{"title":"Diastereodivergent electrophilic trapping of α-boryl lithium derivatives.","authors":"Tereza Pavlíčková, Noam Orbach, Ilan Marek","doi":"10.3762/bjoc.22.68","DOIUrl":"10.3762/bjoc.22.68","url":null,"abstract":"<p><p>α-Boryl carbanions are valuable organoboron intermediates, but controlling their stereoselective reactions remains challenging. Here, we examine the diastereoselective generation and trapping of α-boryl lithium species formed by ring opening of substituted iodomethylcyclopropanes. After lithium-iodine exchange and selective C-C bond cleavage, these intermediates react with a range of electrophiles to give boronic esters bearing vicinal tri- and tetrasubstituted stereocenters in good yields and high diastereoselectivities. Notably, substrates bearing alkyl substituents display the opposite sense of diastereoselectivity to previously studied aryl-substituted analogues. The results suggest that the stereochemical outcome is independent of the initial configuration at C2 and is instead dictated by conformational preferences of the α-boryl lithium intermediate. A simplified steric model is proposed in which lithium coordination induces a pseudo-chelated structure that controls facial selectivity during electrophilic trapping. These findings expand the synthetic utility of α-boryl lithium intermediates and provide insight into the origins of their diastereoselectivity.</p>","PeriodicalId":8756,"journal":{"name":"Beilstein Journal of Organic Chemistry","volume":"22 ","pages":"882-887"},"PeriodicalIF":2.7,"publicationDate":"2026-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13245471/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148209773","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Antonio Angelastro, Jonathan Bargh, Subhajit Guria, Victor Laserna, Louis Luk
{"title":"Site-specific labelling of native peptides and proteins: chemical and enzymatic strategies.","authors":"Antonio Angelastro, Jonathan Bargh, Subhajit Guria, Victor Laserna, Louis Luk","doi":"10.3762/bjoc.22.67","DOIUrl":"10.3762/bjoc.22.67","url":null,"abstract":"<p><p>Site-specific modifications of native-sequence proteins are technologies that underpin progresses in chemical biology, diagnostics and next-generation biotherapeutics. However, the pursuit of site-specificity has often come at the expense of scalability and usability, ultimately limiting translational potential of a modification tool. This review critically compares current key strategies, including terminal, disulfide-rebridging, small-molecule, glycan and enzyme-based modifications. Finally, we present a decision tree for method selection and highlight opportunities for innovation in next-generation native-sequence protein modification technologies.</p>","PeriodicalId":8756,"journal":{"name":"Beilstein Journal of Organic Chemistry","volume":"22 ","pages":"857-881"},"PeriodicalIF":2.7,"publicationDate":"2026-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13245474/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148209766","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Daria A Burmistrova, Vasiliy A Fokin, Oleg P Demidov, Mikhail A Kiskin, Maxim V Arsenyev, Andrey I Poddel'sky, Nadezhda T Berberova, Ivan V Smolyaninov
{"title":"Unsymmetrical sulfoxides with sterically hindered catechol fragment: synthesis, structure, electrochemical properties, and antiradical activity.","authors":"Daria A Burmistrova, Vasiliy A Fokin, Oleg P Demidov, Mikhail A Kiskin, Maxim V Arsenyev, Andrey I Poddel'sky, Nadezhda T Berberova, Ivan V Smolyaninov","doi":"10.3762/bjoc.22.65","DOIUrl":"10.3762/bjoc.22.65","url":null,"abstract":"<p><p>New unsymmetrical sulfoxides containing a redox-active sterically hindered catechol fragment and a nonpolar hydrocarbon substituent at the sulfoxide group were synthesized via the oxidation of the corresponding catechol thioethers with hydrogen peroxide. The yield of the reaction products ranges from 42 to 89%. The crystal structures of catechol sulfoxides with isopropyl, cyclopentyl, adamantyl, benzyl