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

• -like linkages (≈9 M−1 s−1; Scheme 1d) [10], whereas 2-formylphenylboronic acid 3 (FPBA) generates thiazolidino boronate with noticeably improved kinetics (103 M−1 s−1; Scheme 1e) [11][12]. Aldehydes can be introduced at protein N-termini through several strategies: oxidation of serine or threonine with

• biological environment [46]. In a related concept, the Chin group reported the genetic incorporation of the unnatural amino acid 2,3-diaminopropionic acid (DAP, 13), a nucleophilic amine that has a relatively low pKa (6–8) and is structurally analogous to serine or cysteine, enabling identification of native

• ], whereas tosylation is one of the few procedures compatible with red blood cells and animal labelling [51]. Alternatively, benzophenone 18, which can be incorporated in the form of an unnatural amino acid, can form a UV-induced diradical for protein modifications (Scheme 7b) [52][53][54][55]. Proteins

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

• be underestimated. For example, cleavage of one of the Au–phenyl bonds in A (Scheme 2) with a strong acid provides access to the gold borane and silane σ-complexes [(C^N–CH)Au(C6F5)(H–X)]+, X = B(O2C2Me4) or SiEt3 (Scheme 3) [32]. In the presence of traces of moisture, the Au(III)+ Lewis acidity may

• chemical reactivity. For example, 8a proved stable to air, water and acetic acid, although stronger acids like trifluoroacetic lead to decomposition due to protolytic cleavage of one of the Au–phenyl bonds [31][32]. The stabilising effect of the N-donor in C^N^C ligands is seen quite generally and leads to

• into gold hydrides by stepwise O-transfer reactions to phosphine (Scheme 6) [55]. Quite a different mechanism for the conversion of Au–OH into Au–H was found by Goldberg and co-workers for the hydrogenolysis of [(P^C^P)AuOH]+, which requires an acid catalyst [56]. A mechanistically similar heterolytic

Unsymmetrical sulfoxides with sterically hindered catechol fragment: synthesis, structure, electrochemical properties, and antiradical activity

• Daria A. Burmistrova,
• Vasiliy A. Fokin,
• Oleg P. Demidov,
• Mikhail A. Kiskin,
• Maxim V. Arsenyev,
• Andrey I. Poddel’sky,
• Nadezhda T. Berberova and
• Ivan V. Smolyaninov

Beilstein J. Org. Chem. 2026, 22, 828–837, doi:10.3762/bjoc.22.65

• the reaction with the 2,2′-diphenyl-1-picrylhydrazyl radical (DPPH) and the 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS+•). In both assays, the lowest IC50 values among the studied catechol sulfoxides were found for compounds bearing isopropyl and tert-butyl substituents

• , the oxidation of catechols is facilitated under alkaline conditions. Therefore, the oxidation of thioethers 1–7 was carried out in the presence of acetic acid (Scheme 1). This approach proved successful for the selective oxidation of the thioether group, and no products arising from oxidation of the

Total synthesis of the capsular polysaccharide repeating unit towards the development of a glycoconjugate vaccine against Klebsiella pneumoniae ST512

• Shuo Zhang,
• Ondřej Daněk and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2026, 22, 821–827, doi:10.3762/bjoc.22.64

• . Key synthetic challenges including the stereoselective construction of the 1,2-cis glycosidic linkage on the galacturonic acid core and the inherently low reactivity of elongated oligosaccharide intermediates were addressed employing orthogonally protected building blocks. The resulting library of

• repeating unit {3)-[α-ʟ-Rhap-(1→4)]-α-ᴅ-GalpA-(1→2)-α-ʟ-Rhap-(1→2)-α-ʟ-Rhap-(1→2)-α-ʟ-Rhap-(1→3)-β-ᴅ-Galp-(1→}n (Figure 1) [13]. The chemical synthesis of this molecule is challenging due to the stereoselective formation of the 1,2-cis glycosidic linkage on the galacturonic acid core. In addition, the

• (NIS) and trifluoromethanesulfonic acid (TfOH) to afford 7 in 86% yield, neighboring participation effect of the levulinoyl (Lev) group at C2 position provided only the β-product. The linker was introduced in anticipation of conjugation to a carrier protein or a glycan microarray surface [31

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

• -platinum module. Mass spectra were recorded in a Waters Xevo LC-QTof-MS with electrospray ionization. The AQ:AcN mixture (50:50, 0.1% formic acid) was used as eluent. X-ray diffraction data were collected on a Bruker AXS SMART APEX diffractometer. Structure solution and refinement were carried out using

