Synthesis of aryl 2-bromo-2-chloro-1,1-difluoroethyl ethers through the base-mediated reaction between phenols and halothane

• Yukiko Karuo,
• Ayaka Kametani,
• Atsushi Tarui,
• Kazuyuki Sato,
• Kentaro Kawai and
• Masaaki Omote

Beilstein J. Org. Chem. 2021, 17, 89–96, doi:10.3762/bjoc.17.9

• ether was the reaction of phenol with 2-chloro-1,1,1-trifluoroethane, also known as HCFC-133a, in the presence of potassium hydroxide (KOH) to give the gem-difluoromethyl ethers along with the formation of 1-fluoro-2-chlorovinyl ether (route (d), Scheme 1) [41]. On the basis of our previous reports, we

• did not occur at all when potassium carbonate was used as a base, because the deprotonation of phenol became slow due to the low basicity (Table 1, entry 9). With the optimal reaction conditions (Table 1, entry 8) in hand, we next examined the scope of the reaction (Table 2). When an electron-rich

• the product 2a in 27% yield and 1a was recovered in 54% (Scheme 4a). Based on these results, we speculated that the initially generated phenoxide 4 or potassium hydroxide remaining in the reaction mixture could deprotonate halothane to provide the fully halogenated ethylene 5 (Scheme 4b) [32][33][45

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

• a 6-step sequence from 3,4-dihydro-2-ethoxy-2H-pyran (58) [50]. Treatment of 58 with a mixture of butyllithium and potassium tert-butoxide in the presence of TMEDA and pentane, followed by reaction with the corresponding alkyl iodides in THF, and finally, acidic cleavage of the generated acetal

• tetroxide and potassium periodate, to provide (−)-adaline (1) and (−)-euphococcinine (2). Originally, Yu et al. synthesized (−)-adaline (1) with good yields and high enantiomeric excess using catalytic asymmetric allylation from commercially available 58. Additionally, intramolecular allylic transfer led to

• stereospecific semipinacol rearrangement in 78% yield over two steps. The resulting terminal alkene (−)-70 was submitted to Vacker's conditions to produce methyl ketone (−)-71 in 93% yield. The treatment of this ketone with potassium trimethylsilanolate induced a 1,5-Michael type reaction, via attack of tethered

Synthesis of imidazo[1,5-a]pyridines via cyclocondensation of 2-(aminomethyl)pyridines with electrophilically activated nitroalkanes

• Dmitrii A. Aksenov,
• Nikolai A. Arutiunov,
• Vladimir V. Maliuga,
• Alexander V. Aksenov and
• Michael Rubin

Beilstein J. Org. Chem. 2020, 16, 2903–2910, doi:10.3762/bjoc.16.239

• (3.01 g, 10 mmol) in DMF (16 mL) was added potassium phthalimide (1.85 g, 10 mmol) in portions. The mixture was stirred at room temperature for 5 h. Then, water (30 mL) was added, and the formed precipitate was collected by filtration and washed with water. Recrystallization from ethanol afforded

Bifurcated synthesis of methylene-lactone- and methylene-lactam-fused spirolactams via electrophilic amide allylation of γ-phenylthio-functionalized γ-lactams

• Tetsuya Sengoku,
• Koki Makino,
• Ayumi Iijima,
• Toshiyasu Inuzuka and
• Hidemi Yoda

Beilstein J. Org. Chem. 2020, 16, 2769–2775, doi:10.3762/bjoc.16.227

• such as potassium tert-butoxide or sodium hydride resulted in no formation of the desired product 3a because 2a was decomposed under the harsh reaction conditions (Table 1, entries 2 and 3). Thus we opted to employ another substrate 2b bearing a phenylthio group which polarizes the α-C–H bond to lead

• the corresponding stabilized anion [20] and is readily transformed into a hydroxy group by treatment with copper bromide according to our previous work [21]. Allylation of 2b with 1a at room temperature proceeded in the presence of a catalytic amount of Pd(PPh3)4 by using potassium tert-butoxide or

Optical detection of di- and triphosphate anions with mixed monolayer-protected gold nanoparticles containing zinc(II)–dipicolylamine complexes

