Green and sustainable approaches for the Friedel–Crafts reaction between aldehydes and indoles

• Periklis X. Kolagkis,
• Eirini M. Galathri and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2024, 20, 379–426, doi:10.3762/bjoc.20.36

• . demonstrated an unexpected Br2-catalyzed synthesis of BIMs from indole and carbonyl compounds in water (Scheme 9) [92]. First, the reaction took place in acetonitrile with a low catalyst loading (2 mol %), proving sufficient to achieve optimal product yields of up to 98% after just 1 minute, when the reaction

• associated with low catalyst loading, extremely high efficiency and broad substrate scope and the possibility of use of both organic solvents or water, with the drawback however, of the employment of conventional heating [92]. In 2019, Toy et al. proposed an alternative approach for the Friedel–Crafts

• be addressed. The most recent application of halogen bonding in the synthesis of BIMs was introduced in 2023 by Galathri et al., who employed an N-heterocyclic iod(az)olium salt as the monodentate catalyst [96]. This approach utilized water as the reaction solvent and employed a low catalyst loading

Mechanisms for radical reactions initiating from N-hydroxyphthalimide esters

• Carlos R. Azpilcueta-Nicolas and
• Jean-Philip Lumb

Beilstein J. Org. Chem. 2024, 20, 346–378, doi:10.3762/bjoc.20.35

• (Scheme 6A). Stern–Volmer analysis revealed that quenching of the photocatalyst’s excited state by the NHPI ester occurred only in presence of a hydrogen bond donor such as water (H2O) or methanol (MeOH). This supported the hypothesis that activation of NHPI esters towards photoinduced electron transfer

Facile approach to N,O,S-heteropentacycles via condensation of sterically crowded 3H-phenoxazin-3-one with ortho-substituted anilines

• Eugeny Ivakhnenko,
• Vasily Malay,
• Pavel Knyazev,
• Nikita Merezhko,
• Nadezhda Makarova,
• Oleg Demidov,
• Gennady Borodkin,
• Andrey Starikov and
• Vladimir Minkin

Beilstein J. Org. Chem. 2024, 20, 336–345, doi:10.3762/bjoc.20.34

• data of 4c,d,f, 5c, and 10b were obtained at 100 K. Crystals of 5c were obtained in the form of a solvate with molecules of isopropanol and water present. The protons attached to heteroatoms were localized by difference Fourier synthesis and refined with isotropic thermal parameters. The collection of

Elucidating the glycan-binding specificity and structure of Cucumis melo agglutinin, a new R-type lectin

• Jon Lundstrøm,
• Emilie Gillon,
• Valérie Chazalet,
• Nicole Kerekes,
• Antonio Di Maio,
• Ten Feizi,
• Yan Liu,
• Annabelle Varrot and
• Daniel Bojar

Beilstein J. Org. Chem. 2024, 20, 306–320, doi:10.3762/bjoc.20.31

• interaction with the aromatic ring of Tyr26 (Figure 4c). Further, beyond the C2 position of galactose, a cavity filled with coordinated water molecules hinted at the binding mode for C2-substituted galactose. Notably, the seemingly inactive beta site was found to be occupied by a cadmium ion (Figure S4

• . While no direct interactions with the protein backbone were observed, we found one water molecule to mediate hydrogen bonding between the oxygen of the N-acetyl group and the Asn43 side chain oxygen (Figure 4d). Both GalNAc anomers could be observed, showing interactions through water molecule

• -up on the interactions between CMA1 and LacNAc (c) or GalNAc (d), with the 2mFo-DFc electron density map displayed around the sugar ligands at 1 sigma (LacNAc: 0.47 e·Å−3, GalNAc: 0.415 e·Å−3). Water molecules are indicated by red spheres and interactions by proximal residues are indicated by broken

Unveiling the regioselectivity of rhodium(I)-catalyzed [2 + 2 + 2] cycloaddition reactions for open-cage C₇₀ production

• Cristina Castanyer,
• Anna Pla-Quintana,
• Anna Roglans,
• Albert Artigas and
• Miquel Solà

