Pub Date : 2025-02-01Epub Date: 2024-12-09DOI: 10.1016/j.tet.2024.134418
H J Peterson, G W O'Neil
Beta-hydroxy ketones can be reduced using a sequence of ruthenium-catalyzed silyl etherification followed by tetrabutylammonium fluoride (TBAF) promoted intramolecular hydrosilylation. Switching from TBAF to tetrabutylammonium difluorotriphenylsilicate (TBAT), even without first forming the silyl ether, gave cyclic dioxasilinane products. These somewhat sensitive compounds could be isolated pure by column chromatography using florisil as the stationary phase. Alternatively, the dioxasilinane were regioselectively opened with methyl lithium, affording the corresponding differentiated 1,3-diol with selective protection of the secondary alcohol as its diphenylmethylsilyl (DPMS) ether. A mechanism is proposed involving TBAT-catalyzed silyl ether formation followed by TBAT-promoted intramolecular carbonyl hydrosilylation. This mechanism is supported by the observed diastereoselectivity of the reaction, which was consistent with other carbonyl hydrosilylations thought to proceed intramolecularly.
{"title":"TBAT-Catalyzed Dioxasilinane Formation from Beta-Hydroxy Ketones.","authors":"H J Peterson, G W O'Neil","doi":"10.1016/j.tet.2024.134418","DOIUrl":"10.1016/j.tet.2024.134418","url":null,"abstract":"<p><p>Beta-hydroxy ketones can be reduced using a sequence of ruthenium-catalyzed silyl etherification followed by tetrabutylammonium fluoride (TBAF) promoted intramolecular hydrosilylation. Switching from TBAF to tetrabutylammonium difluorotriphenylsilicate (TBAT), even without first forming the silyl ether, gave cyclic dioxasilinane products. These somewhat sensitive compounds could be isolated pure by column chromatography using florisil as the stationary phase. Alternatively, the dioxasilinane were regioselectively opened with methyl lithium, affording the corresponding differentiated 1,3-diol with selective protection of the secondary alcohol as its diphenylmethylsilyl (DPMS) ether. A mechanism is proposed involving TBAT-catalyzed silyl ether formation followed by TBAT-promoted intramolecular carbonyl hydrosilylation. This mechanism is supported by the observed diastereoselectivity of the reaction, which was consistent with other carbonyl hydrosilylations thought to proceed intramolecularly.</p>","PeriodicalId":437,"journal":{"name":"Tetrahedron","volume":"171 ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11720482/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142969110","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01Epub Date: 2024-11-06DOI: 10.1016/j.tet.2024.134350
Jacob W Ford, Jennifer M VanNatta, Deboprosad Mondal, Chen-Ming Lin, Yuling Deng, Ruoli Bai, Ernest Hamel, Mary Lynn Trawick, Kevin G Pinney
Antibody-drug conjugates (ADCs) have advanced as a mainstay among the most promising cancer therapeutics, offering enhanced antigen targeting and encompassing wide diversity in their linker and payload components. Small-molecule inhibitors of tubulin polymerization have found success as payloads in FDA approved ADCs and represent further promise in next-generation, pre-clinical and developmental ADCs. Unique dual-mechanism payloads (previously designed and synthesized in our laboratories) function as both potent antiproliferative agents and promising vascular disrupting agents capable of imparting selective and effective damage to tumor-associated microvessels. These payloads have been incorporated into a variety of drug-linker constructs utilizing the clinically relevant cathepsin B cleavable Val-Cit dipeptide linker, employed within several FDA approved ADCs, along with other non-cleavable constructs. Various synthetic strategies were evaluated to prepare these drug-linker constructs. Aniline-based payloads were incorporated utilizing the Val-Cit dipeptide linker similar to FDA approved ADCs such as Adcetris® (brentuximab vedotin). An additional self-immolative group, previously described in the literature for related model systems, was employed to tether the phenolic payloads. A variety of drug-linker constructs (with each bearing a unique dual mechanism payload) were synthesized and evaluated biologically for their enzyme-mediated release of payload and inhibition of tubulin polymerization. Following deactivation of the highly electrophilic maleimido terminus as its corresponding N-acetyl cysteine (NAC) derivative, the most promising construct (NAC-4) demonstrated approximately 90% release of an aniline-functionalized payload (1) upon treatment with cathepsins B or L over 90 minutes. Building on these promising results, future studies will examine the conjugation of drug-linker construct 4 to selected antibodies and engineered proteins and evaluate the biological activity of the resultant antibody-drug conjugates (ADCs).
