{"title":"Visible-light-mediated C–S bond activation in cysteine derivatives with quinoxalinones for the synthesis of heteroaryl amino acids†","authors":"Shuqi Ling , Jingjie Hai , Xinyao Li","doi":"10.1039/d4qo02213k","DOIUrl":"10.1039/d4qo02213k","url":null,"abstract":"<div><div>Synthetic strategies for selective chemical modification of natural amino acids and peptides are constantly greatly needed in current state-of-the-art therapeutics. Herein, we report photocatalytic C–S bond activation in cysteine derivatives with quinoxalinones for the synthesis of pharmacologically interesting heteroaryl amino acids. A series of quinoxalinone-conjugated amino acids and oligopeptides as well as caffeine- and isoquinoline-containing amino acids were efficiently obtained through desulfurative heteroarylation of cysteine derivatives. The given approach features a wide substrate scope, mild conditions, good yields and operational simplicity. Furthermore, the <em>N</em>-propargyl quinoxalinone-conjugated amino acids produced can be successfully integrated with biotin–PEG3–azide through click chemistry for potential applications in immunology and histochemistry.</div></div>","PeriodicalId":94379,"journal":{"name":"Organic chemistry frontiers : an international journal of organic chemistry","volume":"12 6","pages":"Pages 2018-2024"},"PeriodicalIF":0.0,"publicationDate":"2025-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143027043","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Niklāvs Ūdris , Rebeka Ločmele , Juris Pelšs , Anastasija Ture , Guna Sakaine , Artis Kinēns , Gints Smits
{"title":"Enantiopure piperidines via stereoselective Ireland–Claisen rearrangement: entry into corynanthe alkaloids†","authors":"Niklāvs Ūdris , Rebeka Ločmele , Juris Pelšs , Anastasija Ture , Guna Sakaine , Artis Kinēns , Gints Smits","doi":"10.1039/d4qo02235a","DOIUrl":"10.1039/d4qo02235a","url":null,"abstract":"<div><div>A fully stereo-divergent Ireland–Claisen rearrangement of achiral lactones has been developed, enabling access to all four possible stereoisomers of 3,4-disubstituted piperidines and pyrrolidines. The utility of these building blocks has been showcased in the total synthesis of meroquinene ester and cardioprotective indole alkaloids sitsirikine and dihydrositsirikine.</div></div>","PeriodicalId":94379,"journal":{"name":"Organic chemistry frontiers : an international journal of organic chemistry","volume":"12 6","pages":"Pages 1945-1950"},"PeriodicalIF":0.0,"publicationDate":"2025-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142992607","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Dmitry L. Lipilin , Mikhail O. Zubkov , Mikhail D. Kosobokov , Alexander D. Dilman
{"title":"Photocatalytic anti-Markovnikov addition of carboxylic acids to alkenes: an ionic mechanism under radical conditions†","authors":"Dmitry L. Lipilin , Mikhail O. Zubkov , Mikhail D. Kosobokov , Alexander D. Dilman","doi":"10.1039/d4qo02280g","DOIUrl":"10.1039/d4qo02280g","url":null,"abstract":"<div><div>Since the advent of photocatalysis, radical addition to alkenes has become one of the most fruitful processes for building up molecular complexity. Herein we describe a novel approach towards photocatalytic addition to alkenes, in which both new C–O and C–H bonds are formed by an ionic mechanism, rather than the conventional radical mechanism. This occurs due to two consecutive radical-polar crossover events, enabling the generation of both radical cation and carbanion species during the reaction. Such a transformation is demonstrated by the acridine-catalyzed addition of carboxylic acids to styrenes. This unique mechanism allows one to carry out the reaction in the absence of additives and also to reverse the regioselectivity of conventional ionic addition to alkenes.</div></div>","PeriodicalId":94379,"journal":{"name":"Organic chemistry frontiers : an international journal of organic chemistry","volume":"12 6","pages":"Pages 1918-1926"},"PeriodicalIF":0.0,"publicationDate":"2025-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142975561","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kang Lv , Yihang Zhou , Zitong Meng , Jing Zhang , Tao Liu