Knoevenagel condensation of 4,5- and 1,8-diazafluorenes

• Darya S. Cheshkina,
• Christina S. Becker,
• Alina A. Sonina and
• Maxim S. Kazantsev

Beilstein J. Org. Chem. 2026, 22, 803–812, doi:10.3762/bjoc.22.62

• malononitrile or acetonitrile derivatives [14][19][20]. However, the use of diazafluorenes as the methylene component in condensation reactions remains underexplored. These reactions can be carried out under basic [13][21], acidic [3][5] or Lewis acid catalysis [15][22], but the corresponding literature

• examples are scarce, especially for 1,8-diazafluorene. We have previously reported the condensation of 4,5-diazafluorene (1) with aromatic aldehydes and dialdehydes under ammonium acetate catalysis in acetic acid giving the corresponding products in good yields [5][23]. Remarkably, the only condensation of

• conditions were moderate and the reactivity of aldehydes was insufficient it seemed reasonable to increase their activity by converting them into iminium cations through treatment with ammonium acetate in the presence of acetic acid (Scheme 2). Initially, the Knoevenagel condensation of 1 and 2 was carried

Design, synthesis, and biological evaluation of FXR/ASK1 dual-target modulators

• Xi Zhang,
• Jingyan Wang,
• Ziqiang Zhao,
• Caiyi Wang,
• Zenghui Ye,
• Wei-Yuan Ma,
• Jian-Xing Xu and
• Fengzhi Zhang

Beilstein J. Org. Chem. 2026, 22, 771–781, doi:10.3762/bjoc.22.59

• remain limited. Presently, resmetirom, a THR-β agonist, stands as the sole pharmacotherapy to have received approval, thus underscoring the critical and as yet unmet medical need in this domain [6]. The farnesoid X receptor (FXR), a bile acid-activated nuclear receptor highly expressed in the liver and

• intestine, is a key regulator of genes involved in cholesterol and bile acid homeostasis, hepatic gluconeogenesis, lipogenesis, inflammation, and fibrosis. It has been demonstrated that the substance under discussion also helps to maintain intestinal barrier integrity, to prevent bacterial translocation

• , and to support a balanced gut microbiota [7]. In view of this pleiotropic role, FXR activation has emerged as a well-established pharmacological target for MASH [8]. Consequently, a diverse range of FXR agonists – categorized as bile acid derivatives, non-bile-acid steroidal agonists, non-steroidal

Preparation of 3-(alkylamino)imidazo[1,2-a]pyridine-2-carbaldehydes via Kornblum oxidation and unexpected ring-opening reactions of the corresponding alcohols under oxidative conditions

• Sandile J. Mkhize,
• Memory Zimuwandeyi,
• Manuel A. Fernandes,
• Amanda L. Rousseau and
• Moira L. Bode

Beilstein J. Org. Chem. 2026, 22, 763–770, doi:10.3762/bjoc.22.58

• ]pyridine-2-carbaldehydes is reported. A Groebke–Blackburn–Bienaymé reaction between 2-aminopyridine derivatives, cyclohexyl isocyanide and glyoxylic acid in the presence of methanol and an acid catalyst gave the 2-ester derivatives that were reduced to give the corresponding alcohols. Mild Kornblum

• GBB reaction was performed using a suitably substituted 2-aminopyridine 9a–e, cyclohexyl isocyanide (10) and glyoxylic acid monohydrate (11) in the presence of 0.1 equiv HClO4 (relative to aminopyridine) to afford the imidazo[1,2-a]pyridin-3-amine product 12 unsubstituted at position 2 (Scheme 1

• ), using conditions described by Gladysz et al. [24]. Reaction with glyoxylic acid as the aldehyde component has previously been reported to yield the 2-unsubstituted product as a result of in situ decarboxylation [25]. Unexpectedly, on product isolation we discovered that compounds 13a–d, the methyl

Synthesis and biological evaluation of new brassinosteroid analogs with C-22 benzoate function

• María Núñez,
• Camila Escobar,
• Mario Párraga,
• Mauricio Soto,
• Luis Espinoza-Catalán,
• Katy Díaz and
• Andrés F. Olea

