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

• substrates rac-1a–c. Molybdenum-catalyzed asymmetric metathesis dimerization/kinetic resolution of racemic vinylcymantrenes 1a–c.a Supporting Information Supporting Information File 19: Experimental procedures, NMR spectra (1H and 13C) for all the new compounds, and chiral HPLC chromatograms. Supporting

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

• -terminus (peptide ordered from Genscript), which was subjected to click reaction with the butynyl tweezer (Scheme 1). The coupling protocol was identical to the published version [9][10]. Reaction progress was monitored by analytical HPLC and the product could be purified by preparative HPLC. After

• the included side chain protons [12][13]. HPLC–HRMS analysis finally produced a single chromatographic signal with clean molecular ion peaks for [M + 2H]2+ and [M + 3H]3+. The high purity of 2a was further demonstrated by successful co-crystallization of this tweezer peptide conjugate with survivin

• tweezer peptide conjugates 2e and 2f are much more flexible and may reach lysines in larger distance, which did not show up in manual structure screens. Both tweezer conjugates 2e and 2f were synthesized, purified by preparative HPLC and analytically characterized. They are currently involved in

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

• ideal alkene plane. Stereochemical analysis of C6-substituted oxacyclophenes Next, HPLC analyses using a chiral stationary phase (chiral column) of the C6-substituted oxacyclophenes were conducted. The baseline separations of the enantiomers of 1ab and 1ad were achieved by using CHIRALCEL OJ-H as the

• chiral column at 25 °C (Figure 3) [17]. In sharp contrast to 1ab and 1ad, the HPLC analysis of 1ac showed a plateau between the peaks of the enantiomers at 25 °C, indicating that the interconversion of the enantiomers proceeds on the separation time scale (Figure 4) [18]. The interconversion plateau was

• effect of the phenyl group with the distorted alkene for a jump-rope rotation-type ring-flip (Figure 5) [10]. Enantioenriched samples of compounds 1ab and 1ad were obtained by HPLC separation using preparative scale chiral columns. We evaluated the stereochemical stability of 1ab and 1ad at 25 °C using

Electrosynthetic access to unsymmetrical oxaza[8]helicenes with high chiral stability and strong circularly polarized luminescence (CPL)

• Tin Zar Aye,
• Rubal Sharma,
• Muthu Karuppasamy,
• Daiya Suzuki,
• Haruka Nakajima,
• Yoshitane Imai,
• Mitsuhiro Arisawa,
• Mohamed S. H. Salem and
• Shinobu Takizawa

Beilstein J. Org. Chem. 2026, 22, 372–382, doi:10.3762/bjoc.22.25

• ) relative to their oxaza[7]helicene analogues (<25 kcal/mol). After chiral HPLC separation, the enantiomers display mirror-image CD and strong solution CPL, with |glum| up to 2.6 × 10−3 and fluorescence brightness up to 30.75 M−1 cm−1. Keywords: chemoselectivity; chiroptical; circular dichroism

• ]. Chiroptical features The higher enantiomerization barriers of (P/M)-5a and (P/M)-5b enabled complete separation of their enantiomers by HPLC using a Daicel Chiralpak IA column (see Supporting Information File 1). Despite the rapid enantiomerization of (P/M)-6a and (P/M)-6b, we were able to separate the two

• and second fractions of the chiral HPLC analysis were assigned as the (P)- and (M)-enantiomers, respectively, for all 5a,b and 6a,b. As expected, the increase in helical length (n) from 7 to 8, 5a and 5b exhibited more red-shifted maximum |gabs| values at around 350 nm, whereas 6a and 6b showed values

Synthesis of diaryl phosphates using phytic acid as a phosphorus source

• Kazuya Asao,
• Seika Matsumoto,
• Haruka Mori,
• Riku Yoshimura,
• Takeshi Sasaki,
• Naoya Hirata,
• Yasuyuki Hayakawa and
• Shin-ichi Kawaguchi

Beilstein J. Org. Chem. 2026, 22, 213–223, doi:10.3762/bjoc.22.15

• its light-brown appearance was identical to that of the product synthesized from commercial phytic acid. High-performance liquid chromatography (HPLC) analysis results indicated that the purity of 2a derived from the extracted phytic acid was greater than 95% (Supporting Information File 1, Figure S4