{"title":"Computational study on Pd-catalyzed ipso,meta-dimethylation of ortho-substituted iodoarenes: mechanisms and the role of the base†","authors":"Kang Lv , Yihang Zhou , Zitong Meng , Jing Zhang , Tao Liu","doi":"10.1039/d4qo02168a","DOIUrl":"10.1039/d4qo02168a","url":null,"abstract":"<div><div>Density functional theory (DFT) calculations were performed to study Pd-catalyzed <em>ipso</em>,<em>meta</em>-dimethylation reactions of <em>ortho</em>-substituted iodoarenes. In the presence of K<sub>2</sub>CO<sub>3</sub>, aryl-I oxidative addition on Pd(0) catalysts can generate an arylpalladium(<span>ii</span>) intermediate, which undergoes two sequential processes of C–H activation, CH<sub>3</sub>–I oxidative addition (Ar–C reductive elimination/CH<sub>3</sub>–I oxidative addition/Ar–C oxidative addition), and Ar–C reductive elimination to generate a dimethylated intermediate. Then hydrogen transfer, C-hydride reductive elimination, and ligand exchange can take place to generate 2,6-dimethylanisole . With KOAc as the base, 2,3-dihydrobenzofuran can be obtained <em>via</em> aryl-I oxidative addition, two sequential processes of C–H activation/Ar–C reductive elimination/CH<sub>3</sub>–I oxidative addition/Ar–C oxidative addition/Ar–C reductive elimination, the third C–H activation, reductive elimination, and ligand exchange, respectively. The competition between the third C–H activation and the hydrogen transfer from the dimethylated intermediate determines the selectivity of the reaction. The hydrogen transfer is generally superior to the third C–H activation due to the stronger reactivity of the methyl group in methanol than a normal methyl group. When K<sub>2</sub>CO<sub>3</sub> is used, such an electronic effect is dominant. However, when KOAc is employed, its different structure and properties compared to K<sub>2</sub>CO<sub>3</sub> make the ligand exchange step highly endergonic, thereby rendering subsequent hydrogen transfer unfavorable and leading to 2,3-dihydrobenzofuran as the final product.</div></div>","PeriodicalId":94379,"journal":{"name":"Organic chemistry frontiers : an international journal of organic chemistry","volume":"12 6","pages":"Pages 1792-1802"},"PeriodicalIF":0.0,"publicationDate":"2025-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142937397","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Synthesis of a cross-chain bridging cryptand†‡","authors":"Takafumi Yashima , Ryoga Hori , Taisei Maruyama , Kohta Nakashima , Hiroki Fujihara , Masaya Naito , Shinobu Miyagawa , Yuji Tokunaga","doi":"10.1039/d4qo02330g","DOIUrl":"10.1039/d4qo02330g","url":null,"abstract":"<div><div>We present two methodologies for synthesizing cross-chain bridging cryptand that incorporates tri- and tetra(ethylene glycol) linkers (methods B and C). Method B involves the synthesis through the intramolecular cross-linking of <em>C</em><sub>2</sub>-symmetric crown ether . While this method does not substantially reduce the lengthy reaction steps compared to the previous approach, it improves the overall yield of cryptand containing three tri(ethylene glycol) linkers and allows for the creation of a new form of a cross-chain bridging cryptand with one distinct and two identical linkers. However, method C entails a synthesis accomplished through a triple-linking reaction in a single step. This method offered a streamlined synthesis of cryptand . The crucial triple linking reaction produced cross-chain bridging cryptand as the major isomer and the corresponding linear regioisomer as the minor isomer. Moreover, we observed the interconversion of enantiomers of cryptand , which contains a 28-membered macrocycle, under chiral high-performance liquid chromatographic (HPLC) analytical conditions (with a half-life of 20.7 min at room temperature). Finally, X-ray crystallography confirmed the cross-chain bridging structure in the two chemically equivalent chains in the solid state of cryptand .