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

• 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

• . First, the activated palladium(0) catalyst is inserted into the carbon–iodine bond of the 1-bromo-2-iodoarene 2 via oxidative addition. The intermediate Int-2 then undergoes ligand exchange from iodine and phosphine to acetate and quinoline-2-carboxamide to generate intermediate Int-3. Then, through a

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

Site-specific labelling of native peptides and proteins: chemical and enzymatic strategies

• Antonio Angelastro,
• Jonathan Bargh,
• Subhajit Guria,
• Victor Laserna and
• Louis Luk

Beilstein J. Org. Chem. 2026, 22, 857–881, doi:10.3762/bjoc.22.67

• , with applications in ADC development, radiolabelling and ROS/Ca2+ imaging (Scheme 9a) [86][87][88][89][90][91]. Methionine can also be modified via sulfonium conjugates using hypervalent iodine (23, Scheme 9b) [92] or photoredox approaches (24a/b, Scheme 9c) [93]. Histidine has been targeted using

• serine residue into a cysteine analogue. Examples of small molecule reagents. Modifications of a–c) methionine by oxaziridine 22, hypervalent iodine 23, Michael acceptors (24a/b), d) histidine by thiophosphorodichoridate 25, e) aspartic and glutamic acid by diazo-containing compounds 26. Labelling of

Hydrogen production from formic acid catalyzed by NHC–Cu complexes

• Orlando Santoro and
• Catherine S. J. Cazin

Beilstein J. Org. Chem. 2026, 22, 620–627, doi:10.3762/bjoc.22.48

• 3 hours (Table 1, entry 2). Indeed, this complex proved to be three times more efficient than CuI, the best catalyst identified for this transformation in previous studies [44]. By replacing the chloride ligand with iodine, the conversion drastically decreased (Table 1, entry 4). The same effect was

Melifoliox B, a novel phloroglucin derivative isolated from Melicope barbigera (Rutaceae) and synthesis of new oxidation products from melifoliones A and B

• Horst Weber,
• Kim-Thao Tran-Cong,
• Bernhard Mayer,
• Guido J. Reiss,
• Iryna S. Konovalova,
• Marc S. Appelhans,
• Kenneth R. Wood and
• Claus M. Passreiter

Beilstein J. Org. Chem. 2026, 22, 535–546, doi:10.3762/bjoc.22.39

• benzoxocin derivatives 6 and 7. Oxidation of melifoliones 1 and 2 under a great variety of oxidants and conditions failed to give 3 and 4. Iodine-containing oxidants yielded the products 8, 9, and 10. Combined oxidation with hydrogen peroxide and ferricyanide in alkaline solution resulted in an unexpected

• of 1% iodine/potassium iodide in water) was added dropwise while cooling with ice and stirring. After 30 minutes, the suspension was diluted with water (80 mL), acidified with 0.1 N H2SO4 and mixed with aqueous solution of Na2S2O3 (1%) until discoloration. After usual work up, the ethyl acetate

Synthesis and stereochemical analysis of dynamic planar chiral oxa[7]orthocyclophene

• Yukiho Hashimoto,
• Yuuya Kawasaki,
• Kazunobu Igawa and
• Katsuhiko Tomooka

Beilstein J. Org. Chem. 2026, 22, 436–442, doi:10.3762/bjoc.22.30

• -substituted oxacyclophene 1ad We planned to construct the nine-membered cyclic ether skeleton of 1ad in the final step by an intramolecular Williamson etherification of haloalcohol 2 (Scheme 1). The iodine-substituted Z-alkene moiety of 2 was planned to be introduced through a trans-selective hydroiodination

• alkyne 6. Subsequent preparation of the lithium acetylide using n-BuLi, followed by treatment with formaldehyde, afforded propargyl alcohol 3a in 70% yield over three steps. The reaction of 3a with Red-Al generated a vinyl aluminum species, which was then treated with iodine to provide the iodinated Z

