Effect of substitution position of aryl groups on the thermal back reactivity of aza-diarylethene photoswitches and prediction by density functional theory

• Misato Suganuma,
• Daichi Kitagawa,
• Shota Hamatani and
• Seiya Kobatake

Beilstein J. Org. Chem. 2025, 21, 242–252, doi:10.3762/bjoc.21.16

• absorption band in the visible region disappeared and returned to the initial one by stopping UV light irradiation. These results indicate that all molecules exhibit T-type photochromic reactions based on 6π aza-electrocyclic reaction. The absorption bands of compounds I1(c)–I4(c) are blue-shifted compared

Streamlined modular synthesis of saframycin substructure via copper-catalyzed three-component assembly and gold-promoted 6-endo cyclization

• Asahi Kanno,
• Ryo Tanifuji,
• Satoshi Yoshida,
• Sota Sato,
• Saori Maki-Yonekura,
• Kiyofumi Takaba,
• Jungmin Kang,
• Kensuke Tono,
• Koji Yonekura and
• Hiroki Oguri

Beilstein J. Org. Chem. 2025, 21, 226–233, doi:10.3762/bjoc.21.14

• degassed solvent and light-shielding flask, the oxidative conversion of 12 to the imidate 18 proceeded smoothly. Notably, the transient intermediate 18, exhibiting a sky-blue fluorescence, further underwent a ring opening to afford the tetracyclic 14 with the simultaneous regeneration of both a nitrile and

• gold complex and the silver salt, to efficiently achieve the 6-endo cyclization and subsequent conversions. During the development of this cascade synthesis process, we serendipitously discovered the involvement of a sky-blue fluorescent transient intermediate 18 (Figure 2). We therefore investigated

• displayed a relatively broad peak with a maximum around 490 nm (blue solid line). The excitation spectra of 18 (blue dashed line), corresponding to an emission at 490 nm, was also recorded (Figure S3, Supporting Information File 1 for details). Despite the modest emission quantum yield (Φfl = 0.07, excited

Quantifying the ability of the CF₂H group as a hydrogen bond donor

• Matthew E. Paolella,
• Daniel S. Honeycutt,
• Bradley M. Lipka,
• Jacob M. Goldberg and
• Fang Wang

Beilstein J. Org. Chem. 2025, 21, 189–199, doi:10.3762/bjoc.21.11

• Reichardt's dye [53][54][55] as an indicator. These experiments measure the blue shift of Reichardt's dye upon complexation with an HB donor (Figure 3A, and Figures S13–S18 in Supporting Information File 1), from which the dissociation constant (Kd) of the HB complex can be determined. A smaller Kd value

Hydrogen-bonded macrocycle-mediated dimerization for orthogonal supramolecular polymerization

• Wentao Yu,
• Zhiyao Yang,
• Chengkan Yu,
• Xiaowei Li and
• Lihua Yuan

Beilstein J. Org. Chem. 2025, 21, 179–188, doi:10.3762/bjoc.21.10

• promising potential for designing stimuli-responsive and smart polymers in the future. ESIMS spectrum of an equimolar mixture of G1 and H1 in CHCl3/CH3CN (1:1, v/v), including calculated (blue) and experimental (red) isotopic distribution for [H12 + G12 − 2PF6−]2+. Calculated and found m/z = 2444.3373 and

Facile one-pot reduction of β-nitrostyrenes to phenethylamines using sodium borohydride and copper(II) chloride

• Laura D’Andrea and
• Simon Jademyr

Beilstein J. Org. Chem. 2025, 21, 39–46, doi:10.3762/bjoc.21.4

• ]. Consistently, once the chloride is added, the reduction to free Cu(0) is visually indicated by the immediate disappearance of the blue color of the copper(II) solution, and the formation of a fine suspended black powder. The latter, as metallic copper particles, acts as the actual catalyst. Time plays a

Synthesis, structure and π-expansion of tris(4,5-dehydro-2,3:6,7-dibenzotropone)

• Yongming Xiong,
• Xue Lin Ma,
• Shilong Su and
• Qian Miao

Beilstein J. Org. Chem. 2025, 21, 1–7, doi:10.3762/bjoc.21.1

• the colorless crystal, two of these [5]helicenoid moieties display P and M helix structures respectively, whereas the third moiety (colored in light blue) adopts a structure with approximate plane symmetry, recognized as a transition state for the enantiomerization of helicenes. The central benzene

