Synthesis, structure, ionochromic and cytotoxic properties of new 2-(indolin-2-yl)-1,3-tropolones

• Yurii A. Sayapin,
• Eugeny A. Gusakov,
• Inna O. Tupaeva,
• Alexander D. Dubonosov,
• Igor V. Dorogan,
• Valery V. Tkachev,
• Anna S. Goncharova,
• Gennady V. Shilov,
• Natalia S. Kuznetsova,
• Svetlana Y. Filippova,
• Tatyana A. Krasnikova,
• Yanis A. Boumber,
• Alexey Y. Maksimov,
• Sergey M. Aldoshin and
• Vladimir I. Minkin

Beilstein J. Org. Chem. 2025, 21, 358–368, doi:10.3762/bjoc.21.26

• excess of quinone 3 leads to the formation of 2-(indolin-2-yl)-4,5,6,7-tetrachloro-1,3-tropolones 8a,b as final products. The detailed reaction mechanism in acetic acid solution was studied by the PBE0/6-311+G(d,p) method on the example of the interaction of 2-methylquinolines and 2-methylbenzazoles with

Red light excitation: illuminating photocatalysis in a new spectrum

• Lucas Fortier,
• Corentin Lefebvre and
• Norbert Hoffmann

Beilstein J. Org. Chem. 2025, 21, 296–326, doi:10.3762/bjoc.21.22

• . who employed a ruthenium(II) complex 1 activated through photoinduced electron transfer. The latter is pre-activated by the osmium complex shown in Scheme 1 after irradiation in the red region [18]. According to the mechanism proposed by the authors, the reaction is facilitated when conducted in

• ). The mechanism of the reaction presented by the authors involves two different catalytic cycles as presented in Scheme 3c. After excitation of the osmium complex 13, this latter is reduced via the use of a tertiary amine to give the active species 14 able to oxidize the formed nickel complex 15 in the

• suppress side reactions. The cross-dehydrogenative coupling reactions, under near-infrared irradiation, was found to proceed via an energy-transfer mechanism involving singlet oxygen generation rather than the typical electron-transfer pathway observed in the presented visible-light-mediated reactions in

Molecular diversity of the reactions of MBH carbonates of isatins and various nucleophiles

• Zi-Ying Xiao,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2025, 21, 286–295, doi:10.3762/bjoc.21.21

• has an E,E,E-configuration, while the compound 8a has a Z,E,E-configuration. On the basis of the above experiments and the previously published results [42][43][44][45][46][47][48][49][50][51][52], a plausible reaction mechanism was proposed in Scheme 4 to explain the formation of the various oxindole

• ), CH3CN (5.0 mL), rt, 2 h; yields refer to isolated yields. Proposed reaction mechanism for the various compounds. Optimization of reaction conditions.a Dimerization of MBH carbonates of isatins.a Supporting Information The crystallographic data of compounds 5a (CCDC 2390713), 5j (CCDC 2390714), 6e (CCDC

Three-component reactions of conjugated dienes, CH acids and formaldehyde under diffusion mixing conditions

• Dmitry E. Shybanov,
• Maxim E. Kukushkin,
• Eugene V. Babaev,
• Nikolai V. Zyk and
• Elena K. Beloglazkina

Beilstein J. Org. Chem. 2025, 21, 262–269, doi:10.3762/bjoc.21.18

• compounds 8 and 9, we could show that when the reaction was carried out in the absence of ʟ-proline, the conversion of the starting CH acid 1 after 5 days was less than 50%, and the main products present in the mixture were compounds 2 and 3. The proposed mechanism for the formation of compounds 8 and 9

• participation. Interaction of diketone 1 with formaldehyde under the diffusion mixing conditions. Products of three-component reactions of methylene derivatives, formaldehyde and various dienes. Proposed mechanism for the formation of compounds 8 and 9 in the presence of ʟ-proline. Interconversion of

Synthesis of disulfides and 3-sulfenylchromones from sodium sulfinates catalyzed by TBAI

