Palladium-catalyzed benzocyclization reactions of quinoline-2-carboxamides via sequential C–H/N–H functionalization

• Shoichi Sugita,
• Kentaro Okano and
• Atsunori Mori

Beilstein J. Org. Chem. 2026, 22, 905–914, doi:10.3762/bjoc.22.71

• confirmed by 1H NMR and mass spectra (Scheme 3; see also Supporting Information File 1). This result indicated that the C–C bond was formed first in the reaction. The structures of other products were inferred from their 1H NMR spectra, while the structures of products 3aj and 3ak were also determined by

• NOESY (Figure 1d and e). These results suggested that the carbon–iodine bond in 1-bromo-2-iodobenzene was involved in the formation of the C–C bond, while the carbon–bromine bond was involved in the formation of the C–N bond (Scheme 4). Accordingly, a plausible reaction mechanism is proposed in Scheme 5

• concerted metalation-deprotonation (CMD) process, a carbon–palladium bond is formed to give the palladacycle intermediate Int-4. Next, reductive elimination between the quinoline and arene moieties forms the C–C bond to give intermediate Int-1 and regenerates the palladium(0) catalyst. Another oxidative

Diastereodivergent electrophilic trapping of α-boryl lithium derivatives

• Tereza Pavlíčková,
• Noam Orbach and
• Ilan Marek

Beilstein J. Org. Chem. 2026, 22, 882–887, doi:10.3762/bjoc.22.68

• their stereoselective reactions remains challenging. Here, we examine the diastereoselective generation and trapping of α-boryl lithium species formed by ring opening of substituted iodomethylcyclopropanes. After lithium–iodine exchange and selective C–C bond cleavage, these intermediates react with a

• derivative 1 to afford product 4 as single diastereomers. Specifically, iodide 2 was subjected to tert-butyllithium (t-BuLi) in diethyl ether at −95 °C, efficiently generating cyclopropylmethyllithium 3 via lithium–iodine exchange. Subsequent selective C–C bond cleavage of 3, proceeding exclusively through

The trans-influence in gold chemistry from a catalytic perspective

• Manfred Bochmann

Beilstein J. Org. Chem. 2026, 22, 838–856, doi:10.3762/bjoc.22.66

• to C=C-bond isomerisation, to give the gold vinyls in E/Z ratios of 20:80 (24) and 50:50 (25), respectively (Scheme 12). The Z-isomer is evidently the kinetic product. The gold(III) hydrides that react with DMAD are all neutral or negatively charged complexes carrying electron-rich anionic C-ligands

• optimised by DFT calculations [82]. They clearly fall into two categories: In the C^N and P^N compounds the allyl bonding is very asymmetrical, with a long and a short C–C bond and strong variations in Au–C bond distances, as expected for a σ,π-allyl, while in 27 and its methallyl analogue the bonding is

Synthesis and structural elucidation of a novel bis-spirooxindole from isatin and ethylenediamine

• Irene Moreno-Gutiérrez,
• Josefa L. López-Martínez,
• Sonia Berenguel-Gómez,
• Irene Torres-García,
• Duane Choquesillo-Lazarte,
• Manuel Muñoz-Dorado,
• Miriam Álvarez-Corral and
• Ignacio Rodríguez-García

Beilstein J. Org. Chem. 2026, 22, 813–820, doi:10.3762/bjoc.22.63

• its formation. Indeed, when 24 was treated with either sodium borohydride or sodium cyanoborohydride in methanol, compound 25 was obtained as the sole isolable product (Scheme 4c). These experiments demonstrate that 25 can arise from 24 through an initial imine reduction followed by intramolecular C–C

• bond formation and cyclization. Scheme 5 depicts a hypothetical rationalization of the process. Reaction of isatin (1) with ethylenediamine (23) should initially form the imine 26. Its reaction with a second molecule of isatine should lead to the diimine 24. Under the reaction conditions both imines 26

Synthesis of heterocycles based on azomethine ylides from α-amino acids (or amines) and carbonyl compounds

• Ekaterina V. Berezhnaya,
• Alexander I. Ponyaev,
• Vitali M. Boitsov and
• Alexander V. Stepakov

Beilstein J. Org. Chem. 2026, 22, 705–741, doi:10.3762/bjoc.22.55

Computational prediction of C–H hydricities and their use in predicting the regioselectivity of electron-rich C–H functionalisation reactions

• Rasmus M. Borup,
• Nicolai Ree and
• Jan H. Jensen

Beilstein J. Org. Chem. 2026, 22, 603–610, doi:10.3762/bjoc.22.46

• descriptor rather than a mechanistic assignment. The results are shown in Figure 5. Compound 1 He et al. [38] reported a dirhodium(II)-catalysed intermolecular C–H insertion into securinenine (compound 1) to generate a C–C bond. The reaction occurs at the site with the lowest predicted hydricity, but only

