Synthesis of tricarbonylated propargylamine and conversion to 2,5-disubstituted oxazole-4-carboxylates

• Kento Iwai,
• Akari Hikasa,
• Kotaro Yoshioka,
• Shinki Tani,
• Kazuto Umezu and
• Nagatoshi Nishiwaki

Beilstein J. Org. Chem. 2024, 20, 2827–2833, doi:10.3762/bjoc.20.238

•  3) [13][14]. To a dry THF solution of adduct 4a, butyllithium was added, and the reaction mixture was stirred at −78 °C for 5 min. Following the addition of acetic acid, the reaction mixture was concentrated and subjected to silica gel column chromatography, resulting in the isolation of ethyl 5

• ), the mixture was concentrated under reduced pressure. The residue was purified by column chromatography on silica gel (eluent: hexane/ethyl acetate 70:30, Rf 0.55) to afford diethyl 2-[(4-methylbenzoyl)amino]-2-(phenylethynyl)propanedioate (4a, 122 mg, 0.31 mmol, 78% yield) as yellow oil. 1H NMR (400

• acetic acid (0.1 mL), the solvent was removed under reduced pressure. The residue was purified by column chromatography on silica gel (eluent: hexane/ethyl acetate 70:30, eluent for TLC: hexane/ethyl acetate 80:20, Rf 0.61) to afford ethyl 2-(4-methylphenyl)-5-(phenylmethyl)oxazole-4-carboxylate (5a

Synthesis and antimycotic activity of new derivatives of imidazo[1,2-a]pyrimidines

• Dmitriy Yu. Vandyshev,
• Daria A. Mangusheva,
• Khidmet S. Shikhaliev,
• Kirill A. Scherbakov,
• Oleg N. Burov,
• Alexander D. Zagrebaev,
• Tatiana N. Khmelevskaya,
• Alexey S. Trenin and
• Fedor I. Zubkov

Beilstein J. Org. Chem. 2024, 20, 2806–2817, doi:10.3762/bjoc.20.236

• hemisulfate to its basic form in situ. Thin-layer chromatography (TLC) and high-performance liquid chromatography with mass-spectrometric detection (HPLC–MS) were used to monitor the reaction and to identify the products obtained. It should be noted that in the case of HPLC–MS analysis, the signals registered

Mechanochemical difluoromethylations of ketones

• Jinbo Ke,
• Pit van Bonn and
• Carsten Bolm

Beilstein J. Org. Chem. 2024, 20, 2799–2805, doi:10.3762/bjoc.20.235

• spectroscopy with 1,2-dichloroethane as the internal standard. After these analyses, isolating the products by column chromatography was attempted. Unfortunately, many products were highly volatile and very non-polar, rendering the purification difficult. As a result, in several cases only little or no product

• chromatography, which afforded the products in 53% and 39% yield, respectively. Product 3e with an isobutyl group in para-position was obtained in 63% yield and isolated in 35% yield. Changing the position of the methyl group to the ortho-position led to a decrease in yield (3f: 34%). ortho-Methoxy-substituted

• ketone 1g provided the corresponding product 3g in 56% yield. Difluoromethyl enol ether 3h with three methyl groups was obtained in 56% yield and column chromatography allowed to isolate it in 42% yield. 2-Acetonaphthone was successfully converted to 3i in 66% yield. Besides aryl ketones, arylalkyl

Synthesis of spiroindolenines through a one-pot multistep process mediated by visible light

• Francesco Gambuti,
• Jacopo Pizzorno,
• Chiara Lambruschini,
• Renata Riva and
• Lisa Moni

Beilstein J. Org. Chem. 2024, 20, 2722–2731, doi:10.3762/bjoc.20.230

• yield of 88% each step). Since, during the optimization of the reaction conditions, we have noticed a certain instability of the spiro-compounds through chromatography on silica gel, we have initially carried out the purifications using alumina as the stationary phase. However, during the scope studies

• the solvent and using Et3N as additive for the eluent of the chromatography on silica gel. With these improvements, we have demonstrated that the yields are comparable to those obtained with purification on alumina but reaching significantly higher degrees of purity of the final products (see

