Photochemical reduction of acylimidazolium salts

• Michael Jakob,
• Nick Bechler,
• Hassan Abdelwahab,
• Fabian Weber,
• Janos Wasternack,
• Leonardo Kleebauer,
• Jan P. Götze and
• Matthew N. Hopkinson

Beilstein J. Org. Chem. 2025, 21, 1973–1983, doi:10.3762/bjoc.21.153

• offer many synthetic advantages while the wide availability of chiral NHCs can also allow for high levels of enantioselectivity. As effective enamine and active ester derivatives, Breslow and acylazolium intermediates A and B typically react via classical two-electron polar mechanisms, however, recent

• manifold with carboxylic acid derivatives, numerous coupling processes affording ketone products have been developed. Since the initial report from Scheidt and co-workers using 4-alkyl-substituted Hantzsch esters as coupling partners [31][32][33][34][35][36], several alkyl radical sources have been

• employed including carboxylic acids [37], xanthates [38], electron-rich toluene or heteroatom-substituted species [39][40][41][42], organoboron compounds [43][44] and organosilanes [43][45]. Moreover, three-component radical relay processes employing styrene derivatives have also been widely studied. In

Asymmetric total synthesis of tricyclic prostaglandin D2 metabolite methyl ester via oxidative radical cyclization

• Miao Xiao,
• Liuyang Pu,
• Qiaoli Shang,
• Lei Zhu and
• Jun Huang

Beilstein J. Org. Chem. 2025, 21, 1964–1972, doi:10.3762/bjoc.21.152

• allylation to install the side chain at C8, and a diastereoselective spirolactonization to generate the spiroketal moiety in 26. This total synthesis is promising for divergent total syntheses of other PGs and structurally related pharmaceutical derivatives. Representative prostaglandins and general

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

• enantioselective acylation of glycerol derivatives [53]. Since then, desymmetrization strategies for prochiral 1,3-diols involving transition-metal-catalyzed acylation have been developed. Trost and co-workers then developed a Zn-based catalyst for asymmetric aldol reactions [54][55], later adapting it to the

• desymmetrization strategy for serinol derivatives using a bisoxazoline (BOX)–CuCl2 complex as catalyst in 2008 [62]. They further applied this method in 2013 to the synthesis of (−)-kaitocephalin, a glutamate receptor antagonist from Eupenicillium shearii (Scheme 22) [63]. Diol 158, which was accessed in two steps

• indole derivatives mediated by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) is an efficient strategy that the Cook group utilized in the total synthesis of several indole alkaloids [75][76][77]. In 2005, they reported the synthesis of vincamajine-related indole alkaloids, among which

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

• , including molecular bowls [11][12][13] and medium-sized macrocycles containing a saddle-shaped eight-membered ring [14][15]. In the past decades, despite rapid progress in chiral macrocycles, inherent chirality is largely limited to calix[n]arene derivatives. This underscores a critical opportunity to

• palladium (Pd)-catalyzed arylation of aza[14]metacyclophane derivatives. By modulating the substitutions on the N atoms, two isomeric macrocycles, a C1-symmetric one as the minor fraction (MC1) and a C2v-symmetric one as the major product (MC2), were successfully obtained when 4-tert-butylphenyl groups were

• could be viewed as the aza[14]metacyclophane derivatives, in which two benzene rings are replaced by two pyrenes. The Pd-catalyzed arylation of 3a with Pd(OAc)2, PMe(t-Bu)2·HBF4 and DBU under microwave conditions gave two isomeric macrocycles MC1 and MC2 with four newly formed C–C bonds in yields of 5

Synthesis, biological and electrochemical evaluation of glycidyl esters of phosphorus acids as potential anticancer drugs

• Almaz A. Zagidullin,
• Emil R. Bulatov,
• Mikhail N. Khrizanforov,
• Damir R. Davletshin,
• Elvina M. Gilyazova,
• Ivan A. Strelkov and
• Vasily A. Miluykov

