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

• product, we used density functional theory (DFT) and conformational search techniques based on tight-binding methods to find the energetically minimized structure of 7 (see Supporting Information File 1 for details on all computations). The lowest energy structure is depicted in Figure 3. It shows a

• structure somewhat rotated out of planarity (dihedral angles between aromatic C–C and vinylic CH are 34°). This presumably still allows for some conjugative stabilization from the aromatic rings to the enone π-systems and reduces eclipsing interactions between the ortho-methyl groups and the vinylic H

• calculated transition state structure TS-12a shows a flattened half-chair conformer, which has the aryl rings in pseudo-equatorial positions. TS-12b adopts a different shape, closer to a flattened chair which again allows both aryl groups to be equatorial. There has been much debate in the literature

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

• efficient synthesis of a series of polysubstituted enantioenriched pyrrolidine derivatives 48 possessing a spiroindene molecular structure (Scheme 22) [59]. Based on the results of DFT calculations, it was suggested that the [6 + 3] cycloaddition product for benzofulvene 47 loses aromatic stability and

• configuration and the structure of the transition state [88]. In [1], we developed an efficient protocol for the diastereo- and regioselective synthesis of spiro[cyclopropa[a]pyrrolizine-2,2'-indenes] 128–131 using 1,3-dipolar cycloaddition reactions of stable azomethine ylide 123, obtained in situ by

• constructing the structure of spiro[indoline-3,2'-pyrrole]. In a study by Zhao and co-workers, asymmetric 1,3-dipolar cycloaddition of azomethine ylides derived from isatin and benzylamines to maleimides was catalyzed by Cinchona alkaloid-based squaramide L24 (Scheme 49) [99]. The cycloaddition proceeded

Anti-invasive and cytotoxic evaluation of a (+)-pinoresinol-based semisynthetic library against glioblastoma

• Chen Zhang,
• Kah Yean Lum,
• Jonathan M. White,
• Paul I. Forster,
• Nicholas Booth,
• Sunita A. Ramesh and
• Rohan A. Davis

Beilstein J. Org. Chem. 2026, 22, 691–704, doi:10.3762/bjoc.22.54

• analysis. During our comparison of spectroscopic and chiro-optical data for (+)-salicifoliol (1) with reported literature values [16], we noted that an earlier paper [15] reporting the chemical structure of 1 had misdrawn the stereochemistry. The stereochemical assignment for (+)-salicifoliol (1) has been

• and were also fully characterized following NMR, UV–vis, [α]D, ECD, and ESIMS data analyses. An example of our structure elucidation studies is described below, which focuses on the brominated pinoresinol enantiomer (+)-5,5'-dibromopinoresinol (5). HRESIMS data revealed an ion at m/z 536.9519 [M + Na

• planar structure assignment for 5. Moreover, the relative configuration of the semisynthetic derivative 5 was assigned following ROESY data analysis. Following the slow evaporation of a methanolic solution of (+)-eudesmin (3), suitable crystals were obtained for X-ray crystallographic studies (Figure 4

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

• ). Depressin (1) was isolated from the soft coral Simularia depressa collected from Hainan Province of China [13]. Its structure contains the typical bicyclo[12.1.0]pentadecane casbane diterpenoid skeleton with a cis-disubstituted cyclopropane unit, and a keto group at C5, which is the most frequently oxidized

• ). Supporting Information Supporting Information File 5: Materials, synthetic methods and copies of NMR spectra for all compounds. Supporting Information File 6: X-ray crystal structure of 16. Funding We are grateful to the National Natural Science Foundation of China (No. 82574274) for the financial support.

Harnessing light energy with molecules

• Grace G. D. Han,
• Mogens Brøndsted Nielsen and
• Hermann A. Wegner

Beilstein J. Org. Chem. 2026, 22, 680–682, doi:10.3762/bjoc.22.52

• structure by a heteroatom (oxygen or nitrogen) in donor–acceptor, push–pull NBD derivatives are reported. In a computational study, Pawar and co-workers [7] further expanded the NBD structure by elongating the unsaturated bridge with different heteroatoms or functional groups. Azobenzenes, interconverting

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

• potential for new AI-based tools to expedite the structure-based transformation of peptide hits into small molecule leads. In this Perspective, we highlight how AI-enabled prediction and design tools can potentially span the entire workflow from peptide to small molecule: target protein structure prediction

• drugs derived from native peptide substrates. A classic example is the ACE inhibitor captopril, an analogue of a snake venom peptide, the development of which has been cited as an early success story for structure-based rational drug design [12][13]. Despite the long history, there is still no