• Zhenlei Zhang,
• Ying Wang,
• Xingxing Pan,
• Manqi Zhang,
• Wei Zhao,
• Meng Li and
• Hao Zhang

Beilstein J. Org. Chem. 2025, 21, 253–261, doi:10.3762/bjoc.21.17

• be isolated in 82% yield. Several control experiments were performed to investigate the possible mechanism of the reaction (Scheme 5). In Table 1, entry 17, no disulfide product was formed at 80 °C, however, an 85% yield of thiosulfonate was observed. This indicated that thiosulfonate could be an

• whether the reaction proceeded through a free radical mechanism, different free radical inhibitors were added to the reaction (reaction 7, Scheme 5). The addition of TEMPO ((2,2,6,6-tetramethylpiperidin-1-yl)oxyl) resulted in complete inhibition of the reaction, while BHT (2,6-di-tert-butyl-4-methylphenol

• ) exhibited a lesser effect. Considering that TEMPO, as an oxidizing agent, affected the reaction, it could be concluded that the reaction did not proceed through a free radical mechanism. Based on the results of the control experiments and the related literature [26][30][41][52], a possible mechanism for the

Visible-light-promoted radical cyclisation of unactivated alkenes in benzimidazoles: synthesis of difluoromethyl- and aryldifluoromethyl-substituted polycyclic imidazoles

• Yujun Pang,
• Jinglan Yan,
• Nawaf Al-Maharik,
• Qian Zhang,
• Zeguo Fang and
• Dong Li

Beilstein J. Org. Chem. 2025, 21, 234–241, doi:10.3762/bjoc.21.15

• demonstrates the versatility of our methodology and its potential for further exploration in diverse chemical spaces. To gain a deeper understanding of the mechanism behind the observed reaction, we conducted a series of control experiments as outlined in Scheme 3a. Initially, we performed the model reaction

• mixture, which significantly impeded the progress of the desired reaction. Therefore, on the basis of the above experimental results and previous reports [21][27][28][29][30], we proposed a possible reaction mechanism (Scheme 3b), taking CF2HCOOH as the illustrative example. Initially, a double ligand

• . Reaction conditions: 1 (0.2 mmol), 2 (1.4 mmol), and PIDA (0.8 mmol) in solvent (2 mL) irradiated with 72 W white LEDs at room temperature for 12 h under a N2 atmosphere. Yields refer to isolated yield. aα,α-Difluorobenzeneacetic acid (2 equiv) was used. Control experiments and plausible mechanism

Heteroannulations of cyanoacetamide-based MCR scaffolds utilizing formamide

• Marios Zingiridis,
• Danae Papachristodoulou,
• Despoina Menegaki,
• Konstantinos G. Froudas and
• Constantinos G. Neochoritis

Beilstein J. Org. Chem. 2025, 21, 217–225, doi:10.3762/bjoc.21.13

• the desired thienopyrimidones 5a–e, quinolinopyrimidones 6a–e and indolopyrimidones 7a–e, respectively, as reported in the literature [42][44]. In accordance with the reported mechanism, after the initial formylation of the amino group at position 2, an intramolecular nucleophilic attack by the NH

Dioxazolones as electrophilic amide sources in copper-catalyzed and -mediated transformations

• Seungmin Lee,
• Minsuk Kim,
• Hyewon Han and
• Jongwoo Son

Beilstein J. Org. Chem. 2025, 21, 200–216, doi:10.3762/bjoc.21.12

• theory (DFT) calculations, a proposed reaction mechanism is suggested as shown in Figure 3. Initially, copper acetylide INT-11 is formed by the reaction of acetylene with a copper precatalyst, leading to the formation of an N-acyl nitrene acetylide intermediate INT-12 after the incorporation of

• late-stage functionalizations of complex scaffolds such as peptides, drug molecules, and natural products containing unprotected free OH and NH groups are anticipated. Proposed reaction pathway for the copper-catalyzed synthesis of δ-lactams from dioxazolones. Proposed reaction mechanism for the copper