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

• preparative HPLC, yielding streptoquinolines A (1, 7.50 mg) and B (2, 8.05 mg). The physicochemical properties of 1 and 2 are summarized in Table 1. Compounds 1 and 2 showed characteristic absorption maxima at 200–202, 214, 231–234, 312, and 349–350 nm in UV spectra. Common IR absorption bands at 3414–3427

• crude materials containing 1 and 2 (23.5 mg). These materials were finally purified by preparative HPLC: column, Develosil C30-UG (Nomura Chemical Co., Ltd., Aichi, Japan), i.d. 10 × 250 mm; mobile phase, 55% MeCN aq. isocratic; detection, UV at 210 nm; flow rate, 3.0 mL /min. Under these conditions

Improved synthesis and physicochemical characterization of the selective serotonin 2A receptor agonist 25CN-NBOH

• Adrian G. Rossebø,
• Hannah G. Kolberg,
• Anders E. Tønder,
• Louise Kjaerulff,
• Poul Erik Hansen,
• Karla A. Frydenvang,
• Jesper Østergaard and
• Jesper L. Kristensen

Beilstein J. Org. Chem. 2026, 22, 175–184, doi:10.3762/bjoc.22.11

• sufficient for most biological applications given the high potency of the compound both in vitro and in vivo [6]. Here, we show that if solutions with a higher concentration are needed, pure water could be considered. According to HPLC analysis, 1·HCl was found to be stable in solution in phosphate buffer at

• ). Acetonitrile (Ph. Eur.), absolute ethanol (Reag. Ph. Eur.), ethyl acetate (HPLC grade), dichloromethane (HPLC grade), ammonia (25%, analytical reagent grade), and diethyl ether (reagent grade) were purchased from VWR (Radnor, PA, USA). Sodium hydrogencitrate sesquihydrate (99%), salicylaldehyde (≥98

• ) and water at 25 ± 0.5 °C. The solutions comprising 0.2 mg/mL of 1·HCl were kept in a temperature-controlled incubator, and samples were measured by HPLC immediately after sample preparation as well as after one and four weeks for the experiments in phosphate buffer and after four weeks for experiments

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

• ]. Although basic conditions caused partial racemization during the protection or deprotection step, the Boc-protected amine was obtained in low enantiomeric purity. Chiral HPLC analysis and comparison with an authentic sample revealed the S-configuration of the Mannich adduct [29]. Absolute configurations of

• 20: Experimental procedures, synthetic details, NMR spectra, chiral HPLC chromatograms. Funding The research was funded by the Estonian Ministry of Education and Research (grant No. PRG1031).

Efficient solid-phase synthesis and structural characterization of segetalins A–H, J and K

• Liangyu Liu,
• Wanqiu Lu,
• Quanping Guo and
• Zhaoqing Xu

Beilstein J. Org. Chem. 2025, 21, 2612–2617, doi:10.3762/bjoc.21.202

• strategy for the total synthesis of segetalins A–H, J and K (1–10), bioactive cyclopeptides isolated from Vaccaria segetalis. Linear precursors were assembled on cost-effective 2-chlorotrityl chloride resin via Fmoc-SPPS, followed by PyBOP-mediated head-to-tail cyclization in DMF (10−3 M). After RP-HPLC

• purification, all cyclopeptides were obtained in 45–70% isolated yields. Structural identities were confirmed by HRESIMS, NMR, and HPLC (>95% purity). Circular dichroism (CD) spectroscopy revealed distinct secondary structures, including β-sheets (1, 2, 3, 4, 7, 8, 10) and α-helical elements (5, 6). This

• RP-HPLC. This optimized protocol afforded segetalins A–H, J and K (1–10) with 45% to 70% isolated yields (Figure 1). Structural characterization The synthetic compounds 1–10 were rigorously characterized to confirm their identity and purity (see Supporting Information File 1). High-resolution

Isoorotamide-based peptide nucleic acid nucleobases with extended linkers aimed at distal base recognition of adenosine in double helical RNA