</div></div>","PeriodicalId":94379,"journal":{"name":"Organic chemistry frontiers : an international journal of organic chemistry","volume":"12 6","pages":"Pages 1754-1762"},"PeriodicalIF":0.0,"publicationDate":"2025-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2025/qo/d4qo02330g?page=search","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142939653","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Chunmei Chen , Jian Cai , Chun Yang , Yi Chen , Manli Liu , Wei Fang , Bin Yang , Huaming Tao , Yonghong Liu , Xuefeng Zhou
{"title":"From monomers to pentamers, diverse antimicrobial benzofuran polyketides from marine-derived Striaticonidium cinctum†","authors":"Chunmei Chen , Jian Cai , Chun Yang , Yi Chen , Manli Liu , Wei Fang , Bin Yang , Huaming Tao , Yonghong Liu , Xuefeng Zhou","doi":"10.1039/d4qo02409e","DOIUrl":"10.1039/d4qo02409e","url":null,"abstract":"<div><div>Chemical investigation of the mangrove sediment-derived fungus <em>Striaticonidium cinctum</em> SCSIO 41432 resulted in the isolation of 27 new benzofuran polyketides, including diverse monomeric (), dimeric ( and ), trimeric (), tetrameric ( and ) and pentameric () derivatives. Their structures including absolute configurations were confirmed by extensive analysis of the spectroscopic data, Mosher's method, Mo<sub>2</sub>(OAc)<sub>4</sub>-induced circular dichroism, ECD calculations and single-crystal X-ray diffraction. Structurally, di-stribenfurans A and B ( and ) were deduced to be rare nonsymmetric C–C linked benzofuran dimers, while trimeric to pentameric benzofurans () were unprecedented polymers with sulfinyl and ether bridges. The antimicrobial assay against twelve plant pathogenic fungi and four bacterial strains revealed that most of the monomers showed better antibiotic activities than monomeric glycosides and polymers. The sulfinyl moiety in monomers leads to stronger antibacterial effects instead of antifungal activity. Remarkably, stribenfuran U () displayed the strongest antifungal activity against <em>Colletotrichum gloeosporioides</em> with a MIC value of 0.78 μg mL<sup>−1</sup>. Further microscopy analysis showed that could destroy the cell membrane structure of the hyphae of <em>C. gloeosporioides</em> and cause the surface to exhibit obvious pits and folds. This study expanded the structural variety of natural benzofuran derivatives and laid a robust foundation for the development of benzofurans as antifungal lead drugs.</div></div>","PeriodicalId":94379,"journal":{"name":"Organic chemistry frontiers : an international journal of organic chemistry","volume":"12 6","pages":"Pages 1725-1732"},"PeriodicalIF":0.0,"publicationDate":"2025-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143050736","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mengzhe Pan , Feng-Wei Guo , Xinjie Sun , Jie Zhang , Wei Lu , Lubin Xu , Fangzhi Hu , Shuai-Shuai Li
{"title":"Divergent application of 5-amino-isoxazoles for the construction of nitrogen heterocycles via the hydride transfer strategy†","authors":"Mengzhe Pan , Feng-Wei Guo , Xinjie Sun , Jie Zhang , Wei Lu , Lubin Xu , Fangzhi Hu , Shuai-Shuai Li","doi":"10.1039/d4qo02059f","DOIUrl":"10.1039/d4qo02059f","url":null,"abstract":"<div><div>The hydride transfer-enabled divergent application of 5-amino-isoxazoles for the controllable construction of diverse tetrahydroquinolines and tetrahydroquinazolines was disclosed unprecedentedly by the process of ring-cleavage/Beckmann rearrangement, dearomative-spirocyclization, or <em>N</em>,<em>N</em>′-dialkylation of the amino group with the employment of different Lewis acids.</div></div>","PeriodicalId":94379,"journal":{"name":"Organic chemistry frontiers : an international journal of organic chemistry","volume":"12 6","pages":"Pages 1867-1873"},"PeriodicalIF":0.0,"publicationDate":"2025-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142987685","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Feng Chen , Yijun Duan , Ye Guo , Yuncheng Liu , Ming Lang , Jinbao Peng , Shiyong Peng
