Pengkuo Shi, Chun Yang, Nana Shen, Haiyun Xu, Xinying Zhang, Xuesen Fan
Presented herein is a concise and divergent synthesis of oxindole spirohydropyridine derivatives based on the reaction of enaminone with diazo oxindole. In forming the hydropyridine skeleton, one enaminone acts as a C2N1 synthon and another enaminone acts as a C2 synthon while diazo oxindole acts as a C1 synthon. Interestingly, by altering the substructure of enaminone, spirotetrahydropyridine or spirodihydropyridine scaffold could be constructed in a highly selective manner. To our knowledge, this should be the first report on the synthesis of diversely substituted oxindole spirohydropyridine derivatives based on alkenyl C−H bond activation-initiated cascade reaction of enaminone with diazo compound. In general, this novel protocol features simple and affordable substrates, valuable products, concise one-pot procedure, intriguing reaction pathway, excellent selectivity, good step-/atom-economy, and ready scalability.
{"title":"CHA-Initiated [3 + 2 + 1] Spiroannulation of Enaminone with Diazo Oxindole Leading to Concise and Divergent Synthesis of Oxindole Spirohydropyridines","authors":"Pengkuo Shi, Chun Yang, Nana Shen, Haiyun Xu, Xinying Zhang, Xuesen Fan","doi":"10.1039/d5qo01702e","DOIUrl":"https://doi.org/10.1039/d5qo01702e","url":null,"abstract":"Presented herein is a concise and divergent synthesis of oxindole spirohydropyridine derivatives based on the reaction of enaminone with diazo oxindole. In forming the hydropyridine skeleton, one enaminone acts as a C2N1 synthon and another enaminone acts as a C2 synthon while diazo oxindole acts as a C1 synthon. Interestingly, by altering the substructure of enaminone, spirotetrahydropyridine or spirodihydropyridine scaffold could be constructed in a highly selective manner. To our knowledge, this should be the first report on the synthesis of diversely substituted oxindole spirohydropyridine derivatives based on alkenyl C−H bond activation-initiated cascade reaction of enaminone with diazo compound. In general, this novel protocol features simple and affordable substrates, valuable products, concise one-pot procedure, intriguing reaction pathway, excellent selectivity, good step-/atom-economy, and ready scalability.","PeriodicalId":97,"journal":{"name":"Organic Chemistry Frontiers","volume":"64 1","pages":""},"PeriodicalIF":5.4,"publicationDate":"2026-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146115609","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Alejandro Lumbreras-Teijeiro, Daniel Pérez de los Cobos-Pérez, Susi Hervàs-Arnandis, Marta Mon, Judit Oliver-Meseguer, Antonio Leyva-Perez
We show here that the ester-assisted hydration of alkynyl β-ketoesters does not require any commercial metal catalyst but just protons in water (either in solution or on a recyclable solid) or metals recycled from e-waste (typically Au) to give not the expected ketones but a variety of polymethylated carbocycle compounds (hydroindanes, decalines, cyclohexanones and fluorenes) in good yields and selectivity, after a three-to-five step cascade reaction.
{"title":"A metal-free or metal e-waste catalysed alkyne hydrationcondensation-decarboxylation cascade reaction in water gives access to (fused) carbocycles","authors":"Alejandro Lumbreras-Teijeiro, Daniel Pérez de los Cobos-Pérez, Susi Hervàs-Arnandis, Marta Mon, Judit Oliver-Meseguer, Antonio Leyva-Perez","doi":"10.1039/d5qo01729g","DOIUrl":"https://doi.org/10.1039/d5qo01729g","url":null,"abstract":"We show here that the ester-assisted hydration of alkynyl β-ketoesters does not require any commercial metal catalyst but just protons in water (either in solution or on a recyclable solid) or metals recycled from e-waste (typically Au) to give not the expected ketones but a variety of polymethylated carbocycle compounds (hydroindanes, decalines, cyclohexanones and fluorenes) in good yields and selectivity, after a three-to-five step cascade reaction.","PeriodicalId":97,"journal":{"name":"Organic Chemistry Frontiers","volume":"108 1","pages":""},"PeriodicalIF":5.4,"publicationDate":"2026-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146101953","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Herein, we report a Pd-catalyzed, base-controlled divergent cyclization strategy for the synthesis of polycyclic indole derivatives. Utilizing 3-propargyl indoles and ortho-iodophenyl-ynones as substrates, the reaction pathway can be tuned by the choice of a base: (1) with DIPA, the reaction proceeds through Pd-catalyzed cross-coupling, propargylic Alder ene-type reaction (1,8-H transfer), and indole-migrative cyclization to afford cycloheptatriene[b]indole scaffolds; (2) NIS was incorporated into the reaction system with the purpose of capturing the indole-allene intermediate, and it successfully yielded spiro cyclopentene[b]indole derivatives; (3) alternatively, DBU promotes a distinct pathway involving Pd-catalyzed cross-coupling, propargyl-allenyl isomerization (1,3-H transfer), [4+2] cycloaddition and aromatization to generate carbazole scaffolds. The proposed reaction mechanism is supported by experimental investigations.
