{"title":"Gold extraction at the molecular level using α- and β-cyclodextrins.","authors":"Susana Santos Braga","doi":"10.3762/bjoc.21.89","DOIUrl":"10.3762/bjoc.21.89","url":null,"abstract":"<p><p>Cyclodextrins (CDs) are known for their ability to form supramolecular interactions with a wide range of guest molecules. In this review, focus is given on the inclusion of complex aurate ions such as tetrabromoaurate, dicyanoaurate and a few other tetrahaloaurates. The review describes the properties of self-assembly of cyclodextrins with these ions, with highlight to α-CD and, more recently, β-CD, requiring the use of a co-former/precipitating agent. Practical applications of this ability are directed to the selective isolation of gold from a variety of sources, spanning from gold-rich mining ores and tailings/mining wastes to gold-bearing metal scraps obtained from disposed electronic devices. Moreover, it describes the development of a method based on spontaneous complex formation between α-CD and tetrabromoaurate and its current status of use in a few mining sites in the United States.</p>","PeriodicalId":8756,"journal":{"name":"Beilstein Journal of Organic Chemistry","volume":"21 ","pages":"1116-1125"},"PeriodicalIF":2.2,"publicationDate":"2025-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12152312/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144274131","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}
Erich Gebel, Cornelia Göcke, Carolin Gruner, Norbert Sewald
{"title":"A versatile route towards 6-arylpipecolic acids.","authors":"Erich Gebel, Cornelia Göcke, Carolin Gruner, Norbert Sewald","doi":"10.3762/bjoc.21.88","DOIUrl":"10.3762/bjoc.21.88","url":null,"abstract":"<p><p>Pipecolic acid is known as a non-proteinogenic amino acid with a secondary amine. It contains a six-membered ring and is, like its five-membered correlate, known for its secondary structure inducing properties, which are particularly useful in the design of peptide conformations. We present a new and improved way to generate enantiomerically pure pipecolic acid derivatives with aryl modifications in C<sup>6</sup> position by utilising the chiral pool of a non-proteinogenic amino acid in combination with transition metal-catalysed cross-coupling reactions. Moreover, we present an in-depth NMR analysis of the key intermediate steps, which illustrates the conformational constraints in accordance with coupling constants and resulting dihedral angles.</p>","PeriodicalId":8756,"journal":{"name":"Beilstein Journal of Organic Chemistry","volume":"21 ","pages":"1104-1115"},"PeriodicalIF":2.2,"publicationDate":"2025-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12152316/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144274130","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}
Krishna Pandey, Lucas X Orton, Grayson Venus, Waseem A Hussain, Toby Woods, Lichang Wang, Kyle N Plunkett
{"title":"Supramolecular assembly of hypervalent iodine macrocycles and alkali metals.","authors":"Krishna Pandey, Lucas X Orton, Grayson Venus, Waseem A Hussain, Toby Woods, Lichang Wang, Kyle N Plunkett","doi":"10.3762/bjoc.21.87","DOIUrl":"10.3762/bjoc.21.87","url":null,"abstract":"<p><p>This study explores the solution- and solid-state assembly of phenylalanine-based hypervalent iodine macrocycles (HIMs) with lithium and sodium cations. The metal cation binding of HIMs was evaluated by addition of lithium tetrakis(pentafluorophenyl)borate ethyl etherate LiBArF<sub>20</sub> and sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate NaBArF<sub>24</sub>. The electron-rich, outwardly projected carbonyl oxygens of the HIM co-crystalize with the cations into bent supramolecular architectures. Both crystal structures show a pattern of assembly between HIM and metal cation in 2:1 ratio. While association with sodium leads to a polymer-like network, the lithium crystal structure was limited to dimeric assemblies of HIM. In the lithium-coordinating complex, the oxygen-lithium-oxygen bond angle is approximately 98.83°, displaying a closer arrangement of two HIMs. In contrast, the sodium complex exhibits a more open orientation of two HIMs with an oxygen-sodium-oxygen bond angle close to 167.98°. Lastly, a comparative study of association constants and binding energies for phenylalanine-based HIM with LiBArF<sub>20</sub> and NaBArF<sub>24</sub> are presented.</p>","PeriodicalId":8756,"journal":{"name":"Beilstein Journal of Organic Chemistry","volume":"21 ","pages":"1095-1103"},"PeriodicalIF":2.2,"publicationDate":"2025-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12130623/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144214791","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":"Salen-scandium(III) complex-catalyzed asymmetric (3 + 2) annulation of aziridines and aldehydes.","authors":"Linqiang Wang, Jiaxi Xu","doi":"10.3762/bjoc.21.86","DOIUrl":"10.3762/bjoc.21.86","url":null,"abstract":"<p><p>Oxazolidine is one of the crucial structural moieties of biologically active compounds. A salen-scandium triflate complex-catalyzed asymmetric (3 + 2) annulation of dialkyl 1-sulfonylaziridine-2,2-dicarboxylates and aldehydes generated optically active functionalized oxazolidine derivatives in moderate to good yields and good to excellent enantioselectivities and high diastereoselectivities. A reasonable reaction mechanism was proposed and rationalized the experimental results.