Dialkylaminoalkylation of β-ketosulfones via ring-opening of 3-sulfonylpyrrolidines

• Evgeny M. Buev,
• Alexander V. Pavlushin,
• Vladimir S. Moshkin and
• Vyacheslav Y. Sosnovskikh

Beilstein J. Org. Chem. 2026, 22, 383–389, doi:10.3762/bjoc.22.26

• the fast increase of the molecular complexity, remains significant. Unlike the classical aminoethylation of nucleophilic compounds [28][29], Batey et al. recently developed a two-step approach consisted in addition of terminal ynimides I to various electrophiles with subsequent reduction of the C≡C

• bond (Figure 2b) [30]. At the same time, Yang et al. presented a domino radical reaction of CH2-active compounds II and N,N-dimethylanilines III promoted by di-tert-butyl peroxide (DTBP), allowing the formation of the ethylene link via a domino-process of the methylenation and subsequent aminomethyl

Ring contraction and ring expansion reactions in terpenoid biosynthesis and their application to total synthesis

• Nicolas Kratena,
• Nicolas Heinzig and
• Peter Gärtner

Beilstein J. Org. Chem. 2026, 22, 289–343, doi:10.3762/bjoc.22.21

• from the 5/7/7/3-ring system towards a 6/6/7/3-system was proposed by Qiu, Zhou and Yue et al. in the isolation reports of pepluanols A–D [138][139][140]. Here, a retro-aldol reaction was invoked to cleave the C–C bond rupturing the 5- and 7-membered ring. The C-4 ketone can then enolise in a way that

Arene activation via π-bond localization: concepts and opportunities

• Paul Meiners,
• Julian J. Melder and
• Tobias Morack

Beilstein J. Org. Chem. 2026, 22, 257–273, doi:10.3762/bjoc.22.19

• induces localization within the aromatic ring, resulting in a residual diene motif, a phenomenon reflected in the alternating C–C bond lengths of the ring [69]. Over the past decades, this coordination mode has been explored across a spectrum of transition metals, with palladium and nickel serving as the

• deuteration, η4-arene complexes exhibit a compelling repertoire of C–C bond-forming reactions [101][102][103]. Notably, reactions with benzyl halides [99], iminium salts [104], nitrones [105], and ketenes [98] reveal rich synthetic potential. In a striking example, the [Mn(CO)3(η4-C6H6)]− complex acts as a

Base-promoted deacylation of 2-acetyl-2,5-dihydrothiophenes and their oxygen-mediated hydroxylation

• Vladimir G. Ilkin,
• Margarita Likhacheva,
• Igor V. Trushkov,
• Tetyana V. Beryozkina,
• Vera S. Berseneva,
• Vladimir T. Abaev,
• Wim Dehaen and
• Vasiliy A. Bakulev

Beilstein J. Org. Chem. 2026, 22, 192–204, doi:10.3762/bjoc.22.13

• oxidation of ketones includes C‒C-bond cleavage, and carboxylic acids are predominantly formed. This can be achieved by the treatment of acyclic ketones with hypohalites [13], in the nitroarene-catalyzed oxidation with oxygen under basic conditions [14] or by the use of hypervalent iodine compounds (Scheme

Streptoquinolines A and B, new antibacterial meroterpenoids produced by Streptomyces sp. TMPU-A0679

• Akiho Yagi,
• Hitomi Tomura,
• Ami Konno and
• Ryuji Uchida

Beilstein J. Org. Chem. 2026, 22, 185–191, doi:10.3762/bjoc.22.12

• '. HMBC correlations were observed from the sp3 methylene proton H2-11 to C-8, C-1', and the oxygenated sp2 quaternary carbon C-6' (δ 143.8). These correlations indicated that the quinoline unit was fused to a drimane-type sesquiterpene through two key links: a C–O bond between C-8 and C-6' and a C–C bond

Highly electrophilic, gem- and spiro-activated trichloromethylnitrocyclopropanes: synthesis and structure

• Ilia A. Pilipenko,
• Mikhail V. Grigoriev,
• Olga Yu. Ozerova,
• Igor A. Litvinov,
• Darya V. Spiridonova,
• Aleksander V. Vasilyev and
• Sergey V. Makarenko

Beilstein J. Org. Chem. 2026, 22, 123–130, doi:10.3762/bjoc.22.5

• nitro group upon breaking the C–C bond [16][17]. Substituted nitrocyclopropanes in reactions with various nucleophiles form linear precursors for the synthesis of γ-substituted α-aminobutyric acids [18][19], cyclic nitropyrrolines [20] and isoxazoline N-oxides [18]. The nitrocyclopropane fragment is a