• experimental co-crystal structure of the bound complex, standard medicinal chemistry principles are used to probe structure–activity relationships (SAR) and determine the key interactions that form a minimal pharmacophore, supported by classical physics-based molecular modelling methods such as molecular

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

• ; PROTAC; protein–protein interaction; selectivity; ubiquitination; Introduction The cell is the fundamental unit of structure and function in the human body [1][2]. More than 20,000 proteins act in concert to regulate the entire cellular life process [1]. To date, dysregulated protein function has been

• imperative to minimize the degradation of non-targeted proteins. While conventional inhibitors often exhibit lacking selectivity towards proteins with high sequence similarity, PROTACs leverage their heterobifunctional structure to achieve exquisite selectivity [24][27]. This is accomplished by fine-tuning

• -containing compound 33 can almost completely degrade p38δ, but in the degradation of p38α, it is restricted. In contrast, the structure of compound 30 having additional carbon atoms added to the linker, resulted in less than 50% degradation of both subtypes at the maximum efficiency. It can be seen that the

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

• broader kinome perturbation. The first design objective was therefore to identify a suitable exit vector for linker attachment that would allow productive E3-ligase recruitment without compromising the established binding geometry of CAM4066. Inspection of the co-crystal structure of 1 bound to CK2α

• geometry, and E3 ligase selection. Conclusion In summary, we have developed a modular synthetic platform for the construction of CK2-targeting degraders 23–26, 28, and 29 based on the selective bivalent inhibitor CAM4066. Structure-guided design enabled identification of a solvent-accessible exit vector

• degraders and lays the groundwork for future optimisation toward achieving effective and selective CK2 degradation. Design strategy and validation. A) Structure of CAM4066 (1) that served as a model design for the development of CK2 targeted PROTACs with a general structure 2. Crystal structures showcased

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

• solvation model. We then conduct re-optimization in ORCA (v.5.0.4) [17][18], using the composite electronic structure method r2SCAN-3c [19] and the conductor-like polarizable continuum model (CPCM) [20] as the implicit solvation model. r2SCAN-3c is chosen as the optimal functional based on a benchmark study

• that evaluates the accuracy of different levels of theory, ranging from semiempirical methods (xTB [16]), composite electronic structure methods (r2SCAN-3c [19]) to DFT methods (M06-2X[21], CAM-B3LYP [22][23]). All methods are evaluated either as single-point calculations or optimization and frequency

• random conformer, we produce 20 random conformers from a SMILES string and optimise the structure with molecular mechanics force fields (MMFF) [33] using RDKit [12]. The CM5 atomic charges of the lowest-energy conformer are then used to generate atomic descriptors based on sorting the CM5 charges for a

Design and synthesis of an erdafitinib-based selective FGFR2 degrader

• Yumeng Jin,
• Shidong Wang,
• Sihan Pan,
• Shuqi Huang,
• Weichen Zhou,
• Xiaohao Huang,
• Lei Zheng and
• Lingfeng Chen

Beilstein J. Org. Chem. 2026, 22, 583–591, doi:10.3762/bjoc.22.44

• proper ligand binding, thus promoting uncontrolled cell proliferation [11][14]. Mutations in FGFR2 may alter its structure, enabling it to bypass normal regulatory mechanisms and activate downstream oncogenic pathways independently of external stimuli, which also contributes to tumor development. Gene

• purpose the clinically validated inhibitor erdafitinib as a POI binder that selectively targets FGFR2. Based on the analysis of the co-crystal structure of erdafitinib bound to the FGFR kinase domain (PDB: 5EW8, https://doi.org/10.2210/pdb5EW8/pdb) [30], we observed that the aliphatic amine group is

• development of novel therapeutic strategies against FGFR2-driven tumors. Chemical structures of severel FGFR inhibitors and degraders. Rationale of the FGFR2 degrader design. a) Structure of the erdafitinib–FGFR complex. The figure was generated by PyMOL (PDB: 5EW8, https://doi.org/10.2210/pdb5EW8/pdb) [30

Continuous-flow carbonyl hydrogenation under subatmospheric to atmospheric hydrogen pressure enabled by robust heterogeneous Pt–Fe catalysts

• Hiroyuki Miyamura,
• Ryosuke Kajiyama,
• Shun-ya Onozawa,
• Yoshihiro Kon and
• Shū Kobayashi

Beilstein J. Org. Chem. 2026, 22, 575–582, doi:10.3762/bjoc.22.43

• ][10][11][12]. In this context, advanced technologies represented by the precise control of the bimetallic structure of a heterogeneous catalyst, mechanochemical hydrogenation, and continuous-flow methods using packed-bed reactors greatly contributed to advancing this transformation [9][11][12][13