{"title":"Skeletal diversity-oriented synthesis of cycloheptatriene[b]indole, spiro-cyclopentene[b]indole and carbazole derivatives via Pd-catalyzed sequential reaction involving indolyl allene intermediates","authors":"Yu Xin, Xinxin Chen, Zebang Meng, Ruwei Shen, Shugao Zhu","doi":"10.1039/d5qo01651g","DOIUrl":"https://doi.org/10.1039/d5qo01651g","url":null,"abstract":"Herein, we report a Pd-catalyzed, base-controlled divergent cyclization strategy for the synthesis of polycyclic indole derivatives. Utilizing 3-propargyl indoles and ortho-iodophenyl-ynones as substrates, the reaction pathway can be tuned by the choice of a base: (1) with DIPA, the reaction proceeds through Pd-catalyzed cross-coupling, propargylic Alder ene-type reaction (1,8-<em>H</em> transfer), and indole-migrative cyclization to afford cycloheptatriene[<em>b</em>]indole scaffolds; (2) NIS was incorporated into the reaction system with the purpose of capturing the indole-allene intermediate, and it successfully yielded spiro cyclopentene[<em>b</em>]indole derivatives; (3) alternatively, DBU promotes a distinct pathway involving Pd-catalyzed cross-coupling, propargyl-allenyl isomerization (1,3-<em>H</em> transfer), [4+2] cycloaddition and aromatization to generate carbazole scaffolds. The proposed reaction mechanism is supported by experimental investigations.","PeriodicalId":97,"journal":{"name":"Organic Chemistry Frontiers","volume":"6 1","pages":""},"PeriodicalIF":5.4,"publicationDate":"2026-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146115610","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Chiral fluorinated amine compounds are valuable and important synthetic intermediates for the synthesis of biologically active compounds and natural products. Therefore, developing efficient synthetic methods for these compounds holds great significance for both theoretical research and industrial applications. Over the past few decades, chemists have made relentless efforts and developed a series of methods for synthesizing chiral α-trifluoromethyl amines. Herein, we focus on reviewing recent research progress in the synthesis of α-trifluoromethyl amines through asymmetric catalytic reactions of trifluoromethylated imines, mainly divided into two parts: the asymmetric reduction of trifluoromethylated imines and the nucleophilic addition to trifluoromethylated imines.