One-pot synthesis of ethylmaltol from maltol

• Immanuel Plangger,
• Marcel Jenny,
• Gregor Plangger and
• Thomas Magauer

Beilstein J. Org. Chem. 2025, 21, 2755–2760, doi:10.3762/bjoc.21.212

• GmbH, Am Brunnen 1, 5330 Fuschl am See, Austria 10.3762/bjoc.21.212 Abstract A novel route to the flavor enhancer ethylmaltol, a synthetic 4-pyrone, from naturally abundant maltol is disclosed. Two strategies were explored for the required C1 homologation. The most direct approach, C–C bond formation

Recent advancements in the synthesis of Veratrum alkaloids

• Morwenna Mögel,
• David Berger and
• Philipp Heretsch

Beilstein J. Org. Chem. 2025, 21, 2657–2693, doi:10.3762/bjoc.21.206

• out, displaying an almost linear sequence. Featuring a key Wagner–Meerwein-type rearrangement from a diol to an homoallylic alcohol, most transformations are on the green and, thus, desirable spectrum of our color code. Note that a semisynthetic approach always lacks real C–C bond connection (dark

Visible-light-driven NHC and organophotoredox dual catalysis for the synthesis of carbonyl compounds

• Vasudevan Dhayalan

Beilstein J. Org. Chem. 2025, 21, 2584–2603, doi:10.3762/bjoc.21.200

• arylcyclopropanes 5 by applying NHC/ photoredox cooperative organocatalysis under visible-light irradiation. This method allows sequential C–O and C–C bond formation, leading to access to various γ-aroyloxy keto-ester derivatives 6 in good yield up to 81% and excellent functional group tolerance, including electron

Transformation of the cyclohexane ring to the cyclopentane fragment of biologically active compounds

• Natalya Akhmetdinova,
• Ilgiz Biktagirov and
• Liliya Kh. Faizullina

Beilstein J. Org. Chem. 2025, 21, 2416–2446, doi:10.3762/bjoc.21.185

• , particularly iridoids. One of the promising methods for ring contraction in the absence of multiple bonds in the six-membered ring of terpenoids was proposed by Grishko et al. [26] (Scheme 6). The key step of 2,3-fragmentation was the cleavage of an enolized C–C bond at a keto group, followed by an

Comparative analysis of complanadine A total syntheses

• Reem Al-Ahmad and
• Mingji Dai

Beilstein J. Org. Chem. 2025, 21, 2334–2344, doi:10.3762/bjoc.21.178

• hemiaminal opening and amine–ketone condensation, iminium ion 65 was produced for the next pyrrole nucleophilic addition to form a strategically important C–C bond and afford 66, which was protected as Boc carbamate in the same pot to give 67 in 96% yield from 64. In this tandem sequence, the nucleophilicity

• of the electron-rich pyrrole group is essential for the key C–C bond formation. In the next step, the pyrrole group was converted to the pyridine group encoded by the natural product. This single-atom skeletal editing step (67 → 68) was achieved using the Ciamician–Dennstedt rearrangement, a reaction

• synthesis, they used an electron-rich and nucleophilic pyrrole as the precursor of the electron-deficient pyridine to enable a tandem sequence involving an intramolecular nucleophilic addition of the pyrrole to an iminium ion to form a key C–C bond. The pyrrole group was then converted to the desired

Pathway economy in cyclization of 1,n-enynes

• Hezhen Han,
• Wenjie Mao,
• Bin Lin,
• Maosheng Cheng,
• Lu Yang and
• Yongxiang Liu

Beilstein J. Org. Chem. 2025, 21, 2260–2282, doi:10.3762/bjoc.21.173

• 60 °C initiated nickel-mediated intramolecular [2 + 2] cycloaddition to form dihydrocyclobuta[c]quinolin-3-one framework 164. Conversely, when the temperature was elevated to 140 °C, thermal ring-expansion of the four-membered intermediate was induced through C–C bond cleavage/reorganization

Thiadiazino-indole, thiadiazino-carbazole and benzothiadiazino-carbazole dioxides: synthesis, physicochemical and early ADME characterization of representatives of new tri-, tetra- and pentacyclic ring systems and their intermediates

• Gyöngyvér Pusztai,
• László Poszávácz,
• Anna Vincze,
• András Marton,
• Ahmed Qasim Abdulhussein,
• Judit Halász,
• András Dancsó,
• Gyula Simig,
• György Tibor Balogh and
• Balázs Volk

Beilstein J. Org. Chem. 2025, 21, 2220–2233, doi:10.3762/bjoc.21.169

• derivatives 10a,b exhibiting an extended aromatic ring system were isolated instead of the expected primarily formed congeners 11a,b, due to in situ oxidation of the C–C bond. Alternatively, when the one-pot method (method B, bismuth nitrate pentahydrate + PPA, MeOH, closed vial, 110 °C) was applied for the

