Chemoenzymatic synthesis of the cardenolide rhodexin A and its aglycone sarmentogenin

• Fuzhen Song,
• Mengmeng Zheng,
• Dongkai Wang,
• Xudong Qu and
• Qianghui Zhou

Beilstein J. Org. Chem. 2025, 21, 2637–2644, doi:10.3762/bjoc.21.204

• . Based on the above preliminary results, we subsequently performed extensive optimization of fermentation conditions for a scalable synthesis of 4. As shown in Table 1, when the substrate loading was increased to 0.25 g/L, a much longer reaction time (2 days) was required to allow complete conversion

• natural products. Representative CGs with promising biological activities. Retrosynthetic analysis of rhodexin A and sarmentogenin. Chemoenzymatic synthesis of sarmentogenin (2). Synthesis of rhodexin A. Optimization of the fermentation conditions of the biocatalytic C14–H α-hydroxylation. Supporting

Thiazolidinones: novel insights from microwave synthesis, computational studies, and potentially bioactive hybrids

• Luan A. Martinho,
• Victor H. J. G. Praciano,
• Guilherme D. R. Matos,
• Claudia C. Gatto and
• Carlos Kleber Z. Andrade

Beilstein J. Org. Chem. 2025, 21, 2618–2636, doi:10.3762/bjoc.21.203

• -membered and the five-membered rings. A relaxed dihedral scan – which allows a geometry optimization at every step – indicated that torsion barriers exceed 25 kJ/mol (Figure 5), indicating that the torsion angle is about twice as rigid as the torsion of a regular sigma bond in ethane (≈12 kJ/mol) [77][78

• solutions, adapted from ref. [92][93]. Optimization of reaction conditions for the synthesis of (Z)-5-benzylidene-2-thioxothiazolidin-4-one under microwave heating.a Experimental and Boltzmann-weighted B97-D/def2-TZVPP chemical shifts (ppm) of molecules 3n and 4n. Boltzmann-weighted B97-D/def2-TZVPP

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

• existing methodologies and the biological significance of the segetalins, we sought to develop an efficient, scalable, and generally applicable solid-phase synthesis strategy for the Vaccaria segetalis cyclopeptide family. Results and Discussion Synthesis strategy and optimization While both solution-phase

Total syntheses of highly oxidative Ryania diterpenoids facilitated by innovations in synthetic strategies

• Zhi-Qi Cao,
• Jin-Bao Qiao and
• Yu-Ming Zhao

Beilstein J. Org. Chem. 2025, 21, 2553–2570, doi:10.3762/bjoc.21.198

• function as an engine, consistently pushing the boundaries of the discipline. From the early synthesis of simple molecules to the current precise assembly of complex natural products and functional materials, the iteration of methods and optimization of strategies have always been key to breaking through

• , thereby facilitating targeted molecular optimization. In 2016, the Inoue group accomplished the total synthesis of cinncassiol A (9) and B (7), cinnzeylanol (6), and 3-epi-ryanodol (5) through precisely controlled reactions with high stereoselectivity [15] (Scheme 6). Their approach allowed for the

• platform for synthesizing other family members and their structural analogues. The synthetic sequence commenced with common intermediate 103 as the starting material. Stereoselective reduction of 103 yielded compound 111 as a single diastereomer. Systematic optimization of reaction conditions revealed that

Rapid access to the core of malayamycin A by intramolecular dipolar cycloaddition

• Yilin Liu,
• Yuchen Yang,
• Chen Yang,
• Sha-Hua Huang,
• Jian Jin and
• Ran Hong

Beilstein J. Org. Chem. 2025, 21, 2542–2547, doi:10.3762/bjoc.21.196

• ]-ring necessitates tedious optimization to properly install three continuous tertiary centers (C2, C3, and C4). To circumvent the influence of the electron-withdrawing group on the nitrogen atom, we anticipated that cleaving the N–O bond prior to breaking the C2–C2’ bond would be feasible. However

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

• green, white, red, and blue, respectively. Synthesis of the Db1 monomer (8). Synthesis of Db2 monomer 15. Synthesis of Db3 monomer 21. Microwave promoted optimization of glutaric anhydride opening with 12a. Binding dataa for PNA containing Db monomers using UV thermal meltingb and isothermal titration

Assembly strategy for thieno[3,2-b]thiophenes via a disulfide intermediate derived from 3-nitrothiophene-2,5-dicarboxylate