</p>","PeriodicalId":8756,"journal":{"name":"Beilstein Journal of Organic Chemistry","volume":"21 ","pages":"1087-1094"},"PeriodicalIF":2.2,"publicationDate":"2025-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12130625/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144214790","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":"Recent advances in synthetic approaches for bioactive cinnamic acid derivatives.","authors":"Betty A Kustiana, Galuh Widiyarti, Teni Ernawati","doi":"10.3762/bjoc.21.85","DOIUrl":"10.3762/bjoc.21.85","url":null,"abstract":"<p><p>Cinnamic acid derivatives represent a significant class of biologically active compounds exhibiting a broad spectrum of activities, such as antifungal, antidengue, antimetastatic, antimicrobial, antibacterial, and anticancer properties. Their preparation has attracted considerable attention due to their versatile applications across the pharmaceutical, food, and chemical sectors. This review elucidates the functional groups of cinnamic acid that are instrumental in the rational design of biologically active derivatives. A comprehensive representative of recent advancements in synthetic methodologies over the past five years is presented, particularly emphasizing the active scaffolds of bioactive cinnamic acid derivatives. The review provides a strategic overview of alternative synthetic routes and highlights the latest innovations, including more efficient, highly selective, and environmentally sustainable approaches. Given the widespread incorporation of the cinnamic acid framework in various therapeutic agents, this review delivers critical insights into a molecular design for hit-to-lead optimization, offering detailed synthetic strategies for diverse functional modifications. By critically examining these methodologies, the paper underscores their role in expanding the utility of cinnamic acid derivatives and addressing prevailing challenges.</p>","PeriodicalId":8756,"journal":{"name":"Beilstein Journal of Organic Chemistry","volume":"21 ","pages":"1031-1086"},"PeriodicalIF":2.2,"publicationDate":"2025-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12130629/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144214789","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":"Biobased carbon dots as photoreductants - an investigation by using triarylsulfonium salts.","authors":"Valentina Benazzi, Arianna Bini, Ilaria Bertuol, Mariangela Novello, Federica Baldi, Matteo Hoch, Alvise Perosa, Stefano Protti","doi":"10.3762/bjoc.21.84","DOIUrl":"10.3762/bjoc.21.84","url":null,"abstract":"<p><p>We investigated the potential application of six types of carbon dots (CDs) obtained from different organic sources as photoreductants. Such carbon nanomaterials were synthesized by two different approaches, either hydrothermal or pyrolytic, from citric acid and glucose as the starting organic substrates. On the other hand, carbon dots deriving from fishery waste (bass scales) and fruit processing waste (blackberries) have been also prepared. Diethylenetriamine was employed in some cases as the nitrogen source. The hydrothermal syntheses yielded amorphous CDs, which were either non-doped (a-CDs) or nitrogen-doped (a-N-CDs), whereas the pyrolytic treatment afforded graphitic CDs (g-CDs). The efficiency of the so obtained carbon nanomaterials was studied in the model photoreduction reaction of triarylsulfonium salts to diaryl sulfides. A comparison carried out on the results obtained points out the key role of the starting substrates in determining the photophysics and the photochemical efficiency of the resulting CDs. In this context, citric acid-derived materials (both graphitic and amorphous) were found as the most promising materials, while less satisfactory results have been observed when using CDs derived from glucose and biowastes.</p>","PeriodicalId":8756,"journal":{"name":"Beilstein Journal of Organic Chemistry","volume":"21 ","pages":"1024-1030"},"PeriodicalIF":2.2,"publicationDate":"2025-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12130624/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144214788","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":"Pd-Catalyzed asymmetric allylic amination with isatin using a P,olefin-type chiral ligand with C-N bond axial chirality.","authors":"Natsume Akimoto, Kaho Takaya, Yoshio Kasashima, Kohei Watanabe, Yasushi Yoshida, Takashi Mino","doi":"10.3762/bjoc.21.83","DOIUrl":"10.3762/bjoc.21.83","url":null,"abstract":"<p><p>In this study, we implemented the P,olefin-type chiral ligand (a<i>R</i>)-(-)-<b>6</b>, which contains a cyclohexyl group and a cinnamoyl group on the nitrogen atom, in the Pd-catalyzed asymmetric allylic amination of allylic esters with isatin derivatives <b>11</b> as nucleophiles. The reaction proceeds efficiently, yielding the products (<i>S</i>)-<b>13</b> with good-to-high enantioselectivity. A scale-up reaction was also successfully conducted at a 1 mmol scale. Additionally, when malononitrile was added to the resulting product (<i>S</i>)-<b>13a</b> in the presence of FeCl<sub>3</sub> as the catalyst, the corresponding malononitrile derivative (<i>S</i>)-<b>16</b> was obtained without any loss in optical purity.