{"title":"Synthesis of Chiral α-Trifluoromethyl amines via Asymmetric reaction of Trifluoromethylated Imines","authors":"Wei Chen, Wei Chen, Qin Yang, Yiyuan Peng","doi":"10.1039/d6qo00001k","DOIUrl":"https://doi.org/10.1039/d6qo00001k","url":null,"abstract":"Chiral fluorinated amine compounds are valuable and important synthetic intermediates for the synthesis of biologically active compounds and natural products. Therefore, developing efficient synthetic methods for these compounds holds great significance for both theoretical research and industrial applications. Over the past few decades, chemists have made relentless efforts and developed a series of methods for synthesizing chiral α-trifluoromethyl amines. Herein, we focus on reviewing recent research progress in the synthesis of α-trifluoromethyl amines through asymmetric catalytic reactions of trifluoromethylated imines, mainly divided into two parts: the asymmetric reduction of trifluoromethylated imines and the nucleophilic addition to trifluoromethylated imines.","PeriodicalId":97,"journal":{"name":"Organic Chemistry Frontiers","volume":"180 1","pages":""},"PeriodicalIF":5.4,"publicationDate":"2026-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146070730","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xin Liu, Min Liang, Jingyi Guo, Jin Yang, Jingyu Zhang, Yingsheng Zhao
In the frontier of organofluorine chemistry, the synthesis of fluorinated amino acids remains a critical challenge that demands further methodological development. This study reports the exploration of carbon-carbon coupling reactions using fluoroamino acids as coupling substrates, revealing an unconventional pathway for obtaining Z-alkene products. The coordination interactions between the oxygen atom in the amino acid scaffold and the palladium catalytic center induce stereoselectivity. The analysis of the systematic reaction pathway, synthesis and characterization of key intermediates, and computational investigations were conducted for a comprehensive mechanistic elucidation. Beyond establishing a protocol for synthesizing Z-fluoro dehydroalkynyl amino acids, we highlight the dual role of amino acid frameworks. Although traditionally recognized for their bioactivity, these structural motifs can uniquely direct the catalytic cycles. Our mechanistic insights can offer valuable guidance for the rational design of fluorinated amino acid derivatives required in synthetic and pharmaceutical applications.
{"title":"Palladium-Catalyzed Z-Selective Alkynylation of gem-Difluoro alkenes via Carbon-Fluorine Bond Activation: Mechanistic Insights into Oxygen-Directed Regiocontrol","authors":"Xin Liu, Min Liang, Jingyi Guo, Jin Yang, Jingyu Zhang, Yingsheng Zhao","doi":"10.1039/d5qo01674f","DOIUrl":"https://doi.org/10.1039/d5qo01674f","url":null,"abstract":"In the frontier of organofluorine chemistry, the synthesis of fluorinated amino acids remains a critical challenge that demands further methodological development. This study reports the exploration of carbon-carbon coupling reactions using fluoroamino acids as coupling substrates, revealing an unconventional pathway for obtaining Z-alkene products. The coordination interactions between the oxygen atom in the amino acid scaffold and the palladium catalytic center induce stereoselectivity. The analysis of the systematic reaction pathway, synthesis and characterization of key intermediates, and computational investigations were conducted for a comprehensive mechanistic elucidation. Beyond establishing a protocol for synthesizing Z-fluoro dehydroalkynyl amino acids, we highlight the dual role of amino acid frameworks. Although traditionally recognized for their bioactivity, these structural motifs can uniquely direct the catalytic cycles. Our mechanistic insights can offer valuable guidance for the rational design of fluorinated amino acid derivatives required in synthetic and pharmaceutical applications.","PeriodicalId":97,"journal":{"name":"Organic Chemistry Frontiers","volume":"3 1","pages":""},"PeriodicalIF":5.4,"publicationDate":"2026-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146098113","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rihárd Sisa, János Tivadar Csenki, Flavián Domány, Dóra Ágocsi-Kiss, Levente Dókus, Gábor Mező, Péter Pál Fehér, András Stirling, Anna Kiss-Szeman, Zoltán Novák
A methodology for peptide cross-linking was developed via direct fluoroalkenylation of tyrosine, utilizing a special fluoroalkyl-aryl iodonium salt derived from HFO1234yf gas. The approach enables selective conjugation of two phenolic OH groups, facilitating covalent linkage within tyrosine-containing peptides. Beyond the amino acid compatibility screen, as a key demonstration, a tyrosine-based pentapeptide was successfully cross-linked under optimized conditions, highlighting the method’s potential in peptide engineering and bioconjugation. Besides peptides, the strategy was also applicable to various functionalized phenols, to synthesize unique 1,2-diaryloxyethenes. Mechanistic insights were supported by theoretical calculations, providing a deeper understanding of the transformation pathway.