• Roman A. Irgashev

Beilstein J. Org. Chem. 2025, 21, 2489–2497, doi:10.3762/bjoc.21.191

• -nucleophiles to form sulfide 2 and disulfide 3. Optimization of the reaction conditions for the reduction–alkylation of disulfide 3. Supporting Information Supporting Information File 12: Full experimental details, characterization data, copies of NMR spectra and HRMS for all new compounds. Acknowledgements

Palladium-catalyzed regioselective C1-selective nitration of carbazoles

• Vikash Kumar,
• Jyothis Dharaniyedath,
• Aiswarya T P,
• Sk Ariyan,
• Chitrothu Venkatesh and
• Parthasarathy Gandeepan

Beilstein J. Org. Chem. 2025, 21, 2479–2488, doi:10.3762/bjoc.21.190

• carbazole, which is presented in this study (Scheme 1c). Results and Discussion Optimization of the reaction parameters To evaluate the feasibility of the reaction, we commenced our studies by exploring palladium-catalyzed regioselective ortho-C–H nitration of the N-pyridylcarbazole 1a as the model

• substrate, using silver nitrate as the nitrating agent (Table 1). After detailed optimization studies, we found that the treatment of 1a with AgNO3 in the presence of Pd2(dba)3 as the catalyst in 1,4-dioxane afforded the desired C1-nitrated product 2a in 69% isolated yield (Table 1, entry 1). Product 2a was

• of our method. Key mechanistic studies. Optimization studies.a Supporting Information Supporting Information File 9: Experiment details, characterization data, copy of NMR spectra of synthesized compounds, and single-crystal X-ray diffraction data. Supporting Information File 10: CIF file for 2a

Synthesis of the tetracyclic skeleton of Aspidosperma alkaloids via PET-initiated cationic radical-derived interrupted [2 + 2]/retro-Mannich reaction

• Ru-Dong Liu,
• Jian-Yu Long,
• Zhi-Lin Song,
• Zhen Yang and
• Zhong-Chao Zhang

Beilstein J. Org. Chem. 2025, 21, 2470–2478, doi:10.3762/bjoc.21.189

• proceeds via an unusual 1,3-C shift to afford M, i.e. through an interrupted [2 + 2] cyclization/retro-Mannich reaction. Results and Discussion Conditions optimization Our study commenced with the evaluation of the proposed PET-based tandem [2 + 2] cyclization/retro-Mannich reaction. We selected compound

The intramolecular stabilizing effects of O-benzoyl substituents as a driving force of the acid-promoted pyranoside-into-furanoside rearrangement

• Alexey G. Gerbst,
• Sofya P. Nikogosova,
• Darya A. Rastrepaeva,
• Dmitry A. Argunov,
• Vadim B. Krylov and
• Nikolay E. Nifantiev

Beilstein J. Org. Chem. 2025, 21, 2456–2464, doi:10.3762/bjoc.21.187

• determined by 1H NMR spectroscopy. (A) Conformers arising during the rotation around the C5–C6 bond in pyranosides. (B) Furanoside ring conformers of monosaccharide 2 in the pseudorotation diagram. The dashed colored circles denote the initial conformations taken for optimization. Solid colored circles

• colored circles denote the initial conformations taken for optimization. Solid colored circles correspond to obtained conformations. (C) Calculated Gibbs free energies for various conformers of monosaccharides 3 and 4. For conformers 4-a and 4-b, the optimal torsional angles ω1 and ω of the side chain are

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

• , cyclopentanone 234 and the Grob fragmentation product, enone 235, were isolated from the reaction mixture. Cyclopentanone 234 can be used in the synthesis of 7-ketologanin (236) after optimization of the transformation. The product of the Wagner–Meerwein rearrangement, cyclopentanone 234, was formed according to

The high potential of methyl laurate as a recyclable competitor to conventional toxic solvents in [3 + 2] cycloaddition reactions

• Ayhan Yıldırım and
• Mustafa Göker

Beilstein J. Org. Chem. 2025, 21, 2389–2415, doi:10.3762/bjoc.21.184

• the reaction medium after five minutes. e) The spectrum of the isolated product 3a. Molecular structures of parent compounds 1a–f, 2a–d and cycloadducts 3a–u. Endo and exo stereoisomeric approaches of nitrone 1a and maleimide 2a in [3 + 2] cycloaddition reaction. Optimization of the [3 + 2