• -catalyzed synthesis of 1,2,4-triazole analogues from dioxazolones and N-iminoquinolinium ylides. Proposed reaction mechanism for the copper(I)-catalyzed synthesis of N-acyl amidines. Proposed reaction pathway for the copper-mediated synthesis of N-arylamides from dioxazolones. Proposed reaction pathway for

Recent advances in electrochemical copper catalysis for modern organic synthesis

• Yemin Kim and
• Won Jun Jang

Beilstein J. Org. Chem. 2025, 21, 155–178, doi:10.3762/bjoc.21.9

• decreasing the oxidation potential. A range of functional groups, such as halides, ethers, and heterocycles, were tolerated well, yielding the corresponding enantioenriched products 14 with high enantioselectivity in the presence of chiral bisoxazoline ligand L2. A possible mechanism is depicted in Figure 5

• enantioenriched nitrile products 29. The proposed mechanism is illustrated in Figure 8. [Mes-Acr-Ph]+* is generated through the photoexcitation of the photocatalyst [Mes-Acr-Ph]+, which undergoes electron transfer to the heteroarene 28, resulting in the formation of the [Mes-Acr-Ph]• and heteroarene radical

• standard Cu-catalyzed electrochemical protocol. Based on mechanistic studies, the proposed mechanism is shown in Figure 9. First, hydroquinone 34 is oxidized at the anode to generate a quinone intermediate 38. Meanwhile, the chiral copper catalyst reacts with the Schiff base 33, generating a nucleophilic

Nickel-catalyzed cross-coupling of 2-fluorobenzofurans with arylboronic acids via aromatic C–F bond activation

• Takeshi Fujita,
• Haruna Yabuki,
• Ryutaro Morioka,
• Kohei Fuchibe and
• Junji Ichikawa

Beilstein J. Org. Chem. 2025, 21, 146–154, doi:10.3762/bjoc.21.8

• ]benzofuran (3fa) in 81% yield. Next, we explored the mechanism of the coupling reactions between 2-fluorobenzofurans 1 and arylboronic acids 2. Because these reactions proceed under mild conditions despite involving aromatic C–F bond activation [19], direct oxidative addition of C–F bonds is unlikely (Scheme

• , reductive elimination from G yields the coupling products 3. The following experiments were performed to elucidate the mechanism. Under the same conditions as the coupling reaction, stoichiometric amounts of Ni(cod)2, PCy3, and cod were treated with fluoronaphthofuran 1b at room temperature for 13 h

Cu(OTf)₂-catalyzed multicomponent reactions

• Sara Colombo,
• Camilla Loro,
• Egle M. Beccalli,
• Gianluigi Broggini and
• Marta Papis

Beilstein J. Org. Chem. 2025, 21, 122–145, doi:10.3762/bjoc.21.7

• behavior or reactivity properties. The ambiguity related to the role of Cu(OTf)2 is particularly relevant for cycloaddition reactions, where it is even more difficult to justify the activation of the copper species as a Lewis acid or metal catalyst [12][13][14]. The reaction mechanism involved can be ionic

• to multiple C–C bonds generates extended carbon radicals capable of giving further functionalization. Regarding the ionic mechanism, the key step generally comprises the complexation with the unsaturated substrate leading to activation of the alkenyl/alkynyl moiety towards a nucleophilic attack. In

• . Among various Lewis acids, only Cu(OTf)2 in combination with TMSCN was effective or a valuable alternative was the use of acetone cyanohydrin combined with a catalytic amount of TEA (5 mol %). The mechanism involves the formation of an imine facilitating the addition of the nitrile group. Among the