{"title":"Iodonium based cross-linking tool for tyrosine conjugation","authors":"Rihárd Sisa, János Tivadar Csenki, Flavián Domány, Dóra Ágocsi-Kiss, Levente Dókus, Gábor Mező, Péter Pál Fehér, András Stirling, Anna Kiss-Szeman, Zoltán Novák","doi":"10.1039/d5qo01572c","DOIUrl":"https://doi.org/10.1039/d5qo01572c","url":null,"abstract":"A methodology for peptide cross-linking was developed via direct fluoroalkenylation of tyrosine, utilizing a special fluoroalkyl-aryl iodonium salt derived from HFO1234yf gas. The approach enables selective conjugation of two phenolic OH groups, facilitating covalent linkage within tyrosine-containing peptides. Beyond the amino acid compatibility screen, as a key demonstration, a tyrosine-based pentapeptide was successfully cross-linked under optimized conditions, highlighting the method’s potential in peptide engineering and bioconjugation. Besides peptides, the strategy was also applicable to various functionalized phenols, to synthesize unique 1,2-diaryloxyethenes. Mechanistic insights were supported by theoretical calculations, providing a deeper understanding of the transformation pathway.","PeriodicalId":97,"journal":{"name":"Organic Chemistry Frontiers","volume":"2 1","pages":""},"PeriodicalIF":5.4,"publicationDate":"2026-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146070729","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Wei Sun, Xue-Song Peng, Guo-Yin Sun, Juan Liao, Lei Yang, Yan-Ping Zhang, Jian-Qiang Zhao, Ming-Qiang Zhou, Wei-Cheng Yuan
A palladium-catalyzed decarboxylation of α,α-diester-δ-vinylvalerolactones was developed to in situ generate all-carbon π-allylpalladium species that can act as 1,4-dipoles. These intermediates were successfully applied in [4+2] cycloaddition reaction with 3-alkenyloxindoles and 2-benzylideneindan-1,3-diones for the construction of a diverse array of spirocyclohexane compounds in high yields with excellent diastereoselectivities. Furthermore, the same in situ generated 1,4 dipoles were also employed in [4+2] cycloaddition with 2-benzylidenemalononitriles for the synthesis of polysubstituted cyclohexanes. Notably, the current cycloaddition reactions proceed via the all-carbon π-allylpalladium intermediates acting as 1,4-dipoles with exclusive branch selectivity, which is different from the previously reported serving as 1,6-dipoles with liner selectivity. The practicality of this methodology was further demonstrated by a gram-scale reaction and further transformations of products.
{"title":"Palladium-catalyzed decarboxylative [4+2] cycloaddition of δ-vinylvalerolactones for the synthesis of spirocyclohexane compounds","authors":"Wei Sun, Xue-Song Peng, Guo-Yin Sun, Juan Liao, Lei Yang, Yan-Ping Zhang, Jian-Qiang Zhao, Ming-Qiang Zhou, Wei-Cheng Yuan","doi":"10.1039/d5qo01724f","DOIUrl":"https://doi.org/10.1039/d5qo01724f","url":null,"abstract":"A palladium-catalyzed decarboxylation of α,α-diester-δ-vinylvalerolactones was developed to in situ generate all-carbon π-allylpalladium species that can act as 1,4-dipoles. These intermediates were successfully applied in [4+2] cycloaddition reaction with 3-alkenyloxindoles and 2-benzylideneindan-1,3-diones for the construction of a diverse array of spirocyclohexane compounds in high yields with excellent diastereoselectivities. Furthermore, the same in situ generated 1,4 dipoles were also employed in [4+2] cycloaddition with 2-benzylidenemalononitriles for the synthesis of polysubstituted cyclohexanes. Notably, the current cycloaddition reactions proceed via the all-carbon π-allylpalladium intermediates acting as 1,4-dipoles with exclusive branch selectivity, which is different from the previously reported serving as 1,6-dipoles with liner selectivity. The practicality of this methodology was further demonstrated by a gram-scale reaction and further transformations of products.","PeriodicalId":97,"journal":{"name":"Organic Chemistry Frontiers","volume":"17 1","pages":""},"PeriodicalIF":5.4,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146098114","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The tandem Scholl reaction serves as a facile synthetic method to access large polycyclic aromatic hydrocarbons due to its capability in constructing both intra-and intermolecular C-C bonds in one process. In this work, we synthesize two simple substrate molecules each containing a naphthyl unit and examine their reactivity under the classic conditions of the Scholl reaction. As a consequence, twisted nanographenes 2 and 4 featuring an appealing π-scaffold of doubly helical and helicalaxial-helical arrangement, respectively, are obtained. The mechanisms behind these two interesting Scholl reactions are rationalized by means of the DFT calculations. Owing to a blend of three stereogenic centers in the structure of 4, we separate two pairs of enantiomers, namely 4a and 4b, that adopt (P,S,M)/(M,R,P) and (P,S,P)/(M,R,M) configuration, respectively. The thermal isomerization of 4b gives rise to another pair of enantiomers, (P,R,P)/(M,S,M)-4, which exists in an equilibrium with 4b through the rotation at the axially chiral linkage. However, the flipping of the [6]helicene moieties in 4 is prohibited due to the considerably large energy barrier. Our study enriches the versatile use of the Scholl reaction in the construction of π-aromatic nanocarbons.