Synthetic study toward vibralactone

• Liang Shi,
• Jiayi Song,
• Yiqing Li,
• Jia-Chen Li,
• Shuqi Li,
• Li Ren,
• Zhi-Yun Liu and
• Hong-Dong Hao

Beilstein J. Org. Chem. 2025, 21, 2376–2382, doi:10.3762/bjoc.21.182

• ][21]. Additionally, a series of vibralactone homodimers and oxime esters 10–12 were reported by the groups of Liu and Zhang, respectively [22][23]. Through modification of the primary hydroxy group, a structure-based optimization of vibralactone (6) was carried out by Liu and co-workers and yielded

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

• . This further corroborates the decisive role of the macrocyclic architecture in the anion recognition process. Quantum chemical calculations were performed with the ORCA 5.0.3 software [29]. The geometry optimization was performed by using B3LYP with the def2-SVP basis set. As illustrated in the

Adaptive experimentation and optimization in organic chemistry

• Artur M. Schweidtmann and
• Philippe Schwaller

Beilstein J. Org. Chem. 2025, 21, 2367–2368, doi:10.3762/bjoc.21.180

• automation and artificial intelligence is creating unprecedented opportunities for accelerating chemical discovery and optimization [1][2]. This thematic issue explores how adaptive experimentation, automation, and human–AI synergy are reshaping organic chemistry research. Several key technological advances

• analyze experiments using machine learning optimization algorithms [5][6]. Together, these capabilities are dramatically increasing the speed and efficiency of chemical optimization with respect to economic and environmental objectives [7]. The contributions in this thematic issue showcase innovative

• approaches across multiple areas. Quijano Velasco et al. review recent advances in high-throughput automated chemical reaction platforms and machine learning algorithms for reaction optimization, showing how these approaches reduce experimentation time and human intervention [8]. They also discuss current

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

• ; and subsequent conversion of the ketone in 20 to the vinyl iodide in 21 – via hydrazone formation, lithium–halogen exchange, and final nucleophilic substitution – secured the Norrish–Yang cyclization precursor 22. Following systematic optimization of reaction conditions, irradiation of 22 with 100 W

• safety and controllability of the reaction, and at the same time, it is also conducive to the rapid optimization of reaction conditions and scale-up production. Finally, the Norrish–Yang reaction can utilize artificial intelligence to assist in designing reaction routes in the future, and through big

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

• nexus for the rational design and optimization of highly effective, selective homogeneous catalytic systems. In 2013, Barriault and co-workers demonstrated that strategic modulation of steric and electronic ligand parameters within gold(I)-catalyzed cyclization pathways enables the selective assembly of

• accelerating reaction optimization. Furthermore, expanding this concept to other reaction manifolds – such as electrocyclic processes and photoredox catalysis – may uncover new avenues for molecular innovation. The pursuit of pathway-economical synthesis represents a paradigm shift toward sustainable and

Pd-catalyzed dehydrogenative arylation of arylhydrazines to access non-symmetric azobenzenes, including tetra-ortho derivatives

• Loris Geminiani,
• Kathrin Junge,
• Matthias Beller and
• Jean-François Soulé

Beilstein J. Org. Chem. 2025, 21, 2234–2242, doi:10.3762/bjoc.21.170

• bromotoluene (Table 1, entries 5–8). For subsequent optimizations, we selected t-BuXPhos for practical reasons, as it is less sensitive to oxidative conditions. Further optimization revealed that Cs2CO3 is more efficient than NaH for this reaction (Table 1, entry 9). However, reactions conducted with a new

• formed to minimize steric clashes. Finally, reductive elimination leads to the formation of N,N-diarylhydrazine (D), which has been identified and characterized during the optimization process (see Supporting Information File 1 for details). In a second catalytic cycle, the N,N-diarylhydrazine (D

• palladium-catalyzed dehydrogenative C–N coupling with 2-bromotoluene (2a). Application to the synthesis of tetra-, tri or di-ortho-substituted azobenzenes via palladium-catalyzed dehydrogenative C–N coupling. aIsolated with 85–95% purity. Selected optimization of conditions for the synthesis of azobenzene

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

• accelerated hepatic clearance (Clint) due to the metabolic sensitivity of this class of compounds. Thus, a strategy for additional lead optimization towards central nervous system drug candidates, commencing with compound 3e, is advised based on the preliminary ADME data. Conclusion The aforementioned