• °C at 451 nm (blue LEDs) under magnetic stirring for 24 h. The reaction mixture was treated with Et3N (3 equiv, 1.44 mmol, 200 µL), concentrated and the residue was purified by column chromatography on silica gel with PE/Et2O (from 85:15 to 75:25) to give 3a (121 mg, 61%), as yellow oil; IR (ATR) ν̃

Synthesis of benzo[f]quinazoline-1,3(2H,4H)-diones

• Ruben Manuel Figueira de Abreu,
• Peter Ehlers and
• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 2708–2719, doi:10.3762/bjoc.20.228

• -Flight (TOF) LC–MS. The solvent, toluene, was purchased as dry solvent and applied without further purification. Other reagents, catalysts, ligands, acids, and bases were used as purchased from commercial suppliers. Column chromatography was performed on Merck Silica gel 60 (particle size 63–200 μm

• ). Solvents for extraction and column chromatography were distilled prior employment. Synthesis of 4a–i The synthesis of 4a–f has been previously reported. Novel derivatives 4g–i were prepared according to our previously reported procedure [65]. 1,3-Dimethyl-5-phenyl-6-(phenylethynyl)pyrimidine-2,4(1H,3H

• combined organic layers were dried over Na2SO4, concentrated under reduced pressure, and purified by column chromatography (heptane/ethyl acetate). 2,4,8-Trimethyl-6-(p-tolyl)benzo[f]quinazoline-1,3(2H,4H)-dione (5a). According to general procedure, compound 5a was obtained as a brown solid in 99% yield

Synthesis of fluoroalkenes and fluoroenynes via cross-coupling reactions using novel multihalogenated vinyl ethers

• Yukiko Karuo,
• Keita Hirata,
• Atsushi Tarui,
• Kazuyuki Sato,
• Kentaro Kawai and
• Masaaki Omote

Beilstein J. Org. Chem. 2024, 20, 2691–2703, doi:10.3762/bjoc.20.226

• and 11). We predicted that the product yield would decrease because 2k is labile in column chromatography. Utilizing a boronic acid bearing an n-butyl group as a primary alkyl group (4m), the cross-coupling did not proceed due to β-elimination (Table 3, entry 12). In contrast, the reaction with

• EtOAc. The organic phase was washed with brine (40 mL), dried over Na2SO4 and filtered. Then, the filtrate was concentrated under reduced pressure. The residue was purified by column chromatography and preparative TLC to afford 2. 2-Chloro-1-fluoro-2-phenylethenyl phenyl ether (2a): Compound 2a was

• purified by column chromatography and preparative TLC (hexane only), and obtained in 96% yield (122.0 mg) as a pale yellow oil; 1H NMR (400 MHz, CDCl3) δ 7.04–7.22 (m, 2H), 7.26–7.50 (m, 6H), 7.55–7.69 (m, 2H); 13C NMR (100 MHz, CDCl3) δ 101.4 (d, J = 30.9 Hz), 102.5 (d, J = 48.0 Hz), 116.5 (d, J = 3.8 Hz

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

• vacuum, and the residue was purified using silica-gel column chromatography. Compounds 3aa [21], 3ba [21], 3ea [21], 3eb [21], 3fa [21], 3fb [22], 3ga [21], and 3ja [21] were synthesized using the similar method as reported previously by us. General procedure for the synthesis of 2-hydroxybenzophenones

• 4aa–ka. 1 mmol Cs2CO3 was added to a solution of 3-arylbenzofuran-2(3H)-ones 3aa–ka (1 mmol) in 2 mL of freshly distilled THF, and the mixture was heated at 50 °C with stirring under open atmosphere. The progress of the reaction was monitored by thin-layer chromatography (TLC). After completion of the

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

• , including piperidone [10], amines [5][10], and amides [3][5][10] have been also observed in certain species. The analyses of SGS in vipers (Viperidae) focused on New World pit vipers (Crotalinae). Early analyses of SGS lipids by thin-layer chromatography (TLC) [14], indicated that two pit vipers, the Timber

• acids, comparison with in-house and other spectral libraries revealed no close match with known compounds. High-resolution EI gas chromatography (HREI–GC–MS) of compound D suggested a molecular formula of C14H26O2 (m/z 226.18962 [M]+, calcd 226.19328), and two double-bond equivalents. The characteristic

• diastereomers were then subjected to silver nitrate column chromatography to separate the geometric isomers. This separation was only partially achieved (Supporting Information File 1, Figure S10), but one diastereomer was enriched and the sample was subjected to NOESY NMR experiments. Coupling was observed