{"title":"Drug-Linker Constructs Bearing Unique Dual-Mechanism Tubulin Binding Payloads Tethered through Cleavable and Non-Cleavable Linkers.","authors":"Jacob W Ford, Jennifer M VanNatta, Deboprosad Mondal, Chen-Ming Lin, Yuling Deng, Ruoli Bai, Ernest Hamel, Mary Lynn Trawick, Kevin G Pinney","doi":"10.1016/j.tet.2024.134350","DOIUrl":"10.1016/j.tet.2024.134350","url":null,"abstract":"<p><p>Antibody-drug conjugates (ADCs) have advanced as a mainstay among the most promising cancer therapeutics, offering enhanced antigen targeting and encompassing wide diversity in their linker and payload components. Small-molecule inhibitors of tubulin polymerization have found success as payloads in FDA approved ADCs and represent further promise in next-generation, pre-clinical and developmental ADCs. Unique dual-mechanism payloads (previously designed and synthesized in our laboratories) function as both potent antiproliferative agents and promising vascular disrupting agents capable of imparting selective and effective damage to tumor-associated microvessels. These payloads have been incorporated into a variety of drug-linker constructs utilizing the clinically relevant cathepsin B cleavable Val-Cit dipeptide linker, employed within several FDA approved ADCs, along with other non-cleavable constructs. Various synthetic strategies were evaluated to prepare these drug-linker constructs. Aniline-based payloads were incorporated utilizing the Val-Cit dipeptide linker similar to FDA approved ADCs such as Adcetris<sup>®</sup> (brentuximab vedotin). An additional self-immolative group, previously described in the literature for related model systems, was employed to tether the phenolic payloads. A variety of drug-linker constructs (with each bearing a unique dual mechanism payload) were synthesized and evaluated biologically for their enzyme-mediated release of payload and inhibition of tubulin polymerization. Following deactivation of the highly electrophilic maleimido terminus as its corresponding <i>N</i>-acetyl cysteine (NAC) derivative, the most promising construct (NAC-<b>4</b>) demonstrated approximately 90% release of an aniline-functionalized payload (<b>1</b>) upon treatment with cathepsins B or L over 90 minutes. Building on these promising results, future studies will examine the conjugation of drug-linker construct <b>4</b> to selected antibodies and engineered proteins and evaluate the biological activity of the resultant antibody-drug conjugates (ADCs).</p>","PeriodicalId":437,"journal":{"name":"Tetrahedron","volume":"171 ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11722312/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142969089","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-28DOI: 10.1016/j.tet.2024.134388
Haoran Yang , Shaoqing Liu , Ruwei Shen , Li-Biao Han
Phosphorus-containing unsaturated hydrocarbons, including alkenyl, allenyl, and alkynyl phosphoryl compounds, constitute a significant subclass of organophosphorus intermediates that have extensive applications in organic synthesis and related fields. Among various synthetic approaches, the transition metal-mediated reactions of the readily accessible hydrogen phosphoryl chemicals with alkynes stand out as one of the most efficient and straightforward methods for their preparation. Here, we summarize the recent advancement in transition metal-catalyzed P(O)–H alkenylation, allenylation, and alkynylation reactions to reflect a current research trend of the field.
{"title":"Transition metal-catalyzed P(O)–H alkenylation, allenylation and alkynylation reactions: A recent trend","authors":"Haoran Yang , Shaoqing Liu , Ruwei Shen , Li-Biao Han","doi":"10.1016/j.tet.2024.134388","DOIUrl":"10.1016/j.tet.2024.134388","url":null,"abstract":"<div><div>Phosphorus-containing unsaturated hydrocarbons, including alkenyl, allenyl, and alkynyl phosphoryl compounds, constitute a significant subclass of organophosphorus intermediates that have extensive applications in organic synthesis and related fields. Among various synthetic approaches, the transition metal-mediated reactions of the readily accessible hydrogen phosphoryl chemicals with alkynes stand out as one of the most efficient and straightforward methods for their preparation. Here, we summarize the recent advancement in transition metal-catalyzed P(O)–H alkenylation, allenylation, and alkynylation reactions to reflect a current research trend of the field.</div></div>","PeriodicalId":437,"journal":{"name":"Tetrahedron","volume":"170 ","pages":"Article 134388"},"PeriodicalIF":2.1,"publicationDate":"2024-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142743626","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-26DOI: 10.1016/j.tet.2024.134386
Shraddha Tivari , Mohd Zaheeruddin Beg , Akanksha Kashyap , Pravin K. Singh , Praveen P. Singh , Sudhanshu Kanaujia , Vishal Srivastava
Visible light-induced photoredox catalyzed, metal-free multicomponent reaction among salicylaldehydes, dimedone and indoles for synthesis of Indolyl-4H-chromenes has been reported. This new approach involving the use of visible light to form Indolyl-4H-chromenes through simultaneous reaction which involves C–O and C–C bonds formation with significant yield of the desired product in remarkably moderate reaction conditions. This one-pot synthetic method has many advantages, including a wide range of substrates, readily available starting materials and high efficiency.