• Al2O3 to form a stabilized composite support [32]. A plausible scenario for the formation of the bimetallic structure of Pt‒Fe nanoparticles during the catalyst preparation would be the same as that for the formation of Pt–Ni bimetallic structures, and it involves the following steps [33]. Na2PtCl6∙6H2O

• grown from the existing Pt nanoparticles. Therefore, a bimetallic structure of Pt and Fe is generated, and both elements are observed with similar distributions by STEM‒EDS mapping analysis (Figure S1, Supporting Information File 1). The Pt nanoparticles are isolated by the surrounding Fe species, which

Kinetic resolution of racemic planar-chiral vinylcymantrenes by molybdenum-catalyzed asymmetric metathesis dimerization

• Haruna Imazu,
• Hitoshi Izu,
• Yasuhiro Ohki and
• Masamichi Ogasawara

Beilstein J. Org. Chem. 2026, 22, 568–574, doi:10.3762/bjoc.22.42

• revealed that the unit cell contains two independent molecules, having slightly different conformations, and the structure of one of the two crystallographically independent molecules is shown in Figure 1 with the selected bond lengths and angles (see Supporting Information File 1 and Supporting

• Information File 2 for details). The two cyclopentadienides and the olefinic moiety are nearly coplanar with a C2–C13–C14–C8 torsion angle of 175.4(2)°. The Flack parameter for this structure was determined to be –0.010(4), and the absolute configuration of (–)-2b was unambiguously determined to be (S,S) (see

• ], reveals that the molybdenum-catalyzed asymmetric metathesis reactions are powerful tools to control planar chirality in various transition-metal complexes. ORTEP drawing of the X-ray structure of (S,S)-(–)-2b with atom numbering (thermal ellipsoids set at the 30% probability level). Selected bond lengths

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

• . demonstrated that survivin contributes most of the binding energy to this critical complex with histone H3 [8]. In 2011, a crystal structure was solved depicting structural details of the H3 N-terminus (1–21) bound by survivin’s BIR domain (Figure 2). Only the first six residues (ARpTKQT) show electron density

• in solution, as shown by the fluorescence polarization measurements where the K121A mutation has drastically reduced affinity. In the new crystal structure, the apolar pyrrolidine of Pro-26 occupies half of the tweezer cavity, while from the opposite side, a density that most likely corresponds to a

• + ions that were surprisingly observed in the center of the aromatic ring structure, perhaps due to their weaker binding of the hydrate shell. However, this early crystal structure was obtained with the diacetoxytweezer in organic solution [18]. Interestingly, a similar unexpected inclusion of a

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

• epoxide ring and acetylation resulted in the formation of two corresponding chloro-acetate isomers. The structure of one of the chloro-acetate isomers was determined via crystallographic analysis and the other by 1D and 2D NMR spectroscopy. DFT computations confirm the regioselectivity of the methanolysis

• corresponding acetates 10 and 11 using AcCl in CH2Cl2. The reaction mixture was chromatographed on a silica gel column with n-hexane/ethyl acetate 85:15 as eluent to give pure acetates 10 and 11 in 57% and 35% yields, respectively. The structure of compound 10 was unambiguously determined by single crystal X

• intermediate 12 with the anti-face of the benzoate to give compound 14. Similarly, the chloride anion attacks by SN2-type the epoxide ring of intermediate 15 to give the sole product 16. The structure of acetate 11 was investigated using 1D (1H and 13C) and 2D (COSY, NOESY, NOE-diff, and HMQC) NMR

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

• to new acetophenones and 2H-chromenes, the dichlormethane extract from leaves of Melicope barbigera A. Gray (Rutaceae) afforded a mixture of the isomeric melifoliones A (1) and B (2) as well as an oxidation product of 2, whose structure was elucidated as the para-quinol 4. For an independent

• formerly found in Melicope latifolia (syn. Euodia latifolia [4]. We now report on the identification and structure elucidation of a new natural compound 4 in the dichloromethane extract of leaves of Melicope barbigera, which was characterized as an oxidation product of melifolione B (2) by means of high

• resolution electrospray ionization mass spectrometry (HRESIMS) and NMR spectra. However, the isomeric compound 3 could not be detected in the extract (Figure 1). Since 4 could be an artefact, built by oxidation of 2 during working up of the extract, and to finally confirm the structure, the isomeric

Get a better glimpse on sequential photoreactions of trisnorbornadienes with ¹⁹F NMR spectroscopy