• -hexahydro[1,2,3]thiadiazino[6,5-a]carbazole 1,1-dioxide (3e) has been identified as a promising central nervous system drug candidate for pharmacological testing and eventual further structure–activity optimization. Experimental Compounds 5a, 5b, 7a–j, (E)-9a, (E)-9b, 3a–j, 10a, 10b are new and

Synthesis of triazolo- and tetrazolo-fused 1,4-benzodiazepines via one-pot Ugi–azide and Cu-free click reactions

• Xiaoming Ma,
• Zijie Gao,
• Jiawei Niu,
• Wentao Shao,
• Shenghu Yan,
• Sai Zhang and
• Wei Zhang

Beilstein J. Org. Chem. 2025, 21, 2202–2210, doi:10.3762/bjoc.21.167

• scaffolds in a highly efficient manner. It was found that brominated azides do not undergo lactamization under the current conditions which presents an opportunity for further optimization of reaction conditions to expand the scope. Experimental General procedure for synthesis of analogs 7 and 8 A solution

Multicomponent reactions IV

• Thomas J. J. Müller and
• Valentyn A. Chebanov

Beilstein J. Org. Chem. 2025, 21, 2082–2084, doi:10.3762/bjoc.21.163

• optimization of promising lead structures has therefore inspired the development of powerful synthetic strategies. A glance at Web of Science reveals that one-pot methods and multicomponent reactions (MCRs) [1] have attracted steadily increasing attention within the scientific community over the past 25 years

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

• the reaction selectivity can be directed towards the formation of arylated dienes 10, which would directly contribute to our previous work [26]. Therefore, we performed optimization of the arylation conditions (Table 1) to improve the reaction selectivity towards the aryldiene 10a formation, indicated

• optimization see Supporting Information File 1. Next, we switched to internal N-nucleophiles. N-Nosylated starting material 7f under standard arylation conditions gave the 2-(1-(tert-butyldimethylsilyl)vinyl)-1-((4-nitrophenyl)sulfonyl)pyrrolidine (14) with a 56% yield. Most likely in this case sulfonamide N–H

• . aThe reaction was performed under modified conditions: I-2 (3.0 equiv), 20 h because under standard reaction conditions incomplete conversion was observed (with 48% recovered 16c). Reaction conditions optimization for the arylation of aliphatic chain-containing propargylsilane 7a. Aryldiene scope

Asymmetric total synthesis of tricyclic prostaglandin D2 metabolite methyl ester via oxidative radical cyclization

• Miao Xiao,
• Liuyang Pu,
• Qiaoli Shang,
• Lei Zhu and
• Jun Huang

Beilstein J. Org. Chem. 2025, 21, 1964–1972, doi:10.3762/bjoc.21.152

• ester 4. Optimization of conditions to convert diketone 15 into cyclopentanone 14.a Supporting Information Supporting Information File 42: Experimental procedures, characterization data and copies of 1H and 13C NMR spectra. Acknowledgements We thank Prof. Zhen Yang (Peking University) for helpful

Stereoselective electrochemical intramolecular imino-pinacol reaction: a straightforward entry to enantiopure piperazines

• Margherita Gazzotti,
• Fabrizio Medici,
• Valerio Chiroli,
• Laura Raimondi,
• Sergio Rossi and
• Maurizio Benaglia

Beilstein J. Org. Chem. 2025, 21, 1897–1908, doi:10.3762/bjoc.21.147

• reaction and a screening of reaction parameters such as solvents, electrodes materials, electrolytes, total charges, and concentrations of the reaction mixture was performed. All optimization studies were carried out using 0.5 mmol of 1a in the presence of methanesulfonic acid in an undivided cell (5 mL

• comprehensive optimization of the flow reaction conditions was carried out using the model substrate 1a systematically varying key parameters such as the working electrodes, the current intensity, the total charge, the flow rate, and the equivalents of the employed electrolyte. Following this in-depth screening

Fe-catalyzed efficient synthesis of 2,4- and 4-substituted quinolines via C(sp²)–C(sp²) bond scission of styrenes

• Prafull A. Jagtap,
• Manish M. Petkar,
• Vaishnavi R. Sawant and
• Bhalchandra M. Bhanage

Beilstein J. Org. Chem. 2025, 21, 1799–1807, doi:10.3762/bjoc.21.142

• . Plausible reaction mechanism. Optimization of reaction conditions.a Supporting Information Supporting Information File 24: Experimental section, characterization of synthesized compounds, and copies of spectra. Funding P.A.J. gratefully acknowledges the Chhatrapati Shahu Maharaj Research Training and