Beilstein J. Org. Chem. 2026, 22, 753–762, doi:10.3762/bjoc.22.57

• , abscisic acid and gibberellin do not cause BES1 accumulation [47], therefore this assay is accurate and complements the biological tests performed above. Thus, in this study, the Western blot analysis was used to detect BES1 in presence of different exogenously applied BR analogs (12, 14 and 17–22). The

• of the signaling process. Structures of natural occurring brassinosteroids. Structures of C-22 benzoate-functionalized brassinosteroid analogs 4–14 and 17–22 prepared from the known precursor 16 [29], analog 16a [29] and structure of starting material 23,24-bisnor-5-cholenic acid 3β-acetate (15

• new BR analogs 17–22, from 23,24-bisnor-5-cholenic acid 3β-acetate (15). Conditions: a) p-R-PhCOCl/CH2Cl2/py, DMAP, rt, 2 h, 96.7%, 78.0%, 91.2%, 95.3%, 95.6%, and 93.6% yields for 23–28, respectively. b) DHQD-CLB, CH3SO2NH2, K2CO3, K3[Fe(CN)6], OsO4, t-BuOH/H2O (1:1 v/v), rt, 36 h, 77.8%, 67.9%, 65.8

Rongalite addition to dienones: diastereoselectivity in cyclic sulfone synthesis; stereochemical rationalization and prospects as a general conjugate nucleophile

• Melina Goga,
• Hao Zong,
• James Franco,
• Jazmine Prana,
• Rudolph Michel,
• Antonia Muro,
• Elana Rubin,
• Janet Brenya,
• Henk Eshuis and
• Magnus W. P. Bebbington

Beilstein J. Org. Chem. 2026, 22, 742–752, doi:10.3762/bjoc.22.56

• high concentration of ≈80% acetic acid (pH ≈3), it seemed plausible that activation of the dienone carbonyl group would occur by hydrogen-bonding, rather than complete proton transfer to the carbonyl oxygen lone pairs [29]. We therefore included explicit solvation with acetic acid in our computational

• 1b. Minimized structure of dienone 7 (calculated using the PBE0 functional [26] and the def2-SVP basis set [27] (see Supporting Information File 1 for full computational details)). Modeling of cyclization transition states (the solvating acetic acid molecules were omitted for clarity, and the

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

• pyrrolizidine alkaloids with diverse biological activity [6][7][8]. An analysis of experimental and review articles showed that (3 + 2) cycloaddition reactions are carried out, in most cases, using two main strategies for obtaining azomethine ylides, depending on the amino acid derivative used: a free amino

• acid or its ester (Scheme 1). In both cases, condensation of amino acids with carbonyl compounds occurs; however, in the first case, decarboxylation occurs with the in situ formation of azomethine ylides, which subsequently undergo cycloaddition to unsaturated substrates. The advantage of the first

• multicomponent one-pot (3 + 2) cycloaddition reactions involving azomethine ylides from isatins and amino acids [21][35]. The main feature of this review is that we have attempted to consider all currently known systems for generating azomethine ylides based on carbonyl compounds and amino acid derivatives (or

Synthesis of depressin, cryptomeridiol and 4-epi-cryptomeridiol enabled by a terpenoid chiral pool-producing platform

• Yao Kong,
• Tao Wang,
• Chen Wang,
• Pengcheng Zhang,
• Yuanning Liu,
• Kaibiao Wang,
• Fen Liu,
• Hongli Jia and
• Zhengren Xu

Beilstein J. Org. Chem. 2026, 22, 683–690, doi:10.3762/bjoc.22.53

• hydroxy group allowed the synthesis of compound 1 from 4 in nine steps. Selective acid-mediated 5,10-transannular cyclization of 5 followed by hydration reaction furnished both products 2 and 3 in two steps. Keywords: chemoenzymatic synthesis; chiral pool; isopentenol utilization pathway; terpene

• condensation of dimethylallyl pyrophosphate (DMAPP) with different numbers of isopentenyl pyrophosphate (IPP) [6]. Two naturally existing pathways, i.e., the methylerythritol phosphate (MEP) pathway and mevalonic acid (MVA) pathway, as well as artificially designed pathways, such as the isopentenol utilization

• pathway, have been adopted to provide the two key five-carbon building blocks DMAPP and IPP. With the recent advancement in the field of synthetic biology, more chiral terpenes (e.g., guaia-6,10(14)-diene [7][8], drimenol [9][10], and ent-atiserenoic acid [11] as shown in Figure 1b) became easily

