Light-enabled intramolecular [2 + 2] cycloaddition via photoactivation of simple alkenylboronic esters

• Lewis McGhie,
• Hannah M. Kortman,
• Jenna Rumpf,
• Peter H. Seeberger and
• John J. Molloy

Beilstein J. Org. Chem. 2025, 21, 854–863, doi:10.3762/bjoc.21.69

• translate 2D to 3D chemical space have also been explored [48][49][50][51][52]. Here, efficient excitation, via EnT catalysis, is typically contingent on extended chromophores ≥ 4π electrons, with less conjugated systems requiring more powerful catalysts. A recent elegant example by Masarwa and co-workers

• ] cycloaddition observed, despite the use of higher catalyst loadings. The efficient isomerization of 1a during these reactions indicated that substrate lifetime for efficient intermolecular reactivity may be problematic. While substrate-tethered reactivity, developed by Brown and co-workers was unsuccessful [49

• strategies for cyclobutyl scaffolds [53][54][55], products 6 and 7 could be synthesized via mild conditions [68]. Inspired by recent advances by Nolan and co-workers demonstrating the synthetic power of gold catalysts in EnT catalysis [31][69][70][71][72], we probed the reactivity of [Au(SIPr)(Cbz)] in our

Unraveling cooperative interactions between complexed ions in dual-host strategy for cesium salt separation

• Zhihua Liu,
• Ya-Zhi Chen,
• Ji Wang,
• Qingling Nie,
• Wei Zhao and
• Biao Wu

Beilstein J. Org. Chem. 2025, 21, 845–853, doi:10.3762/bjoc.21.68

• found to be co-stabilized by three 18-crown-6 macrocycles. Next, a solid–liquid extraction experiment was conducted for Cs2SO4 salts. A solution of hexaurea receptor L and two equivalents of 18-crown-6 in CHCl3 were prepared, and solid Cs2SO4 was added into the solution. Under stirring at 60 °C for 5

• ion-dipole and ion-pairing are shown. Single crystal structure of complexed Cs2SO4 with 18-crown-6 and tripodal receptor L (CCDC: 2411573). One sulfate anion is encapsulated inside the hexaurea cavity through 12 × N–H···O hydrogen bonds. One Cs+ cation is co-stabilized by electrostatic interactions

Chitosan-supported CuI-catalyzed cascade reaction of 2-halobenzoic acids and amidines for the synthesis of quinazolinones

• Xuhong Zhao,
• Weishuang Li,
• Mengli Yang,
• Bojie Li,
• Yaoyao Zhang,
• Lizhen Huang and
• Lei Zhu

Beilstein J. Org. Chem. 2025, 21, 839–844, doi:10.3762/bjoc.21.67

• methods, the cascade reaction between ortho-halogen (e.g., chlorine, bromine or iodine) substituted benzoic acids and amidines has become a prominent route to synthesize the corresponding quinazolinones [10][11][12][13][14][15][16][17][18]. In 2009, Fu and co-workers found that copper(I) could effectively

Synthesis and photoinduced switching properties of C₇-heteroatom containing push–pull norbornadiene derivatives

• Daniel Krappmann and
• Andreas Hirsch

Beilstein J. Org. Chem. 2025, 21, 807–816, doi:10.3762/bjoc.21.64

• intermediates in total [29][30] and bio-synthesis protocols [31], e.g., in inositol chemistry [32] or towards aminocyclitols [33]. The potential of these compounds as functional photoswitches was primarily assessed in the 1960s and 1970s by Prinzbach and co-workers, who identified a variety of rearrangement

• Bansal and co-workers [44] revealed the potential formation of aza-QC derivatives at low temperatures. However, isolation of these derivatives proved difficult, as rapid rearrangement to azepine analogues occurred at temperatures exceeding 0 °C. On the basis of the quadricyclane or azepine structure

