Salen–scandium(III) complex-catalyzed asymmetric (3 + 2) annulation of aziridines and aldehydes

• Linqiang Wang and
• Jiaxi Xu

Beilstein J. Org. Chem. 2025, 21, 1087–1094, doi:10.3762/bjoc.21.86

• enantioselectivities and high diastereoselectivities. A reasonable reaction mechanism was proposed and rationalized the experimental results. Keywords: aldehyde; annulation; aziridine; oxazolidine; ring expansion; scandium triflate; Introduction Oxazolidine derivatives are an important class of nitrogen and oxygen

• uses readily available components. On the basis of the experimental results and a previous report [16], a possible reaction mechanism is presented in Scheme 3. The catalyst (Cat) is first generated from salen L1 and Sc(OTf)3. Aziridines 1 coordinate to the Sc ion in the catalyst with their two

• functionalized oxazolidine derivatives in moderate to good yields and good to excellent enantioselectivities and high diastereoselectivities. The stereocontrol was rationalized in the proposed reaction mechanism. Experimental Unless otherwise noted, all materials were purchased from commercial suppliers. Toluene

Recent advances in synthetic approaches for bioactive cinnamic acid derivatives

• Betty A. Kustiana,
• Galuh Widiyarti and
• Teni Ernawati

Beilstein J. Org. Chem. 2025, 21, 1031–1086, doi:10.3762/bjoc.21.85

• –380 via an α-borylation–protodeborylaton mechanism involving intermediates 381 and 382 (Scheme 83A) [141]. On the one hand, Vilotijevic and co-workers (2021) reported a phosphine-mediated partial hydrogenation of conjugated alkynes using water as the hydrogen source to obtain the corresponding cis

• migratory insertion (407) (Scheme 86A) [145]. On the other hand, Werner and Liu (2020) reported a Mn-catalyzed coupling of alcohols and phosphorus ylide 408 to afford the corresponding E-isomers of cinnamate esters 409–411 via an acceptorless dehydrogenative coupling mechanism (Scheme 86B) [146]. In

Pd-Catalyzed asymmetric allylic amination with isatin using a P,olefin-type chiral ligand with C–N bond axial chirality

• Natsume Akimoto,
• Kaho Takaya,
• Yoshio Kasashima,
• Kohei Watanabe,
• Yasushi Yoshida and
• Takashi Mino

Beilstein J. Org. Chem. 2025, 21, 1018–1023, doi:10.3762/bjoc.21.83

• -catalyzed asymmetric allylic amination of allyl esters with isatin using (aR)-(−)-6 possesses an S-configuration. This stereochemical outcome follows the same reaction mechanism as the Pd-catalyzed asymmetric allylic substitution of allyl esters with indoles using (aR)-(−)-6 [31]. To explore further

• allylic amination of acetate 12 with isatin (11a).a Supporting Information Data of thermal racemization of 7, DFT calculations for investigating racemization mechanism of 7, general methods and materials, experimental procedures and characterization data, 1H, 13C and 31P NMR spectra for 9 and 10, 1H, 13C

Harnessing tethered nitreniums for diastereoselective amino-sulfonoxylation of alkenes

• Shyam Sathyamoorthi,
• Appasaheb K. Nirpal,
• Dnyaneshwar A. Gorve and
• Steven P. Kelley

Beilstein J. Org. Chem. 2025, 21, 947–954, doi:10.3762/bjoc.21.78

• examples of amino-sulfonoxylations using tethered nitreniums. Putative reaction mechanism. (A) Scale-up and (B) applications. Optimization results. Structure–reactivity relationship with nitrenium tethers. Examination of sulfonic acid scope. Substrate scope exploration with an emphasis on stereocontrol and

Silver(I) triflate-catalyzed post-Ugi synthesis of pyrazolodiazepines

• Muhammad Hasan,
• Anatoly A. Peshkov,
• Syed Anis Ali Shah,
• Andrey Belyaev,
• Chang-Keun Lim,
• Shunyi Wang and
• Vsevolod A. Peshkov

Beilstein J. Org. Chem. 2025, 21, 915–925, doi:10.3762/bjoc.21.74

• was not isolated. Instead, the reaction mixture was concentrated and directly subjected to the subsequent heteroannulation step. This approach proved to be feasible, affording the model pyrazolo[1,5-a][1,4]diazepine 16a in 65% overall yield over two steps (Scheme 4). The tentative mechanism for the