Beilstein J. Org. Chem. 2025, 21, 1909–1916, doi:10.3762/bjoc.21.148

• compounds is a dynamic field of research, with numerous synthetic methodologies being explored to create novel phosphorus derivatives [19][20][21]. Recent studies have highlighted the increasing relevance of three-membered strained cycles containing phosphorus in various domains such as agrochemicals

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, agrochemicals, and pharmacologically active compounds. Enantiomerically pure 1,2-diamines and their derivatives are also increasingly used in stereoselective synthesis, particularly as chiral auxiliaries or as ligands for metal complexes in asymmetric catalysis [1]. Metal-based reductants

• development of technology-driven sustainable strategies to alfa and beta amination of carbonyls and carboxylic acids derivatives- TECHNO”, financed by EU - Next Generation EU, Mission 4 Component 1 CUP G53D23003280006. M. Gazzotti thanks Università degli Studi di Milano for a PhD fellowship.

Preparation of spirocyclic oxindoles by cyclisation of an oxime to a nitrone and dipolar cycloaddition

• Beth L. Ritchie,
• Alexandra Longcake and
• Iain Coldham

Beilstein J. Org. Chem. 2025, 21, 1890–1896, doi:10.3762/bjoc.21.146

• an important class of compounds with significant biological activities. Spirocyclic derivatives are present in a variety of natural products. We describe here the formation of spirooxindoles using an intermolecular nitrone cycloaddition reaction. The nitrone dipole was prepared in situ by cyclisation

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

• derivatizations. Based on experimental and computational studies, the origin of helical chirality in this method was elucidated. We proposed that the asymmetric Povarov reaction would generate a pair of diastereomeric tetrahydroquinoline derivatives displaying helical conformation, with a modest energetic barrier

• catalytic kinetic resolution of racemic helical polycyclic phenols through an organocatalyzed enantioselective dearomative amination reaction [30]. The racemic polycyclic phenol derivatives 25, which exist as single diastereomers featuring both central chirality and helical chirality, were readily prepared

• asymmetric transfer hydrogenation employing Hantzsch ester HEH-1 as the reductant afforded both helically chiral tetrahydroquinoline derivatives (M)-30 and the recovered aza[6]helicene starting material (P)-29 with good to high enantioselectivity, achieving an s-factor of up to 121 (Scheme 8). Moreover, by

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

• capability. What is surprising, however, is that the conversions for Me2BDC-NH2 are much lower than those observed for all our KSU-1 derivatives despite the presumably lower basicity of the MOF-immobilized amino groups due to the dicarboxylates coordinating to Zn2+ clusters. This unexpected result indicates

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

• heterocyclic imines [36][37][38]. The Z-isomers of the unsubstituted derivatives adapt different conformations: T-shaped for the N-phenyl and twisted for the N-pyrazoles. The half-lives follow the same trends already discussed beforehand. In contrast with the azopyrazoles, mono- and di-ortho-amination of the

• aryl ring of 11a and 11b yield iminopyrazoles with longer half-lives and negative photochromism (Figure 7, top). This unusual behaviour can be explained by the absence of adjacent non-bonding lone pairs in the imine bond [37]. Conversely, in the case of N-phenyl derivatives 11c and 11d (Figure 7

•  14, box) and repulsion between the aryl and the carbonyl group in the E-isomer. Some studies on N-acylindigo derivatives reported, besides the expected spectral blue-shift, also a decrease in the fatigue resistance due to photochemical rearrangements [68][69]. Dube and co-workers reported a series of

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

• -disubstituted and 4-substituted quinoline molecules. The developed strategy involves an earth-abundant Fe-catalyzed C(sp2)–C(sp2) bond cleavage of styrene, followed by the hydroamination of the cleaved synthons with arylamines and subsequent C–H annulation to yield two valuable quinoline derivatives. Key

• activation; C–H annulation; iron metal catalysis; quinolines; styrene; Introduction Quinolines are one of the essential heteroaromatic motifs that play a crucial role across diverse scientific fields due to their wide range of applications. In contemporary medicine, quinoline derivatives frequently appear