• Grant D. Walby,
• Brandon R. Tessier,
• Tristan L. Mabee,
• Jennah M. Hoke,
• Hallie M. Bleam,
• Angelina Giglio-Tos,
• Emily E. Harding,
• Vladislavs Baskevics,
• Martins Katkevics,
• Eriks Rozners and
• James A. MacKay

Beilstein J. Org. Chem. 2025, 21, 2513–2523, doi:10.3762/bjoc.21.193

• reversed-phase HPLC, these PNAs were studied against model RNA hairpins containing a purine-rich 5’-end and a variable base pair, Y–Z (Figure 6). The expected matched HRP1 (Y = U; Z = A) was designed to test affinity for the newly prepared Db nucleobases and mismatched HRP2–HRP4 were utilized to test

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

• with MeI in presence of benzyltrimethylammonium fluoride (BTAF). At this stage, to prepare optically active natural product, the racemic mixture of 51 was separated using chiral HPLC to afford (+)-51 and (−)-51, which were used to prepare both enantiomers of complanadine A for biological evaluations

Recent advances in Norrish–Yang cyclization and dicarbonyl photoredox reactions for natural product synthesis

• Peng-Xi Luo,
• Jin-Xuan Yang,
• Shao-Min Fu and
• Bo Liu

Beilstein J. Org. Chem. 2025, 21, 2315–2333, doi:10.3762/bjoc.21.177

• phenol delivered 1,2-naphthoquinone 106. Notably, enantiomer (−)-106 could be prepared from (+)-105, which was in turn obtained by preparative HPLC on a chiral stationary phase from (±)-105. Following extensive screening, it was found that photoirradiation of quinone (−)-106 under the optimized

A chiral LC–MS strategy for stereochemical assignment of natural products sharing a 3-methylpent-4-en-2-ol moiety in their terminal structures

• Rei Suo,
• Raku Irie,
• Hinako Nakayama,
• Yuta Ishimaru,
• Yuya Akama,
• Masato Oikawa and
• Shiro Itoi

Beilstein J. Org. Chem. 2025, 21, 2243–2249, doi:10.3762/bjoc.21.171

• -hydroxy-2-methylbutanoate (3) [25][26]. We then explored LC–MS conditions for their separation. In our initial trial, the stereoisomeric mixture of 3 was successfully separated by preparative high performance liquid chromatography (HPLC) using a chiral column (data not shown). However, each stereoisomer

• chiral HPLC columns and with various elution profiles, the four stereoisomers of 6 were successfully separated on a CHIRALPAK ID-3 column at 40 °C with aqueous MeOH gradient elution (Figure S3, Supporting Information File 1). The developed method for absolute configuration assignment of MPO was applied

• followed by ozonolysis to generate 3-((4-bromobenzoyl)oxy)-2-methylbutanoic acid. The four stereoisomers of this fragment were prepared through two separate Evans aldol reactions, each affording a pair of diastereomers. The final four stereoisomers were resolved by chiral HPLC (CHIRALPAK IA column with

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

• ), CCDC 2447635 [(E)-7a], CCDC 2447644 (7b), CCDC 2447641 (7d), CCDC 2447634 (7e), CCDC 2447643 [(E)-7f], CCDC 2447642 [(Z)-7h], CCDC 2447640 (7i) and CCDC 2447637 [(E)-9a]. All solvents used in the pharmacokinetic characterization and for HPLC measurements were of analytical grade, purchased from Merck

• during HPLC analysis. In vitro gastrointestinal permeability assay. For in vitro GI PAMPA permeability studies, only compounds with a kinetic solubility higher than 10 µM were chosen. Like in the kinetic solubility assay, 5 μL of DMSO stock solutions was pipetted into a 96-well plate containing 495 μL

• at 37 °C for 4 hours. Then samples were taken from the donor and acceptor wells and analyzed along with the initial solutions by HPLC. Effective permeability and membrane retention were calculated with Equation 1 and Equation 2 as suggested by Avdeef [48]: where A is the filter area (0.24 cm2), t is

Discovery of cytotoxic indolo[1,2-c]quinazoline derivatives through scaffold-based design