• conducted in screw cap vials at 90 °C for 7 hours and isolated yields are reported. aConducted on a 3.5 mmol scale. bConducted on a 0.5 mmol scale. Telescope procedure for the synthesis of 16a. Tentative mechanism for the silver-catalyzed heteroannulation. Reductive post-assembly modifications of the

Recent advances in controllable/divergent synthesis

• Jilei Cao,
• Leiyang Bai and
• Xuefeng Jiang

Beilstein J. Org. Chem. 2025, 21, 890–914, doi:10.3762/bjoc.21.73

• environment around the copper center disfavors a direct interaction with nucleophilic alkyl radicals. Instead, the reaction proceeds via an outer-sphere mechanism, where the alkyl radical reacts with the copper-activated C=N unsaturated bond, enabling stereocontrolled C(sp3)–C(sp3) coupling. In contrast, with

• -29. This intermediate undergoes reductive elimination via an inner-sphere mechanism to generate the C(sp3)–N-coupled chiral product 22. Notably, benzoic acid acts as a critical additive, likely by stabilizing key intermediates and modulating the steric/electronic environment for enhanced

• -methylacryloylbenzamides, and 2-iodobiphenyls – thereby selectively synthesizing silacyclic compounds with varying ring sizes, including ten-membered, seven-membered, and five-membered rings. Mechanism (Scheme 15): Substrate 53 undergoes oxidative addition with Pd(0), followed by intramolecular carbopalladation to form

Cu–Bpin-mediated dimerization of 4,4-dichloro-2-butenoic acid derivatives enables the synthesis of densely functionalized cyclopropanes

• Patricia Gómez-Roibás,
• Andrea Chaves-Pouso and
• Martín Fañanás-Mastral

Beilstein J. Org. Chem. 2025, 21, 877–883, doi:10.3762/bjoc.21.71

• not result in the formation of the dimerization product and complex mixtures of products were observed in these cases. To gather insight into the reaction mechanism, several control experiments were performed (Scheme 3). We first observed that the reaction does not take place in the absence of B2pin2

• mechanism for the copper-catalyzed diastereoselective dimerization of 4,4-dichoro-2-butenoic acid derivatives (Scheme 4). Initially, the LCu–pin complex generated through reaction between LCu–Ot-Bu and B2pin2 undergoes coordination and regioselective insertion into 1 giving rise to β-borylated organocopper

• mechanism for the Cu-catalyzed dimerization of 4,4-dichoro-2-butenoic acid derivatives. a) KOt-Bu-mediated intramolecular cyclization of 9. b) Direct formation of cyclopropane 20 from gem-dichloride 5 using KOt-Bu as base. Optimization studies. Synthesis of densely functionalized (2,2-dichlorovinyl

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

• state catalyst are not operational (see Supporting Information File 1 for full details), providing support for an EnT mechanism, while exposing the Z-isomer (Z)-1a to the model reaction conditions, led to the generation of a similar photostationary state equilibrium of isomers, characteristic of an EnT

• as an operational mechanism. While intermolecular alkene quenching to enable [2 + 2] cycloaddition was inefficient, presumably due to poor substrate lifetime, intramolecular [2 + 2] reactivity with both acrylates and alkenylboronic esters was effective. The small 3D, boron-containing fragments could

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

• higher reactivity than 2-bromobenzoic acid derivatives. Based on previously reported literature [7][13], a mechanism for the copper-catalyzed formation of quinazolinones is proposed in Scheme 3. Initially, the 2-halobenzoic acid 1 coordinates with CS@CuI to form intermediate I in the presence of Na2CO3

• (0.2 mmol), amidine hydrochloride 2 (0.3 mmol, 1.5 equiv), CS@CuI (5.0 mol %), Na2CO3 (1.25 mmol, 2.5 equiv), iPrOH/H2O 9:1 (2.0 mL), 90 °C, 12 h, argon atmosphere. Proposed mechanism for the CS@CuI-catalyzed synthesis of quinazolinones. Scaling-up experiment (a) and recyclability of CS@CuI (b

Substituent effects in N-acetylated phenylazopyrazole photoswitches

• Radek Tovtik,
• Dennis Marzin,
• Pia Weigel,
• Stefano Crespi and
• Nadja A. Simeth

Beilstein J. Org. Chem. 2025, 21, 830–838, doi:10.3762/bjoc.21.66

• mechanism is one of the fastest relaxation mechanism for heterocyclic azobenzenes (typically for most of the azo dyes [45]). However, the nature of the mechanism is still a matter of current debate, and additional factors, such as the presence of tautomerizable groups [46][47], and the involvement of the