• potential for iodine. Retrosynthesis of oxacyclophene 1ad. Synthesis of C6-iodo-substituted oxacyclophene 1ad. Synthesis of derivatives 1ab and 1ac, and ORTEP drawing of 1ac (ellipsoid set at 50% probability level). Epoxidation of (S)-1ab. Supporting Information Supporting Information File 25: Experimental

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

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

• applications One of the earliest demonstrations of the unusual reactivity of small-ring-annelated arenes is found in benzocyclopropene, which undergoes facile dearomatization [29]. For example, upon exposure to iodine and UV-light, it transforms into 1,6-diiodocycloheptatriene, highlighting the pronounced

• metal center with α-pinene and subsequent ligand substitution proceeds with retention of configuration, the corresponding Mo(0) complex undergoes racemization during substitution (Scheme 2A). This obstacle was overcome by a redox-based approach: oxidation of the Mo(0)–α-pinene complex with iodine to 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

Circumventing Mukaiyama oxidation: selective S–O bond formation via sulfenamide–alcohol coupling

• Guoling Huang,
• Huarui Zhu,
• Shuting Zhou,
• Wanlin Zheng,
• Fangpeng Liang,
• Zhibo Zhao,
• Yifei Chen and
• Xunbo Lu

Beilstein J. Org. Chem. 2026, 22, 158–166, doi:10.3762/bjoc.22.9

• transformation of sulfinamides with hypervalent iodine reagents to afford hexavalent sulfonimidates using volatile alcohols as both solvent and nucleophile. While distinct in oxidation state and substrate class, this study offers a valuable precedent for constructing sulfinimidate esters [15][16][17]. More

• PIDA-mediated oxidative esterification of sulfenamides, rely on stoichiometric hypervalent iodine reagents and have not demonstrated broadly efficient reactivity with sterically demanding or chiral alcohols such as ʟ-menthol, where only modest conversion was observed in our hands. Motivated by these

Asymmetric Mannich reaction of aromatic imines with malonates in the presence of multifunctional catalysts

• Kadri Kriis,
• Harry Martõnov,
• Annette Miller,
• Mia Peterson,
• Ivar Järving and
• Tõnis Kanger

Beilstein J. Org. Chem. 2026, 22, 151–157, doi:10.3762/bjoc.22.8

• between the catalyst and the reagents. The chirality of the catalysts is derived from either amino acid or amino alcohols (including cinchona alkaloid derivatives). There are three exceptional structures: catalysts A-H and E-H, which are the hydrogen analogues of the corresponding iodine-containing

• compounds, and catalyst J as a trifluoroacetylated chiral tertiary amine, which lacks iodine. The reaction of imine 1 with dimethyl malonate was selected for the investigation as a model reaction. Based on our previous experience the catalyst screening was carried out in toluene in the presence of 10 mol

• (Table 2, entry 2). Substituting a sterically demanding iodine atom in the phenyl ring with the methyl group (catalyst K-Me) increased the stereoselectivity (Table 2, entry 3, 56% ee). However, the N-methylated catalyst led to a diminished reaction rate and exhibited complete loss of selectivity

Reactivity umpolung of the cycloheptatriene core in hexa(methoxycarbonyl)cycloheptatriene

• Dmitry N. Platonov,
• Alexander Yu. Belyy,
• Rinat F. Salikov,
• Kirill S. Erokhin and
• Yury V. Tomilov

Beilstein J. Org. Chem. 2026, 22, 64–70, doi:10.3762/bjoc.22.2

• dynamic equilibrium or total rearrangement of 5 into 6 upon formation. Thus, halogenation of hexa(methoxycarbonyl)cycloheptatrienyl anion 2 formed from 3 led to different outcomes with chlorine, bromine and iodine (Scheme 1). Chlorination gave exclusively i-substituted symmetric cycloheptatriene 4a in an

• transition states with an adjacent ester group, not to the stability of the main conformer. Conversely, the reactions with halogens and diazonium salts are immediate at room temperature and the α-selectivity, when observed, can be due to the stability of the main conformer. The transition from iodine to

