Switchable pathways of multicomponent heterocyclizations of 5-amino-1,2,4-triazoles with salicylaldehydes and pyruvic acid

• Yana I. Sakhno,
• Oleksander V. Buravov,
• Kostyantyn Yu. Yurkov,
• Anastasia Yu. Andryushchenko,
• Svitlana V. Shishkina and
• Valentyn A. Chebanov

Beilstein J. Org. Chem. 2025, 21, 2030–2035, doi:10.3762/bjoc.21.158

• formation of heterocyclic systems in a minimal number of steps and offer several ways to vary substituents and they are widely used in drug discovery and development, as well as in diversity-oriented synthesis [1][2][3][4]. In addition, the application of condition-based divergence strategy [5] and the

• I–VI were formed (Scheme 1) [8][18][19]. It is known that substituents in aminoazoles can significantly influence their behavior in multicomponent heterocyclization reactions [4][8][20][21]. However, the reactions of 5-amino-1,2,4-triazoles containing substituents in position 3, which can also

• -aminotriazoles 1a,b having pronounced electron-donating substituents (methylthio- and methoxy groups). On the other hand, the MCR of the reagents 1a, 2a–c and 3 under ultrasonic irradiation for 2 h at room temperature (25 °C) (Scheme 3) afforded a mixture of 5-(2-hydroxyphenyl)-2-(methylthio)-7-((3-(methylthio

Measuring the stereogenic remoteness in non-central chirality: a stereocontrol connectivity index for asymmetric reactions

• Ivan Keng Wee On,
• Yu Kun Choo,
• Sambhav Baid and
• Ye Zhu

Beilstein J. Org. Chem. 2025, 21, 1995–2006, doi:10.3762/bjoc.21.155

• , and the stereochemical-defining substituents. The indices can be generated based on analysis of the chemical structures of the starting materials and products, without mechanistic insights of the transformation. Representative examples of reactions that establish point chirality, axial chirality

• molecule is characterized by the absence of mirror planes and centers of inversion. Central chirality arises when four distinct substituents (a, b, c, and d) are arranged tetrahedrally around a central atom (Scheme 1A). Non-central chirality – such as axial and planar chirality – are becoming increasingly

• within three-dimensional molecular frameworks that restrict conformational freedom. The geometric scaffolds can be a central atom, an axis, or a plane, and the combination and spatial arrangement of chemically distinct substituents establish the stereogenicity. Therefore, despite the apparent differences

Aryl iodane-induced cascade arylation–1,2-silyl shift–heterocyclization of propargylsilanes under copper catalysis

• Rasma Kroņkalne,
• Rūdolfs Beļaunieks,
• Armands Sebris,
• Anatoly Mishnev and
• Māris Turks

Beilstein J. Org. Chem. 2025, 21, 1984–1994, doi:10.3762/bjoc.21.154

• -donating substituents demonstrated higher yields (p-Tol > p-BrC6H4) (Table 2, entries 3 and 4). The p-bromo-substituted iodane I-6, albeit in a more modest yield, gave the diene 10d with 98:2 selectivity. Switching to the more sterically challenged triisopropylsilyl (TIPS) group (Table 2, entry 2) resulted

Enantioselective desymmetrization strategy of prochiral 1,3-diols in natural product synthesis

• Lihua Wei,
• Rui Yang,
• Zhifeng Shi and
• Zhiqiang Ma

Beilstein J. Org. Chem. 2025, 21, 1932–1963, doi:10.3762/bjoc.21.151

• enhanced the reaction performance. However, excessively bulky substituents at C4 and substitutions at both C4 and C5 hindered the coordination between substrate and catalyst, and led to reduced enantioselectivity. As to the structure of 128, the electronic effect of the bromo-substituted pyridine moiety

• from diester 157, underwent enantioselective monobenzoylation with complex 159 as catalyst to form benzoate 160 in 90% yield with 90% de. The size of the C4-substituent in the oxazoline moiety crucially influenced the enantioselectivity and conversion of the reaction: smaller substituents reduced the

• differential ability between two hydroxy groups, while bulky substituents hindered the formation of coordination bonds between the substrate and catalyst. As previously reported, with a suitable substituent at C4, an additional C5-substituent slightly enhanced the catalytic performance of the complex [62]. For

