). If potassium fluoride or cesium carbonate were used as a base, the initial phosphonate 6e was consumed in a few hours, but unidentified products were

The biomimetic synthesis of balsaminone A and ellagic acid via oxidative dimerization

• Sharna-kay Daley and
• Nadale Downer-Riley

Beilstein J. Org. Chem. 2020, 16, 2026–2031, doi:10.3762/bjoc.16.169

• ), was subjected to the oxidants activated carbon (Act-C), potassium ferricyanide (K3[Fe(CN)6]), p-benzoquinone and stannic chloride (SnCl4). As shown in Scheme 4, with the exception of SnCl4, all oxidants resulted in the re-oxidation of the hydroxylated substrate to naphthoquinone 7. SnCl4, however

Syntheses of spliceostatins and thailanstatins: a review

• William A. Donaldson

Beilstein J. Org. Chem. 2020, 16, 1991–2006, doi:10.3762/bjoc.16.166

• -methyl-3-buten-1-yl tosylate in the presence of Grubbs’ 2nd generation catalyst yielded 59, which, upon elimination with potassium tert-butoxide led to the diene 50. The reductive amination of 50 afforded an inseparable mixture of the C-14 amines (6:1 ratio). However, the amidation of this mixture with

Metal-free synthesis of phosphinoylchroman-4-ones via a radical phosphinoylation–cyclization cascade mediated by K₂S₂O₈

• Qiang Liu,
• Weibang Lu,
• Guanqun Xie and
• Xiaoxia Wang

Beilstein J. Org. Chem. 2020, 16, 1974–1982, doi:10.3762/bjoc.16.164

• afforded the title compounds in moderate yields. Keywords: chroman-4-ones; diphenylphosphine oxide; metal-free; potassium persulfate; radical cyclization; Introduction The chroman-4-one framework is a privileged structural motif found in numerous natural products and pharmaceuticals with extraordinary

• potassium persulfate [42][43][44]. Based on literature precedent [29][30][42][43][44][45][46] and preliminary mechanistic experiments, a plausible mechanism was proposed in Scheme 5 which was different from the predominant mechanism observed in the Ag-catalyzed radical cascade for the preparation of

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

• -azido ketones in iPrOH in the presence of potassium ethylxanthate as a catalyst [28], (b) by exploiting the reaction of arylglyoxals with an excess amount of ammonium acetate in water [29], (c) by the cathodic reduction of 2-azido-1-phenylethanone in a DMF/LiClO4 medium [30], (d) by radical chain

Design, synthesis and application of carbazole macrocycles in anion sensors

• Alo Rüütel,
• Ville Yrjänä,
• Sandip A. Kadam,
• Indrek Saar,
• Mihkel Ilisson,
• Astrid Darnell,
• Kristjan Haav,
• Tõiv Haljasorg,
• Lauri Toom,
• Johan Bobacka and
• Ivo Leito

Beilstein J. Org. Chem. 2020, 16, 1901–1914, doi:10.3762/bjoc.16.157

• calibration and pH-sensitivity measurements. Both the control and MC005 sensors were more selective for chloride than for acetate. When these sensors were combined with the reference electrode, which had a 1 M potassium chloride outer filling solution, the chloride interfered and caused drifting

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

• single electron-transfer process (Figure 36). In the first place, a bidentate chelated species is formed by the coordination of 1-naphthylamine derivatives with copper salt. The subsequent oxidation of this intermediate with potassium persulfate produces a Cu(III) species, furnishing a radical cation on

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

• amine/base with DMSO as an activator. Potassium ethylxanthate [64][65] and sodium sulfide as a sulfur sources in the presence of Et3N in DMSO (Table 1, entries 8 and 9) also did not furnish the desired product 2bA. A decomposition of the product was observed in the case of Na2S. Interestingly, the

Facile synthesis of 7-alkyl-1,2,3,4-tetrahydro-1,8-naphthyridines as arginine mimetics using a Horner–Wadsworth–Emmons-based approach

• Rhys A. Lippa,
• John A. Murphy and
• Tim N. Barrett

Beilstein J. Org. Chem. 2020, 16, 1617–1626, doi:10.3762/bjoc.16.134

• , exploiting the base stability of the phosphoramidate protecting group. A variety of bases were trialed at 0 °C for the initial N-phosphorylation, with 10 minutes allowed for complete deprotonation to occur (Table 1). Only minimal phosphorylation was observed when using potassium tert-butoxide (Table 1, entry