• chlorine is associated with an increase in energy of the lowest unoccupied molecular orbital of halogen molecules and a decrease in their electrophilicity. Therefore, if an electrophilic mechanism takes place, iodine apparently reacts with the main conformer faster than a transition to conformer 2' may

Total synthesis of asperdinones B, C, D, E and terezine D

• Ravi Devarajappa and
• Stephen Hanessian

Beilstein J. Org. Chem. 2025, 21, 2730–2738, doi:10.3762/bjoc.21.210

• amino acid reagent that could be removed under non-acidic conditions after the cross-coupling reaction. To this end, we prepared iodo N-Fmoc-ᴅ-alanyl anthranilamide methyl ester 29 from ᴅ-serine. Treatment of prenylindoles 14–17 with iodine and KOH followed by acetylation afforded the corresponding

Mechanistic insights into hydroxy(tosyloxy)iodobenzene-mediated ditosyloxylation of chalcones: a DFT study

• Jai Parkash,
• Sangeeta Saini,
• Vaishali Saini,
• Omkar Bains and
• Raj Kamal

Beilstein J. Org. Chem. 2025, 21, 2703–2715, doi:10.3762/bjoc.21.208

• -substituents; α,β-unsaturated carbonyl compounds; Introduction Hypervalent iodine compounds exhibit a range of bonding patterns which making these compounds powerful reagents or catalysts for a number of organic transformations [1][2][3][4] – oxidation of alcohols [5], epoxidation of alkenes [6], oxidative

• dearomatization [7], amination [8], oxidative coupling [9], ring contraction [10][11][12], oxidative rearrangement [13][14][15], dihydroxylation of alkenes, arylation [16], oxidation of sulfides [17] and many more. These hypervalent compounds contain iodine in higher oxidation state than its usual −(I) valence

• ) compounds [18][19]. Hypervalent iodine(III) reagents have synthetic importance not only due to their nontoxic nature, but also because of milder reaction conditions, higher atom economy, and multipurpose oxidative characteristics over toxic/expensive heavy metal reagents containing Tl(III) or Pb(IV). Due to

Recent advances in total synthesis of illisimonin A

• Juan Huang and
• Ming Yang

Beilstein J. Org. Chem. 2025, 21, 2571–2583, doi:10.3762/bjoc.21.199

• of 85 with iodine and BnOH enabled the intermolecular iodoetherification to yield ketal 86. A KF-promoted intramolecular alkylation of the cyclopentadiene moiety then delivered compound 87. To introduce the C4 hydroxy group and C1 functional handle for further elaboration, a nitroso-Diels–Alder

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

• (benzil, semipinacol, with the participation of thallium- and iodine-based oxidants, photochemical, Wolff, Meinwald, Wagner–Meerwein and Favorskii) are presented. The review summarizes literature data covering the last 12 years, with some exceptions of earlier works due to the importance of the published

• and Favorskii reaction), using oxidants based on thallium and iodine, with a focus on recent works published in the period from 2014 to 2024. Review 1 Recyclization A common method for converting cyclohexene 1 into cyclopentene 2 is the ozonolytic cleavage of the double bond followed by intramolecular

• (III) and iodine(III), and Wolff rearrangement. 2.1 Benzilic acid and semipinacol-type rearrangements The strategy of ring contraction using the benzilic acid-type rearrangement was used by Zhang et al. [38] for the asymmetric synthesis of 4β-acetoxyprobotryane-9β,15α-diol (52). This compound contains

Conformational effects on iodide binding: a comparative study of flexible and rigid carbazole macrocyclic analogs

• Guang-Wei Zhang,
• Yong Zhang,
• Le Shi,
• Chuang Gao,
• Hong-Yu Li and
• Lei Xue

Beilstein J. Org. Chem. 2025, 21, 2369–2375, doi:10.3762/bjoc.21.181

• towards downfield, with a displacement of 0.6015 ppm to 8.5940 ppm. This phenomenon may be due to the formation of noncovalent bonds between the iodine ions encapsulated inside the macrocyclic and the hydrogen atoms on the macrocyclic framework, which reduces the density of the electron cloud of aromatic