Beilstein J. Org. Chem. 2024, 20, 272–279, doi:10.3762/bjoc.20.28

• applications are still in various stages of research and development. The functionalization of fullerenes makes them versatile materials, broadening the range of potential applications [17][18]. It allows the properties of these carbon cages to be tuned, making them more soluble (especially in water for

Substitution reactions in the acenaphthene analog of quino[7,8-h]quinoline and an unusual synthesis of the corresponding acenaphthylenes by tele-elimination

• Ekaterina V. Kolupaeva,
• Narek A. Dzhangiryan,
• Alexander F. Pozharskii,
• Oleg P. Demidov and
• Valery A. Ozeryanskii

Beilstein J. Org. Chem. 2024, 20, 243–253, doi:10.3762/bjoc.20.24

• of quinoquinolines, their planar structure, and very easy coordination to acidic and electrophilic sites (including water [15][22] or the C–H bond of chloroform [11]) almost always lead to co-crystallization. For example, there is no such crystallographic information for quinoquinoline 3 itself. In

• -substituent led to a rather unexpected result. After cooling, dilution with water, basification, and extraction from the reaction mass, a single substance was isolated in almost quantitative yield, which turned out to be monosubstituted acenaphthylene 16, rather than the expected disubstituted acenaphthene 17

• dinitroacenaphthylene 12. Basicity of key compounds in acetonitrile. Comparison of basicity (in water scale) and synthetic availability of quinoline-type azaarenes and "proton sponge" 1. Formation of complex 9 and its slow hydrolytic degradation into protic salt 5·HCl. Dinitration of compound 5 and the initially

Photochromic derivatives of indigo: historical overview of development, challenges and applications

• Gökhan Kaplan,
• Zeynel Seferoğlu and
• Daria V. Berdnikova

Beilstein J. Org. Chem. 2024, 20, 228–242, doi:10.3762/bjoc.20.23

• water. Thus, the thermal Z–E relaxation of 20b could be significantly accelerated (ca. 300 times) by addition of water to organic solvent because of specific interactions between the NH groups and water molecules. Photochromic N-aryl-N'-alkylindigos In 2017 Hecht, Jacquemin, and co-workers prepared

• Corporation [79], in which the inventors succeeded in the synthesis of water-soluble indigo derivatives and applied these compounds as solar energy storage systems using the aforementioned energy storage mechanism. However, detailed studies on kinetics and thermodynamics of the photoisomerization and thermal

• soft materials. A possibility to apply photochromic mono-arylated indigo derivatives as water sensors with high sensitivity was demonstrated by Dube and co-workers in 2018 [66]. The detection principle relied on a remarkable acceleration (up to 300 times) of the thermal Z–E relaxation of compound 20b

Optimizations of lipid II synthesis: an essential glycolipid precursor in bacterial cell wall synthesis and a validated antibiotic target

• Milandip Karak,
• Cian R. Cloonan,
• Brad R. Baker,
• Rachel V. K. Cochrane and
• Stephen A. Cochrane

Beilstein J. Org. Chem. 2024, 20, 220–227, doi:10.3762/bjoc.20.22

• -anomers of compound 5. It is noteworthy to mention that the benzyl ether in compound 4 exhibited successful cleavage upon treatment with sodium bromate/sodium dithionite in ethyl acetate/water, while other protecting functionalities like acetyl and phenylsulfonylethyl ester groups remained intact [45

Chiral phosphoric acid-catalyzed transfer hydrogenation of 3,3-difluoro-3H-indoles

• Yumei Wang,
• Guangzhu Wang,
• Yanping Zhu and
• Kaiwu Dong

Beilstein J. Org. Chem. 2024, 20, 205–211, doi:10.3762/bjoc.20.20

• , synthesized in situ from a chiral boron phosphate complex with water, for asymmetric indole reduction (Scheme 1b) [30]. The mild reaction conditions, low catalyst loading, and high enantioselectivity rendered this transformation an attractive approach to synthesize optically active indolines. However, these

Comparison of glycosyl donors: a supramer approach

• Anna V. Orlova,
• Nelly N. Malysheva,
• Maria V. Panova,
• Nikita M. Podvalnyy,
• Michael G. Medvedev and
• Leonid O. Kononov