Synthesis of N-doped chiral macrocycles by regioselective palladium-catalyzed arylation

• Shuhai Qiu and
• Junzhi Liu

Beilstein J. Org. Chem. 2025, 21, 1917–1923, doi:10.3762/bjoc.21.149

• revealed the formation of isomeric products depending on the substituents on the N atoms. Notably, two intrinsically chiral macrocycles MC1 and MC3 with C1 symmetry were successfully obtained. These macrocycles exhibit exceptional photophysical properties, particularly remarkable high fluorescence quantum

Stereoselective electrochemical intramolecular imino-pinacol reaction: a straightforward entry to enantiopure piperazines

• Margherita Gazzotti,
• Fabrizio Medici,
• Valerio Chiroli,
• Laura Raimondi,
• Sergio Rossi and
• Maurizio Benaglia

Beilstein J. Org. Chem. 2025, 21, 1897–1908, doi:10.3762/bjoc.21.147

• products with complete stereoselectivity. Substrates bearing electron-donating or electron-withdrawing groups on the aromatic rings provided good to excellent yields, indicating that both types of substituents are well tolerated under the reaction conditions. Although modest yields were obtained under flow

• (0.125 M), were then applied to evaluate the scope of the reaction. Under these conditions a small library of chiral enantiopure tetrasubstituted piperazines 2b–j bearing both electron-withdrawing and electron-donating substituents, was synthetized. The results are summarized in Scheme 5. The chiral

• ), as well as electron-donating groups like methoxy (2f), aryl/alkyl (2h,i), and alkenyl substituents (2e), were well tolerated. Notably, the sterically hindered derivative 2h was isolated with the highest yield of 87% indicating that bulky ortho-substituents on the aromatic rings do not influence the

Chiral phosphoric acid-catalyzed asymmetric synthesis of helically chiral, planarly chiral and inherently chiral molecules

• Wei Liu and
• Xiaoyu Yang

Beilstein J. Org. Chem. 2025, 21, 1864–1889, doi:10.3762/bjoc.21.145

• and polycyclic ketone 2, they achieved the efficient asymmetric synthesis of various helically chiral azahelicenes 3 (Scheme 1). To address the inherent length-scale challenges of molecular helicene frameworks, the authors designed and synthesized novel CPAs bearing extended π-substituents at the

• ortho-positions. The dual hydrogen-bonding interactions were critical for this reaction, ensuring that the reaction proceeded within the chiral pocket of the CPA catalyst. Moreover, the authors proposed that the extended π-substituents at the ortho-positions of CPA could engage in π–π-stacking

• component, which facilitated the asymmetric synthesis of substituted [5]- and [6]pyridohelicenes 15 with ortho-phenolic substituents in position C1 with high enantioselectivity (Scheme 4) [21]. Notably, utilizing one equivalent of DDQ for semioxidation of the tetrahydroquinoline product of the Povarov

Systematic pore lipophilization to enhance the efficiency of an amine-based MOF catalyst in the solvent-free Knoevenagel reaction

• Pricilla Matseketsa,
• Margret Kumbirayi Ruwimbo Pagare and
• Tendai Gadzikwa

Beilstein J. Org. Chem. 2025, 21, 1854–1863, doi:10.3762/bjoc.21.144

• overall surface tension. Along with reduced conversions, we also found that our anticipated trend in catalyst efficiency, i.e. increasing conversions with the increasing lipophilicity of the carbamate substituents, was not consistently followed (Table 2B). While conversions increased going from no

• extent of alkyl grafting, the –CH2– content in the pores of KSU-1n-Hex and KSU-1C14 is still greater than for KSU-1iPr and KSU-1t-Bu, assuming a uniform distribution of alkyl chains. Additionally, although the introduction of large alkyl substituents in a MOF is associated with a reduction in pore

• , Supporting Information File 1). We found that the conversions were significantly better than those reported for H2BDC-NH2 under more forcing conditions (60 °C, 6 h) [52], which makes sense given that the methyl substituents on the carboxylate increase the basicity of –NH2, which should increase the catalytic