• triplet state [48], appear to play a role. Specifically, the rotation mechanism does not explain the low activation entropy observed in azobenzene systems [49] sparking new discussions on the possibility of alternative isomerization pathways [34]. Recently, Reimann et al. computationally showed that the

• involvement of a triplet state mechanism, which crosses the transition state for the Z→E relaxation, could explain the low values of the activation entropy. The same authors also showed experimental evidence for this proposal by an external heavy atom effect on Z→E isomerization. To understand the thermal Z→E

4-(1-Methylamino)ethylidene-1,5-disubstituted pyrrolidine-2,3-diones: synthesis, anti-inflammatory effect and in silico approaches

• Nguyen Tran Nguyen,
• Vo Viet Dai,
• Luc Van Meervelt,
• Do Thi Thao and
• Nguyen Minh Thong

Beilstein J. Org. Chem. 2025, 21, 817–829, doi:10.3762/bjoc.21.65

• active site of enzyme iNOS. Synthesis of 4-[1-(4-methoxybenzyl)amino]ethylidene-1,5-disubstituted pyrrolidine-2,3-diones 3a–e. Synthesis of 4-(1-methylamino)ethylidene-1,5-disubstituted pyrrolidine-2,3-diones 5a–e. Proposed mechanism for the reaction between 4-[1-(4-methoxybenzyl)amino]ethylidene-1,5

Regioselective formal hydrocyanation of allenes: synthesis of β,γ-unsaturated nitriles with α-all-carbon quaternary centers

• Seeun Lim,
• Teresa Kim and
• Yunmi Lee

Beilstein J. Org. Chem. 2025, 21, 800–806, doi:10.3762/bjoc.21.63

• 98% yield. Ortho-bromoaryl-substituted nitrile 3m also underwent tandem amidation and copper-catalyzed cyclization, efficiently producing lactam 9 in a 98% yield. Scheme 7 illustrates a plausible reaction mechanism based on previous studies [34]. The process begins with the formation of NHC–copper

• conditions: allene 4 (0.3 mmol), (iBu)2Al-H (0.3 mmol), IPrCuCl (5 mol %), TsCN (0.25 mmol), THF (0.2 M), under N2. The yields of the isolated products are given. Gram scale reaction. Synthetic applications. Proposed mechanism. Supporting Information Supporting Information File 40: General information

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

• -bidentate groups were unable to accelerate this reaction. To perform the reaction in an electrochemical environment, they used graphite (felt form) and nickel (nickel foam) electrodes as the anode and cathode, respectively, under a constant current of 8 mA at 110 °C. A non-radical reaction mechanism process

• -withdrawing groups such as –Cl, –Br, and –CO2Me. It was observed that carbazole derivatives with an extended conjugated system showed enhanced reactivity. Like the above P–N coupling mechanism, the reaction proceeded by an anodic oxidation of iodide to iodine followed by a reaction with dialkylphosphine oxide

• to give I–P(O)(R)2. The exact mechanism of this coupling reaction is not yet fully understood; however, the possibility of direct radical cross-coupling between the nitrogen radical derived from carbazole and the phosphoryl radical intermediate cannot be completely ruled out. In another

Development and mechanistic studies of calcium–BINOL phosphate-catalyzed hydrocyanation of hydrazones

• Carola Tortora,
• Christian A. Fischer,
• Sascha Kohlbauer,
• Alexandru Zamfir,
• Gerd M. Ballmann,
• Jürgen Pahl,
• Sjoerd Harder and
• Svetlana B. Tsogoeva

Beilstein J. Org. Chem. 2025, 21, 755–765, doi:10.3762/bjoc.21.59

• rearrangement under mild conditions [6], and the Nazarov-type electrocyclization of alkenyl aryl carbinols [7]. Exploiting the ease with which calcium forms hydrides, hydrogenation of aldimines, transfer hydrogenation of alkenes, and even deuteration of benzene by an SNAr mechanism, have been recently achieved

• in elucidating the mechanism by which these bifunctional compounds act as powerful catalysts [21][22][23][24][25][26][27][28][29]. Since Ishihara disclosed the crucial role of calcium in many purportedly purely organocatalytic BINOL phosphate-catalyzed reactions [30][31], several asymmetric synthesis

• –BINOL phosphate complex as catalyst. Herein, we report the development of the first Ca–BINOL phosphate-catalyzed asymmetric hydrocyanation of hydrazones and the results from DFT calculations to elucidate the mechanism of this transformation. Results and Discussion We first set out to study the