• Julian Felix Maria Hebborn,
• Ben Eric Merten,
• Thomas Paululat and
• Heiko Ihmels

Beilstein J. Org. Chem. 2026, 22, 527–534, doi:10.3762/bjoc.22.38

• exemplarily with a trifluorinated trisnorbornadienylbenzene that 19F NMR spectroscopy may be applied as a useful complementary method for the investigation of sequential photoreactions. The trisnorbornadiene core structure was used as it figures as promising scaffold for molecular solar thermal (MOST) energy

• lines, 1H NMR spectroscopy is a very useful method to follow the photoreaction, ideally upon direct irradiation in the NMR probehead (in situ NMR), because it potentially enables accurate structure elucidation. But even though this method may enable the accurate monitoring of a stepwise photochromic

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

• described the total synthesis of the marine natural product [19] and shortly thereafter, also its simplified structure, 1, was assembled and showed similar anticancer behavior [19][21]. Since 2010, the mesylate salt of 1 is approved by the U.S. Food and Drug Administration (FDA) for the treatment of

• tissue sarcomas. Moreover, ongoing studies aim to optimize combination therapies involving 1 with targeted agents, immunotherapies, and other chemotherapeutics to enhance its efficacy and reduce adverse effects [51][52][53][54][55][56][57][58][59][60][61][62][63][64][65]. Given the challenging structure

• epoxide 98. Deprotection of the alcohol motif of 98 enabled the cyclization towards tetrahydropyran 99. Next, 99 underwent an esterification with acrylic acid, was cyclized via Grubbs metathesis and the remaining double bond was hydrogenated leading to bicyclic core structure of 101. Notably, during the

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

• % yield. Its structure was confirmed by 1H NMR, 13C NMR, and HRMS. The uranium(VI) extraction efficiency of PCP HA was evaluated by solid–liquid extraction experiments, using uranyl acetate as the uranium source, with measurements performed by gamma spectroscopy. PCP HA demonstrated good performance

• amount of solid KCN in aqueous hydroxylamine has been reported for the solution-phase hydroxylamination of esters previously described by Ho et al. [52]. This study demonstrated that the extent of ester conversion and the formation of carboxylic acid by-products vary markedly with the structure of the

• %). The structure of PCP HA was fully characterized by 1H NMR and 13C NMR (DMSO-d6) as well as by HRMS (ESI+) (Figures S3–S6, and S9 in Supporting Information File 1). In the 1H NMR spectrum, two sets of singlets at 4.41 and 4.76 ppm (CH2) were attributed to the –O=C–CH2–O– groups of the E/Z isomers of

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

• . Examples of structure elucidation utilizing cryo-EM for class I HDAC complexes include the MiDAC and SIN3 complexes [8][9]. However, despite these advances, obtaining high-resolution structures of flexible multiprotein complexes can still prove challenging. One such example of this includes the tripartite

• CoREST complex that encompasses HDAC1/2, the co-repressor of REST (CoREST) and the lysine-specific demethylase 1 (LSD1). Cryo-EM and small angle X-ray scattering revealed that the CoREST complex exists as a bi-lobed structure [10]. Enzyme kinetics studies showed that HDAC1 and LSD1 do not act

• , like other benzamide HDAC inhibitors, exhibits slow on/off binding kinetics, hence once bound to the HDAC within the complex it should not readily dissociate [16]. A crystal structure of HDAC2 bound to an analogue of CI-994 (PDB: 4LY1) revealed that the acetamide moiety is oriented outside the HDAC

Structural reassignment of compound 968, an allosteric glutaminase inhibitor

• Lindsey A. Albertelli,
• Sainabou Jallow,
• Chun Li and
• Scott M. Ulrich

Beilstein J. Org. Chem. 2026, 22, 455–460, doi:10.3762/bjoc.22.33

• anticancer drug target. Compound 968 is a glutaminase inhibitor that is widely used to probe cancer cells’ dependence on glutaminase activity. Here, we show by NMR spectroscopy and X-ray crystallography that the reported benzo[c]phenanthridine structure of compound 968 is incorrect; its true structure is the

• not produce benzo[c]phenanthridine 1 as product, but instead yields the isomeric benzo[c]acridine 2 (Figure 2). Upon learning of these results, we became concerned that the accepted structure of compound 968 is incorrect. We then sought to determine whether compound 968 is a benzo[c]phenanthridine 1

• or benzo[c]acridine 2. Clarifying this issue would benefit the community of cancer biologists who use compound 968, enable medicinal chemistry around the compound 968 scaffold, as well as correct the structure displayed by vendors of this compound. Results and Discussion To determine whether the