and 1-naphthyl moieties were established by single-crystal X-ray analysis. The possibility of forming intra- and intermolecular hydrogen bonds has been shown for these compounds. The electrochemical behavior of sulfoxides was studied in comparison with that of the parent catechol thioethers. The redox transition corresponding to catechol fragment oxidation is shifted to the anodic region relative to the initial thioethers, which is attributed to the more electron-withdrawing nature of the S=O group. The second redox stage characterizes the transformation of the sulfoxide fragment and is observed in most cases at 1.82-1.91 V. The radical-scavenging activity and antioxidant properties of the unsymmetrical sulfoxides and their precursor thioethers were evaluated using the reaction with the 2,2'-diphenyl-1-picrylhydrazyl radical (DPPH) and the 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS<sup>+•</sup>). In both assays, the lowest IC<sub>50</sub> values among the studied catechol sulfoxides were found for compounds bearing isopropyl and <i>tert</i>-butyl substituents on the sulfoxide group.</p>","PeriodicalId":8756,"journal":{"name":"Beilstein Journal of Organic Chemistry","volume":"22 ","pages":"828-837"},"PeriodicalIF":2.7,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13245472/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148209702","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The <i>trans</i>-influence in gold chemistry from a catalytic perspective.","authors":"Manfred Bochmann","doi":"10.3762/bjoc.22.66","DOIUrl":"10.3762/bjoc.22.66","url":null,"abstract":"<p><p>Gold catalysis has developed into an increasingly important method in organic synthesis. Especially the potential of gold(I,III) redox systems and gold(III) complexes has more recently become a focus of interest. Although often underestimated or not considered, the ligand <i>trans</i>-influence is a crucial factor in determining the reactivity of gold(III) compounds; it modifies not only bond polarisation, dissociation energies and thermal stability but also controls the nature of the gold frontier orbitals. This Perspective highlights recent insights into the origins and consequences of the ligand <i>trans</i>-influence and its importance for the energetics of gold-catalysed reactions, with special emphasis on the <i>trans</i>-influence in gold(III) hydrides and recent mechanistic insights.</p>","PeriodicalId":8756,"journal":{"name":"Beilstein Journal of Organic Chemistry","volume":"22 ","pages":"838-856"},"PeriodicalIF":2.7,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13245473/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148209688","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Total synthesis of the capsular polysaccharide repeating unit towards the development of a glycoconjugate vaccine against <i>Klebsiella pneumoniae</i> ST512.","authors":"Shuo Zhang, Ondřej Daněk, Peter H Seeberger","doi":"10.3762/bjoc.22.64","DOIUrl":"10.3762/bjoc.22.64","url":null,"abstract":"<p><p><i>Klebsiella pneumoniae</i> ST512 is an emerging multidrug-resistant pathogen whose capsular polysaccharide represents a prime target for vaccine development. Here, we report the first total synthesis of the branched hexasaccharide repeating unit of the <i>K. pneumoniae</i> ST512 CPS, together with four structurally related oligosaccharide analogues. Key synthetic challenges including the stereoselective construction of the 1,2-<i>cis</i> 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 conjugation-ready oligosaccharides, equipped with aminopentyl linkers, enables glycan microarray-based identification of minimal immunogenic epitopes. This work establishes a robust chemical foundation for the rational development of semi-synthetic glycoconjugate vaccines targeting <i>K. pneumoniae</i> ST512.</p>","PeriodicalId":8756,"journal":{"name":"Beilstein Journal of Organic Chemistry","volume":"22 ","pages":"821-827"},"PeriodicalIF":2.7,"publicationDate":"2026-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13224054/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148148049","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Darya S Cheshkina, Christina S Becker, Alina A Sonina, Maxim S Kazantsev