Beilstein J. Org. Chem. 2024, 20, 181–192, doi:10.3762/bjoc.20.18

• and −21.248) as described previously [37]. After initial thermal stabilization of the sample (placed in a jacketed cell connected to a circulating water thermostat) within the instrument (10 min), a series of 10 successive measurements of the sample was made within a 2–3 min period followed by another

• CH2Cl2 (8.0 mL), 2,4,6-collidine (1.4 mL, 10.6 mmol) was added. The solution was cooled to 0 °C (ice–water bath), and a solution of chloroacetic anhydride (906 mg, 5.30 mmol) in anhydrous CH2Cl2 (11.5 mL) was added dropwise while stirring. The reaction mixture was stirred at 0 °C for 70 min until

• complete consumption of the starting material (TLC monitoring, Rf = 0.10 (5), Rf = 0.49 (6), EtOAc/petroleum ether 35:65). Saturated aqueous NaHCO3 (5 mL) was added, and the mixture was well shaken and then allowed to warm to ≈20 °C, diluted with CH2Cl2 (50 mL), washed with water (100 mL), 1 M aqueous

Synthesis of the 3’-O-sulfated TF antigen with a TEG-N₃ linker for glycodendrimersomes preparation to study lectin binding

• Mark Reihill,
• Hanyue Ma,
• Dennis Bengtsson and
• Stefan Oscarson

Beilstein J. Org. Chem. 2024, 20, 173–180, doi:10.3762/bjoc.20.17

• Celite® and concentrated in vacuo. The resulting residue was taken up in EtOAc (700 mL) and washed with 10% aq Na2S2O3 (700 mL), water (700 mL) and brine (700 mL). The organic phase was then dried over MgSO4, filtered and reduced to dryness. Flash chromatography on silica gel (toluene→toluene/EtOAc, 3:2

• the suspension was filtered through Celite®. The filtrate was then washed with water (400 mL), brine (400 mL), dried over MgSO4, filtered and concentrated in vacuo. Compound 7 was isolated by flash chromatography on silica gel (toluene→toluene/EtOAc, 1:4) as an orange foam (8.97 g, 79%). Rf = 0.5

Tandem Hock and Friedel–Crafts reactions allowing an expedient synthesis of a cyclolignan-type scaffold

• Viktoria A. Ikonnikova,
• Cristina Cheibas,
• Oscar Gayraud,
• Alexandra E. Bosnidou,
• Nicolas Casaretto,
• Gilles Frison and
• Bastien Nay

Beilstein J. Org. Chem. 2024, 20, 162–169, doi:10.3762/bjoc.20.15

• rearrangement. Since the Hock rearrangement results in the formation of a molecule of water, we attempted to add a water scavenger to the reaction solution. Additives like molecular sieves 4 Å or Na2SO4 (2 equiv) did not show any improvement (Table 1, entry 3), while MgSO4 (2 equiv) had a stunning effect

Perspectives on push–pull chromophores derived from click-type [2 + 2] cycloaddition–retroelectrocyclization reactions of electron-rich alkynes and electron-deficient alkenes

• Michio Yamada

Beilstein J. Org. Chem. 2024, 20, 125–154, doi:10.3762/bjoc.20.13

• acetonitrile for 8 h, 38 is obtained with 98% yield. Microscopic observations suggest that the vesicle structure, with water as the core, plays a pivotal role in the transformation of 4 into 37. A similar reaction of TCBD with water was also reported by Bruce et al. [118]. The reaction of the anthracene

Visible-light-induced radical cascade cyclization: a catalyst-free synthetic approach to trifluoromethylated heterocycles

• Chuan Yang,
• Wei Shi,
• Jian Tian,
• Lin Guo,
• Yating Zhao and
• Wujiong Xia

Beilstein J. Org. Chem. 2024, 20, 118–124, doi:10.3762/bjoc.20.12

• Chuan Yang Wei Shi Jian Tian Lin Guo Yating Zhao Wujiong Xia College of Chemical and Material Engineering, Quzhou University, Quzhou 324000, China State Key Lab of Urban Water Resource and Environment, School of Science, Harbin Institute of Technology (Shenzhen), Shenzhen, 518055, China School of

• was also supported by State Key Laboratory of Urban Water Resource and Environment (Harbin Institute of Technology) (No.2022TS23), and the Open Research Fund of the School of Chemistry and Chemical Engineering, Henan Normal University.