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

• traces of residual moisture. Reactions were monitored by thin-layer chromatography (TLC) using E. Merck silica gel plates and components were visualized by illumination with short wavelength UV light and/or staining (ninhydrin or basic KMnO4). All aldehydes were distilled right before use. All aryl

• better accuracy on small coupling constants, resolution in 1H NMR was enhanced using Traficante. All compounds were purified by flash column chromatography on silca gel unless otherwise noted. Melting points were obtained using an Electrothermal IA9200 series digital apparatus with thin-wall glass tube

• temperature, the mixture was filtered through Celite and washed with EtOAc (2 × 10 mL). The filtrate was evaporated under reduced pressure and the crude product was purified by using 60–120 silica mesh column chromatography using 10–20% ethyl acetate in hexane as eluent afforded target compound 4a (69% yield

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

• benzotrifluoride (BTF, 0.4 mL). The mixture was heated at 80 °C for 24 h in air. After the reaction was completed, the mixture was filtered through a short Celite pad with AcOEt (20 mL). The filtrate was concentrated under reduced pressure. Finally, the residue was purified by preparative thin-layer chromatography

Anion-dependent ion-pairing assemblies of triazatriangulenium cation that interferes with stacking structures

• Yohei Haketa,
• Takuma Matsuda and
• Hiromitsu Maeda

Beilstein J. Org. Chem. 2024, 20, 2567–2576, doi:10.3762/bjoc.20.215

• sheets coated with silica gel 60 (Merck 5554). Column chromatography was performed on Wakogel C-300. Preparation of ion pairs 4,8,12-Tris(2,6-dimethylphenyl)-4,8,12-triazatriangulenium as a BF4− ion pair, 2+-BF4−. According to the literature procedure [26], to a Schlenk tube were added 2,6

• gel column chromatography (Wakogel C-300, eluent: MeOH/CH2Cl2 with an increment of MeOH). The residue was chromatographed over ion-exchanged resin (Amberlite IRA402BL, eluent: MeOH/CH2Cl2) and solvents were removed by evaporation. Then, to a MeOH solution (150 mL) of the solid was added AgBF4 (269 mg

• , 1.38 mmol), and the reaction mixture was stirred at rt for 10 min, followed by filtration, and evaporation to dryness. The residue was purified by silica gel column chromatography (Wakogel C-300; eluent: MeOH/AcOEt/CH2Cl2 1:2:8) and was recrystallized from CH2Cl2/n-hexane to afford 2+-BF4− (143 mg

Machine learning-guided strategies for reaction conditions design and optimization

• Lung-Yi Chen and
• Yi-Pei Li

Beilstein J. Org. Chem. 2024, 20, 2476–2492, doi:10.3762/bjoc.20.212

• . [47]. Literature-extracted yields can be derived from different methods, such as crude yield, isolated yield, quantitative NMR, and liquid chromatography area percentage, and they can also vary in precision due to human bias or equipment quality. HTE data for specific reactions, however, are usually

Phenylseleno trifluoromethoxylation of alkenes

• Clément Delobel,
• Armen Panossian,
• Gilles Hanquet,
• Frédéric R. Leroux,
• Fabien Toulgoat and
• Thierry Billard

Beilstein J. Org. Chem. 2024, 20, 2434–2441, doi:10.3762/bjoc.20.207

• derivative 2k, and the estrone derivative 2l were also successfully bis-functionalized. Some products appeared to be sensitive during purification by chromatography on silica gel. Suspecting acid sensitivity, compound 2a was treated with trifluoroacetic acid to confirm this hypothesis (Scheme 3). The product

• by chromatography. Examples of trifluoromethoxylated drugs. Proposed mechanism of the reaction and 19F NMR of the DDPYOCF3/PhSeBr mixture. Phenylseleno trifluoromethoxylation of various alkenes. Yields determined by 19F NMR spectroscopy with PhCF3 as internal standard (in parentheses isolated yields