Electrochemical cyclization of alkynes to construct five-membered nitrogen-heterocyclic rings

• Lifen Peng,
• Ting Wang,
• Zhiwen Yuan,
• Bin Li,
• Zilong Tang,
• Xirong Liu,
• Hui Li,
• Guofang Jiang,
• Chunling Zeng,
• Henry N. C. Wong and
• Xiao-Shui Peng

Beilstein J. Org. Chem. 2025, 21, 2173–2201, doi:10.3762/bjoc.21.166

• , A proceeded an intramolecular nucleophilic attack by N and deprotonation to finish 15a. The other possible pathway was radical route, in which PhSe• dimerized to reform 14a or added to C≡C bond in 13a to afford B. The subsequent anodic oxidation of B gave C, which underwent nucleophilic cyclization

• -exo-dig N-radical addition into the C≡C bond to generate the cyclic species C. The radical anion D was then obtained via single electron reduction of C at the cathode. The subsequent protonation of D gave α-aminyl radical E [215][216][217], which was converted into the anion F by further cathodic

C2 to C6 biobased carbonyl platforms for fine chemistry

• Jingjing Jiang,
• Muhammad Noman Haider Tariq,
• Florence Popowycz,
• Yanlong Gu and
• Yves Queneau

Beilstein J. Org. Chem. 2025, 21, 2103–2172, doi:10.3762/bjoc.21.165

• -proline as a catalyst (Scheme 25) [100]. The C–C-bond formation between biomass-based feedstock by aldol condensation reactions of furfural with 1-hydroxyacetone has been reported by Subrahmanyam and co-workers (Scheme 26) [101]. C4 biobased carbonyl platforms Acetoin Acetoin is a very important C4

Bioinspired total syntheses of natural products: a personal adventure

• Zhengyi Qin,
• Yuting Yang,
• Nuran Yan,
• Xinyu Liang,
• Zhiyu Zhang,
• Yaxuan Duan,
• Huilin Li and
• Xuegong She

Beilstein J. Org. Chem. 2025, 21, 2048–2061, doi:10.3762/bjoc.21.160

• propose the biosynthetic pathway, which has not yet been reported in Duh’s isolation report (Scheme 1a). In our proposal, the linear sesquiterpenoid trans-nerolidol (1) with a chiral tertiary alcohol undergoes dihydroxylation to generate triol 2, which further proceeds a C–C bond cleavage to afford

• evidences of chemical transformations. Thus, a bioinspired total synthesis was investigated (Scheme 1b). Synthetically, we did not start from trans-nerolidol (1) to construct a C–C bond cleavage. Instead, a convergent coupling approach was selected to quickly access the aldehyde precursor. Phenyl sulfide 5

• as a single isomer, which further underwent a migratory rearrangement and afforded iboluteine. On the other hand, oxidation of ibogaine with molecular iodine achieved both indole and amine oxidations, delivering lactam 35. Intermediate 35 could be oxidized with H2O2 through C–C bond cleavage to give

Understanding the origin of stereoselectivity in the photochemical denitrogenation of 2,3-diazabicyclo[2.2.1]heptene and its derivatives with non-adiabatic molecular dynamics

• Leticia A. Gomes and
• Steven A. Lopez

Beilstein J. Org. Chem. 2025, 21, 2007–2020, doi:10.3762/bjoc.21.156

• calculations have provided valuable insights into the photochemical stereoselectivities of cyclic azoalkenes. In 1998, Yamamoto and co-workers investigated the reaction paths for α-C–N and β-C–C bond cleavage during the direct and sensitized photolysis of DBH [81]. The minimum energy geometries in S0, S1, T1

• with the experimentally observed preferred product. Notably, all trajectories leading to retained housane passed through a region characterized by dihedral angles exceeding 110°, corresponding to the inverted housane if the C–C bond is formed and to the inverted diradical if it is not. This observation

• with CASSCF (8,9)/ANO-S-VDZP, monitoring C–C-bond formation, H–C–C–C dihedral angle, and relative energy for 1 (b), 3 (c), and 5 (d). The energy is relative to the lowest total energy of each trajectory. The red trajectories return to reactant, the green trajectories form retained housane, the blue

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

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

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

• derivatives 9a–c. We observed a distinct preference for (E)-geometry formation in the resulting C=C bond. Internal alcohol, ester, and acylamide functional groups were found to be compatible with the reaction conditions, whereas for external nucleophiles N- or O-arylation precedes that of the alkyne. In the

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

• a single diastereomer (Table 1, entry 4). To explain this diastereoselectivity, we hypothesize that the C–O bond, which occupies an axial position in the proposed transition state TS-1, could avert an additional hyperconjugative interaction (σ*C-O/π) that renders the reacting C=C bond electron