Recent advances in organocatalytic atroposelective reactions

• Henrich Szabados and
• Radovan Šebesta

Beilstein J. Org. Chem. 2025, 21, 55–121, doi:10.3762/bjoc.21.6

• reacted with aminoarylaldehydes 5 to form axially chiral 2-arylquinoline derivatives 6 (Scheme 2). Using the pyrrolidine derivative C2 as the most efficient organocatalyst, a range of quinoline derivatives were obtained in high yields and enantiomeric purities. The postulated mechanism consists of iminium

• ) annulation of enals with ynamides 8 to afford axially chiral 7-arylindolines 9 was reported [20]. The reaction mechanism, rationalized by DFT calculations, is believed to occur through catalyst C3 activation of the substrate 8, dehydration, and deprotonation with tautomerization leading to the enamine

• [27]. This transformation led to a series of axially chiral cycl[3.2.2]azines 24 in good yields and high enantiomeric purities (Scheme 8). The proposed mechanism comprises enamine activation, condensation with nitroolefin 23, ring closure, and catalyst elimination to provide the axially chiral product

Hot shape transformation: the role of PSar dehydration in stomatocyte morphogenesis

• Remi Peters,
• Levy A. Charleston,
• Karinan van Eck,
• Teun van Berlo and
• Daniela A. Wilson

Beilstein J. Org. Chem. 2025, 21, 47–54, doi:10.3762/bjoc.21.5

• . However, when the membrane gets too stiff, the deformation is prevented regardless of the increased force that is applied. For further affirmation of the mechanism circular dichroism (CD) spectroscopy was employed to give more insight on the morphological changes in the polymers secondary structure

Facile one-pot reduction of β-nitrostyrenes to phenethylamines using sodium borohydride and copper(II) chloride

• Laura D’Andrea and
• Simon Jademyr

Beilstein J. Org. Chem. 2025, 21, 39–46, doi:10.3762/bjoc.21.4

• . Proposed mechanism for the formation of the hydroxylamine side product b. N-Phenethylhydroxylamine (d), originated during the reduction process, reacts with the acetaldehyde e resulting from the hydrolysis of the aldoxime precursor c. The reduced β-nitrostyrene scaffolds with their corresponding products

Reactivity of hypervalent iodine(III) reagents bearing a benzylamine with sulfenate salts

• Beatriz Dedeiras,
• Catarina S. Caldeira,
• José C. Cunha,
• Clara S. B. Gomes and
• M. Manuel B. Marques

Beilstein J. Org. Chem. 2024, 20, 3281–3289, doi:10.3762/bjoc.20.272

• . A plausible mechanism is proposed, suggesting a possible radical pathway. Keywords: electrophilic amination; hypervalent iodine reagents; sulfinamide; sulfonamide; Introduction Iodine(III) compounds, known as λ3-iodanes, have been extensively applied in organic synthesis. Although initially used

• from the simultaneous formation of sulfinamide 6ea also isolated in this reaction for the first time (both in trace amounts). Reaction mechanism The inability to detect sulfinamide 6 and the isolation of sulfonamide 5, along with other byproducts (3, 4, and 7), stimulated us to propose a plausible

• reaction mechanism that would support both the obtained yields and the formation of unexpected species. As mentioned above, the presence of light influences the reaction outcome. When the reaction was carried out in the absence of light, only 4a, 3a, and 7a were isolated (under these conditions, there was

Non-covalent organocatalyzed enantioselective cyclization reactions of α,β-unsaturated imines

• Sergio Torres-Oya and
• Mercedes Zurro

Beilstein J. Org. Chem. 2024, 20, 3221–3255, doi:10.3762/bjoc.20.268

• Michael addition product was obtained with low diastereoselectivity. The mechanism is described in Scheme 4: the bifunctional squaramide activates the azadiene through hydrogen bonding while the malononitrile is deprotonated by the tertiary amine present in the backbone of the catalyst, establishing

• -azadienes bearing substituents at the ortho-position were tested, the enantioselectivities decreased, probably due to higher steric hindrance. The mechanism of the reaction is depicted in Scheme 7; firstly, the dual activation of the azadiene and the enol form of the azlactone through hydrogen bonding with