• represent the helicity of the three [5]helicenoid moieties. The geometry of 3 deviates from ideal C2 symmetry, as the light blue moiety of 3 (top view in Figure 3) is shaped like a saddle. However, the 1H NMR spectrum of 3 shows only 12 different signals in the aromatic region, indicating a two-fold

• clarification). Structure of (M,P,M)-3 in the crystal of 3·CH2Cl2 (carbon and oxygen atoms are shown as grey and red ellipsoid at the level of 50% probability, and hexyl groups and hydrogen atoms are removed for clarity). UV–vis absorption spectrum (black line) and emission spectrum (blue line, excited at 400

Synthesis of 2H-azirine-2,2-dicarboxylic acids and their derivatives

• Anastasiya V. Agafonova,
• Mikhail S. Novikov and
• Alexander F. Khlebnikov

Beilstein J. Org. Chem. 2024, 20, 3191–3197, doi:10.3762/bjoc.20.264

• situation. Dibenzyl ester 11c was prepared using traditional activation of carboxylic acid 6a, although the yield was only 23%. A higher yield of the branched ester 11d (86%, as a mixture of diastereomers) was obtained by carbene insertion, generated by blue LED irradiation of methyl 2-diazo-2-phenylacetate

Advances in the use of metal-free tetrapyrrolic macrocycles as catalysts

• Mandeep K. Chahal

Beilstein J. Org. Chem. 2024, 20, 3085–3112, doi:10.3762/bjoc.20.257

• -containing macrocycles and metalloporphyrins. Despite the impressive progress in photoredox catalysis, due to their most intensive electronic absorption band at 420 nm (Soret band, extinction coefficient of 105 M−1 cm−1), most porphyrin photocatalysts reported so far have been mainly utilized under blue

• light turned out to be as effective as blue light, providing good yields of various photochemical reactions that proceed via both oxidative and reductive quenching mechanisms. Further, using of metal-free porphyrins as photocatalysts in bioorthogonal chemistry was explored. They can be utilized in

• ) using substituted anilines 101 and t-BuONO (Figure 18). The reactions were conducted under light irradiation (blue light/sunlight) for 30 minutes in DMSO within an inert atmosphere. All corroles demonstrated catalytic activity with only 0.5% loading, while control experiments without a catalyst or light

Extension of the π-system of monoaryl-substituted norbornadienes with acetylene bridges: influence on the photochemical conversion and storage of light energy

• Robin Schulte,
• Dustin Schade,
• Thomas Paululat,
• Till J. B. Zähringer,
• Christoph Kerzig and
• Heiko Ihmels

Beilstein J. Org. Chem. 2024, 20, 3061–3068, doi:10.3762/bjoc.20.254

• derivatives during the photoreaction, whereas the blue-shifted maximum of the photoproduct was formed. In addition, isosbestic points were observed for the derivatives 1h (A), 1i (B), 1k (D), and 1l (E). The irradiations of the derivatives 1h, 1i, 1k, and 1l were stopped once no more changes of the absorbance

Chemical structure metagenomics of microbial natural products: surveying nonribosomal peptides and beyond

• Thomas Ma and
• John Chu

Beilstein J. Org. Chem. 2024, 20, 3050–3060, doi:10.3762/bjoc.20.253

• ) Incorporation of the first five amino acid BBs in daptomycin (highlighted in blue) is illustrated herein. In NRP biosynthesis, modules are arranged in an assembly line fashion; each module incorporates one BB into the growing peptide intermediate, which is then passed onto the next module. b) Within each module

• based on a dataset of known pairs of nonribosomal code/substrate BB. c) An analysis that compared the known vs predicted NRP BBs grouped based on their chemical structures found both oversampled (green)/underexplored (blue) niches in the NRP chemical space; the analysis was performed across all bacteria

Cyclodextrin-based rotaxanes for polymer materials: challenge on simultaneous realization of inexpensive production and defined structures

• Yosuke Akae

Beilstein J. Org. Chem. 2024, 20, 3026–3049, doi:10.3762/bjoc.20.252

• fluorescence (Figure 15C,D). Namely, the fluorescence of the initial RCP in DMF was observed as a blue emission by the naked eye, while according to the degradation, the dumbbell species spread throughout the solution and the [3]rotaxane structure disappeared, resulting in the light green color fluorescence of

• , meaning the introduction of CD units affects the fluorescence in a similar manner to the solvent, probably because two CD units have densely placed many (36) substituents on them. Thus, PAc-α-CD-based [3]rotaxane showed blue-shifted fluorescence compared with the dumbbell 13, which was observed before and