• , antibacterial, and anti-inflammatory activities [10][11][12][13]. In the field of optoelectronics, especially with 2,4-diarylquinoline derivatives, extensive studies have highlighted their applicability in organic light-emitting diode (OLED) systems as functional materials [14][15] and cutting-edge fluorescent

[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

• fluoride, is used for the synthesis of spirocyclic derivatives from arylidene-azolones. Four types of the corresponding heterocycles have been studied. A series of 7-thia-3-azaspiro[4.4]nonan-4-ones was obtained with yields varying from 17 to 99%. The stereochemical study revealed selective formation of

• single either cis or trans stereoisomers, dependent on the heterocycle core used. Keywords: arylidene-azolones; cycloaddition; nitrogen heterocycles; sulfur heterocycles; thioformylium methylide; Introduction Spirocyclic derivatives of heterocycles occupy an important place in modern organic and

• bioorganic chemistry [1]. Such substances are actively investigated in drug design, since their rigid 3D structure allows them to bind more selectively and effectively to biological targets in comparison to classical planar heterocycles [1][2][3][4][5]. Spirocyclic derivatives containing at least one five

Research progress on calixarene/pillararene-based controlled drug release systems

• Liu-Huan Yi,
• Jian Qin,
• Si-Ran Lu,
• Liu-Pan Yang,
• Li-Li Wang and
• Huan Yao

Beilstein J. Org. Chem. 2025, 21, 1757–1785, doi:10.3762/bjoc.21.139

• solubility, this can be improved through derivatization. Water-soluble calixarene derivatives can be obtained through functional modifications, including the introduction of sulfonic acid, amine, and carboxylic acid groups [57][58][59]. These water soluble macrocycle derivatives can be used to increase the

• dual modifications [69]. These derivatives have emerged as a research hotspot due to their unique combination of water solubility, biocompatibility, and host–guest encapsulation capability [47][52][70]. The aggregation behavior of amphiphilic CAs is closely related to the size of the macrocycle, the

• characteristics, CAs hold potential for applications in drug delivery systems. 1.2 PAs: structure and properties Since Ogoshi et al. first introduced pillar[n]arenes in 2008, these macrocycles have become essential to the synthetic macrocyclic receptor field [74]. Research on PAs and their derivatives has become

Unique halogen–π association detected in single crystals of C–N atropisomeric N-(2-halophenyl)quinolin-2-one derivatives and the thione analogue

• Mai Uchibori,
• Nanami Murate,
• Kanako Shima,
• Tatsunori Sakagami,
• Ko Kanehisa,
• Gary James Richards,
• Akiko Hori and
• Osamu Kitagawa

Beilstein J. Org. Chem. 2025, 21, 1748–1756, doi:10.3762/bjoc.21.138

• unstable and standing for a long period in the solution state resulted in several decomposed products). Conclusion We found that crystallization of racemic and optically pure C–N atropisomeric N-(halophenyl)quinolin-2-one derivatives led to the formation of homochiral layered polymer chains, which consist

• were formed through an n–π* interaction between a lone electron pair on the halogen atom and a π*orbital of the quinolinone ring. Thus, chirality (racemic/optically pure)-dependent halogen bonding was observed in single crystals of not only 3-(2-halophenyl)quinazolin-4-one derivatives but also N-(2

• -halophenyl)quinolin-2-one derivatives. Furthermore, it was revealed that the intermolecular association of C–N atropisomeric quinoline-2-thione significantly differs from that of quinolinones. That is, in contrast to the homochiral layered polymer found in quinolinone derivatives, in the single crystal of

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

• ) [41][42][43] have been used for attaching the crown ether macrocycle, although this strategy has the advantage that the 2,2'-hydroxy groups remain intact and can be used for further binding or functionalization. Our group recently became interested in synthesizing BINOL derivatives featuring