Recent advances in the electrochemical synthesis of organophosphorus compounds

• Babak Kaboudin,
• Milad Behroozi,
• Sepideh Sadighi and
• Fatemeh Asgharzadeh

Beilstein J. Org. Chem. 2025, 21, 770–797, doi:10.3762/bjoc.21.61

• amides with electron-withdrawing or electron-donating groups on their aromatic ring, producing products with yields ranging from 51% to 82%. In 2023, Lei and co-workers [47] reported an electrochemical C–P bond formation via a coupling reaction of C–H bonds of alkynes, alkenes, and aryl compounds with

• meta or ortho positions, which may be due to steric and electronic effects. The reaction proceeded via a radical process by forming Ph2P(O)H (Scheme 16). The reaction failed to give the corresponding product when using TEMPO in the reaction mixture. Zhang and co-workers [61] reported an electrochemical

• another study, Ding and co-workers [69] recently reported an electrochemical method for synthesizing S-heteroaryl phosphorothioates without using any transition metal catalysts and oxidants at 90 °C. This method is compatible with various functional groups and can be easily scaled up to a gram scale. The

New advances in asymmetric organocatalysis II

• Radovan Šebesta

Beilstein J. Org. Chem. 2025, 21, 766–769, doi:10.3762/bjoc.21.60

• progressed from the original amine catalysts is the work of Shirakawa and co-workers. In this contribution, the authors employed a binaphthalene-derived sulfide organocatalyst for enantioselective bromolactonizations of α- and β-substituted 5-hexenoic acids to produce the corresponding chiral lactones [23

• ]. Kowalczyk and co-workers showed how asymmetric organocatalysis can benefit from mechanochemical activation. They established that Michael additions of thiomalonates to enones, catalyzed by cinchona-derived primary amines, is efficient and enantioselective under ball-milling conditions [24]. Kondratyev and

• ]. The enantioselective addition of propargyltrichlorosilane to aldehydes was studied by Prabhakar, Takenaka, and co-workers. This transformation was catalyzed by a biisoquinoline N,N’-dioxide catalyst, which acted as a chiral Lewis base [26]. Torres-Oya and Zurro reviewed the recent developments in

Copper-catalyzed domino cyclization of anilines and cyclobutanone oxime: a scalable and versatile route to spirotetrahydroquinoline derivatives

• Qingqing Jiang,
• Xinyi Lei,
• Pan Gao and
• Yu Yuan

Beilstein J. Org. Chem. 2025, 21, 749–754, doi:10.3762/bjoc.21.58

• remains a formidable challenge, primarily due to the inherent ring strain and the difficulties associated with achieving high diastereoselectivity during cyclization [4]. Recently, Chen and co-workers developed a chiral phosphoric acid (CPA)-catalyzed multicomponent reaction of anilines, aldehydes, and

• azetidinones, enabling the efficient and enantioselective synthesis of tetrahydroquinoline-fused azetidines with three contiguous stereocenters in a single step [23]. Later, Tanaka, Nagashima, and their co-workers established a chemo-, regio-, and diastereoselective dearomative transformation of quinolines

Synthesis of HBC fluorophores with an electrophilic handle for covalent attachment to Pepper RNA

• Raphael Bereiter and
• Ronald Micura

Beilstein J. Org. Chem. 2025, 21, 727–735, doi:10.3762/bjoc.21.56

• fluorescent protein (GFP), has revolutionized genetics by providing highly accurate real-time detection of fusion proteins in vitro and in vivo [1]. Pioneering work on GFP-tagged proteins for real-time monitoring of gene expression was first reported by Chalfie and co-workers in 1994 [2]. For a long time

• better solubility in the reaction buffer and did not require DMSO as co-solvent, making it a very promising candidate for in vivo applications. To complete the study, and given that the mesyloxy group has shown superior efficacy over all other functional groups tested for Pepper alkylation, we

• (left side). Bar graph (right side) illustrating the relative yields of covalent tethering under the following conditions: 2.5 µM RNA, 50 µM HBC ligand, 100 mM KCl, 2 mM MgCl2, 50 mM HEPES buffer, pH 7.0, 5 h at 37 °C. The numbers in the orange bars indicate the percentage of DMSO (%) used as co-solvent

