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

• included oxidation of aldehydes 4 with Oxone to acids 5 and the conversion of the latter into acid chlorides with thionyl chloride. The first reaction sequence was suitable for obtaining compounds 1a–c,e,f with substituents tolerant to radical reaction conditions. A significant advantage of the method is

• the conversion of the latter to the acid chlorides 1 with thionyl chloride proceeded with yields of 77–92%. This made it possible to synthesize the target isoxazoles 1b,d,g–j with fairly high yields. Having in hand a set of isoxazoles 1a–i containing aryl substituents at the 3-position of the

Direct trifluoroethylation of carbonyl sulfoxonium ylides using hypervalent iodine compounds

• Radell Echemendía,
• Carlee A. Montgomery,
• Fabio Cuzzucoli,
• Antonio C. B. Burtoloso and
• Graham K. Murphy

Beilstein J. Org. Chem. 2024, 20, 3182–3190, doi:10.3762/bjoc.20.263

• scope and limitations of this novel transformation (Scheme 2). Initially, we investigated the effects of introducing various substituents around the ester group of the carbonyl sulfoxonium ylide. We discovered that the reaction worked very well for various alkyl ester derived substrates (3b–g). For

Hypervalent iodine-mediated intramolecular alkene halocyclisation

• Charu Bansal,
• Oliver Ruggles,
• Albert C. Rowett and
• Alastair J. J. Lennox

Beilstein J. Org. Chem. 2024, 20, 3113–3133, doi:10.3762/bjoc.20.258

• fluoride and BF3·OEt2 as activator. A range of unsaturated amines 5 were cyclised to racemic β-fluorinated piperidines 6. Good yields were reported for all compounds except those with substituents present on the alkene. Homologation of the carbon chain from 5 to 6 carbons gave both 6- and 7-membered rings

• , intramolecular aminofluorination of a range of unsaturated amines formed β-fluorinated piperidines 6 and 3-fluoroazepanes 7 in good yields. Again, yields only significantly fell with substrates containing substituents on the alkene. Depending on the length of the alkyl chain, both 6- and 7-membered rings were

• . Aminoacetylation of the alkene competed with the aminofluorination to form 3-acetoxypiperidines 11. Other sources of fluoride were tested, with metal fluoride salts giving no or trace products. The authors reported that only 6-membered rings were formed, with a range of substituents on the β-carbon of the alkene

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

• , photocatalysts, and electrocatalysts are presented here. The effect of macrocyclic structural modifications such as their functionalization with different substituents, distortion from planarity, conformational flexibility and rigidity towards catalytic activity are presented, highlighting the potential of these

• other binding sites required for substrate binding and/or promotion of the catalytic activity. Past studies have shown that modifying the porphyrin core with urea functionalities and amino acid substituents leads to the formation of ureaporphyrins, which significantly enhance sugar binding in non-polar

• electron-withdrawing substituents at the meso- and/or β-positions and highly saddle-distorted geometry (27, 29–31) are inactive (Table 2). Mono-N-alkylation of the macrocycles resulted in a slight improvement of activity giving up to 50–62% conversion for 34 and 37, both of which are alkylated versions of

Synthesis of the 1,5-disubstituted tetrazole-methanesulfonylindole hybrid system via high-order multicomponent reaction

• Cesia M. Aguilar-Morales,
• América A. Frías-López,
• Nadia V. Emilio-Velázquez,
• Alejandro Islas-Jácome,
• Angelica Judith Granados-López,
• Jorge Gustavo Araujo-Huitrado,
• Yamilé López-Hernández,
• Hiram Hernández-López,
• Luis Chacón-García,
• Jesús Adrián López and
• Carlos J. Cortés-García

Beilstein J. Org. Chem. 2024, 20, 3077–3084, doi:10.3762/bjoc.20.256

• importance of the tert-butyl and cyclohexyl substituents in the imidazole can be deduced. According to the IC50 results presented in Figure 1, it can be seen that all cyclohexyl-substituted derivatives tested show activity. In contrast, those carrying the tert-butyl group are inactive, except for 18i and 18a