Photoinduced in situ generation of DNA-targeting ligands: DNA-binding and DNA-photodamaging properties of benzo[c]quinolizinium ions

• Julika Schlosser,
• Olga Fedorova,
• Yuri Fedorov and
• Heiko Ihmels

Beilstein J. Org. Chem. 2024, 20, 101–117, doi:10.3762/bjoc.20.11

• pronounced intramolecular charge transfer [68]. In water, the absorption maxima showed only a small shift of the absorption maxima of 1–4 nm as compared with the ones in acetonitrile (Figure 1B, Supporting Information File 1, Table S1). The absorption spectra of compounds 2a and 2c could not be recorded

• because of their low water solubility. The styrylpyridine derivatives 2a–g were irradiated in oxygen-saturated solutions in MeCN, H2O, MeOH, or MeCN/H2O with a high-pressure Hg lamp (λ > 220 nm), and the course of the photocyclization reaction was monitored by absorption spectroscopy (Figure 2). In

• S6A). Because of the low water solubility of the styrylpyridine derivatives 2a–g, solvent mixtures of MeCN/H2O or pure MeCN were used for the preparative photocyclization reactions (Scheme 3, cf. Supporting Information File 1, Figure S2C,D) to provide sufficient solubility of the substrates, as well

Optimizing reaction conditions for the light-driven hydrogen evolution in a loop photoreactor

• Pengcheng Li,
• Daniel Kowalczyk,
• Johannes Liessem,
• Mohamed M. Elnagar,
• Dariusz Mitoraj,
• Radim Beranek and
• Dirk Ziegenbalg

Beilstein J. Org. Chem. 2024, 20, 74–91, doi:10.3762/bjoc.20.9

• , Germany 10.3762/bjoc.20.9 Abstract Photocatalytic hydrogen production from water is a promising way to fulfill energy demands and attain carbon emission reduction goals effectively. In this study, a loop photoreactor with a total volume of around 500 mL is presented for the photocatalytic hydrogen

• in a proper way, solar energy can be converted to hydrogen fuels. Hydrogen as an energy carrier has zero carbon emission and a high energy density [11][12]. While significant efforts are directed towards developing effective photocatalysts for solar water splitting [13][14][15][16], a crucial

• stirring speed of 560 rpm. The regions of interests (ROIs) shown on frame of 1.2 s are denoted as left side (blue ROI), draft tube (green ROI), and right side (yellow ROI). The color of water changed first in the draft tube and then outside the draft tube until the mixing was complete. Thus, the liquid was

Preparing a liquid crystalline dispersion of carbon nanotubes with high aspect ratio

• Keiko Kojima,
• Nodoka Kosugi,
• Hirokuni Jintoku,
• Kazufumi Kobashi and
• Toshiya Okazaki

Beilstein J. Org. Chem. 2024, 20, 52–58, doi:10.3762/bjoc.20.7

• , Figure S1e) [26]. The DWCNT powder was dispersed with a surfactant of sodium cholate (SC) in water by a two-step process [22][23] (see the Experimental section). The size distribution of the DWCNTs in the dispersion was estimated by DCS method (Figure 1a). The observed intense peak at approximately 9 nm

• 200 mL of water, the DWCNT-glycerol mixture was filtered through a 1.0 μm pore size polytetrafluoroethylene (PTFE) membrane (Merck, Omnipore 47mm). To ensure complete removal of glycerol from the DWCNTs, we repeated the washing process until 2 L of water had passed through the membrane, resulting in

• only SC and water molecules. The DWCNT dispersion was repeatedly subjected to centrifugation at 1,000g for 5 minutes (KOKUSAN H-36) and stirred with a pipette to prevent DWCNT re-aggregation, resulting in the production of the condensed DWCNT dispersion. The dispersions' concentrations were adjusted by