Photoswitches beyond azobenzene: a beginner’s guide

• Michela Marcon,
• Christoph Haag and
• Burkhard König

Beilstein J. Org. Chem. 2025, 21, 1808–1853, doi:10.3762/bjoc.21.143

• with a photoswitch, several factors must be considered: substituents, temperature, and solvent strongly affect the photophysical properties. For instance, the presence of electron-withdrawing (for instance -Cl, -Br, -CN, -NO2) and electron-donating groups (-alkyl, -OR, -NR2), which are directly

• tautomerism is an intermolecular process that depends not only on the choice of aryl rings and substituents but also on concentration, solvent polarity, and the presence of proton sources [5][15]. In conclusion, the choice of aryl rings, substituents, and substitution position are all crucial to determine the

• -phenylazopyrazoles notably increased the half-lives with respect to the unsubstituted ones, probably a result of favourable weak interactions between the pyrazole ring and the ortho-substituents in the Z-form [30]. Despite the high intensity of the nπ* absorption band, the absorption spectra of the two isomers are

Fe-catalyzed efficient synthesis of 2,4- and 4-substituted quinolines via C(sp²)–C(sp²) bond scission of styrenes

• Prafull A. Jagtap,
• Manish M. Petkar,
• Vaishnavi R. Sawant and
• Bhalchandra M. Bhanage

Beilstein J. Org. Chem. 2025, 21, 1799–1807, doi:10.3762/bjoc.21.142

• this methodology. As summarized in Scheme 2, we initially investigated the scope and effect of arylamine functionalities on this transformation. Under optimized reaction conditions, arylamines bearing either electron-rich or electron-deficient substituents at the para-position demonstrated good

• with 3m′ and 3n′ in high yields. Slightly lower yields were observed when styrenes bearing electron-withdrawing substituents (2d and 2f) were examined, giving the final products ranging from 56% to 75% isolated yields. Nevertheless, meta-substituted styrene (2g) was also evaluated in this reaction

[3 + 2] Cycloaddition of thioformylium methylide with various arylidene-azolones in the synthesis of 7-thia-3-azaspiro[4.4]nonan-4-ones

• Daniil I. Rudik,
• Irina V. Tiushina,
• Anatoly I. Sokolov,
• Alexander Yu. Smirnov,
• Alexander R. Romanenko,
• Alexander A. Korlyukov,
• Andrey A. Mikhaylov and
• Mikhail S. Baranov

Beilstein J. Org. Chem. 2025, 21, 1791–1798, doi:10.3762/bjoc.21.141

• relative configuration (cis or trans) of the substituents. Therefore, the structures of the obtained compounds were determined by single crystal X-ray analysis (Figure 1). Thus, all the obtained derivatives of oxo-rhodanine 6, rhodanine 8 and imidazolone 9 had a cis configuration, while the derivatives of

Synthesis of chiral cyclohexane-linked bisimidazolines

• Changmeng Xi,
• Qingshan Sun and
• Jiaxi Xu

Beilstein J. Org. Chem. 2025, 21, 1786–1790, doi:10.3762/bjoc.21.140

• different substituents on the NH moiety of the imidazoline ring. Herein, we designed and synthesized several sulfonylated cyclohexane-1,2-linked bisimidazoline (cHBim) ligands (Figure 1). Results and Discussion The synthesis of the chiral cyclohexane-linked bisimidazoline ligands started from enantiopure

Thermodynamics and polarity-driven properties of fluorinated cyclopropanes

• Matheus P. Freitas

Beilstein J. Org. Chem. 2025, 21, 1742–1747, doi:10.3762/bjoc.21.137

• polarity, with these effects varying based on the amount, position, and orientation of the fluorine substituents [7][8]. Mondal and colleagues have extensively reviewed additional properties of fluorinated cyclopropanes, including the conformational behavior of substituents attached to a fluorinated

3,3'-Linked BINOL macrocycles: optimized synthesis of crown ethers featuring one or two BINOL units

• Somayyeh Kheirjou,
• Jan Riebe,
• Maike Thiele,
• Christoph Wölper and
• Jochen Niemeyer