Using generative AI to transform peptide hits into small molecule leads

• Joshua Mills and
• Yu Heng Lau

Beilstein J. Org. Chem. 2026, 22, 672–679, doi:10.3762/bjoc.22.51

• fails to yield hits [9]. While the term peptidomimetics has been used to describe a variety of molecular classes, including modified peptides and molecular scaffolds for display of amino acid side-chains, this Perspective focuses on non-peptidic small molecules with the appropriate shape and

• translation (also known as RaPID, random non-standard peptides integrated discovery [4]). Key interactions that comprise the pharmacophores were experimentally determined by alanine scanning and other amino acid substitutions to explore SAR, coupled with analysis of co-crystal structures obtained for the

• bound complexes, including computational analysis of the amino acid interactions (SiteMap [16]) and hydration in the binding pocket (grid inhomogeneous solvation theory [17] in AmberTools [18]). The pharmacophores were then used as the basis for virtual screening with docking (Glide [19][20]) to obtain

Photoorganocatalytic trifluoromethylation of (het)arenes in green conditions

• Egor N. Boronin,
• Svetlana E. Kaurkina,
• Milena M. Svetlakova,
• Anton S. Bolshakov,
• Maxim V. Arsenyev,
• Vasilii F. Otvagin,
• Alexey Yu. Fedorov,
• Timothy Noël and
• Alexander V. Nyuchev

Beilstein J. Org. Chem. 2026, 22, 662–671, doi:10.3762/bjoc.22.50

• ) under blue-light irradiation in acetonitrile (Scheme 1d) [17]. Also, photoelectrochemical trifluoromethylation procedures using trifluoroacetic acid or its salt were published recently [18][19]. Inspired by these methodologies, we sought to combine their advantages to develop a metal- and base-free

• originally reported by Bazyar and Hosseini-Sarvari [20]. A comparison of the atom efficiencies of various CF3 sources clearly indicates that trifluoroacetic acid (TFA) is the most atom-efficient and, moreover, the least expensive CF3 source (Table 1). Although iodotrifluoromethane, triflyl chloride, and the

• Langlois and Ruppert–Prakash reagents formally exhibit higher atom efficiencies than trifluoroacetic anhydride (TFAA), they are significantly costlier and challenging to prepare. In contrast, trifluoroacetic acid generated as a by-product can be readily converted back into TFAA, especially in large-scale

Advantages of PROTACs in achieving selective degradation of homologous protein families

• Luxi Yang,
• Xinfei Mao,
• Jingyi Zhang,
• Jing Shu,
• Wenhai Huang,
• Xiaowu Dong,
• Yinqiao Chen and
• Mingfei Wu

Beilstein J. Org. Chem. 2026, 22, 628–661, doi:10.3762/bjoc.22.49

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

• 289, 9000 Gent, Belgium 10.3762/bjoc.22.48 Abstract The first NHC–Cu-catalyzed decomposition of formic acid (FA) is reported. In the presence of PhSiH3, only hydrogen is generated while CO2 is captured by a silane species. The decomposition of an equimolar mixture of FA and an amine provided an

• equimolar mixture of H2 and CO2. The efficiency of the catalysis showed to be strongly dependent on the nature of the amine. Keywords: copper N-heterocyclic carbene; formic acid dehydrogenation; hydrogen storage; metal hydride; silanes; Introduction The discovery and utilization of alternative and

• realization of a hydrogen economy [6][7]. Amongst the various H2 sources investigated to date, formic acid (HCO2H, FA) is considered one of the most promising. Indeed, FA contains 4.4% H2, is inexpensive and is liquid under ambient conditions, thus easy to handle and transport. In addition, the CO2 generated

Towards the targeted protein degradation of CK2: design and synthesis of CAM4066-based PROTACs

• Sophie Day-Riley,
• Sona Krajcovicova,
• Aryaman Raj Sokhal,
• Jan L. Venne,
• Paul Brear,
• Marko Hyvönen,
• Benjamin C. Whitehurst,
• Jason S. Carroll and
• David R. Spring

Beilstein J. Org. Chem. 2026, 22, 611–619, doi:10.3762/bjoc.22.47

• undesired alkylation of the base and significantly improved the isolated yield up to 84%. Introduction of an acetic acid handle was then achieved via alkylation with bromoacetic acid under DIPEA mediation, giving intermediate 6, which served as the common attachment point for linkers 7–10 (for full