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

• column chromatography using AcOEt/Hex 1:20 as an eluent, 0.2117 g (0.86 mmol) of the title compound (86% yield) were isolated. Rf 0.52 (Hex/AcOEt 5:1); 1H NMR (300.40 MHz, CDCl3) δ 3.71–3.76 (m, 2H), 5.21 (d, J = 12.3 Hz, 1H), 5.28 (d, J = 12.3 Hz, 1H), 7.34–7.44 (m, 5H); 13C NMR (75.45 MHz, CDCl3) δ

• in 79% yield after silica gel column chromatography using Hex/AcOEt 6:1 as an eluent. Rf 0.51 (Hex/AcOEt 4:1); 1H NMR (300.40 MHz, CDCl3) δ 0.88 (t, J = 6.9 Hz, 3H), 1.26 (brs, 14H), 1.60 (quint, J = 6.9 Hz, 2H), 2.49 (t, J = 7.5 Hz, 2H), 2.74 (dd, J = 3.6, 17.7 Hz, 1H), 2.83 (dd, J = 9.0, 17.7 Hz

Homogeneous continuous flow nitration of O-methylisouronium sulfate and its optimization by kinetic modeling

• Jiapeng Guo,
• Weike Su and
• An Su

Beilstein J. Org. Chem. 2024, 20, 2408–2420, doi:10.3762/bjoc.20.205

• was collected and analyzed by high-performance liquid chromatography (HPLC, ThermoFisher Ulcel3000), and the conversion of the samples was derived from the external standard method based on the regression equation of the HPLC standard curve. HPLC detection conditions: C18 column (10 μm, 4.6 × 250 mm

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

• employing a bulkier allyl-transfer reagent 116. They used a novel pre-formed chiral triborate catalyst 115 in tandem with a non-chiral Brønsted acid and expanded the scope to aliphatic homoallylic amines (Scheme 24). The new method established a scalable, chromatography-free purification protocol for the

• of the allyl donor reagent (up to 25 g). Importantly, benzophenone was easily recovered by recrystallisation after the workup (no chromatography, 80% yield) and then converted back into the allyl donor 116 (86% yield), thus boosting the overall atom-economy of the process. Also, the recovery of the

• (R)-VANOL ligand 115 was attained by column chromatography in 92%. In 2015, further development of the 2-aza-Cope rearrangement strategy was reported by Johnson [43]. This work expanded the scope of the reaction to β-formyl amides 119 under the conditions of dynamic kinetic resolution (DKR) by

Hydrogen-bond activation enables aziridination of unactivated olefins with simple iminoiodinanes

• Phong Thai,
• Lauv Patel,
• Diyasha Manna and
• David C. Powers

Beilstein J. Org. Chem. 2024, 20, 2305–2312, doi:10.3762/bjoc.20.197

• unprotected alcohol is tolerated in our procedure, with product 3l delivered at 50% NMR yield; 3l is sensitive to column chromatography, and thus aziridine-opening to a cyclic ether was observed (31% isolated yield) during purification. Aziridination of cis- or trans-4-octene afforded aziridine 3m as a 1.3

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

• value of the reaction mixture was adjusted to neutral using a saturated NaHCO3 solution, and the reaction mixture was extracted with CH2Cl2 (3 × 20 mL). The organic solution was dried with anhydrous Na2SO4, and the crude product was purified by column chromatography on 300–400 mesh silica gel (petroleum

• organic solution was dried with anhydrous Na2SO4, and the crude product was purified by column chromatography on 30–400 mesh silica gel (petroleum ether (60–90 °C)/ethyl acetate 20:1, v/v) to give 3a (53.8 mg, 90%). Synthesis of α-keto thioesters and β-keto amides. Synthesis of β-keto thioesters 2

Electrochemical allylations in a deep eutectic solvent

• Sophia Taylor and
• Scott T. Handy

Beilstein J. Org. Chem. 2024, 20, 2217–2224, doi:10.3762/bjoc.20.189

• flash column chromatography. In between reactions, the tin electrodes were rinsed with DI water and acetone, then polished using diamond polish. This helped prevent buildup on the electrode surfaces. General C/C procedure with TBAB/EG To a 10 mL ElectraSyn 2.0 vial containing a magnetic stir bar were

• sulfate, filtered, and the solvent removed in vacuo to afford the crude product, which was first analyzed by 1H NMR spectroscopy and then purified using flash column chromatography. The graphite electrodes were not polished in between reactions, but were rinsed with DI water and then acetone. General Sn