• azadiene in a stepwise mechanism: firstly, the vinylogous Michael addition of the dienolate to the double bond of the α,β-unsaturated N-sulfonylimine occurs in a stereoselective fashion. Subsequently, cyclization due to an intramolecular aza-Michael reaction and protonation leads to the enantioenriched

Synthesis of 2H-azirine-2,2-dicarboxylic acids and their derivatives

• Anastasiya V. Agafonova,
• Mikhail S. Novikov and
• Alexander F. Khlebnikov

Beilstein J. Org. Chem. 2024, 20, 3191–3197, doi:10.3762/bjoc.20.264

• not isomerize at room temperature, which is typical for highly sterically congested isoxazoles containing a 3-tert-butyl substituent [26]. The mechanism of such isomerizations of isoxazoles has been previously discussed using DFT calculations [25][26], which revealed the formation of an isoxazole–Fe

Direct trifluoroethylation of carbonyl sulfoxonium ylides using hypervalent iodine compounds

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

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

• reactants. Finally, DFT calculations provided insights about the mechanism of this transformation, which strongly suggest that an SN2 reaction is operative. Keywords: alkylation; DFT calculations; fluorine chemistry; hypervalent iodine; sulfoxonium ylide; sulphur ylides; Introduction Introducing fluorine

• in 87% yield (Scheme 3b). To gain insight into the mechanism, we modelled two reaction pathways commonly suggested for the 2,2,2-trifuoroethyl(mesityl)iodonium triflate salt, and for related diaryliodonium salts (Figure 2). The first mechanism explored was the associative pathway that terminates via

• with them being viable electrophilic sites for halogen bond formation with 1a, supporting the mechanism in path 1. We also expressed the LUMO and LUMO+1 molecular orbitals of 2a’ (Figure 3, middle and right, respectively), which showed lobes centered on the I–C bonds to both the trifluoroethyl and

Multicomponent reactions driving the discovery and optimization of agents targeting central nervous system pathologies

• Lucía Campos-Prieto,
• Aitor García-Rey,
• Eddy Sotelo and
• Ana Mallo-Abreu

Beilstein J. Org. Chem. 2024, 20, 3151–3173, doi:10.3762/bjoc.20.261

• ). Finally, recent research has implicated melatonin in modulating the Nrf2/ARE pathway, a crucial defense mechanism against OS and inflammation. In this study, FATMHs and LATMHs were synthesized through Ugi reaction and evaluated for their therapeutic potential in AD. Among these compounds, FATMH 6a emerged

Controlled oligomerization of [1.1.1]propellane through radical polarity matching: selective synthesis of SF₅- and CF₃SF₄-containing [2]staffanes

• Jón Atiba Buldt,
• Wang-Yeuk Kong,
• Yannick Kraemer,
• Masiel M. Belsuzarri,
• Ansh Hiten Patel,
• James C. Fettinger,
• Dean J. Tantillo and
• Cody Ross Pitts

Beilstein J. Org. Chem. 2024, 20, 3134–3143, doi:10.3762/bjoc.20.259

• formation [35][48]. For instance, in 2022, we reported a method for chloropentafluorosulfanylation of [1.1.1]propellane, i.e., to make SF5-BCP-Cl (4), that ostensibly proceeds through a radical chain propagation mechanism [36]. Under optimized conditions, we obtained product 4 in 86% yield, and the

Hypervalent iodine-mediated intramolecular alkene halocyclisation

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

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

• 4 [9][10] (Figure 1). Halogenated cyclised structures have also been found to exhibit medicinal and pharmaceutical properties, including antibacterial [11], antibiotic [12], and enzyme inhibition [13] among others. The general mechanism for the HVI-mediated halocyclisation of alkenes proceeds

• -, stereo-) of the reaction, which is influenced by the type of HVI reagent, the nature of the substrates employed and the proposed mechanism from the authors are all described. The halocyclisation of alkenes to make halogenated carbo or heterocycles is yet to be covered by a review, which is the vacancy