• (1.5–2.4 equiv) and proceeded in <1 h. Sodium hydride was investigated as a heterogeneous alternative to potassium tert-butoxide, although a lower isolated yield of the final amine was obtained. All amines were formed in high NMR and LC–MS purity without the need for purification by column

• taking place (Scheme 8) [24][25][26]. The autoxidation of phosphonates under THF/potassium tert-butoxide has been reported previously [27]. In order to circumvent racemisation of aldehyde 22 during the Horner–Wadsworth–Emmons olefination, alkylation of phosphoramidate 13 was explored using commercially

Recent synthesis of thietanes

• Jiaxi Xu

Beilstein J. Org. Chem. 2020, 16, 1357–1410, doi:10.3762/bjoc.16.116

• chloromethylthiirane (epithiochlorohydrin, 398a), with hard and weak nucleophiles [105][106][107][108][109], including phenoxides [105], carboxylates and dicarboxylates [106][107], potassium cyanide, sodium azide, hydroxylamine, trifluoromethanesulfonamide, and pyridine [108]. However, the method could only applied to

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

• intramolecular Heck cross-coupling reaction of the octahydroindoles 9/10 to the pentacycles 11, the process was explored with the simple substrates 8c,d and 8g (Scheme 4). Thus, the Pd(0)-catalyzed cyclization of the latter vinylpyrroles with potassium acetate and using acetonitrile or dimethylacetamide (DMA) as

• ). Optimized reaction conditions were established by using 9j as the model substrate and changing the catalyst, base and solvent. Palladium acetate was not efficient for the conversion, even though the base was modified (Table 3, entries 1 and 2). Pd(PPh3)4 was a better catalyst when employing potassium

Synthesis of 3-substituted isoxazolidin-4-ols using hydroboration–oxidation reactions of 4,5-unsubstituted 2,3-dihydroisoxazoles

• Lívia Dikošová,
• Júlia Laceková,
• Ondrej Záborský and
• Róbert Fischer

Beilstein J. Org. Chem. 2020, 16, 1313–1319, doi:10.3762/bjoc.16.112

• , respectively, according to our procedure [7][10]. The compounds 5a and 5b were first converted into the isoxazolidine-4,5-diols by the treatment with potassium osmate/N-methylmorpholine N-oxide (NMO). The dihydroxylation reactions proceeded with an excellent trans selectivity with respect to the substituent at

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

• soluble bases such as amines and tetrabutylammonium salts (Table 2, entries 1–5) proved unfortunately not successful, neither in batch nor flow, so we extended the investigation to inorganic bases. Among the bases tested, potassium hydrogenphosphates K2HPO4 and KH2PO4 led to increased yields, reaching up

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

• . investigated the chemical activation with sodium or potassium hydroxide by the use of an anthracite precursor [8][13][14]. Wood Non-fossil precursors for the preparation of activated carbons are of great interest due to an increasing demand of these materials. Wood and the lignocellulosic wastes from forestry

• solutions Xu et al. used energy-rich carbon precursors for the spherical carbon preparation via ultrasonic spray pyrolysis. Lithium, sodium or potassium propiolates are one class of such energy rich materials and exhibit leaving groups such as CO, CO2 or C2H2 eliminated by decarbonylation or decarboxylation

• found that KOH plays a crucial role in the formation of porosity. Metallic potassium is formed during the carbonization of the carbon precursor, which intercalates in the carbon structure and is responsible for further release of carbon dioxide, carbon monoxide and hydrogen [71]. According to Marsh and

Photocatalysis with organic dyes: facile access to reactive intermediates for synthesis

• Stephanie G. E. Amos,
• Marion Garreau,
• Luca Buzzetti and
• Jerome Waser

Beilstein J. Org. Chem. 2020, 16, 1163–1187, doi:10.3762/bjoc.16.103

• salt 6.1 was promoted by the acridinium photocatalyst OD2. The resulting alkyl radical can be intercepted by a protonated heteroarene 6.2. The addition of potassium persulfate leads to the regeneration of the photocatalyst and the rearomatization of the intermediate, delivering the desired alkylated

Synthesis of novel multifunctional carbazole-based molecules and their thermal, electrochemical and optical properties