• column chromatography. The electrodes were washed with DI water and acetone before polishing. General C/C procedure with CC/EG To a 10 mL ElectraSyn 2.0 vial containing a magnetic stir bar were added the carbonyl compound (0.5 mmol), allyl bromide (0.6 mmol), CC/EG DES (2 mL), and 10% DI water (0.2 mL

Natural resorcylic lactones derived from alternariol

• Joachim Podlech

Beilstein J. Org. Chem. 2024, 20, 2171–2207, doi:10.3762/bjoc.20.187

Novel truxene-based dipyrromethanes (DPMs): synthesis, spectroscopic characterization and photophysical properties

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2024, 20, 2163–2170, doi:10.3762/bjoc.20.186

• purified through silica-gel column chromatography. After successfully synthesizing these easy-to-make yet interesting molecules, they were fully characterized by means of the standard spectroscopic techniques (1H NMR, 13C NMR and HRMS). We are of the opinion that these truxene-based systems will be useful

• . Analytical thin-layer chromatography (TLC) was performed on aluminium plates coated with silica gel by using a suitable mixture of EtOAc and petroleum ether for development purpose. Column chromatography was performed by using silica gel (100–200 mesh) with an appropriate mixture of EtOAc and petroleum ether

• product which was then purified by silica gel column chromatography (as suitable mixture of ethyl acetate and petroleum ether) to give the anticipated products in 12 (85%), 15 (80%), and 17 (90%) yields. 1-(5,5,10,10,15,15-Hexabutyl-10,15-dihydro-5H-diindeno[1,2-a:1',2'-c]fluoren-2-yl)ethan-1-one (12

Efficacy of radical reactions of isocyanides with heteroatom radicals in organic synthesis

• Akiya Ogawa and
• Yuki Yamamoto

Beilstein J. Org. Chem. 2024, 20, 2114–2128, doi:10.3762/bjoc.20.182

• radical, which induces 5-exo cyclization. The following hydrogen abstraction, intramolecular ionic cyclization, and hydrolysis during chromatography on silica gel affords the cyclic amide in good yield. They further applied this radical cyclization reaction as a key step in the synthesis of (±)-α-kainic

From perfluoroalkyl aryl sulfoxides to ortho thioethers

• Yang Li,
• Guillaume Dagousset,
• Emmanuel Magnier and
• Bruce Pégot

Beilstein J. Org. Chem. 2024, 20, 2108–2113, doi:10.3762/bjoc.20.181

• was mixed with a sufficient volume of a saturated NH4Cl solution, then extracted 3 times with diethyl ether. The combined organic layers were dried over MgSO4, filtered, concentrated under reduced pressure, and purified by preparative TLC or flash chromatography. [3,3]-Rearrangement of aryl sulfoxides

Allostreptopyrroles A–E, β-alkylpyrrole derivatives from an actinomycete Allostreptomyces sp. RD068384

• Marwa Elsbaey,
• Naoya Oku,
• Mohamed S. A. Abdel-Mottaleb and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2024, 20, 1981–1987, doi:10.3762/bjoc.20.174

• chromatography followed by ODS HPLC to yield compounds 1–5. Allostreptopyrrole A (1) was obtained as a greenish yellow amorphous solid. The molecular formula was determined to be C15H23NO4 based on a molecular ion peak at m/z 280.1550 [M − H]− (calcd for 280.1554) observed in a negative HRESITOF mass spectrum

• , and isolation Details on the supplier of Allostreptomyces sp. RD068384, fermentation, extraction, and fractionation are described in Supporting Information File 1. While a CHCl3/MeOH 2:1-eluting fraction by silica gel open column chromatography eventually yielded allostreptamide [24], a less polar

• CHCl3/MeOH 10:1 fraction contained compounds with characteristic UV absorption. This fraction, obtained as 395 mg of brown solid from 4 L culture in A-3M medium, was fractionated by octadecyldimethylsilyl (ODS) silica gel column chromatography with a gradient of MeCN/0.1% HCO2H solution (2:8, 3:7, 4:6

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

• products were separated by column chromatography and characterized. Heterocyclizations–photochemical [2 + 2]- and [2 + 4]-cycloaddition reactions: The formation of oxetanes as a result of photochemical cycloaddition of fluoroketones or fluoroaldehydes and 1,2-difluoroethylene was previously described by