• Daniil V. Khabarov,
• Valeria A. Litvinova,
• Lyubov G. Dezhenkova,
• Dmitry N. Kaluzhny,
• Alexander S. Tikhomirov and
• Andrey E. Shchekotikhin

Beilstein J. Org. Chem. 2025, 21, 2062–2071, doi:10.3762/bjoc.21.161

• a series of 6-aminomethyl-substituted indoloquinazoline derivatives 14а–d (Scheme 5). The structures of all compounds were analyzed and confirmed by NMR and HRMS methods. Samples of all indolo[1,2-c]quinazoline derivatives with good analytical purity (HPLC, ≥95%) were further subjected to biological

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

• and 17). The obtained diene 10a contained 13–15% of silylindene 11a as impurity. Products 10a and 11a are separable by preparative HPLC. Lowering the starting material concentration in the reaction mixture to 0.05 mmol/mL significantly decreased the diene 10a yield due to the formation of other

Rhodium-catalysed connective synthesis of diverse reactive probes bearing S(VI) electrophilic warheads

• Scott Rice,
• Julian Chesti,
• William R. T. Mosedale,
• Megan H. Wright,
• Stephen P. Marsden,
• Terry K. Smith and
• Adam Nelson

Beilstein J. Org. Chem. 2025, 21, 1924–1931, doi:10.3762/bjoc.21.150

• diverse co-substrates. A high-throughput approach was used to identify promising substrate/co-substrate/catalyst combinations which were then prioritised for purification by mass-directed HPLC to yield a total of thirty reactive probes. The structural diversity of the probe set was increased by the

• products observed by analytical HPLC. Structures and structure elucidation of intermolecular reaction products. The relevant reactivity modes are indicated by colour: O–H insertion (green); N–H insertion (blue); formal C–H insertion (yellow); and cyclopropanation (pink). Synthesis of α-diazoamide

Synthesis of N-doped chiral macrocycles by regioselective palladium-catalyzed arylation

• Shuhai Qiu and
• Junzhi Liu

Beilstein J. Org. Chem. 2025, 21, 1917–1923, doi:10.3762/bjoc.21.149

• yields (ΦF up to 0.69). Furthermore, enantiomeric resolution of inherent chiral MC1 was achieved using preparative chiral HPLC, enabling detailed investigation of its chiroptical behavior through circular dichroism and circularly polarized luminescence spectroscopy. Keywords: dihydroindolocarbazole

• existence of inherent chirality for both MC1 and MC3, chiral resolutions using chiral high-performance liquid chromatography (HPLC) were performed. Due to insufficient solubility, MC3 failed in chiral separation via preparative chiral columns. Fortunately, two enantiomers of MC1 were successfully isolated

Unique halogen–π association detected in single crystals of C–N atropisomeric N-(2-halophenyl)quinolin-2-one derivatives and the thione analogue

• Mai Uchibori,
• Nanami Murate,
• Kanako Shima,
• Tatsunori Sakagami,
• Ko Kanehisa,
• Gary James Richards,
• Akiko Hori and
• Osamu Kitagawa

Beilstein J. Org. Chem. 2025, 21, 1748–1756, doi:10.3762/bjoc.21.138

• their spectral data, copies of 1H and 13C{1H} NMR charts of compounds 1–4, chiral MPLC and HPLC chart in compounds 1a,b, 2a, evaluation of rotational barriers of compounds 1a,b, and X-ray crystal data of rac-1a,b, (P)-1a,b, rac-2a (check CIF). Funding This work was partly supported by JSPS KAKENHI (C

Preparation of a furfural-derived enantioenriched vinyloxazoline building block and exploring its reactivity

• Madara Darzina,
• Anna Lielpetere and
• Aigars Jirgensons

Beilstein J. Org. Chem. 2025, 21, 1737–1741, doi:10.3762/bjoc.21.136

• chiral HPLC. This confirmed that no erosion of enantiomeric purity had happened during the deprotection stage. With the enantioenriched vinyloxazoline S-6 in hand, we explored the reaction scope involving its electron-deficient double bond. Unfortunately, the olefin appeared unreactive or gave a mixture