• substituent on the phenyl group, it is interesting to note that the most active compound of the whole series is the fluorinated derivative 18d, followed in order of inhibition by 18j, which has no substituents. The position of this halogen is also relevant since the activity decreases when it is in the 4

Enantioselective regiospecific addition of propargyltrichlorosilane to aldehydes catalyzed by biisoquinoline N,N’-dioxide

• Noble Brako,
• Sreerag Moorkkannur Narayanan,
• Amber Burns,
• Layla Auter,
• Valentino Cesiliano,
• Rajeev Prabhakar and
• Norito Takenaka

Beilstein J. Org. Chem. 2024, 20, 3069–3076, doi:10.3762/bjoc.20.255

• ][15][16][17][18][19], the separation of which is by no means trivial [20] (Scheme 1). Nonetheless, substituents at the carbon atom indicated by γ (R2) of these reagents have been shown to bias the metallotropic rearrangement and/or the kinetic reactivity of the competing regioisomeric intermediates

• toward electrophiles [14][15][16][17][18][19]. Consequently, all reported asymmetric catalytic aldehyde allenylation methods are currently limited to metal/metalloid reagents bearing R2 substituents [21][22][23][24][25][26][27][28][29][30][31][32][33][34], except for the methods with

• , the enantioselectivity consistently decreased as the chiral pocket became narrower while the reactivity remained the same. As such, we reduced the size of the substituents that craft the chiral pocket (7) and found that unsubstituted catalyst 8 was the most enantioselective. This observed catalyst

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

• generations of modified norbornadiene derivatives with diverse variations of donor and acceptor substituents [25][26][27][28][29][30][31][32]. However, such a modification often leads to higher molar masses and thus to lower energy densities [7][25][33]. Consequently, further fine tuning of the substituents

• quadricyclanes from 3.0 h to 7.8 h, which are essentially in the same range as the ones of analogues with an acceptor-substituent in the 3-position of the norbornadiene [34]. Notably, the quadricyclane derivatives with sterically more demanding substituents in the 2-position of the norbornadiene unit, such as 1e

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

• synthesize the rotaxane. For example, Anderson and co-workers reported the synthesis of γ-CD–based [2]rotaxane via the Suzuki reaction using a dicarboxylic acid end-capping reagent; they reported a 17% yield (Scheme 1C) [39]. To perform an end-capping reaction in water, multiple hydrophilic substituents

• , most of their rotaxane structures required a complicated multistep synthesis as well as the introduction of polar substituents, such as carboxylic acid or sulfonic acid groups, to generate a water-soluble system, and these prevent the direct application of those frameworks to polymer systems. As the

• ]rotaxane. In this case, the energy diagram of the deslipping reaction differs from those of the ones bearing a [2]rotaxane intermediate (Figure 9E). As revealed in this study, the CD-based size-complementary rotaxane exhibiting a simple framework (no ionic substituents nor deoxynucleotide) was obtained

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

• pyridine as an acceptor. The introduction of additional substituents to stilbazole makes it possible to change the optical properties of this molecular framework within a wide range [16][17][18][19]. This approach has found many applications in the synthesis of compounds that are used in various optical

• and acceptor groups arranged in a specific sequence, such as in D–π–A chromophores. This creates the conditions for efficient intramolecular charge transfer (ICT), which plays a key role in the DSE phenomenon. Also, additional substituents can affect the geometry and conformation of the molecule

• containing various numbers of substituents at the donor site, which differed in their electron-donating strength, was obtained. It was found that the reaction of pyridine 2 with aromatic aldehydes occurred with complete stereoselectivity – only the E-isomer was obtained as the reaction product. The