• multiple steps towards the desired macrocycles. The route towards the bis-BINOL macrocycles additionally requires the synthesis of the unsymmetric monoiodide 12. In our previous work, the route starting from 12 had been designed to give access to macrocyclic and singly linked bis-BINOL derivatives from a

• single precursor, but this is unnecessary if only macrocyclic bis-BINOL derivatives are desired. For this reason, we sought to find optimized syntheses for such BINOL-based macrocycles (see Figure 2). After investigating different synthetic routes (vide infra), we found that Williamson-type ether

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

• anomeric configuration of the lactol acceptor is particularly challenging when the desired form is not thermodynamically favored, as is the case with β-mannose derivatives. A refined strategy employing cyclic stannanes to lock the anomeric hydroxy group of a mannose-derived lactol in the equatorial

• sucrose derivatives in plants [79][80][81]. In this case, the carboxymethyl group in the 2-thioethyl fructofuranoside was locked by an intramolecular bridge formed by the TIPDS group to the C4–OH [1,4-O-(1,1,3,3-tetraisopropyldisiloxane-1,3-diyl) bridge], resulting in a β-directing fructofuranosyl donor

• its derivatives include the use of β-ᴅ-psicofuranosyl donors [84][85] and the intracellular aglycon delivery (IAD) strategy [86]. Electron-withdrawing groups, often used for the temporary protection of hydroxy functions in pyranoses, can significantly reduce the nucleophilicity of both glycosyl donors

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

• -flow configurations demonstrate superior safety and efficiency. While the synthetic significance of nitration is underscored by the broad utility of nitro derivatives, persistent technical challenges including regioselectivity control, over-nitration phenomena, and substrate oxidation side reactions

• conversion efficiency, selectivity drift toward undesirable polynitrated derivatives, and by-product formation kinetics that are particularly critical in nitration processes. The integration of long-term stability evaluations and stress testing significantly mitigates scale-up failure risks by identifying

• (e.g., dinitro/trinitro derivatives). These hazardous by-products arise from the tendency of electron-rich substrates to undergo overnitration, drastically increasing detonation potential. Consequently, rigorous safety assessments are critically important for processes involving nitration reactions

Structural analysis of stereoselective galactose pyruvylation toward the synthesis of bacterial capsular polysaccharides

• Tsun-Yi Chiang,
• Mei-Huei Lin,
• Chun-Wei Chang,
• Jinq-Chyi Lee and
• Cheng-Chung Wang

Beilstein J. Org. Chem. 2025, 21, 1671–1677, doi:10.3762/bjoc.21.131

• derivatives, enabling the exploration of the practical applications of PSA1 while simultaneously enhancing our understanding of synthetic chemistry. To simplify the synthetic process, glycosylation was facilitated by employing preactivation and the differences in acceptor reactivity. Using the p

• for O4-linked synthesis in preparing various PS A1 derivatives. In our research, we carried out the synthesis of the PSA1 molecule as part of a broader effort to validate chemical synthesis methodologies. This work involved verifying our experimental techniques and understanding the underlying

Influence of the cation in hypophosphite-mediated catalyst-free reductive amination

• Natalia Lebedeva,
• Fedor Kliuev,
• Olesya Zvereva,
• Klim Biriukov,
• Evgeniya Podyacheva,
• Maria Godovikova,
• Oleg I. Afanasyev and
• Denis Chusov

Beilstein J. Org. Chem. 2025, 21, 1661–1670, doi:10.3762/bjoc.21.130

• cation and not its reduction. H2PO3− generated as a result of the first step could reduce a new portion of iminium ions in a similar way forming another molecule of the target amine and ortho-phosphoric acid derivatives. Based on the obtained data we can highlight two main reasons why the developed

Photocatalysis and photochemistry in organic synthesis

• Timothy Noël and
• Bartholomäus Pieber

Beilstein J. Org. Chem. 2025, 21, 1645–1647, doi:10.3762/bjoc.21.128

• ; photochemistry; Soon after its first reported synthesis in 1936 [1], [Ru(bpy)3]Cl2 (bpy = 2,2'-bipyridine) and its derivatives attracted significant attention due to their photophysical properties [2][3][4]. These complexes can efficiently absorb visible light through a metal-to-ligand charge transfer (MLCT