• a/b and c/d both moved slightly to higher field. This indicates that there is a slight difference in the interaction between NH protons and iodine ions of the two structural analogs. Structural analysis showed that since the two single bonds are rotationally restricted, all its accessible

• when interacting with iodine ions, and that flexible PBGs enhance the host–guest complementarity through conformational adjustments, resulting in local conformational fitting changes [25]. To determine the binding ratios and binding constants of the two structural analogs to iodine ions, we designed a

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

• radical initiated intramolecular cascade cyclization of 1,n-enynes to provide structurally diverse heterocycles (Scheme 4) [11]. Solvent selection dictated divergent reaction pathways under I2/TBHP oxidation. When an acetonitrile/water mixed solvent was used, iodine radical addition to the alkyne

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

The application of desymmetric enantioselective reduction of cyclic 1,3-dicarbonyl compounds in the total synthesis of terpenoid and alkaloid natural products

• Dong-Xing Tan and
• Fu-She Han

Beilstein J. Org. Chem. 2025, 21, 2085–2102, doi:10.3762/bjoc.21.164

• reduction of 72, affording the hydroxyketone 74 in 57% yield with 91% ee. Protection of the secondary alcohol in 74 followed by Beckmann rearrangement led to lactam 75. Oxidation state modifications and functional group transformations of 75 afforded ketone 76. Next, the 1,2-addition of 76 with vinyl iodine

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

• 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

• proposed key transformations (Scheme 6). Starting from the diaryl-THF-type precursor 36 with a phenol moiety, oxidation of the phenol with hypervalent iodine reagent PIDA generated the putative oxa-carbenium intermediate 37, which successfully underwent the Friedel–Crafts cyclization to provide

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

• synthetic potential of iodane-mediated carbofunctionalization under copper catalysis. Keywords: arylation reactions; copper-catalysis; iodanes; propargylsilanes; 1,2-silyl shift; Introduction Highly electrophilic hypervalent iodine(III) reagents are considered as arene electrophilic synthons, making them

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

• (37) followed by reduction with Zn/Ba(OH)2 and partial re-oxidation (Scheme 12A) [52]. They can also be obtained from o-halogenated benzyl bromides 40 by lithium–halogen exchange followed by nucleophilic substitution and a second lithium–halogen exchange with iodine (Scheme 12B) or by nickel-catalysed

Convenient alternative synthesis of the Malassezia-derived virulence factor malassezione and related compounds

• Karu Ramesh and
• Stephen L. Bearne

Beilstein J. Org. Chem. 2025, 21, 1730–1736, doi:10.3762/bjoc.21.135

• , ON, Canada). Reactions were monitored using thin-layer chromatography on aluminium-backed silica plates (Sigma-Aldrich) using either UV-light (254 nm), iodine, KMnO4, phosphomolybdic acid, or p-anisaldehyde for visualization. Tetrahydrofuran (THF) was dried and distilled over sodium/benzophenone

Reactions of acryl thioamides with iminoiodinanes as a one-step synthesis of N-sulfonyl-2,3-dihydro-1,2-thiazoles

• Vladimir G. Ilkin,
• Pavel S. Silaichev,
• Valeriy O. Filimonov,
• Tetyana V. Beryozkina,
• Margarita D. Likhacheva,
• Pavel A. Slepukhin,
• Wim Dehaen and
• Vasiliy A. Bakulev

Beilstein J. Org. Chem. 2025, 21, 1397–1403, doi:10.3762/bjoc.21.104

• ]. 2,5-Dihydro-1,2-thiazoles were synthesized by oxidative cyclization of N-arylamides of 3-(alkylamino)prop-2-enethiocarboxylic acids with iodine (Scheme 1А) [16]. 2,3-Dihydro-1,2-thiazoles were first synthesized in 1997 by the reaction of 2,2-dimethyl-N-alkylsulfonyl-N-benzylaminoacetonitrile with