Acyclic cucurbit[n]uril bearing alkyl sulfate ionic groups

• Christian Akakpo,
• Peter Y. Zavalij and
• Lyle Isaacs

Beilstein J. Org. Chem. 2025, 21, 717–726, doi:10.3762/bjoc.21.55

• (CHE-1807486) for past financial support. We thank the National Institute of General Medical Sciences of the National Institutes of Health (R35GM153362) for current financial support of this project. Conflict of Interest L.I. is co-founder and holds equity in Reversal Therapeutics (National Harbor

Recent advances in allylation of chiral secondary alkylcopper species

• Minjae Kim,
• Gwanggyun Kim,
• Doyoon Kim,
• Jun Hee Lee and
• Seung Hwan Cho

Beilstein J. Org. Chem. 2025, 21, 639–658, doi:10.3762/bjoc.21.51

• organolithium species and the other employing chiral organoboron compounds. Copper-mediated stereospecific coupling of chiral organolithium species with allylic electrophiles In the organolithium approach, a breakthrough was achieved by Knochel and co-workers through carefully controlled reaction conditions

• stereochemical integrity. Through these careful experimental controls, Knochel and co-workers effectively addressed the long-standing challenge of handling these traditionally unstable chiral organometallic intermediates. Copper-catalyzed stereospecific coupling of chiral organoboron species with allylic

• configurationally stable organoboron compounds was recently developed by Morken and co-workers, which employs only catalytic amounts of copper [47][48]. Their strategy uses chiral secondary organoboron compounds 20 as precursors to generate chiral alkylcopper species through a carefully controlled activation and

Formaldehyde surrogates in multicomponent reactions

• Cecilia I. Attorresi,
• Javier A. Ramírez and
• Bernhard Westermann

Beilstein J. Org. Chem. 2025, 21, 564–595, doi:10.3762/bjoc.21.45

• between 60–95% for all metal catalysis conditions. The most widely accepted mechanism is as follows: the alkynyl C–H bond is activated by the metal catalyst (Scheme 23). The metal can be added in its proper oxidation state (such as Cu(I)) or generated in situ (as in the case of Au(I), Co(I), Fe(II) and Ni

• (I)) by reducing the suitable salts (containing Au(III), Co(II), Fe(III), and Ni(II), respectively) at the beginning of the catalytic cycle. The metal in its reduced species (depicted in Scheme 23) activates the C–H bond of the alkyne. After this activation step, a weak base (like DBU, TMG, or even

• afford propargyl halide C. Finally, intermediate C reacts with the secondary amine to give the propargylamine product D. As outlined in the catalytic cycle, the presence of a base plays a dual role: co-activation of the alkynyl C–H bond through deprotonation and trapping of the HCl produced during the

Asymmetric synthesis of β-amino cyanoesters with contiguous tetrasubstituted carbon centers by halogen-bonding catalysis with chiral halonium salt

• Yasushi Yoshida,
• Maho Aono,
• Takashi Mino and
• Masami Sakamoto

Beilstein J. Org. Chem. 2025, 21, 547–555, doi:10.3762/bjoc.21.43

• organic chemistry [2][3][4][5], organocatalysis [6][7], metal catalysis [8][9], biochemistry [10][11], materials science [12][13], and supramolecular chemistry [14][15], although its successful application to asymmetric catalysis has been limited (Figure 1) [16][17][18][19][20]. In 2018, Arai and co

• -workers developed chiral amine 1 with an electron-deficient iodine atom, which catalyzed the Mannich reaction in excellent yields and enantioselectivities [17]. In 2020, Huber and co-workers reported the bis(iodoimidazolium) 2-catalyzed Mukaiyama–aldol reaction of carbonyl compounds with enol silyl ethers

• , which provided the products in high yields with up to 33% ee [19]. In 2023, García Mancheño and co-workers reported the tetrakis(iodotriazole) 3-catalyzed dearomatization of halogen-substituted pyridines 4, which formed the corresponding products 5 in high yields with up to 90% ee (Figure 1b) [20