{"title":"Tandem Scholl Reaction for the Synthesis of Twisted Nanographenes","authors":"Zixian Wu, Zheng Zhou, Yuanjian Zhang, Yong Yang","doi":"10.1039/d6qo00004e","DOIUrl":"https://doi.org/10.1039/d6qo00004e","url":null,"abstract":"The tandem Scholl reaction serves as a facile synthetic method to access large polycyclic aromatic hydrocarbons due to its capability in constructing both intra-and intermolecular C-C bonds in one process. In this work, we synthesize two simple substrate molecules each containing a naphthyl unit and examine their reactivity under the classic conditions of the Scholl reaction. As a consequence, twisted nanographenes 2 and 4 featuring an appealing π-scaffold of doubly helical and helicalaxial-helical arrangement, respectively, are obtained. The mechanisms behind these two interesting Scholl reactions are rationalized by means of the DFT calculations. Owing to a blend of three stereogenic centers in the structure of 4, we separate two pairs of enantiomers, namely 4a and 4b, that adopt (P,S,M)/(M,R,P) and (P,S,P)/(M,R,M) configuration, respectively. The thermal isomerization of 4b gives rise to another pair of enantiomers, (P,R,P)/(M,S,M)-4, which exists in an equilibrium with 4b through the rotation at the axially chiral linkage. However, the flipping of the [6]helicene moieties in 4 is prohibited due to the considerably large energy barrier. Our study enriches the versatile use of the Scholl reaction in the construction of π-aromatic nanocarbons.","PeriodicalId":97,"journal":{"name":"Organic Chemistry Frontiers","volume":"102 3 1","pages":""},"PeriodicalIF":5.4,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146057157","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Selective functionalization of remote C(sp3)–H bonds represents a major challenge in organic synthesis. We report a unified visible-light photoredox catalytic strategy for remote C(sp3)–H cyanation and deuteration of amides. Key to this approach is the in situ generation of aryl radicals from ortho-iodobenzoyl-derived amides, which triggers intramolecular 1,5-hydrogen atom transfer to form α-carbon radicals. These intermediates undergo divergent trapping to afford α-cyano- or α-deuterated amides. The cyanation protocol features broad substrate scope, good to excellent yields, and late-stage functionalization capability. The deuteration protocol, using D2O, delivers α-deuterated amides with high deuterium incorporation and functional group tolerance. Mechanistic studies support a pathway involving aryl radical-mediated 1,5-HAT. This strategy offers an efficient and general route to valuable α-functionalized amide derivatives from readily available precursors.