Facile access to pyridinium-based bent aromatic amphiphiles: nonionic surface modification of nanocarbons in water

• Lorenzo Catti,
• Shinji Aoyama and
• Michito Yoshizawa

Beilstein J. Org. Chem. 2024, 20, 32–40, doi:10.3762/bjoc.20.5

• Lorenzo Catti Shinji Aoyama Michito Yoshizawa Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan 10.3762/bjoc.20.5 Abstract Efficient water-solubilization of nanocarbons is desirable for

• )2–Y (Y = OCH3, OH, and imidazole)). The new amphiphiles quantitatively self-assemble into ≈2 nm-sized aromatic micelles in water independent of the side-chain. Importantly, efficient water-solubilization and nonionic surface modification of various nanocarbons (e.g., fullerene C60, carbon nanotubes

• ., graphitic carbon nitride) in the form of 10–30 nm-sized stacks is also demonstrated using the present amphiphiles. Keywords: aromatic micelle; nanocarbon; nonionic surface modification; pyridinium; water-solubilization; Introduction Nanocarbons, such as fullerenes, graphenes, and carbon nanotubes, are

Cycloaddition reactions of heterocyclic azides with 2-cyanoacetamidines as a new route to C,N-diheteroarylcarbamidines

• Pavel S. Silaichev,
• Tetyana V. Beryozkina,
• Vsevolod V. Melekhin,
• Valeriy O. Filimonov,
• Andrey N. Maslivets,
• Vladimir G. Ilkin,
• Wim Dehaen and
• Vasiliy A. Bakulev

Beilstein J. Org. Chem. 2024, 20, 17–24, doi:10.3762/bjoc.20.3

• triazoles 3 Method A. In a manner similar to [17], DBU (0.5 mmol) was added to the solution of amidine 1 (0.5 mmol) in 1,4-dioxane (2 mL) at room temperature and azide 2 (0.5 mmol) was added to the resulting solution 5 min later. The reaction mixture was stirred for 30 min at room temperature, then water (6

• mL) was added and the resulting solution was stirred for additional 5 min. Then, acetic acid (34 µL) was added to the reaction mixture, the formed precipitate was filtered off, washed with water, and dried in a desiccator over P4O10. Method B. Amidine 1 (0.5 mmol) was added into a solution of sodium

• cooling was removed. The reaction mixture was allowed to warm to ambient temperature under stirring and water (8 mL) was added to the mixture. The resulting solution was stirred for 5 min, after which acetic acid (34 µL) was added. The formed precipitate was filtered off, washed with water, and dried in a

Identification of the p-coumaric acid biosynthetic gene cluster in Kutzneria albida: insights into the diazotization-dependent deamination pathway

• Seiji Kawai,
• Akito Yamada,
• Yohei Katsuyama and
• Yasuo Ohnishi

Beilstein J. Org. Chem. 2024, 20, 1–11, doi:10.3762/bjoc.20.1

• metabolites were extracted with 5 mL of ethyl acetate after adjusting the pH to approximately 4 by adding 6 M HCl. The ethyl acetate layer was collected, and it was washed with an equal volume of distilled water to remove the compounds that can be dissolved in water. The ethyl acetate layer was then collected

• 2.6C18 Packed column (2.1 mm ID × 100 mm, Nacalai Tesque) coupled with a model LCMS-8040 liquid chromatography–mass spectrometer (LC–MS) (Shimazu Corp.). The compounds were eluted with a linear gradient of water/acetonitrile containing 0.1% formic acid. Isolation and structural determination of compound

• -II (10 mm ID × 250 mm, Nacalai Tesque), and the metabolites were eluted with a linear gradient of water/acetonitrile containing 0.1% formic acid. Fractions containing compound 6 were concentrated by evaporation. Compound 6 was then desorbed in DMSO-d6, and the structure was determined by the JNM-A600

1-Butyl-3-methylimidazolium tetrafluoroborate as suitable solvent for BF₃: the case of alkyne hydration. Chemistry vs electrochemistry