{"title":"Knoevenagel condensation of 4,5- and 1,8-diazafluorenes.","authors":"Darya S Cheshkina, Christina S Becker, Alina A Sonina, Maxim S Kazantsev","doi":"10.3762/bjoc.22.62","DOIUrl":"10.3762/bjoc.22.62","url":null,"abstract":"<p><p>Diazafluorenylidenes are potential antitumor agents, ligands, and functional materials. However, there are currently only limited methods for their synthesis, which are complicated and typically based on modifications of 4,5-diazafluorenone. Herein, we systematically studied the Knoevenagel condensation of both 4,5- and 1,8-diazafluorenes with aromatic aldehydes and evaluated the diazafluorenes' nature and solvent influence on the mechanism and reactivity. We also identified conditions allowing the preparation of both 4,5- and 1,8-diazafluorenylidenes in yields up to 85% minimizing complicated synthetic or experimental workup procedures. Additionally, the condensation of diazafluorenes with ketones resulted in unique di(pyridin-2-yl)methylene)-9<i>H</i>-diazafluorenes being electron-deficient ligands and functional materials.</p>","PeriodicalId":8756,"journal":{"name":"Beilstein Journal of Organic Chemistry","volume":"22 ","pages":"803-812"},"PeriodicalIF":2.7,"publicationDate":"2026-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13224056/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148148040","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Irene Moreno-Gutiérrez, Josefa L López-Martínez, Sonia Berenguel-Gómez, Irene Torres-García, Duane Choquesillo-Lazarte, Manuel Muñoz-Dorado, Miriam Álvarez-Corral, Ignacio Rodríguez-García
{"title":"Synthesis and structural elucidation of a novel bis-spirooxindole from isatin and ethylenediamine.","authors":"Irene Moreno-Gutiérrez, Josefa L López-Martínez, Sonia Berenguel-Gómez, Irene Torres-García, Duane Choquesillo-Lazarte, Manuel Muñoz-Dorado, Miriam Álvarez-Corral, Ignacio Rodríguez-García","doi":"10.3762/bjoc.22.63","DOIUrl":"10.3762/bjoc.22.63","url":null,"abstract":"<p><p>The reactivity of isatin toward ethylenediamine displays an unexpected stoichiometric divergence, affording either the anticipated diiminoisatin or a previously unreported pentacyclic bis-spirooxindole. A 2:1 isatin-to-diamine ratio provides the diiminoisatin, whereas a 1:2 ratio leads to the formation of a highly symmetric bis-spirooxindole scaffold. The new spirocyclic product was fully characterized by HRMS, IR and extensive 1D/2D NMR analysis, and its structure was unequivocally established by single-crystal X-ray diffraction. In addition, the isolated diiminoisatin can be independently reduced to the same bis-spirooxindole. These results broaden the scope of isatin-diamine condensations and demonstrate their potential to generate structurally complex spirooxindole architectures under simple conditions.</p>","PeriodicalId":8756,"journal":{"name":"Beilstein Journal of Organic Chemistry","volume":"22 ","pages":"813-820"},"PeriodicalIF":2.7,"publicationDate":"2026-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13224053/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148147978","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Synthetic study of <i>vic</i>-bromination of diarylacetylenes, easy purification and separation.","authors":"Akane Togo, Hiyono Suzuki, Yuto Akai, Makoto Matsumoto, Yoshinori Suzuma, Hidehiko Kodama, Kouichi Matsumoto","doi":"10.3762/bjoc.22.61","DOIUrl":"10.3762/bjoc.22.61","url":null,"abstract":"<p><p><i>E</i>-Selective bromination for diphenylacetylene was established by using the combination of NBS and FeBr<sub>3</sub> in CH<sub>2</sub>Cl<sub>2</sub>. In addition, easy purification and separation from the crude product were found. When the crude product was treated with heptane, the <i>E</i> isomer could be recovered as a solid material by utilizing the difference in solubility. On the other hand, the <i>Z</i> isomer could be removed by filtration while remaining in solution.