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

• carried out as part of the investigation of the enzymatic function of cytochrome P-450 with low valent ruthenium complex catalysts. Various phenols 86 bearing para-substituents were transformed into the corresponding tert-butyldioxy dienones 87 smoothly using RuCl2(PPh3)3 as the catalyst (Scheme 31) [83

Synthesis of fluorinated acid-functionalized, electron-rich nickel porphyrins

• Mike Brockmann,
• Jonas Lobbel,
• Lara Unterriker and
• Rainer Herges

Beilstein J. Org. Chem. 2024, 20, 2954–2958, doi:10.3762/bjoc.20.248

• . After metalation with Ni(acac)2 and hydrolysis electron-rich porphyrins were obtained, that are equipped with covalently attached long chain acid substituents. The target compounds have potential applications in catalysis, sensing, and materials science. The fluorinated aliphatic carboxylic acids (TfO

Structure and thermal stability of phosphorus-iodonium ylids

• Andrew Greener,
• Stephen P. Argent,
• Coby J. Clarke and
• Miriam L. O’Duill

Beilstein J. Org. Chem. 2024, 20, 2931–2939, doi:10.3762/bjoc.20.245

• bipyramidal (T-shaped) with the least electronegative group and the two nonbonding electron pairs occupying the equatorial positions, and the most electronegative substituents forming a hypervalent 3-centre-4-electron (3c-4e) bond in the axial position (Figure 1A) [17][18]. The LUMO of this bond is

• concentrated on iodine [19], making it highly electrophilic, while a nonbonding pair of electrons is mainly centred on the axial substituents, causing a build-up of electron density on these positions (Figure 1A) [1][20]. Stabilisation of this charge on the axial substituents by strong electron-withdrawing

• ligand occupies the position trans to the ylid substituent, with the aryl substituent in the equatorial position. Substituents on hypervalent iodine compounds can interconvert via Barry pseudorotation [31] and, interestingly, the crystal structure for compound 1i contains two isomers in its unit cell

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

• dicyanomethylene-functionalised violanthrone derivatives (3a, 3b and 3c) featuring different alkyl substituents. It is found that the introduction of the electron-deficient dicyanomethylene groups significantly improves the optical absorption compared to their previously reported precursors 2a–c. All compounds are

• modification of dihydroxyviolanthrone where the effect of three alkoxy substituents on the 16,17-bis(2-ethylhexyloxy)anthra[9,1,2-cde]benzo[rst]pentaphene-5,10-dione, on aggregation and photovoltaic properties was studied [30]. It was found that derivatives with the shortest linear alkyl chain (n-hexyl

• values of absorption (λonset), and little difference was found with values of 1.47 eV for 3b and 1.46 eV for 3a and 3c. It is noted that the optical properties did not show a significant change upon altering the alkyl chains which indicates that different alkyl substituents have a minimal effect on the

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

• in unsymmetrical diaryliodonium salts the transfer of the aryl group with the relatively lower electron density and less steric hindrance was favoured. A range of electron-rich and electron-deficient substituents positioned para to the aryl ring in the diaryliodonium salts were found to be well

• . Notably, the efficiency of the cross-coupling reaction was observed to increase with the transfer of electron-poor aryl groups from the hypervalent iodine salt. Thus, electron-withdrawing substituents such as trifluoromethyl, m-chloro, and fluorine on the aryl group promoted efficient coupling. Moreover

• various substituents on the aromatic ring. Additionally, a variety of substituted esters, ketones, and nitriles were found to be compatible with the reaction. Additionally, the same approach was used for the aryl sulfonylation. Trisubstituted allylic sulfones 35 were synthesized by reacting MBH acetate 33

Synthesis of pyrrole-fused dibenzoxazepine/dibenzothiazepine/triazolobenzodiazepine derivatives via isocyanide-based multicomponent reactions

• Marzieh Norouzi,
• Mohammad Taghi Nazeri,
• Ahmad Shaabani and
• Behrouz Notash