• Marta David,
• Elisa Galli,
• Richard C. D. Brown,
• Marta Feroci,
• Fabrizio Vetica and
• Martina Bortolami

Beilstein J. Org. Chem. 2023, 19, 1966–1981, doi:10.3762/bjoc.19.147

• well-known and useful reaction in organic chemistry, affording carbonyl compounds based on an atom-economical approach. Indeed, the addition of water to the triple bond of a terminal alkyne leads to the formation of the corresponding methyl ketone or aldehyde, in the case of Markovnikov or anti

• -Markovnikov addition, respectively. On the other hand, the hydration of an internal unsymmetrical alkyne can lead to the formation of the two possible regioisomeric ketones. The hydration reaction requires a catalytic species, able to polarize the alkyne triple bond to facilitate water attack. Initially, in

• hexafluorophosphate (BMIm-PF6) as co-solvent with methanol and water to allow recycling of a phosphine-based Au(I) complex, as an efficient catalytic system for the hydration of terminal alkynes [87]. Moreover, the interesting properties of ILs have also been exploited to synthesize new solid polymeric catalysts for

Long oligodeoxynucleotides: chemical synthesis, isolation via catching-by-polymerization, verification via sequencing, and gene expression demonstration

• Yipeng Yin,
• Reed Arneson,
• Alexander Apostle,
• Adikari M. D. N. Eriyagama,
• Komal Chillar,
• Emma Burke,
• Martina Jahfetson,
• Yinan Yuan and
• Shiyue Fang

Beilstein J. Org. Chem. 2023, 19, 1957–1965, doi:10.3762/bjoc.19.146

• dissolved in water and precipitated with n-BuOH. This gave the CBP-purified ODNs. Analysis of long ODNs with gel electrophoresis and Sanger sequencing One simple method to estimate the length of the long ODNs would be to compare them with authentic samples using gel electrophoresis. However, commercial

Studying specificity in protein–glycosaminoglycan recognition with umbrella sampling

• Mateusz Marcisz,
• Sebastian Anila,
• Margrethe Gaardløs,
• Martin Zacharias and
• Sergey A. Samsonov

Beilstein J. Org. Chem. 2023, 19, 1933–1946, doi:10.3762/bjoc.19.144

• surface and in the extracellular matrix [4]. Due to their charged nature, they bind a large amount of water [5]. Although GAGs were previously considered just an inert glue surrounding the cell, GAG research in the past few decades has illustrated the crucial role in cell signaling processes, including

• functions results principally from their unique physicochemical and structural features, including high negative charge, high viscosity and lubrication propensities, unbranched polysaccharide structures, low compressibility as well as the ability to attract and imbibe large amounts of water [17]. Unlike

• complexes obtained by RS-REMD docking were performed in AMBER20 package [42]. A TIP3P truncated octahedron water box with a distance of 20 Å from the solute to the box’s border was used to solvate complexes. Na+ counterions were used to neutralize the charge of the system. Energy minimization was performed

Biphenylene-containing polycyclic conjugated compounds

• Cagatay Dengiz

Beilstein J. Org. Chem. 2023, 19, 1895–1911, doi:10.3762/bjoc.19.141

• also reported in the same study that the yield of 15b increased up to 62% when the water formed during the reaction was removed with CaH2. The initial results on biphenylene and its more extensively fused counterparts led to another notable study conducted by Jensen and Coleman in 1959 [34]. By

Anion–π catalysis on carbon allotropes

• M. Ángeles Gutiérrez López,
• Mei-Ling Tan,
• Giacomo Renno,
• Augustina Jozeliūnaitė,
• J. Jonathan Nué-Martinez,
• Javier Lopez-Andarias,
• Naomi Sakai and
• Stefan Matile

Beilstein J. Org. Chem. 2023, 19, 1881–1894, doi:10.3762/bjoc.19.140

• . The origin of autocatalysis on π-acidic surfaces was clarified only this year because the involvement of two molecules of water in the decisive transition state XI complicated the situation [70]. This reaction was intriguing for reasons beyond autocatalysis. It is the only example so far where