Tunable full-color dual-state (solution and solid) emission of push–pull molecules containing the 1-pyrindane moiety

• Anastasia I. Ershova,
• Sergey V. Fedoseev,
• Konstantin V. Lipin,
• Mikhail Yu. Ievlev,
• Oleg E. Nasakin and
• Oleg V. Ershov

Beilstein J. Org. Chem. 2024, 20, 3016–3025, doi:10.3762/bjoc.20.251

• Table S1 and Figure S1, Supporting Information File 1). The electronic absorption spectra were characterized by a pronounced maximum in the visible region centered at 431–448 nm. Emission maxima of compound 1c were more significantly affected by the change of polarity and ranged from 475 nm (blue-green

• group, a strong blue shift occurred down to 394 nm. The only exception was a solution of 1i in acetic acid, where two peaks were observed. Apparently, the weaker acetic acid caused just a partial protonation of the amino group, and the equilibrium shown in Scheme 2 was observed. This was evidenced by

• visible region of the spectrum (from blue to red, Figure 3B and Figure 4). Acidic solutions were the most blue-shifted due to the formation of the protonated form 1iH+ (Scheme 2). Two emission maxima were observed in acetic acid and associated with the corresponding absorption maxima. The first, located

Advances in radical peroxidation with hydroperoxides

• Oleg V. Bityukov,
• Pavel Yu. Serdyuchenko,
• Andrey S. Kirillov,
• Gennady I. Nikishin,
• Vera A. Vil’ and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2024, 20, 2959–3006, doi:10.3762/bjoc.20.249

• -AcrClO4 as the photocatalyst has been disclosed (Scheme 24) [67]. According to the authors, the irradiation of the photocatalyst (Acr+-Mes) A with a blue LED leads to the excited state (Acr·-Mes·+) B. The aliphatic carboxylic acid 66 is converted by deprotonation to the corresponding carboxylate, which is

4,6-Diaryl-5,5-difluoro-1,3-dioxanes as chiral dopants for liquid crystal compositions

• Maurice Médebielle,
• Peer Kirsch,
• Jérémy Merad,
• Carolina von Essen,
• Clemens Kühn and
• Andreas Ruhl

Beilstein J. Org. Chem. 2024, 20, 2940–2945, doi:10.3762/bjoc.20.246

• ) LCDs which need a higher HTP or increased dopant concentrations [8][9]. TN and STN displays are still based on liquid crystals in the nematic or cholesteric mesophase. Even higher concentrations of chiral dopants with extremely high HTP tend to induce a Blue Phase, which is a cubic mesophase composed

• of double twist cylinders [10][11]. A prototype of a polymer-stabilized Blue Phase LCD with ultra-fast switching times has been presented in 2008 by Samsung [12]. Another class of materials including high HTP chiral dopants are cholesteric films prepared by the polymerization of reactive mesogens

• the two nematic host mixtures is their polarity: whereas Host 1 is only moderately polar (Δε = 4.0), the mixture Host 2 was developed for Blue Mode LCD application and is extremely polar. As compared to chiral dopants depicted in Figure 1, HTPs are lower and closest analogues for comparison could be

The charge transport properties of dicyanomethylene-functionalised violanthrone derivatives

• Sondos A. J. Almahmoud,
• Joseph Cameron,
• Dylan Wilkinson,
• Michele Cariello,
• Claire Wilson,
• Alan A. Wiles,
• Peter J. Skabara and
• Graeme Cooke

Beilstein J. Org. Chem. 2024, 20, 2921–2930, doi:10.3762/bjoc.20.244

• anhydrous chlorobenzene (6 mL). To the dark blue mixture titanium tetrachloride (100 μL, 0.840 mmol) and pyridine (130 μL, 1.68 mmol) were added and the mixture was stirred under reflux overnight. After cooling the reaction mixture to room temperature, it was poured into ice-water (50 mL) and extracted with

• in anhydrous chlorobenzene (6 mL). To the dark blue mixture, titanium tetrachloride (50.0 μL, 0.420 mmol) and pyridine (70.0 μL, 0.84 mmol) were added and the mixture was stirred under reflux overnight. After cooling the reaction mixture to room temperature, it was poured into ice-water (50 mL) and

• mL). To the dark blue mixture titanium tetrachloride (120 μL, 1.08 mmol) and pyridine (170 μL, 2.16 mmol) were added and the mixture was stirred under reflux overnight. After cooling the reaction mixture to room temperature, it was poured into ice-water (50 mL) and extracted with dichloromethane (3

Recent advances in transition-metal-free arylation reactions involving hypervalent iodine salts