Beilstein J. Org. Chem. 2024, 20, 2870–2882, doi:10.3762/bjoc.20.241

• reaction conditions giving the products 4 in yields ranging from 68% to 87% (Scheme 3, 4a–l). In this reaction, the presence of electron-withdrawing substituents in the aromatic rings of the gem-diactivated olefins led to slightly better yields of the products 4 when compared to the substrates having

• electron-donating substituents (Scheme 3). The cause of this phenomenon is probably related to the electron-widthdawing effect of these substitution groups in olefin, which affects the nucleophilic attack of the isocyanides. When a carboxylate substituent was present instead of the carbonitrile in the gem

• increase and the electron-donating substituents led to a decrease in the reaction efficiency (Scheme 3, 4a–k). In addition, benzothiazepine was used in this protocol and the corresponding pyrrole-fused benzothiazepine was obtained with a yield of 73% (Scheme 3, 4l). Also, various isocyanides were suitable

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

• , both electron-donating and -withdrawing substituents were tolerated. In contrast, isatin-N-glycosides containing electron-withdrawing groups and, thus, the corresponding indirubin-N-glycosides could not be successfully prepared at this point (vide infra). In general, anomerically pure isatin-N

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

• [1,2-a]pyrimidines obtained by various modifications of this method and a number of others described in detail in the review by Goel et al. [4], literature data on the synthesis of tetrahydroimidazo[1,2-a]pyrimidines without substituents in the second and third positions remain limited. In this context

• ). Conclusion Thus, we have proposed an efficient way to construct tetrahydroimidazo[1,2-a]pyrimidines without substituents at the 4 and 5-positions of the imidazole fragment by the reaction of 2-aminoimidazole with N-arylitaconimides and N-substituted maleimides. With the aid of DFT calculations, the most

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

• was obtained. Furthermore, most isolated products had only purities of ca. 90% still containing inseparable impurities (as revealed by NMR spectroscopy). In the first series of substrates, acetophenone derivatives with various para-substituents were applied. Similar to methyl tolyl ketone (1a), which

C–C Coupling in sterically demanding porphyrin environments

• Liam Cribbin,
• Brendan Twamley,
• Nicolae Buga,
• John E. O’ Brien,
• Raphael Bühler,
• Roland A. Fischer and
• Mathias O. Senge

Beilstein J. Org. Chem. 2024, 20, 2784–2798, doi:10.3762/bjoc.20.234

• porphyrin architectures, which could be used in supramolecular assemblies, catalysis, or sensing. In this work a library of arm-extended dodecasubstituted porphyrins was synthesized through the optimization of the classic Suzuki–Miyaura coupling of peripheral haloaryl substituents with a range of boronic

• the porphyrin ring deforming from the mean porphyrin plane either by steric repulsion in the core of the macrocycle or by bulky substituents at the porphyrin periphery [3]. This affords four principle distortion modes, saddle, dome, ruffle or wave [8], which can be quantified by the normal-coordinate

• structural decomposition (NSD) method developed by Shelnutt and co-workers [9] and further implemented and visualized by us [8][10]. Of the four main quantifiable distortion modes, saddle-shaped porphyrins can be afforded by peri-interactions between β-substituents and the meso-substituents [3][11], or

Copper-catalyzed yne-allylic substitutions: concept and recent developments

• Shuang Yang and
• Xinqiang Fang

Beilstein J. Org. Chem. 2024, 20, 2739–2775, doi:10.3762/bjoc.20.232

• related to yne-allylic substitutions. Review Copper-catalyzed yne-allylic substitutions affording 1,3- and 1,4-enynes In 2022, Fang et al. [62] realized the copper-catalyzed yne-allylic substitution involving stabilized “soft” nucleophiles for the first time. Indoles and pyrroles with various substituents

• :1 (Scheme 3, 3e). Carbonates with aryl or styryl residue can undergo the reaction smoothly (Scheme 3, 3f–k), but alkyl-substituted substrates showed low yields (Scheme 3, 3l and 3m). Moreover, secondary amines with various substituents, acyclic amines, primary amines, or even the amine moieties in