Deep-blue emitting 9,10-bis(perfluorobenzyl)anthracene

• Long K. San,
• Sebastian Balser,
• Brian J. Reeves,
• Tyler T. Clikeman,
• Yu-Sheng Chen,
• Steven H. Strauss and
• Olga V. Boltalina

Beilstein J. Org. Chem. 2025, 21, 515–525, doi:10.3762/bjoc.21.39

• Long K. San Sebastian Balser Brian J. Reeves Tyler T. Clikeman Yu-Sheng Chen Steven H. Strauss Olga V. Boltalina Department of Chemistry, Colorado State University, Fort Collins, CO 80523, USA ChemMatCARS, University of Chicago Advanced Photon Source, Argonne, IL 60439, USA 10.3762/bjoc.21.39

• , allows a tentative conclusion that photooxidation proceeds via dearomatization of the central ring due to the formation of the endoperoxide (Figure 4). This suggestion is also supported by a recent work of Sun and co-workers where they observed and structurally characterized the endoperoxide of 9,10-ANTH

• (trifluoromethyl)benzene (1,4-C6H4(CF3)2, Central Glass Co., 99%); dimethyl sulfoxide (DMSO, Fisher Scientific, ACS grade); anhydrous magnesium sulfate (MgSO4, Fisher Scientific); Cu powder (Strem Chemicals, 99%); dichloromethane (EMD Chemicals, ACS grade); acetone (technical grade); THF (Aldrich/Merck, ACS grade

Unprecedented visible light-initiated topochemical [2 + 2] cycloaddition in a functionalized bimane dye

• Metodej Dvoracek,
• Brendan Twamley,
• Mathias O. Senge and
• Mikhail A. Filatov

Beilstein J. Org. Chem. 2025, 21, 500–509, doi:10.3762/bjoc.21.37

• solid state, which are highly dependent on molecular packing. The concept of topochemical reactions was first introduced by Kohlschütter in 1919 [1], and topochemical polymerizations were systematically studied by Schmidt and co-workers in the 1960s and 1970s [2][3][4]. Schmidt's pioneering work

• . Experimental Synthesis The studied bimanes were synthesized following the approach reported by Kosower and co-workers [17][19], and an alternative chlorination method developed by Neogi et al. [31]. The synthetic details can be found in Supporting Information File 1. Compounds were crystallized from a MeOH–DCM

Synthesis of electrophile-tethered preQ₁ analogs for covalent attachment to preQ₁ RNA

• Laurin Flemmich and
• Ronald Micura

Beilstein J. Org. Chem. 2025, 21, 483–489, doi:10.3762/bjoc.21.35

• of the electrophile. We thus identified aldehydes 9 and 10 as suitable branching points, which were easily derivatized to their aminomethyl-modified preQ1 analogs by reductive amination (Scheme 3). Their syntheses by Raney-Ni reduction of nitriles 7 and 8, previously described by Gangjee and co

Organocatalytic kinetic resolution of 1,5-dicarbonyl compounds through a retro-Michael reaction

• James Guevara-Pulido,
• Fernando González-Pérez,
• José M. Andrés and
• Rafael Pedrosa

Beilstein J. Org. Chem. 2025, 21, 473–482, doi:10.3762/bjoc.21.34

• low catalyst loadings and mild reaction conditions. This research focuses on the kinetic resolution of 1,5-dicarbonyl compounds using a retro-Michael reaction, co-catalyzed at room temperature with 20 mol % of the Jørgensen–Hayashi catalyst and PNBA. The study highlights the importance of conducting

• ] using 20 mol % of catalyst A and 20 mol % of p-nitrobenzoic acid (PNBA) as co-catalyst in different solvents at room temperature. The results obtained are summarized in Scheme 3 and Table 1. The progress of the reaction was monitored using thin-layer chromatography (TLC) and 1H NMR analysis of the