• good yields, demonstrating the scope of the reaction. The authors proposed an alternative reaction mechanism to those already described, in which trans-aminopalladation of the alkene, mediated by Pd(II), occurs with intramolecular attack of the nitrogen on the terminal carbon, generating a 6-membered

Advances in the use of metal-free tetrapyrrolic macrocycles as catalysts

• Mandeep K. Chahal

Beilstein J. Org. Chem. 2024, 20, 3085–3112, doi:10.3762/bjoc.20.257

• active groups for a variety of substrates, making their use as supramolecular organocatalysts based on bifunctional activation mechanism (hydrogen-bonding/Lewis basicity) highly promising. At the same time, additional functional groups that are required for the catalysis can be easily installed on the

• ]pyrrole α,β-isomer 4 was found to be catalytically active providing a 57% conversion to 10, suggesting a concerted cycloaddition mechanism. Calix[4]pyrrole α,α-isomer 3 and dipyrromethane 5 were catalytically inactive. The authors concluded that the catalytic inactivity of 3 is caused by the parallel

• , with TBAI as a co-catalyst, up to 74% yields (Table 1). The inactivity of porphyrin 18 was attributed to the inaccessibility of the inner core imine due to its planar structure. The mechanism of the epoxide ring-opening reaction was elucidated by DFT calculations, which suggested that the macrocycle

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

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

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

• chemistry and optical science. A plausible reaction mechanism for the formation of the target molecules 18a–n via a high-order multicomponent reaction is shown in Scheme 3 and consists of two processes: an Ugi-azide reaction and a Pd/Cu-catalyzed heteroannulation reaction. The Ugi-azide reaction mechanism

• cytotoxic compounds. For example, a cytotoxic effect was found in CAL 27 cells, presumably through a mechanism of TNF-α inhibition in vitro, which could be related to the anti-inflammatory effect identified in several studies of NSAIDs that inhibit cancer cell viability in vitro [37][38]. In another study

• aimed at inhibiting tubulin assembly, N-mesyl-2-(1-phenylvinyl)indoles were active against HCT-116 cells on the order of a GI50 of 10 mM, although the mechanism originally sought was not demonstrated [39]. Therefore, in this work, the cytotoxic activity of methanesulfonylindoles 18a–j was explored

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

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

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

• ][34]. In sharp contrast, propargyltrichlorosilane is configurationally stable and only reacts through the SE2’ mechanism under Lewis base-catalyzed conditions [43][44][45], although it was reported that distillation of propargyltrichlorosilane substantially isomerizes it to the thermodynamically more

• structure–enantioselectivity relationship is exactly opposite to that for the analogous allylation reaction reported by Nakajima [47], thus it raises a possibility that the asymmetric induction mechanism could be fundamentally different between the present allenylation with propargyltrichlorosilane and the

• study, Hoveyda and co-workers proposed a similar mechanism for the isomerization of alkynes to allenes catalyzed by 1,8-diazabicyclo[5.4.0]undec-7-ene [61]. Conclusion In this study, we prepared distilled propargyltrichlorosilane with >99% isomeric purity for the first time, developed its asymmetric

Chemical structure metagenomics of microbial natural products: surveying nonribosomal peptides and beyond

• Thomas Ma and
• John Chu

Beilstein J. Org. Chem. 2024, 20, 3050–3060, doi:10.3762/bjoc.20.253

• molecules were screened for various bioactivities and led to the discovery of new antibiotics, antifungals, as well as anticancer compounds (Figure 4). Importantly, the underlying mechanism of bacterial growth suppression has been identified for several Syn-BNP antibiotics, which includes both general mode

• herein are hits from various bioactivity screens. For each Syn-BNP, its name is in bold, the microorganism that harbors the corresponding BGC is italicized, followed by its bioactivity and the target/mechanism of action (if known). a) “Offloading” is the final step of NRP biosynthesis, wherein the mature