Formal synthesis of a selective estrogen receptor modulator with tetrahydrofluorenone structure using [3 + 2 + 1] cycloaddition of yne-vinylcyclopropanes and CO

• Jing Zhang,
• Guanyu Zhang,
• Hongxi Bai and
• Zhi-Xiang Yu

Beilstein J. Org. Chem. 2025, 21, 1639–1644, doi:10.3762/bjoc.21.127

• bridged tetrahydrofluorenone derivatives, represented by molecules V and VI, showed significant ERβ binding affinity and high selectivity [15][16][17][18][19]. So far, there are only two routes for accessing bridged tetrahydrofluorenone derivative VI. The first one shown in Scheme 2A includes a Robinson

• finding new strategies for these molecules and their derivatives are still required for future medicinal investigations. Due to this, we decided to explore a new approach to VI, which is reported here. Our approach is inspired by the Lei’s synthesis of ent-kaurane diterpenoids (Scheme 3A) [22] which share

• target molecule. This route can provide new derivatives for further searching new SERMs. The synthetic strategy can be applied to other molecules with [3.2.1] framework. Of the same importance, the gram scale (4 g) of the [3 + 2 + 1] reaction with 87% reaction yield demonstrates the practical use of this

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

• for the synthesis of benzo[4,5]thieno[3,2-b]pyrroles are lacking and obtaining their derivatives remains challenging [24][25], the reaction we discovered could significantly facilitate access to compounds of this type. To test the generality and usefulness of the reaction, we investigated a variety of

• methanol. The driving force of this process is the formation of an aromatic thiophene system. To demonstrate the practicability and synthetic utility of this method for the synthesis of benzo[4,5]thieno[3,2-b]pyrrole derivatives, several transformations of compound 3b were carried out (Scheme 4

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

• featuring high photostability and strong visible absorption. Perylene–phenothiazine (Pe–PTZ) derivatives have been previously investigated for their excited-state dynamics [15]. Incorporating additional electron-donating groups such as triphenylamine (TPA) onto the PTZ core is expected not only to enhance

• series of novel Pe–PTZ derivatives by incorporating electron-donating triphenylamine (TPA) units and phenyl spacers to systematically modulate the donor strength and the spatial distance between the donor and acceptor. Four compounds – Pe–PTZ, Pe–PTZ(TPA), Pe–PTZ(TPA)2, and Pe–Ph–PTZ(TPA)2 – were

• shown in Supporting Information File 1. Energy levels and steady-state optical properties Time-dependent density functional theory (TD-DFT) calculations were performed to gain insights into the electronic structures of Pe–PTZ derivatives at B3LYP/6-31+G(d,p) level of theory (Figure 2) [18]. The

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

• benzamidine derivatives as a novel pH-responsive molecular switch. Keywords: atropisomer; conformation; isomerization; molecular switch; organobase; Introduction pH-Responsive molecular motors and switches are a class of functional organic molecules capable of reversible structural and electronic changes

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

• another cycle via the single quaternary carbon atom C5 demonstrated significant biological activity, greater than analogs with non-spiro-bonded cyclic fragments [3][4]. Hydantoin derivatives also exhibit a wide range of biological activities. Compounds containing the hydantoin pharmacophore group, are

• of double and triple bonds, most of the described reactions are related to dipolarophiles with C=C, C≡C or C=S bonds [7]. However, the [3 + 2]-cycloaddition of nitrile oxides to exocyclic C=N bonds, is a much less explored area. There are few known reactions of these dipoles with imino derivatives of

• developed for existing spiro systems to the new hybrid drugs. In this work a similar modification of imidazolidine derivatives was performed for the first time for the synthesis of spiro-hydantoins. The title reactions were carried out using two alternative techniques for the generation of the reactive 1,3