Beilstein J. Org. Chem. 2025, 21, 1719–1729, doi:10.3762/bjoc.21.134

• , 45141 Essen, Germany 10.3762/bjoc.21.134 Abstract Chiral macrocycles hold significant importance in various scientific fields due to their unique structural and chemical properties. By controlling their size, shape, and substituents, chiral macrocycles offer a platform for designing and synthesizing

• , thereby enabling further exploration in the field of interlocked and macrocyclic organocatalysts. We successfully established optimized synthetic routes for the synthesis of chiral macrocycles containing one or two stereogenic units, featuring varying ring sizes and substituents (21 examples in total

• , because in initial experiments, we obtained consistently higher yields and fewer side-products in comparison to other bases (such as NEt3 or K2CO3), as reported in the literature for related macrocyclizations [53][54][55]. We then investigated the impact of different substituents on the phenylene linkers

Approaches to stereoselective 1,1'-glycosylation

• Daniele Zucchetta and
• Alla Zamyatina

Beilstein J. Org. Chem. 2025, 21, 1700–1718, doi:10.3762/bjoc.21.133

• substituents, thereby minimizing the likelihood of oxocarbenium ion formation from the silyl aldoside acceptors 50 and 53 (Scheme 5). Nucleophilic attack by 1-O-trimethylsilyl β-pyranosides 50 or 53 on the α-face of the oxocarbenium ions afforded the corresponding β-ketopranosyl α-aldopyranosides 51 and 54

• and K. pneumoniae [74][75]. The application of variably protected 3-azido-3-deoxy-glucose-derived donor 72 and lactol acceptor 73, both allegedly armed due to the presence of multiple electron-donating bulky substituents, did not lead to product formation in the TMSOTf-promoted glycosylation reaction

• -withdrawing substituents leads to improved yields and stereoselectivities. Accordingly, the combination of GlcN-derived lactol 80 and the 2N-Troc-protected GlcN imidate donor 79, both bearing multiple bulky substituents such as dibenzyl phosphate, TBDMS, and Troc protecting groups, resulted in a complex

Continuous-flow-enabled intensification in nitration processes: a review of technological developments and practical applications over the past decade

• Feng Zhou,
• Chuansong Duanmu,
• Yanxing Li,
• Jin Li,
• Haiqing Xu,
• Pan Wang and
• Kai Zhu

Beilstein J. Org. Chem. 2025, 21, 1678–1699, doi:10.3762/bjoc.21.132

• dehydration. This electrophilic species subsequently engages in an aromatic electrophilic substitution, with reaction kinetics heavily influenced by the electronic nature of substituents and acid strength. Table 2 analyzes studies in the literature that utilize the flow-chemistry technology to investigate the

3-Aryl-2H-azirines as annulation reagents in the Ni(II)-catalyzed synthesis of 1H-benzo[4,5]thieno[3,2-b]pyrroles

• Julia I. Pavlenko,
• Pavel A. Sakharov,
• Anastasiya V. Agafonova,
• Derenik A. Isadzhanyan,
• Alexander F. Khlebnikov and
• Mikhail S. Novikov

Beilstein J. Org. Chem. 2025, 21, 1595–1602, doi:10.3762/bjoc.21.123

• . Azirines with both electron-donating and electron-withdrawing C3-aryl substituents tolerate the reaction conditions. The reaction of the N-methylindole analog also provides the annulation product but in moderate yield. The described synthesis is the first example of a dealkoxycarbonylative annulation

• 3-aryl-2H-azirines with different substitution patterns of the aryl group (Scheme 2). As the presented data show, the reaction is insensitive to the electronic effects of substituents in the aryl group and, in the majority of cases, gives very high yields of annulation products. The introduction of

• proceeds through azirine ring opening across the N–C3 bond. Azirines with both electron-donating and electron-withdrawing C3-aryl substituents tolerate the reaction conditions, and give the annulation products in high yields. The synthesized 3-aryl-1H-benzo[4,5]thieno[3,2-b]pyrroles can be effectively

Thermodynamic equilibrium between locally excited and charge transfer states in perylene–phenothiazine dyads

• Issei Fukunaga,
• Shunsuke Kobashi,
• Yuki Nagai,
• Hiroki Horita,
• Hiromitsu Maeda and
• Yoichi Kobayashi