{"title":"Remote C(sp3)–H Cyanation and Deuteration of Amides via Photoredox Catalysis","authors":"Wenjie Yan, Jia-Lin Tu, Zhuohua Li, Lin Guo, Jiabin Shen, Chao Yang, Wujiong Xia","doi":"10.1039/d5qo01746g","DOIUrl":"https://doi.org/10.1039/d5qo01746g","url":null,"abstract":"Selective functionalization of remote C(sp3)–H bonds represents a major challenge in organic synthesis. We report a unified visible-light photoredox catalytic strategy for remote C(sp3)–H cyanation and deuteration of amides. Key to this approach is the in situ generation of aryl radicals from ortho-iodobenzoyl-derived amides, which triggers intramolecular 1,5-hydrogen atom transfer to form α-carbon radicals. These intermediates undergo divergent trapping to afford α-cyano- or α-deuterated amides. The cyanation protocol features broad substrate scope, good to excellent yields, and late-stage functionalization capability. The deuteration protocol, using D2O, delivers α-deuterated amides with high deuterium incorporation and functional group tolerance. Mechanistic studies support a pathway involving aryl radical-mediated 1,5-HAT. This strategy offers an efficient and general route to valuable α-functionalized amide derivatives from readily available precursors.","PeriodicalId":97,"journal":{"name":"Organic Chemistry Frontiers","volume":"87 1","pages":""},"PeriodicalIF":5.4,"publicationDate":"2026-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146048736","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Edem R. Chakalov, Daria I. Tonkoglazova, Anna A. Titova, Maxim L. Kruglov, elena tupikina, Alexander S. Antonov, Peter Tolstoy
Configurational diversity and mechanisms of prototropic tautomerism of 15 N,N’-diarylbenzamidines as potential building blocks in H-bonded polymeric materials are investigated. Variable-temperature 1D and 2D liquid-state NMR spectroscopic studies provide strong evidence of the solvent-dependent dynamic interconversion between all four isomers, E-anti, E-syn, Z-anti and Z-syn. Some of the isomers are prone to either a linear or a cyclic dimerization through H-bonding. A quantitative assessment of the changes in proton-donating ability of the amine functionality depending on electron-donating ability of para-substituents in all three aryl rings of N,N’-diarylbenzamidines is proposed based on the 1H NMR data and Hammett’s substituents constants. A different pattern of the ordered H-bonded network composed exclusively of non-planar E-syn isomers is observed in the solid state by X-ray diffraction studies. DFT calculations confirm the torsional flexibility of the molecules, which are able to closely approach each other and form various linear and cyclic dimers, for which the relative stability is determined by the interplay of NH···N hydrogen bonding and π-π stacking interactions. Rotational barrier calculations offer mechanistic insights into the tautomerization and conformational dynamics observed in the NMR spectra.
{"title":"Hydrogen-Bond-Assisted Configurational Diversity of Benzamidines: Experimental and Theoretical Study","authors":"Edem R. Chakalov, Daria I. Tonkoglazova, Anna A. Titova, Maxim L. Kruglov, elena tupikina, Alexander S. Antonov, Peter Tolstoy","doi":"10.1039/d5qo01450f","DOIUrl":"https://doi.org/10.1039/d5qo01450f","url":null,"abstract":"Configurational diversity and mechanisms of prototropic tautomerism of 15 <em>N</em>,<em>N</em>’-diarylbenzamidines as potential building blocks in H-bonded polymeric materials are investigated. Variable-temperature 1D and 2D liquid-state NMR spectroscopic studies provide strong evidence of the solvent-dependent dynamic interconversion between all four isomers, <em>E</em>-<em>anti</em>, <em>E</em>-<em>syn</em>, <em>Z</em>-<em>anti</em> and <em>Z</em>-<em>syn</em>. Some of the isomers are prone to either a linear or a cyclic dimerization through H-bonding. A quantitative assessment of the changes in proton-donating ability of the amine functionality depending on electron-donating ability of <em>para</em>-substituents in all three aryl rings of <em>N</em>,<em>N</em>’-diarylbenzamidines is proposed based on the <small><sup>1</sup></small>H NMR data and Hammett’s substituents constants. A different pattern of the ordered H-bonded network composed exclusively of non-planar <em>E-syn</em> isomers is observed in the solid state by X-ray diffraction studies. DFT calculations confirm the torsional flexibility of the molecules, which are able to closely approach each other and form various linear and cyclic dimers, for which the relative stability is determined by the interplay of NH···N hydrogen bonding and π-π stacking interactions. Rotational barrier calculations offer mechanistic insights into the tautomerization and conformational dynamics observed in the NMR spectra.","PeriodicalId":97,"journal":{"name":"Organic Chemistry Frontiers","volume":"53 1","pages":""},"PeriodicalIF":5.4,"publicationDate":"2026-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146057158","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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