• Nuray Altinolcek,
• Ahmet Battal,
• Mustafa Tavasli,
• William J. Peveler,
• Holly A. Yu and
• Peter J. Skabara

Beilstein J. Org. Chem. 2020, 16, 1066–1074, doi:10.3762/bjoc.16.93

• potassium acetate (KOAc) and dichlorobis(triphenylphosphine)palladium(II) in 1,4-dioxane [36][37]. Upon chromatography (9-hexylcarbazole-3-yl)boronic acid pinacol ester (5) was obtained as a liquid in good yield. (9-Hexylcarbazole-3-yl)boronic acid pinacol ester (5) was subjected to Suzuki–Miyaura reaction

• either with 2-bromopyridine-4-carbaldehyde (6a) or 2-bromopyridine-5-carbaldehyde (6b) in the presence of potassium carbonate and bis(triphenylphosphine)palladium(II) dichloride in tetrahydrofuran [2]. Upon repeated purification by chromatography, compounds 7a and 7b were obtained as liquids in good

• ), 0.86 (t, J = 7.0 Hz, 4H). (9-Hexylcarbazole-3-yl)boronic acid pinacol ester (5): 5 was synthesised as reported previously [36][37]. Bis(pinacolato)diboron (423 mg, 1.7 mmol), potassium acetate (446 mg, 4.5 mmol) and dichlorobis(triphenylphosphine)palladium(II) (35 mg, 0.05 mmol) catalyst were added to

Fluorinated phenylalanines: synthesis and pharmaceutical applications

• Laila F. Awad and
• Mohammed Salah Ayoup

Beilstein J. Org. Chem. 2020, 16, 1022–1050, doi:10.3762/bjoc.16.91

• the free amines gave amides 28a,b. Treatment of the latter with aqueous potassium hydroxide finally afforded (S)-2-amino-3-(2,3,4,5-tetrafluorophenyl)propionic acid (29a) and (S)-2-amino-3-(2,3,5,6-tetrafluorophenyl)propionic acid (29b) [42] (Scheme 6). Alternatively, phenylalanines 29a,b were also

Suzuki–Miyaura cross coupling is not an informative reaction to demonstrate the performance of new solvents

• James Sherwood

Beilstein J. Org. Chem. 2020, 16, 1001–1005, doi:10.3762/bjoc.16.89

•  1b) [13]. Here, palladium acetate without an auxiliary ligand was used for a pre-catalyst and the base changed to potassium carbonate. Reaction conditions of 20 hours at 65 °C were decided after observing 11% conversion after 2 hours and 33% after 20 hours in NMP at room temperature. The majority of

• ™, GVL, and 2-MeTHF were poor solvents. Replacing potassium carbonate with triethylamine, the conversion in Cyrene™ rose slightly to 10%. Despite the variation between experiments no discernible correlation between any solvent properties and the observed conversions was found. The results achieved in DMI

Aryl-substituted acridanes as hosts for TADF-based OLEDs

• Naveen Masimukku,
• Dalius Gudeika,
• Oleksandr Bezvikonnyi,
• Ihor Syvorotka,
• Rasa Keruckiene,
• Dmytro Volyniuk and
• Juozas V. Grazulevicius

Beilstein J. Org. Chem. 2020, 16, 989–1000, doi:10.3762/bjoc.16.88

• bromide (0.06 g, 0.1 mmol) and potassium hydroxide (0.31 g, 5.7 mmol) were added and the mixture stirred for 30 min. Then, bromoethane (0.31 g, 2.85 mmol) was added dropwise to the reaction mixture with constant stirring and the mixture refluxed for 1 h. The reaction mixture was then poured into ice water

Bipyrrole boomerangs via Pd-mediated tandem cyclization–oxygenation. Controlling reaction selectivity and electronic properties

• Liliia Moshniaha,
• Marika Żyła-Karwowska,
• Joanna Cybińska,
• Piotr J. Chmielewski,
• Ludovic Favereau and
• Marcin Stępień

Beilstein J. Org. Chem. 2020, 16, 895–903, doi:10.3762/bjoc.16.81

• of NDAnH and NMInH carried out in the presence of 6 equiv of potassium acetate produced the corresponding dilactams in higher yields (53–73%) with complete conversion (Table 1, entries 2, 7, 12, and 18). Under these conditions, the cNMI2H and cNMI3H intermediates were not isolated. When the same