• corresponding triflate using triflic anhydride, followed by Suzuki–Miyaura cross-coupling with phenylboronic acid to give 16 in 59% yield (Scheme 1). Boc removal from intermediates 11–14 enabled attachment of the αD binder aldehyde 16 via reductive amination. Interestingly, NaBH(OAc)3 had performed well in the

• yield acid S13. Isothermal titration calorimetry (ITC) revealed that S13 bound CK2α with a dissociation constant (Kd = 600 nM) comparable to that of CAM4066 (350 nM; Figure 1C). This indicated that the exit vector modification and linker installation were well tolerated. Co-crystallisation of S13 with

Regioselective approach to 5-arylsulfonylisoxazoles and their antimicrobial activity

• Artem S. Sazonov,
• Dmitry A. Vasilenko,
• Denis V. Porfiriev,
• Yuri K. Grishin,
• Rimma A. Gazzaeva,
• Alisa P. Chernyshova,
• Maxim A. Kryakvin,
• Anna A. Baranova,
• Vera A. Alferova and
• Elena B. Averina

Beilstein J. Org. Chem. 2026, 22, 592–602, doi:10.3762/bjoc.22.45

• nucleophilic aromatic substitution with thiophenols followed by oxidation with m-chloroperbenzoic acid (mCPBA). The scope of the reactions was explored, demonstrating high yields across a variety of functional groups and substituents. Optimized conditions enabled selective oxidation of thioaryl groups to

Molecular tweezer–peptide conjugates disrupt the protein–protein interaction between survivin and histone H3 essential in mitosis

• Catherine Gsell,
• Philipp Rebmann,
• Karina Opara,
• Christine Beuck,
• Peter Bayer,
• David Bier,
• Ingrid R. Vetter and
• Thomas Schrader

Beilstein J. Org. Chem. 2026, 22, 557–567, doi:10.3762/bjoc.22.41

• ) calcium ion with amino acid side chains – that might also be in part be responsible for the lack of tweezer binding to Lys-121 – but also represents a new binding mode for the tweezer moiety. The (hydrated) Ca2+ ion is apparently too large to enter the cavity of the tweezer ring, in contrast to larger Cs

• 2b on K-121 leaves more room for stabilizing packing effects. Lys-122 is also located in the vicinity of the H3-T3ph binding site; although it forms a protein contact with Asn-118, there is plenty of room around it in the crystal structure (Figure 4). However, to target this amino acid, the linker

Experimental and DFT studies on the regioselective methanolysis of 5-azido-9-oxabicyclo[6.1.0]nonan-4-yl 4-nitrobenzoate isomers

• İlknur Polat,
• Selçuk Eşsiz and
• Emine Salamci

Beilstein J. Org. Chem. 2026, 22, 547–556, doi:10.3762/bjoc.22.40

• , pharmaceutical compounds, and chiral ligands. The Lewis acid-catalyzed ring-opening reaction of cyclohexene oxide by MeZH (Z = O, S, and NH) is well known [20]. However, studies on large-sized bicyclic epoxides remain relatively limited in the published literature. In our previous study, we performed the ring

• each elementary reaction step along these routes were computed. The acid-mediated ring-opening reaction in the isomeric epoxides 9, initiated by protonation, can follow two possible pathways – either along the intermediate 12 or along the intermediate 15. There is a possibility of two products being

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

• synthesis of 4 and its possible isomer 3, the required compounds 1 and 2 were synthesized as a mixture of the isomers starting from chromene 5, briefly heated in a closed microwave apparatus with catalytic amounts of acetic acid. Forced heating of 5 in acetic acid or use of stronger acids lead to the

• made to cyclize 5 into melifolione B (2) with the following results (Scheme 1) Heating of 5 in DMF at 100 °C yielded melifolione A (1) with traces of melifolione B (2). When 5 was heated in acetic acid at 80 °C, only benzoxocin 6 could be isolated. Reaction of 5 with catalytic amounts of p

• -toluenesulfonic acid at 80 °C in toluene afforded benzoxocin (7) as the only product. On the other hand, melifolione A (1) was completely decomposed under these conditions. Irradiation of 5 in methanol with UV-light (300 nm) for 3 days at room temperature gave melifolione B (2) with traces of melifolione A (1

Modern synthetic pathways towards eribulin and its subunits

• Sebastian Dominik Graf

Beilstein J. Org. Chem. 2026, 22, 495–526, doi:10.3762/bjoc.22.37

• modern approaches towards the key fragments and total synthetic strategies for 1 in recent years. Review In 2016, Konda and co-workers reported two approaches for the assembly of the tetrasubstituted tetrahydrofuran unit of 1 (Scheme 2 and Scheme 3) [72]. For the first path, (S,S)-tartaric acid (13) was