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

• , we conducted a 5.0 mmol scale reaction and obtained the target product 3aa in 82% yield (Scheme 3). Based on previous reports, a plausible mechanism was proposed. In the presence of a copper catalyst, aniline reacts with cyclobutanone oxime to form an imine intermediate, which undergoes isomerization

• spirotetrahydroquinoline (STHQ) scaffolds. Substrate scope. General reaction conditions: aniline 1 (0.2 mmol), 2 (0.4 mmol), and Cu(TFA)2 (0.04 mmol) in hexane (2.0 mmol) under air atmosphere, 12 h, 80 °C. Yields refer to isolated yields. Scale-up reaction.a Proposed mechanism. Optimization of reaction conditions.a

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

• transfer, X-ray crystallographic analysis of the (tert-butyl)(adamantyl)Bpin·Li(THF)2 complex revealed that the B–(adamantyl) bond is shorter than the B–(tert-butyl) bond (1.673 vs 1.692 Å). DFT calculations further illuminated the underlying mechanism by comparing two distinct transition states: TS1

• transition states: an open transition state TS7 facilitated by LiOt-Bu and a closed transition state TS6 without base assistance (Scheme 17a). The significant energy difference between these pathways (ΔΔG‡ = 4.3 kcal/mol) strongly favors the open transition state TS7 mechanism, attributed to reduced steric

• interactions and enhanced electronic stabilization through lithium coordination. This explains the critical role of lithium in achieving a high enantioselectivity. Isotope-labeling experiments using 10B-enriched 1,1-diborylalkanes (S)-49 further supported this mechanism, showing a stereoinvertive

Entry to 2-aminoprolines via electrochemical decarboxylative amidation of N‑acetylamino malonic acid monoesters

• Olesja Koleda,
• Janis Sadauskis,
• Darja Antonenko,
• Edvards Janis Treijs,
• Raivis Davis Steberis and
• Edgars Suna

Beilstein J. Org. Chem. 2025, 21, 630–638, doi:10.3762/bjoc.21.50

• 9d-D. Furthermore, monoesters 9 are also prone to spontaneous decarboxylation upon storage. Therefore, freshly prepared material should be used in the electrolysis. Based on experimental evidence, a working mechanism for the formation of 2-aminoproline 6a is proposed (Figure 4). Accordingly, an

• mM concentration, respectively, in 5:1 MeCN/H2O (0.1 M Et4N–BF4). B) Anodic oxidation of pyrrolidine 6a. Plausible mechanism for formation of pyrrolidine 6a and hemiaminal 10a. Preparation of malonic acid monoester 9a. Electrolysis of acid 9d in deuterated solvents. Scope of the decarboxylative

Photocatalyzed elaboration of antibody-based bioconjugates

• Marine Le Stum,
• Eugénie Romero and
• Gary A. Molander

Beilstein J. Org. Chem. 2025, 21, 616–629, doi:10.3762/bjoc.21.49

• a photoredox reaction, whereas when embedded within the protein, the Ru-based ArM complex promoted histidine modification through an energy-transfer mechanism (Figure 5). Based on DFT calculations, this is permitted by the modification of the energy diagram of the ruthenium complex in the presence

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

• ). Additionally, the Tiwari group developed a metal-free protocol using only K2S2O8 as an oxidant for the activation of DMSO to MMS (Scheme 8, path II) [38]. Under these conditions, an alternative mechanism arises in which the imine intermediate B, formed as previously stated through reaction between the aniline

• , methyl aryl ketones, and DMSO under iron(III) catalysis and using K2S2O8 for its activation [39]. The proposed mechanism is very close to those described above, with the methyl aryl ketone taking part of the reaction in place of the styrene component in the Povarov cyclization. In this case, the imine

• derivatives are isolated as side-products. Interestingly, when Liu et al. [40] modified this reaction by using a copper(II) catalyst under aerobic oxidative conditions, the regioisomers III (2-arylquinolines) were obtained (Scheme 9). To rationalize this singular result, the authors proposed a mechanism in

Study of the interaction of 2H-furo[3,2-b]pyran-2-ones with nitrogen-containing nucleophiles

• Constantine V. Milyutin,
• Andrey N. Komogortsev and
• Boris V. Lichitsky

Beilstein J. Org. Chem. 2025, 21, 556–563, doi:10.3762/bjoc.21.44

• established by X-ray analysis. The proposed mechanism of the considered processes is outlined at Scheme 8. Initially, the free nitrogen nucleophile is reversibly generated from the corresponding hydrochloride or acetate. Next, acid-catalyzed addition of the amine component to the carbon atom of the aroyl