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

• nitrogen source followed by thin-layer chromatography and reversed-phase (RP)-HPLC to isolate and purify the compound from a complex mixture of indole alkaloids [11], (ii) prepared by aerobic incubation of indole-3-pyruvic acid at pH 7.4, 37 °C for 24 h followed by isolation and purification using RP-HPLC

Continuous-flow-enabled intensification in nitration processes: a review of technological developments and practical applications over the past decade

• Feng Zhou,
• Chuansong Duanmu,
• Yanxing Li,
• Jin Li,
• Haiqing Xu,
• Pan Wang and
• Kai Zhu

Beilstein J. Org. Chem. 2025, 21, 1678–1699, doi:10.3762/bjoc.21.132

• critical passivation thresholds, necessitating rigorous evaluation of 316L material's corrosion susceptibility under such dynamic operating conditions. The feeding zone of a continuous-flow nitration system typically comprises precision fluid-handling equipment including HPLC pumps, peristaltic pumps, or

• syringe pumps. The selection criteria must account for operational pressure thresholds, reagent rheological properties (e.g., viscosity), and required flow regimes. A representative challenge arises when handling high-viscosity nitration agents like the HNO3/H2SO4 binary acid system for which HPLC pumps

Synthesis of optically active folded cyclic dimers and trimers

• Ena Kumamoto,
• Kana Ogawa,
• Kazunori Okamoto and
• Yasuhiro Morisaki

Beilstein J. Org. Chem. 2025, 21, 1603–1612, doi:10.3762/bjoc.21.124

• simple SiO2 column chromatography. In addition, they were purified using a recyclable high-performance liquid chromatography (HPLC) to remove unidentified impurities to obtain (Sp)-6 and (Sp)-7 in 16% and 3% isolated yields, respectively. The ultraviolet–visible (UV–vis) absorption spectra and normalized

• standard. Analytical thin-layer chromatography (TLC) was performed with silica gel 60 Merck F254 plates. Column chromatography was performed with silica gel 60N (spherical neutral). Recyclable preparative high-performance liquid chromatography (HPLC) was carried out on a Japan Analytical Industry Model

• LC918R (JAIGEL 1H and 2H gel-permeation columns) using CH2Cl2 as an eluent. Recyclable chiral chromatography (HPLC) was carried out on a YMC LC Forte/R (Chiralpak® IA column). High-resolution mass spectra (HRMS) was obtained on a Bruker Daltonics microTOF II spectrometer (APCI) by using sodium formate

pH-Controlled isomerization kinetics of ortho-disubstituted benzamidines: E/Z isomerism and axial chirality

• Ryota Kimura,
• Satoshi Ichikawa and
• Akira Katsuyama

Beilstein J. Org. Chem. 2025, 21, 1568–1576, doi:10.3762/bjoc.21.120

• liquid chromatography (RP-HPLC) using an acidic mobile phase [H2O (0.1% CF3CO2H)/MeCN 72:28]. As shown in Figure 4, the HPLC analysis of amidine 2 showed two peaks corresponding to the E and Z isomers which could be explained by the existence of E/Z isomers of amidine 2 trifluoroacetate salt. After

• separation of the two peaks, HPLC analysis of each separated component showed single peaks, suggesting that the E and Z isomers of amidine 2 trifluoroacetate salt could be separated by standard RP-HPLC. The configuration of the amidine moiety of each component was characterized by NOE experiments (for

• details, see Supporting Information File 1). The NMR and HPLC experiments clearly indicate that protonation of the amidine moiety increases the rotational barrier of the C–N bond, a result which is consistent with our DFT study. Since it was found that the E/Z isomers of amidine could be isolated as a TFA

Wittig reaction of cyclobisbiphenylenecarbonyl

• Taito Moribe,
• Junichiro Hirano,
• Hideaki Takano,
• Hiroshi Shinokubo and
• Norihito Fukui

Beilstein J. Org. Chem. 2025, 21, 1454–1461, doi:10.3762/bjoc.21.107

• and rac-5 was conducted using high-performance liquid chromatography (HPLC) equipped with DAICEL CHIRALPAK IE as the chiral stationary phase (eluent: CH2Cl2/hexane 3:2 for 3 and 1:9 for 5). The absolute configurations of the enantiomers were determined by transformation of enantiomerically pure CBBC