• Ritu Mamgain,
• Kokila Sakthivel and
• Fateh V. Singh

Beilstein J. Org. Chem. 2024, 20, 2891–2920, doi:10.3762/bjoc.20.243

• mechanism by adding 2 equivalents of TEMPO to the reaction mixture. The absence of the desired product indicated the involvement of a radical pathway in the process. The proposed reaction mechanism begins with the activation of eosin Y by visible light from 5 W blue LEDs, transitioning it to its excited

• corresponding heteroaryl–aryl compounds 32 in moderate to good yield. The use of blue LEDs (456 nm), nitrogen atmosphere, and HFIP/H2O 4:1 solvent mixture improved the yield of the product by up to 90%. Various substituted azauracils were used to study the reaction and it was observed that different substituted

• Morita–Baylis–Hillman (MBH) acetates using a variety of diaryliodonium triflates [65]. The reaction was carried out with MBH acetate 33 and diphenyliodonium triflate 16 in the presence of different photocatalysts and bases. Methylene blue trihydrate (MB·3H2O) was identified as a highly active

N-Glycosides of indigo, indirubin, and isoindigo: blue, red, and yellow sugars and their cancerostatic activity

• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 2840–2869, doi:10.3762/bjoc.20.240

• their activity against various types of cancer. N-Glycosides of indigo, indirubin, and isoindigo, blue, red, and yellow sugars, turned out to be of special interest because of their high cancerostatic activity and structural novelty. The present article provides an account on the synthesis and

• anticancer activity of these compounds. Keywords: cancerostatic activity; carbohydrates; heterocycles; N-glycosides; indirubin; Introduction Indigo (1a), known for more than 6000 years and originally produced from indigo plants in India, represents a famous traditional blue pigment which was an expensive

• , indirubin, and isoindigo which can be regarded as blue, red, and yellow sugars, respectively. Review Indigo-N-glycosides (blue sugars) In 2002, Laatsch and Maskey reported the isolation of the akashins A, B and C, indigo-N-glycosides, from terrestric Streptomyces (Scheme 2) [17][18]. These natural products

Investigation of a bimetallic terbium(III)/copper(II) chemosensor for the detection of aqueous hydrogen sulfide

• Parvathy Mini,
• Michael R. Grace,
• Genevieve H. Dennison and
• Kellie L. Tuck

Beilstein J. Org. Chem. 2024, 20, 2818–2826, doi:10.3762/bjoc.20.237

• the presence of various anions/sulfur compounds; spectra measured in 10 mM Tris HCl buffer (pH 7.4) with λex = 250 nm. Green bar: [Tb.1·3Cu]3+ alone (5 µM). Blue bar: [Tb.1·3Cu]3+ (5 µM) and Na2S (15 µM). Grey bars: [Tb.1·3Cu]3+ (5 µM) and anion/sulfur compound (50 µM). Black bars: [Tb.1·3Cu]3+ (5 µM

Interaction of a pyrene derivative with cationic [60]fullerene in phospholipid membranes and its effects on photodynamic actions

• Hayato Takagi,
• Çetin Çelik,
• Ryosuke Fukuda,
• Qi Guo,
• Tomohiro Higashino,
• Hiroshi Imahori,
• Yoko Yamakoshi and
• Tatsuya Murakami

Beilstein J. Org. Chem. 2024, 20, 2732–2738, doi:10.3762/bjoc.20.231

• -methyl-1-pyrrolidone-N-oxide (DEPMPO) were respectively used (schemes in Figure 5). Our previous study demonstrated that both 1O2 and O2•– were generated under irradiation of triad molecules in DMSO/H2O [8]. Under irradiation by a blue LED (464–477 nm, 23 lm·W–1), significant ESR signals corresponding to

• Sciences AG (Farmingdale, NY, USA). FeSO4, DETAPAC and NADH was bought from Sigma-Aldrich (St. Louis, Missouri, USA). DMPO was bought from TCI (Tokyo Chemical Industry Co. Ltd., Tokyo, Japan). Irradiation was performed by blue LED light (464–477 nm, 23 lm·W–1) from Lumiflex300 Pro RGB LED Stripes

• solution (335 µM) was added instead of 10 µM of PBS(–). The solution was subjected to O2 bubbling for 30 seconds and then taken into 50 µL capillary and sealed. The solution was then irradiated with blue LED light for 30 minutes. The capillary was taken into the ESR tube for measurement at room temperature