• provide the highest enantiomeric ratio. The influence of catalyst, co-catalyst, and temperature on the reaction progress and enantioselectivity was further investigated. Different essays using 0.028 M toluene solutions were carried out, and the results are summarized in Table 2. The reaction also occurs

Photomechanochemistry: harnessing mechanical forces to enhance photochemical reactions

• Francesco Mele,
• Ana M. Constantin,
• Andrea Porcheddu,
• Raimondo Maggi,
• Giovanni Maestri,
• Nicola Della Ca’ and
• Luca Capaldo

Beilstein J. Org. Chem. 2025, 21, 458–472, doi:10.3762/bjoc.21.33

• grinding serves to dissociate the more loosely bound 2.3 from 2.2, where a release of strain energy and formation of a more thermodynamically stable 2.1·2.2 complex for a subsequent turnover are favored. The first preparative example of photomechanochemistry via manual grinding was reported by Wang and co

• % yield, albeit after 72 h of irradiation. This experiment proved that 4.2 can be used in a sub-stoichiometric way, in fact acting as a catalyst. More recently, based on their previous approach via manual grinding (Scheme 2) [64], MacGillivray and co-workers adopted the vortex grinding method to enable

• exposing fresh material to light. In 2016, König and co-workers exploited rod milling to develop a photomechanochemical approach for the riboflavin tetraacetate (RFTA)-catalyzed photocatalytic oxidation of alcohols to the corresponding carbonyl compounds upon irradiation with five LEDs (λ = 455 nm) [69

Electrochemical synthesis of cyclic biaryl λ³-bromanes from 2,2’-dibromobiphenyls

• Andrejs Savkins and
• Igors Sokolovs

Beilstein J. Org. Chem. 2025, 21, 451–457, doi:10.3762/bjoc.21.32

• -[1,1'-biphenyl]-2-amines 3 with sodium nitrite and an acid under aqueous conditions. Recently, Wencel-Delord and co-workers disclosed an improved protocol toward diazonium intermediates 2 under non-aqueous conditions (t-BuONO and MsOH in acetonitrile) [4]. Nevertheless, the improved method still

Beyond symmetric self-assembly and effective molarity: unlocking functional enzyme mimics with robust organic cages

• Keith G. Andrews

Beilstein J. Org. Chem. 2025, 21, 421–443, doi:10.3762/bjoc.21.30

• therefore can be subjected to automated and high-throughput crystallization studies and, with Szczypiński, Slater, Cooper and co-workers, we were able to isolate all five calculated lowest-energy conformers of cage 1 in the solid state (see crystal cavity heights marked under conformers in Figure 9A) [40

Unraveling aromaticity: the dual worlds of pyrazole, pyrazoline, and 3D carborane

• Zahra Noori,
• Miquel Solà,
• Clara Viñas,
• Francesc Teixidor and
• Jordi Poater

Beilstein J. Org. Chem. 2025, 21, 412–420, doi:10.3762/bjoc.21.29

• computed to characterize the optimized structures as minima (zero imaginary frequencies). Aromaticity was first evaluated by means of the nucleus-independent chemical shift (NICS) [12][69][70][71], proposed by Schleyer and co-workers as a magnetic descriptor of aromaticity. NICS is defined as the negative

Identification and removal of a cryptic impurity in pomalidomide-PEG based PROTAC

• Bingnan Wang,
• Yong Lu and
• Chuo Chen

Beilstein J. Org. Chem. 2025, 21, 407–411, doi:10.3762/bjoc.21.28

• impurity generated in this process. Nucleophilic acyl substitution competes with aromatic substitution to displace glutarimide and gives a byproduct that can co-elute with the desired product on HPLC throughout the remainder of the synthesis. Scavenging with taurine is a convenient way to minimize this

• confirmed the presence of 6 that similarly co-eluted with 3 and 7 that completely overlapped with 4 on HPLC under our standard conditions (MeCN/0.1% TFA in water, 10%→60% 0→7 min, 60%→100% 7→10 min, 100% 10→15 min) (Figure 3). The identity of these impurities was further confirmed by independent synthesis