Beilstein J. Org. Chem. 2025, 21, 1577–1586, doi:10.3762/bjoc.21.121

• an increasing number of TPA substituents. This observation suggests the presence of an additional emission band originating from the PTA-substituted PTZ unit, in addition to the emissions from the LE state of the Pe moiety and the CT state. The assignment of this band will be discussed in detail

• moiety. Femtosecond-to-nanosecond transient absorption spectroscopy To gain deeper insights into the effects of the electron-donating TPA substituents on the excited-state dynamics, femtosecond-to-nanosecond transient absorption spectroscopy measurements were carried out. While the excited-state dynamics

pH-Controlled isomerization kinetics of ortho-disubstituted benzamidines: E/Z isomerism and axial chirality

• Ryota Kimura,
• Satoshi Ichikawa and
• Akira Katsuyama

Beilstein J. Org. Chem. 2025, 21, 1568–1576, doi:10.3762/bjoc.21.120

• not coalesced even at 383 K, indicating that the C–N bond rotation was sufficiently slow on the NMR time scale (Figure 3b). To separate each E/Z isomer, amidine 2 with two different substituents on the same nitrogen atom, was prepared, and racemic 2 was analyzed by reversed-phase high performance

• 3–7, with different electron-donating or electron-withdrawing substituents at the para-position of the phenyl ring conjugated with the amidine moiety. The same kinetic analysis was performed for compounds 3–7 at pH 4.0, 4.5, 5.0, and 5.5, and the results are summarized in Table 1. In addition, the

• calculated pKa values of the amidines are also shown in Table 1. As a result, the C–N isomerization was accelerated by an electron-withdrawing chloro substituent, and electron-donating substituents (Me, OMe and NMe2 groups) decreased the isomerization rate. Figure 7a illustrates the effect of the electronic

Facile synthesis of hydantoin/1,2,4-oxadiazoline spiro-compounds via 1,3-dipolar cycloaddition of nitrile oxides to 5-iminohydantoins

• Juliana V. Petrova,
• Varvara T. Tkachenko,
• Victor A. Tafeenko,
• Anna S. Pestretsova,
• Vadim S. Pokrovsky,
• Maxim E. Kukushkin and
• Elena K. Beloglazkina

Beilstein J. Org. Chem. 2025, 21, 1552–1560, doi:10.3762/bjoc.21.118

• -oxadiazoline spiro-compounds using a 1,3-dipolar cycloaddition of nitrile oxides to C=N bonds of 5-iminohydantoins. The efficiency of the approach was demonstrated by varying the substituents at four positions of the resulting spirocyclic molecules. Cytotoxicity of the target hydantoin/1,2,4-oxadiazolines was

• in the compound as one of the substituents in the central cycle [8][20]. We believe that this approach has the potential to be a successful combination of the presented design strategies. It enables the pharmacophore fragments to be positioned relative to one another in a specific manner, as

• generated nitrile oxide seems to be less significant. It was found that the low solubility of products containing aromatic substituents in non-polar solvents allows for their isolation by washing the crude reaction mixture with diethyl ether to remove organic impurities and then with water to eliminate

Azobenzene protonation as a tool for temperature sensing

• Antti Siiskonen,
• Sami Vesamäki and
• Arri Priimagi

Beilstein J. Org. Chem. 2025, 21, 1528–1534, doi:10.3762/bjoc.21.115

• Due to the lone pairs on their nitrogen atoms, azobenzenes are weak bases. Their basicity can be increased by electron-donating substituents on the benzene rings. para-Alkoxy substitution effectively increases the electron density at the azo-nitrogens without introducing additional protonation sites

• strong acidity of MSA, moderate polarity of DCE, and the electron-donating substituents of 3, only 76 equivalents of acid (3.08 mM) is needed for nearly full protonation as indicated by the almost complete disappearance of the absorption peak at 360 nm. Similar data for compounds 1 and 2 in MSA/DCE

• temperatures could reflect enhanced solvation, leading to weaker ion pairing. Thus, the hydrogen-bonded geometry predicted computationally may better represent conditions at higher temperatures, when the dielectric constant is lower. Future work could explore how additional substituents on the azobenzene core