• Lena Reinke,
• Julia Bartl,
• Marcus Koch and
• Stefan Kubik

Beilstein J. Org. Chem. 2020, 16, 2687–2700, doi:10.3762/bjoc.16.219

• with a complementary base sequence [10], the AuNPs with peripheral carboxylate groups introduced by the Hupp group [11] that responded to divalent transition metal ions, or Chen at al.’s crown ether-decorated AuNPs that allowed the sensing of potassium ions [12]. Numerous other such probes have been

• nanoparticle surface after immobilization. Compound 2 was prepared by starting from potassium phthalimide and 1,12-dibromododecane (Scheme 2). The product resulting from this step was treated with bis(2-pyridylmethyl)amine to give a DPA derivative that was coupled to (R)-lipoic acid after deprotection to

• . Conditions: i) potassium phthalimide, DMF, 25 °C, 18 h, 67%; ii) 2,2'-dipicolylamine, K2CO3, KI, acetone, reflux 14 h, 50%; iii) N2H4⋅H2O, ethanol, 25 °C, 16 h, 56%; iv) (R)-lipoic acid, EDC⋅HCl, DMAP, CH2Cl2, 25 °C, 18 h, 52%. Minimum salt concentrations required to precipitate and to subsequently

Particle size effect in the mechanically assisted synthesis of β-cyclodextrin mesitylene sulfonate

• Stéphane Menuel,
• Sébastien Saitzek,
• Eric Monflier and
• Frédéric Hapiot

Beilstein J. Org. Chem. 2020, 16, 2598–2606, doi:10.3762/bjoc.16.211

• %) and potassium hydroxide (90%) were purchased from Sigma-Aldrich. All chemicals were used without further purification. Preparation of β-CD samples Analogously as described in [14]. General procedure for the synthesis of mono-6-O-(2-mesitylenesulfonyl)-β-cyclodextrin β-CD (1500 mg, 1.32 mmol) and MtsCl

Synthesis of novel fluorinated building blocks via halofluorination and related reactions

• Attila Márió Remete,
• Tamás T. Novák,
• Melinda Nonn,
• Matti Haukka,
• Ferenc Fülöp and
• Loránd Kiss

Beilstein J. Org. Chem. 2020, 16, 2562–2575, doi:10.3762/bjoc.16.208

• interactions are marked with two-headed arrows. Mechanism of the halofluorination reactions of the substrate 19. X = Br (compounds a), I (compounds b), Cl (compounds c). Synthesis and halofluorination of the imide 24. Cyclizations of halofluorinated diesters with potassium tert-butoxide. Relevant NOESY

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

• Discussion Synthesis of the host TBTQ-(OG)6. The sugar-functionalized host TBTQ-(OG)6 was synthesized starting from the known compound TBTQ-(OH)6 (Scheme 1) [31][32][33]. The reaction of TBTQ-(OH)6 with propargyl bromide in the presence of potassium carbonate gave the hexakis-propargyl ether, TBTQ-(OP)6, in

• imaging. Freeze drying was conducted on a Scientz-18N freeze dryer (Scientz Biotech, Zhejiang, China). Synthesis of TBTQ-(OP)6. A mixture of TBTQ-(OH)6 (2.17 g, 5.56 mmol), potassium carbonate (9.23 g, 66.8 mmol), and propargyl bromide (5.40 g, 44.5 mmol, 98 wt %) in acetonitrile (100 mL) was stirred and

NMR Spectroscopy of supramolecular chemistry on protein surfaces

• Peter Bayer,
• Anja Matena and
• Christine Beuck

Beilstein J. Org. Chem. 2020, 16, 2505–2522, doi:10.3762/bjoc.16.203

• been used to design custom plugs for the negatively charged central cavity of tetrameric proteins, exploiting the four-fold symmetry of the ligand [39][40]. In the case of tetrameric voltage-dependent potassium channels, binding of the calixarene to the central pore of the channel results in reversible

• inhibition of potassium ion transport [39]. Another guanidinium-calixarene variant was designed to hold together the four tetramer subunits of a p53-R337H tumor suppressor mutant and thus restore tetramer stability [40]. Further examples for ligands targeting negatively charged patches on proteins include

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