• -, stereo-, and enantioselectivities, resulting in a series of chiral yne-allylic sulfone compounds with different substituents (Scheme 13, 14a–q). Due to the high steric hindrance of the γ-site, nucleophilic substitutions preferentially occur at the α-site. Through subsequent control experiments, they

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

• known which allow for an individual introduction of substituents at both positions [37][38][51][52][53][54][55][56][57][58][59][60][61]. In our previous work, we developed a new method which enables both positions to be independently functionalised by Sonogashira- and Suzuki–Miyaura cross-coupling

• are known compounds, the synthesis of derivatives 4g–i has not been previously reported (Scheme 2). Yields were generally lower in case of the presence of electron-withdrawing substituents. Subsequently, the cyclisation of 4a–i to 5a–i by acid-mediated cycloisomerisation was studied. In our first

• -group-containing compounds 5d and 5f are bathochromically shifted by ≈80 nm and ≈100 nm, respectively. The other compounds show similar emission maxima at ≈405 nm, hinting to a limited impact of the aryl substituents and their functional groups on the emission properties for these compounds. Moreover

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

• -chloro-1,1,1-trifluoroethane (halothane) in good yields (Scheme 1D) [42]. Compound 1 has a unique structure possessing three types of halogen atoms, namely bromine, chlorine, and fluorine, and it would be expected to afford multisubstituted fluoroalkenes by installing various substituents to bromine or

• cross-coupling between 1e, derived from m-aminophenol, and 4a proceeded in only 15% yield (Table 3, entries 17 and 18). We performed Sonogashira cross-couplings between 1 and a variety of alkynes 5 (Table 4). Arylacetylenes, which have electron-donating substituents on the aromatic ring (5b–f), and 2

• -naphthylacetylene (5g) provided the corresponding enynes (3b–g) in 43–92% yields (Table 4, entries 1–6). On the contrary, electron-withdrawing substituents such as chloro, trifluoromethyl and nitro groups resulted in low cross-coupling yields (3h–j) (Table 4, entries 7–9). p-Acetyl or p-formylphenylacetylene (5k or

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

• structure (Figure 1a) [14][15][16]. Our extensive efforts have revealed that introducing electron-donating alkoxy and electron-withdrawing cyano groups at both ends of the diphenylacetylene scaffold slows the internal conversion to the πσ* excited state. Further incorporating four fluoro substituents in the

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

• an in silico approach to design asymmetric frustrated Lewis pairs (FLPs) aimed at controlling reaction stereochemistry. Four FLP scaffolds, incorporating diverse Lewis acids (LA), Lewis bases (LB), and substituents, were assessed via volcano plot analysis to identify the most promising catalysts. By

• strategically modifying LB substituents to induce asymmetry, a stereoselective catalytic scaffold was developed, favouring one enantiomer from both epoxide enantiomers. This work advances the in silico design of FLPs, highlighting their potential as asymmetric CCU catalysts with implications for optimising

• colleagues [1]. These compounds, which feature a Lewis acid (LA) and a Lewis base (LB), whose interaction is hindered by bulky substituents or chain strain, have garnered significant attention. Initially explored for their ability to trap small molecules [2][3], such as H2 [4], CO2 [5][6][7], N2O [8][9], and

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

• -absorbing as well as photo-antioxidant properties via an intramolecular hydrogen transfer [5]. The structure–activity relationship between the substituents of 2-hydroxybenzophenones and their UV-absorption properties has been reported previously [6]. It was concluded that the ability to absorb UV light and

• of 3-arylbenzofuran-2(3H)-ones with both electron-donating as well as electron-withdrawing substituents reacted smoothly to afford the corresponding benzophenones 4aa–ka in good to high yields. Substitutions at the 5, 6, or 7 positions of the benzofuranones did not hamper the reaction, although a