• used as a starting material and was protected as acetonide within the first step to enable the reduction of both acid moieties towards 14 (Scheme 2). Bn-protection, followed by oxidation and olefination yielded sulfone 15, which was vinylated leading to 16 as a single diastereomer. Further Grubbs

• the secondary alcohol unit of 71 was changed via oxidation and stereospecific reduction, then 1,4-reduction of the enone and treatment with camphorsulfonic acid led to fully cyclized intermediate 72 as a single isomer. During this process the acetate groups were cleaved off and had to be reinstalled

Synthesis and uranyl(VI) extraction performance of a calix[4]pyrrole–tetrahydroxamic acid receptor

• Sara Karnib,
• Rana Baydoun,
• Wissam Zaidan,
• Nancy AlHaddad,
• Omar El Samad,
• Bilal Nsouli,
• Francine Cazier-Dennin and
• Pierre-Edouard Danjou

Beilstein J. Org. Chem. 2026, 22, 486–494, doi:10.3762/bjoc.22.36

• extractants. Here, we report the design and synthesis of PCP HA, a phenoxycalix[4]pyrrole scaffold functionalized with four hydroxamic acid (HA) groups, and evaluate its uranium(VI) extraction potential. PCP HA was synthesized from its ester precursor (PCP E) via hydroxyaminolysis using KOH, achieving a 95

• , removing up to 95% of uranyl(VI) from aqueous solutions (1 mM) at acidic pH, likely due to the strong coordination provided by its hydroxamic acid groups. Further studies revealed that the extraction efficiency also depends on the ligand-to-metal molar ratio. These findings establish PCP HA as a promising

• supramolecular material for the removal of uranyl from aqueous media. Keywords: gamma spectroscopy; hydroxamic acid; phenoxycalix[4]pyrrole; solid–liquid extraction; uranyl(VI) extraction; Introduction Over the past few decades, supramolecular chemistry has advanced intensively establishing itself as a central

Synthesis of a HDAC inhibitor–nanogold probe for cryo-EM visualization in class I HDAC co-repressor complexes

• Wiktoria A. Pytel,
• John W. R. Schwabe and
• James T. Hodgkinson

Beilstein J. Org. Chem. 2026, 22, 480–485, doi:10.3762/bjoc.22.35

• routes (Scheme 1) [14][15][18]. Intermediates 5–7 were prepared in a manner analogous to Smalley et al. [14]. The first step in the linker synthesis for Au–(CI-994) involved a monoprotection of nonanedioic acid with a benzyl group to give 5 which proceeded in moderate yield due to the formation of the

• dibenzylated by-product. Compound 5 was then coupled to the CI-994 intermediate 3 via HATU-mediated amide bond formation to produce 6 in good yield. Removal of the benzyl protecting group was performed by catalytic hydrogenation and acid 7 was obtained in near quantitative yield. Intermediate 7 was converted

Recent advances in the stereoselective synthesis of distal biaxially chiral molecules

• Fanxing Zhou,
• Chen Zhang,
• Lingyu Sun,
• Yiyun Fang,
• Siming Zheng,
• Lina Hu,
• Mengyang Shen,
• Zhen Zhao,
• Wei Xu,
• Yunqiang Sun and
• Zi-Qiang Rong

Beilstein J. Org. Chem. 2026, 22, 461–479, doi:10.3762/bjoc.22.34

• carboxylic acid derivatives (Scheme 2b) [43]. They revealed that ortho-alkoxy substitution on the benzene-derived alkyne markedly enhanced both reactivity and enantioselectivity, while incorporation of a naphthyl substituent into the diyne enabled access to remote biaxially chiral molecules. Subsequent

• studies have further broadened the synthetic toolbox for remote biaxial chirality. Du and co-workers designed a series of chiral phosphoric acid catalysts derived from protected axially chiral diols 13, employing a boronic acid-mediated coupling strategy to construct remote biaxially chiral phosphoric

• polarized BOP bis(2-oxo-3-oxazolidinyl)phosphonic substituent and the extended π system in the arylboronic acid coupling partner. In 2018, Razler and co-workers described an approach for the synthesis of an architecturally complex API 57 having multiple chiral axes (Scheme 14) [53]. Their strategy relied on