• conditions: 1c (1 mmol, 0.30 g), hydroxylamine hydrochloride (1.2 mmol, 0.08 g), EtOH (5 mL). Proposed reaction mechanism. Synthesis of product 13. Reaction conditions: 8o (1 mmol, 0.37 g), pivaloyl chloride (3 mmol, 0.36 g), MeCN (5 mL). Optimization of the reaction conditionsa. Supporting Information

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

• present reaction, and products 17l and 17m were isolated in high yields with moderate to high stereoselectivities. The plausible reaction mechanism is shown in Figure 3. First, the removal of the acidic proton of the pre-nucleophile by potassium carbonate to form intermediate I, which undergoes cation

• -amino cyanoesters with contiguous tetrasubstituted carbon stereogenic centers by the catalytic Mannich reaction. Further investigations into the reaction mechanism and product applications are ongoing in our group. Selected examples and applications of chiral halogen-bonding catalysts. Selected examples

• for the construction of contiguous tetrasubstituted carbon centers via the Mannich reaction and this work. Plausible reaction mechanism. Catalyst screening for the asymmetric Mannich reaction. All yields were determined by 1H NMR spectroscopy using 1,3,5-trimethoxybenzene as an internal standard. N

Vinylogous functionalization of 4-alkylidene-5-aminopyrazoles with methyl trifluoropyruvates

• Judit Hostalet-Romero,
• Laura Carceller-Ferrer,
• Gonzalo Blay,
• Amparo Sanz-Marco,
• José R. Pedro and
• Carlos Vila

Beilstein J. Org. Chem. 2025, 21, 533–540, doi:10.3762/bjoc.21.41

• . Considering the high diastereoselectivity observed both in the presence and absence of the squaramide catalyst, we propose a plausible mechanism (Scheme 3) that involves hydrogen bonding activation of the methyl trifluoropyruvate by the NH₂ group of the aminopyrazole. This interaction directs the attack of

• chromatography. Diastereoisomeric ratio (dr) determined by 1H NMR of the crude reaction mixture. Plausible mechanism and X-ray structure of compound 5aca. Optimization of the reaction conditions.a Supporting Information Supporting Information File 14: Detailed experimental procedures, characterization data, and

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

• suggest potential triplet-state formation, which is involved in the proposed mechanism for the cycloaddition reaction. Although Me4B could theoretically form triplet states, given its fluorescence quantum yield of 51.7–67.3%, its crystallographic structure is not conducive to this reaction, regardless of

• bimane (Figure 7). The hypsochromic shift in this reaction means that provided correct irradiation wavelength is used, a 100% yield of the dimer could theoretically be achieved. Tentative mechanism The observed reaction likely follows a five-step mechanism, as suggested by previous studies [29][30]. The

• diradical. This triplet diradical undergoes another ISC, returning to the singlet state, which then forms a second single bond (Figure 8). This mechanism, involving both singlet-excited states and triplet states via ISC, is consistent with the relatively low fluorescence quantum yields observed for Cl2B

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

• the overall oxidation of 4a to 1a likely is a two-electron process, suggesting that the second oxidation step may involve disproportionation of putative Br(II) species (see Scheme 3D). Based on the control experiments described above we propose a plausible mechanism as shown in Scheme 3D. The reaction

• improving the substrate scope and understanding the reaction mechanism are in progress in our laboratory. Synthesis of cyclic diarylbromonium compounds. Substrate scope. Reactions were performed on a 0.15 mmol scale. Yields were determined by 1H NMR spectroscopy of the reaction mixture using 1,2,3,4

• : Representative jp vs v0.5 slope values for oxidation of Martin’s bromane precursor 6 (ref. [17]). D: Plausible reaction mechanism. Optimization of electrochemical oxidation/cyclization conditions.a Supporting Information Crystallographic data for the structure reported in this paper have been deposited with the

New tandem Ugi/intramolecular Diels–Alder reaction based on vinylfuran and 1,3-butadienylfuran derivatives

• Yuriy I. Horak,
• Roman Z. Lytvyn,
• Andrii R. Vakhula,
• Yuriy V. Homza,
• Nazariy T. Pokhodylo and
• Mykola D. Obushak

Beilstein J. Org. Chem. 2025, 21, 444–450, doi:10.3762/bjoc.21.31

• a coordinated mechanism. Noteworthy, the primary kinetic product of the cycloaddition reaction 5 is not transformed into the thermodynamic product 6 via a H-shift at the last stage. The expected aromatization with the formation of a furan ring, as happens in similar reactions, does not occur (Scheme