A facile and practical method for the synthesis of trans-(±)-taxifolin and its derivatives via Darzens reaction

• Bo Peng,
• Panpan Yang,
• Maaz Khan,
• Xiaotong Lin,
• Jiang Wu,
• Peng Fu and
• Qingqing Wu

Beilstein J. Org. Chem. 2026, 22, 443–450, doi:10.3762/bjoc.22.31

• reaction being the key step. It is highlighted by simple operation, high yields, and most importantly, by the avoidance of the use of peroxides (such as H2O2), which enables the safe scale-up and synthesis of taxifolin derivatives with oxidant-sensitive functionalities. The structure of the highly

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

• X-ray crystallographic analysis was performed (CCDC 2513894). The solid-state structure of 1ac shows that the phenyl group on the E-alkene is directed antiparallel to the fused benzene ring. The dihedral angle of the alkene moiety (∠C4–C5–C6–C7) of 1ac is 146.4°, which is distorted by 33.6° from an

Synthesis and anti-cancer activity of naphthalimide–organylselanyl conjugates

• Rajkumar Ravi and
• Selvakumar Karuthapandi

Beilstein J. Org. Chem. 2026, 22, 416–435, doi:10.3762/bjoc.22.29

• Rajkumar Ravi Selvakumar Karuthapandi Department of Chemistry, School of Advanced Sciences, VIT-AP University, Amaravati-522237, Andhra Pradesh, India 10.3762/bjoc.22.29 Abstract The structure-based approach remains a valuable tool for rapid and high-throughput drug discovery and lead

• optimisation. In this study, we report the in-silico modelling and anticancer activity of two 1,8-napthalimide (NAP) derivatives containing organyl selanyl groups. The organylselanyl function n-octylselanyl (n-OctSe) or phenylselanyl (PhSe) was introduced at the 6-position of a naphthalimide structure having a

• binding components, including electron-deficient, electron-rich, and hydrophobic regions, which offer greater affinities towards biological targets. Structures of these compounds were confirmed through various spectroscopic analyses. The structure of compound 7 was confirmed using single-crystal XRD

Cone p-aminocalix[4]arenes enriched with ‘clickable’ alkyne or azide functionalities

• Ilia Korniltsev,
• Vasily Bazhenov,
• Alexander Gorbunov,
• Dmitry Cheshkov,
• Stanislav Bezzubov,
• Vladimir Kovalev and
• Ivan Vatsouro

Beilstein J. Org. Chem. 2026, 22, 399–415, doi:10.3762/bjoc.22.28

• units of the macrocycles. There was no doubt in establishing the structure of the trinitrated calix[4]arene 14, as its NMR spectra contained a single set of resonances from propyl groups and two sets of those from the TBS-protected propargyl groups, which indicated clearly the symmetry plane passing

• calixarene 12, which is additional evidence for its structure. The structure of trinitrated calix[4]arene 16 having a single TBS-protected propargyl group at the narrow rim was unambiguously established from X-ray diffraction data. Suitable crystals were collected upon slow evaporation of a dichloromethane

• /methanol solution of compound 16. Similarly, single crystals of the exhaustively nitrated calix[4]arene 15 having two TBS-protected propargyl groups at the narrow rim were collected, and the molecular structure of this compound was also established (Figure 3) [94]. The results showed clearly, that in

Design, synthesis and biological evaluation of 2,5-diaryloxazolo[4,5-d]pyrimidin-7-ylamines as selective cytotoxic agents against HeLa cells

• Maryna V. Kachaeva,
• Agnieszka B. Olejniczak,
• Marta Denel-Bobrowska,
• Victor V. Zhirnov,
• Yevheniia S. Velihina,
• Stepan G. Pilyo and
• Volodymyr S. Brovarets

Beilstein J. Org. Chem. 2026, 22, 390–398, doi:10.3762/bjoc.22.27

• potential. Therefore, further functionalization of 2,4-diaryl[1,3]oxazolo[4,5-d]pyrimidines at position 7 of the structure-forming core was carried out in this work. Results and Discussion Chemistry The synthesis of 1,3-oxazolo[4,5-d]pyrimidine derivatives 1–9 was accomplished according to the previously

• therapeutic potential. Analyzing the structure–activity relationship with respect to the HeLa cancer cell line, it can be seen that among the diphenyloxazolopyridine derivatives, the substitution of the piperidine functional motif at position 7 in compound 1 by 4-ethylpiperazine leads to a decrease in the