{"title":"An unexpected Lewis acid-catalyzed cascade reaction of bicyclo[1.1.0]butanes with triazinanes toward biscyclobutenyl amines†","authors":"Feng Chen , Yijun Duan , Ye Guo , Yuncheng Liu , Ming Lang , Jinbao Peng , Shiyong Peng","doi":"10.1039/d4qo02245a","DOIUrl":"10.1039/d4qo02245a","url":null,"abstract":"<div><div>An unexpected In(OTf)<sub>3</sub>-catalyzed cascade reaction of bicyclo[1.1.0]butanes with triazinanes is reported, providing a series of butterfly-shaped biscyclobutenyl amines in good yields. This reaction features simple operation, mild reaction conditions, and broad substrate scope. A rational mechanism involving a key carbocation intermediate is proposed.</div></div>","PeriodicalId":94379,"journal":{"name":"Organic chemistry frontiers : an international journal of organic chemistry","volume":"12 6","pages":"Pages 1815-1820"},"PeriodicalIF":0.0,"publicationDate":"2025-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142936513","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xiaojie Li , Yishuai Fan , Haoran Yang , Ruwei Shen
{"title":"Bridged rings from phenolic feedstocks: regio- and diastereoselective substitution-hemiketalization cyclization of bridged benzoxocin-4-ones with Grignard reagents†‡","authors":"Xiaojie Li , Yishuai Fan , Haoran Yang , Ruwei Shen","doi":"10.1039/d4qo02197e","DOIUrl":"10.1039/d4qo02197e","url":null,"abstract":"<div><div>The efficient and controllable generation of bridged polycycles with structural complexity and diversity from readily available feedstocks is highly important for modern organic synthesis, chemical biology and drug discovery. Here, we present a unique substitution-hemiketalization cyclization of readily available bridged benzoxocin-4-ones with Grignard reagents, which leads to a facile synthesis of a diverse portfolio of bridged benzoxocin-2-ol frameworks. The reaction features high regioselectivity and diastereoselectivity, while accommodating a broad scope of Grignard reagents. The electrophilic capture of organomagnesium intermediates generated in the reaction enables one-pot access to bridged polycyclic benzoxocin-2-ols with enhanced complexity and diversity. Collectively, this work showcases a conceptual strategy that can efficiently generate structurally rich and complex bridged ring skeletons essentially from phenolic feedstocks.</div></div>","PeriodicalId":94379,"journal":{"name":"Organic chemistry frontiers : an international journal of organic chemistry","volume":"12 6","pages":"Pages 1858-1866"},"PeriodicalIF":0.0,"publicationDate":"2025-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142936509","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Qi Xue , Zheng-Li Fu , Wen-Yu Zhang , Xia-Lu Cheng , Yang Li , Hu Cai , Jin-Heng Li
{"title":"Palladium-catalyzed multicomponent [4 + 2] cycloaddition of 1,4-enynes with CO and arylamines to access polycyclic γ-lactams via dearomative rearrangement†","authors":"Qi Xue , Zheng-Li Fu , Wen-Yu Zhang , Xia-Lu Cheng , Yang Li , Hu Cai , Jin-Heng Li","doi":"10.1039/d4qo02304h","DOIUrl":"10.1039/d4qo02304h","url":null,"abstract":"<div><div>Herein we report a palladium-catalyzed intermolecular dearomative [4 + 2] cycloaddition of 1,4-enynes with CO and arylamines. Compared with the well-known Himbert intramolecular arene/allene cycloaddition, this method provides a facile platform for the synthesis of polycyclic γ-lactams, through the formation of four new chemical bonds (three C–C bonds and one C–N bond) in a single step, with excellent functional-group tolerance and high atom-economy.</div></div>","PeriodicalId":94379,"journal":{"name":"Organic chemistry frontiers : an international journal of organic chemistry","volume":"12 6","pages":"Pages 1827-1832"},"PeriodicalIF":0.0,"publicationDate":"2025-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142937396","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}