</p>","PeriodicalId":8756,"journal":{"name":"Beilstein Journal of Organic Chemistry","volume":"21 ","pages":"1018-1023"},"PeriodicalIF":2.2,"publicationDate":"2025-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12117205/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144172561","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}
Ruben Manuel Figueira de Abreu, Robin Tiedemann, Peter Ehlers, Peter Langer
{"title":"Synthesis of pyrrolo[3,2-<i>d</i>]pyrimidine-2,4(3<i>H</i>)-diones by domino C-N coupling/hydroamination reactions.","authors":"Ruben Manuel Figueira de Abreu, Robin Tiedemann, Peter Ehlers, Peter Langer","doi":"10.3762/bjoc.21.82","DOIUrl":"10.3762/bjoc.21.82","url":null,"abstract":"<p><p>A variety of pyrrolo[3,2-<i>d</i>]pyrimidine-2,4(3<i>H</i>)-diones were prepared by a combination of Sonogashira reaction and subsequent cyclization by domino C-N coupling/hydroamination reaction. The optical properties (UV-vis absorption and fluorescence) depend on the substitution pattern of the compounds.</p>","PeriodicalId":8756,"journal":{"name":"Beilstein Journal of Organic Chemistry","volume":"21 ","pages":"1010-1017"},"PeriodicalIF":2.2,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12117214/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144172591","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":"Recent total synthesis of natural products leveraging a strategy of enamide cyclization.","authors":"Chun-Yu Mi, Jia-Yuan Zhai, Xiao-Ming Zhang","doi":"10.3762/bjoc.21.81","DOIUrl":"10.3762/bjoc.21.81","url":null,"abstract":"<p><p>Enamides are distinctive amphiphilic synthons that can be strategically incorporated into cyclization reactions. The iminium species generated from enamides via nucleophilic addition or substitution are capable of engaging in further electrophilic additions or isomerization processes. Exploiting the multiple reactivities of enamides facilitates the development of diverse cyclization modes that provide entries to various <i>N</i>-heterocycles, some of which serve as key structural motifs in natural alkaloids. This review highlights recent advancements in enamide-based cyclization reactions, including enamide-alkyne cycloisomerization, [3 + 2] annulation, and polycyclization, with a particular emphasis on their pivotal role as a strategy in the total synthesis of natural products.</p>","PeriodicalId":8756,"journal":{"name":"Beilstein Journal of Organic Chemistry","volume":"21 ","pages":"999-1009"},"PeriodicalIF":2.2,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12117209/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144172585","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}
Daniel Straub, Markus Gross, Mona E Arnold, Julia Zolg, Alexander J C Kuehne
{"title":"On the photoluminescence in triarylmethyl-centered mono-, di-, and multiradicals.","authors":"Daniel Straub, Markus Gross, Mona E Arnold, Julia Zolg, Alexander J C Kuehne","doi":"10.3762/bjoc.21.80","DOIUrl":"10.3762/bjoc.21.80","url":null,"abstract":"<p><p>Organic radicals with light-emitting properties and exceptional stability offer exciting opportunities to address spin-statistical limitations in organic electronics and advance quantum technologies. These radicals, acting as small molecular magnets, exhibit sensitivity to minute magnetic fields and can be tailored with diverse spin centers, making them ideal for spin-optical interfaces, representing key components in quantum communication systems. Furthermore, their ability to form organized, higher-dimensional assemblies presents a promising avenue for overcoming scalability challenges in quantum technologies. Despite their potential, achieving high luminescence quantum yields has largely been limited to donor-functionalized monoradicals, and a detailed understanding of the luminescent behavior of open-shell organic molecules remains elusive. This review delves into the photoluminescent properties and spin ground states of trityl-based mono-, di-, and multiradicals, examining the strategies employed to enhance their performance. Additionally, we review predictive methods for determining the luminescence and spin states of radicals, highlighting critical unresolved questions that must be addressed to unlock the full potential of trityl-based radicals in advanced technological applications.</p>","PeriodicalId":8756,"journal":{"name":"Beilstein Journal of Organic Chemistry","volume":"21 ","pages":"964-998"},"PeriodicalIF":2.2,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12117217/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144172559","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}