• by which glutarimide displacement affects quality control analysis, we tested a series of amines and compared the retention times of 8 and 9 (Table 1). Rather surprisingly, the length of amino-PEG-OH had no effect on the relative retention time of 8 and 9. The byproduct co-eluted with the desired

The effect of neighbouring group participation and possible long range remote group participation in O-glycosylation

• Rituparna Das and
• Balaram Mukhopadhyay

Beilstein J. Org. Chem. 2025, 21, 369–406, doi:10.3762/bjoc.21.27

• pairs in glycosylation mechanisms was first reported by Rhind-Tutt and Vernon [44], and later reiterated by various authors, including the seminal graphical analysis of Lemieux and co-workers [45][46][47]. Thus, complete categorisation of the reaction in either of the subdomains of substitution reaction

• is not only difficult but is also defective in principle. This dynamic continuum has also been depicted by an elaborate computational simulation report by Fu et al. in 2021 [41] which was a major follow-up of the work by Crich and co-workers in 2018 [29]. In general cases, the axial glycosides also

• -(benzoyloxymethyl)benzoyl [89] and 2-[(tert-butyldiphenylsilyloxy)methyl]benzoyl [90] among others. Sekine and co-workers developed the 2-(azidomethyl)benzoyl (AZMB) group for protecting the hydroxy groups and the exo-amino functionality of the nucleosides [91]. Despite their disarming nature, Iadonisi et al

Synthesis, characterization, antimicrobial, cytotoxic and carbonic anhydrase inhibition activities of multifunctional pyrazolo-1,2-benzothiazine acetamides

• Ayesha Saeed,
• Shahana Ehsan,
• Muhammad Zia-ur-Rehman,
• Erin M. Marshall,
• Sandra Loesgen,
• Abdus Saleem,
• Simone Giovannuzzi and
• Claudiu T. Supuran

Beilstein J. Org. Chem. 2025, 21, 348–357, doi:10.3762/bjoc.21.25

• [9]. Pyrazolobenzothiazines have also been synthesized and explored as p38α MAPK inhibitors [35]. In 2015, Sabatini and co-workers synthesized a novel series of pyrazolobenzothiazines and identified as new generation anti-inflammatory agents. Two of these compounds are reported with an IC50 of 0.5 µM

• oxygen atom [50]. Preferential N-alkylation (over O-alkylation) of 1,2-benzothiazine scaffolds has also been carried out by Ahmad and co-workers in 2014 and Szczęśniak-Sięga and companions in 2018 [37][51]. Structure elucidation of all the synthesized derivatives was carried out using 1H, 13C NMR, and

Oxidation of [3]naphthylenes to cations and dications converts local paratropicity into global diatropicity

• Abel Cárdenas,
• Zexin Jin,
• Yong Ni,
• Jishan Wu,
• Yan Xia,
• Francisco Javier Ramírez and
• Juan Casado

Beilstein J. Org. Chem. 2025, 21, 277–285, doi:10.3762/bjoc.21.20

• also been reported as model systems to investigate redox charged species experiencing evolutions from neutral non-aromatic, to antiaromatic, and to aromatic structures. Xia and co-workers recently reported a modular method to synthesize molecules containing cyclobutadienoid (CBD) groups [18][19][20

Synthesis and characterizations of highly luminescent 5-isopropoxybenzo[rst]pentaphene

• Islam S. Marae,
• Jingyun Tan,
• Rengo Yoshioka,
• Zakaria Ziadi,
• Eugene Khaskin,
• Serhii Vasylevskyi,
• Ryota Kabe,
• Xiushang Xu and
• Akimitsu Narita

Beilstein J. Org. Chem. 2025, 21, 270–276, doi:10.3762/bjoc.21.19

• facile access to BPP was reported by Amsharov and co-workers through the so-called "dehydrative π-extension (DPEX)” reaction [12]. However, functionalized derivatives of BPP have scarcely been explored in comparison to the extensive studies on the derivatives of other PAHs, such as pyrene [15][16][17