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

• materials (Scheme 1d). The synthetic procedure is achieved using blue light irradiation and bromotrichloromethane (BrCCl3), as a one-pot procedure, minimizing chemical wastes, avoiding purification of intermediates, and simplifying practical aspects. Results and Discussion We have recently published the one

• synthetic process in a one-pot manner, adding all the components from the very beginning. So, the blue-light-promoted reaction between N-Ph-THIQ, 3-methoxyaniline and tert-butyl isocyanide in the presence of BrCCl3 was extensively optimized by varying several parameters, such as solvent, relative quantity

• of components and temperature (Table 2). We firstly irradiated with blue LEDs (451 nm) the mixture of the three components in the presence of 1.5 equiv of BrCCl3 for 18 h at room temperature under argon atmosphere (Table 2, entry 1). To our surprise, the reaction provided only traces of the expected

Photoluminescence color-tuning with polymer-dispersed fluorescent films containing two fluorinated diphenylacetylene-type fluorophores

• Kazuki Kobayashi,
• Shigeyuki Yamada,
• Motohiro Yasui and
• Tsutomu Konno

Beilstein J. Org. Chem. 2024, 20, 2682–2690, doi:10.3762/bjoc.20.225

• and effective luminescence color-tuning method is proposed to investigate the photoluminescence behavior of two-component polymer dispersion films blended with two types of fluorinated diphenylacetylenes, namely blue- and yellow- or red-fluorescent fluorinated diphenylacetylenes. It is confirmed that

• if blue and green–yellow or yellow fluorophores are blended in appropriate ratios, a binary blend with color coordinates (0.20, 0.32) can be achieved, which approaches the white point of pure white emission. These findings contribute to the development of effective lighting and display devices as new

• has been severely delayed [4][5][6]. However, since Tang et al. first reported the aggregation-induced emission phenomenon in 2001 [7], the development of solid-state light-emitting materials has accelerated significantly [8][9][10]. Many photoluminescent materials that emit blue, green, and yellow

Computational design for enantioselective CO₂ capture: asymmetric frustrated Lewis pairs in epoxide transformations

• Maxime Ferrer,
• Iñigo Iribarren,
• Tim Renningholtz,
• Ibon Alkorta and
• Cristina Trujillo

Beilstein J. Org. Chem. 2024, 20, 2668–2681, doi:10.3762/bjoc.20.224

• (PO) and CO2 and the five catalyst scaffolds under study. The position of the LB along with an appropriate number of substituents is indicated by blue dots and that of the LA by pink dots. Capture reactions of CO2 or an epoxide by FLP. Asymmetric catalysis studied. On the left, the catalyst proposed

Applications of microscopy and small angle scattering techniques for the characterisation of supramolecular gels

• Connor R. M. MacDonald and
• Emily R. Draper

Beilstein J. Org. Chem. 2024, 20, 2608–2634, doi:10.3762/bjoc.20.220

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

• (Figures S22–25 in Supporting Information File 1) [31]. The absorption band at 524 nm was blue-shifted by 4 nm compared to that of N-phenyl-substituted 1b+-BF4− [15]. This can be ascribed to the lesser conjugation of the core TATA+ unit with the introduced 2,6-dimethylphenyl moieties owing to the more

• ) packing structures and (ii) enlarged views for the columnar structures. In (i), cation and anion are represented in cyan and magenta colors, respectively. In (ii), brown, pink, yellow, blue, yellow green, orange, and green (spherical) refer to carbon, hydrogen, boron, nitrogen, fluorine, phosphorus, and

• chlorine, respectively. Hirshfeld surface analysis mapped with dnorm of closely contacted two 2+ in (a) 2+-BF4− and (b) 2+-PF6−. Atom color code: brown, pink, and blue refer to carbon, hydrogen, and nitrogen, respectively. Hirshfeld surface analysis mapped with dnorm of closely contacted ion pairs: (a) 2

A review of recent advances in electrochemical and photoelectrochemical late-stage functionalization classified by anodic oxidation, cathodic reduction, and paired electrolysis

• Nian Li,
• Ruzal Sitdikov,
• Ajit Prabhakar Kale,
• Joost Steverlynck,
• Bo Li and
• Magnus Rueping

Beilstein J. Org. Chem. 2024, 20, 2500–2566, doi:10.3762/bjoc.20.214

• in the late functionalization of complex drug molecules. Due to the versatility of the azide group, the direct C(sp3)–H azidation is an extremely valuable transformation. Lei and coworkers achieved this transformation using electrochemistry upon irradiation with blue LEDs [69]. Under photoelectric