Ambident reactivity of enolizable 5-mercapto-1H-tetrazoles in trapping reactions with in situ-generated thiocarbonyl S-methanides derived from sterically crowded cycloaliphatic thioketones

• Grzegorz Mlostoń,
• Małgorzata Celeda,
• Marcin Palusiak,
• Heinz Heimgartner,
• Marta Denel-Bobrowska and
• Agnieszka B. Olejniczak

Beilstein J. Org. Chem. 2025, 21, 1508–1519, doi:10.3762/bjoc.21.113

• situ-generated 1 towards enolizable 5-mercapto-1H-tetrazoles 4 bearing various aliphatic and aromatic substituents at the N(1) atom. Competition between the expected S–H and N–H insertion processes was of primary interest. In extension of the synthetically oriented study, bioactivity of selected

Photoredox-catalyzed arylation of isonitriles by diaryliodonium salts towards benzamides

• Nadezhda M. Metalnikova,
• Nikita S. Antonkin,
• Tuan K. Nguyen,
• Natalia S. Soldatova,
• Alexander V. Nyuchev,
• Mikhail A. Kinzhalov and
• Pavel S. Postnikov

Beilstein J. Org. Chem. 2025, 21, 1480–1488, doi:10.3762/bjoc.21.110

• reaction yields allowed us to establish the dependency from the electronic effects of substituents in the diaryliodonium salts. Diaryliodonium salts containing electron-deficient aryls afforded products 2 in higher yields compared to those bearing electron-donating groups (EDG). Specifically, the reaction

• (4-NO2C6H4) compared to (4-OMeC6H4) [45]. Therefore, despite the fact that literature data mostly suggest similar reactivity for aryl radicals with different substituents in the phenyl ring, the formation itself is more favorable for EWG-substituted radicals. To gain a deeper understanding of the

Advances in nitrogen-containing helicenes: synthesis, chiroptical properties, and optoelectronic applications

• Meng Qiu,
• Jing Du,
• Nai-Te Yao,
• Xin-Yue Wang and
• Han-Yuan Gong

Beilstein J. Org. Chem. 2025, 21, 1422–1453, doi:10.3762/bjoc.21.106

• the optical, chiroptical, and stimuli-responsive behavior of azahelicenes, providing strategic design avenues for next-generation chiral optoelectronic materials. In 2023, Langer’s group synthesized a series of double aza[4,6]helicenes 18a–l featuring diverse peripheral substituents through a one-pot

• [33] and Ishigaki’s [34] groups independently reported a class of highly twisted nitrogen-doped heptalene derivatives (e.g., compound 20a), which exhibit consistent absorption at 315 nm and blue fluorescence centered near 450 nm, regardless of the substituents. These compounds display redox and

• -workers introduced various boryl substituents at both termini of a series of nitrogen-doped [5]helicenes, yielding helicenoids 42a–h [57] (Table 14). The Bpin-substituted derivatives 42a–e exhibited broad emission across the 400–800 nm range, whereas their analogues 42f and 42g showed negligible emission

Tautomerism and switching in 7-hydroxy-8-(azophenyl)quinoline and similar compounds

• Lidia Zaharieva,
• Vera Deneva,
• Fadhil S. Kamounah,
• Nikolay Vassilev,
• Ivan Angelov,
• Michael Pittelkow and
• Liudmil Antonov

Beilstein J. Org. Chem. 2025, 21, 1404–1421, doi:10.3762/bjoc.21.105

• , printing, and coloring agents for various materials, due to their excellent color fastness, high stability, and ease of synthesis. The azo functionality allows for a wide range of colors to be achieved by altering the substituents on the azo group, improving the color intensity, lightfastness, and wash

• CH3 group) and 3 leads to destabilization of K, while placing a substituent in positions 5 (weakly) and 6 stabilizes it. The effect on position 4 is mixed – electron donors stabilize the K form, while acceptors rise its energy. All substituents in position 8 stabilize K, but the effect of the

• ) (Figure 8b) the needed reduction is observed in position 2 for CH3 group (weakly), substantially for NR2 in position 4 and strongly for all substituents in position 6. The value of ΔE(KE-E) (Figure 8c) has to be larger than 2, but it cannot be achieved. Almost all functional groups on position 2 and all