</p>","PeriodicalId":8756,"journal":{"name":"Beilstein Journal of Organic Chemistry","volume":"22 ","pages":"795-802"},"PeriodicalIF":2.7,"publicationDate":"2026-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13202478/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148040961","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Martina Vachtlová, Michaela Fecková, Vítězslav Zima, Jan Podlesný, Milan Klikar, Oldřich Pytela, Patrik Pařík, Jakub Opršal, Eliška Juhaňáková, Veronika Chrtová, Filip Bureš
{"title":"Halogenated azobenzene acrylates: from efficient solution photoswitching to stable solid-state photochromic materials.","authors":"Martina Vachtlová, Michaela Fecková, Vítězslav Zima, Jan Podlesný, Milan Klikar, Oldřich Pytela, Patrik Pařík, Jakub Opršal, Eliška Juhaňáková, Veronika Chrtová, Filip Bureš","doi":"10.3762/bjoc.22.60","DOIUrl":"10.3762/bjoc.22.60","url":null,"abstract":"<p><p>The design, synthesis, and comprehensive characterization of six novel halogenated azobenzene acrylate monomers bearing fluorine, chlorine or bromine substituents is reported. The monomers were prepared via a facile three-step synthetic route involving azo-coupling, <i>O-</i>alkylation and <i>O</i>-acylation. Apart from the steady electrochemical properties, halogen substitution proved to be a very useful tool to tune the thermal and optical properties, light-induced switching in particular. Monohalogen derivatives exhibited up to 93% <i>E</i> → <i>Z</i> photoconversion efficiency in solution, whereas the efficiency of dihalogen analogues is lower by 20%, which is ascribed to their nonplanar arrangement. Kinetics studies identified the most stable <i>Z</i>-isomer of the difluoro derivative (<i>τ</i> <sub>1/2</sub> = 3.74/6.59 h at 60 °C in DCE/CDCl<sub>3</sub>). The monofluoro derivative embedded in a polystyrene film demonstrated photoresponsive behavior and remarkable stability by maintaining a macroscopically visible color change for over 90 days. These findings demonstrate that <i>ortho</i>-halogenation is a powerful tool for tuning the properties of photoresponsive materials for potential applications in colorimetric thermal sensing and light-controlled functional systems.</p>","PeriodicalId":8756,"journal":{"name":"Beilstein Journal of Organic Chemistry","volume":"22 ","pages":"782-794"},"PeriodicalIF":2.7,"publicationDate":"2026-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13202476/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148040973","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xi Zhang, Jingyan Wang, Ziqiang Zhao, Caiyi Wang, Zenghui Ye, Wei-Yuan Ma, Jian-Xing Xu, Fengzhi Zhang
{"title":"Design, synthesis, and biological evaluation of FXR/ASK1 dual-target modulators.","authors":"Xi Zhang, Jingyan Wang, Ziqiang Zhao, Caiyi Wang, Zenghui Ye, Wei-Yuan Ma, Jian-Xing Xu, Fengzhi Zhang","doi":"10.3762/bjoc.22.59","DOIUrl":"10.3762/bjoc.22.59","url":null,"abstract":"<p><p>The dual modulation of FXR and ASK1 is considered a promising therapeutic strategy for metabolic dysfunction-associated fatty liver disease (MAFLD) and its progressive form, metabolic dysfunction-associated steatohepatitis (MASH). GW4064 and GS-4997 are effective regulators for FXR and ASK1, respectively. Through the effective functional group splicing strategy, a new dual-target modulator is designed. Compound <b>Z8</b>, which acts on both targets, was found to more potently reduce intracellular lipid droplet accumulation in OA-treated HepG2 cells than the FXR agonist GW4064 and the ASK1 inhibitor selonsertib (GS-4997).</p>","PeriodicalId":8756,"journal":{"name":"Beilstein Journal of Organic Chemistry","volume":"22 ","pages":"771-781"},"PeriodicalIF":2.7,"publicationDate":"2026-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13202473/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148040944","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}