{"title":"Photoredox catalyzed multi component synthesis of indolyl-4H-chromenes via HAT","authors":"Shraddha Tivari , Mohd Zaheeruddin Beg , Akanksha Kashyap , Pravin K. Singh , Praveen P. Singh , Sudhanshu Kanaujia , Vishal Srivastava","doi":"10.1016/j.tet.2024.134386","DOIUrl":"10.1016/j.tet.2024.134386","url":null,"abstract":"<div><div>Visible light-induced photoredox catalyzed, metal-free multicomponent reaction among salicylaldehydes, dimedone and indoles for synthesis of Indolyl-4<em>H</em>-chromenes has been reported. This new approach involving the use of visible light to form Indolyl-4<em>H</em>-chromenes through simultaneous reaction which involves C–O and C–C bonds formation with significant yield of the desired product in remarkably moderate reaction conditions. This one-pot synthetic method has many advantages, including a wide range of substrates, readily available starting materials and high efficiency.</div></div>","PeriodicalId":437,"journal":{"name":"Tetrahedron","volume":"170 ","pages":"Article 134386"},"PeriodicalIF":2.1,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142743627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-25DOI: 10.1016/j.tet.2024.134384
Arif Baran , Tahir Savran , Gökay Aydın , Mustafa Emirik
In this study, a new stereospecific strategy for the preparation of C8N aminocyclohexenols such as C7N, validamine analogs were developed from starting compound 4 via intramolecular aza-michael β-amination reaction between α, β-unsaturated ketones and ammonia in methanol. The strategy was to produce C8N derivatives such as validamine C7N via Kornblum-DeLaMare rearrangement, which involves stereocontrolled amination of a double bond, esterification, carbonyl group reduction, benzofuran ring opening, ammonolysis of acetate groups. The mechanism of target molecules is discussed. Pseudosugars with different configurations containing an amino group at the anomeric position were tested against α-glucosidase, β-glucosidase, and α-amylase. Among these compounds, compound 12 against α-glucosidase, compound 14 against β-glucosidase, and compound 21 against α-amylase exhibited the best activity compared to acarbose. Moreover, enzyme kinetic studies to understand the enzyme inhibition mechanism and DFT studies to investigate binding interactions with enzyme active sites were performed on these compounds (12, 14, and 21). Additionally, the pharmacokinetic parameters (ADME) were examined using the QikProp module to determine their potential as drug candidates.
{"title":"Metal catalyst-free β-amination of branched rac-C8N-type such as C7N carbasugars via intramolecular aza-michael addition: Biological evolution, DFT studies and ADME properties","authors":"Arif Baran , Tahir Savran , Gökay Aydın , Mustafa Emirik","doi":"10.1016/j.tet.2024.134384","DOIUrl":"10.1016/j.tet.2024.134384","url":null,"abstract":"<div><div>In this study, a new stereospecific strategy for the preparation of C<sub>8</sub>N aminocyclohexenols such as C<sub>7</sub>N, validamine analogs were developed from starting compound <strong>4</strong> via intramolecular <em>aza</em>-michael <em>β</em>-amination reaction between <em>α</em>, <em>β</em>-unsaturated ketones and ammonia in methanol. The strategy was to produce C<sub>8</sub>N derivatives such as validamine C<sub>7</sub>N via Kornblum-DeLaMare rearrangement, which involves stereocontrolled amination of a double bond, esterification, carbonyl group reduction, benzofuran ring opening, ammonolysis of acetate groups. The mechanism of target molecules is discussed. Pseudosugars with different configurations containing an amino group at the anomeric position were tested against <em>α</em>-glucosidase, <em>β</em>-glucosidase, and <em>α</em>-amylase. Among these compounds, compound <strong>12</strong> against <em>α</em>-glucosidase, compound <strong>14</strong> against <em>β</em>-glucosidase, and compound <strong>21</strong> against <em>α</em>-amylase exhibited the best activity compared to acarbose. Moreover, enzyme kinetic studies to understand the enzyme inhibition mechanism and DFT studies to investigate binding interactions with enzyme active sites were performed on these compounds (<strong>12</strong>, <strong>14</strong>, and <strong>21</strong>). Additionally, the pharmacokinetic parameters (ADME) were examined using the QikProp module to determine their potential as drug candidates.</div></div>","PeriodicalId":437,"journal":{"name":"Tetrahedron","volume":"170 ","pages":"Article 134384"},"PeriodicalIF":2.1,"publicationDate":"2024-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142743628","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-21DOI: 10.1016/j.tet.2024.134385
Mohamed Magdi Ahmed , Dominika Nowacka , Anna Maria Skwierawska , Michal Řezanka
Cyclodextrin (CD)-functionalized membranes represent a promising advancement in the domain of organic chemistry, particularly in the development of functional materials. The unique toroidal structure of CDs facilitates their well-known host-guest interactions, enabling the encapsulation of various organic molecules and enhancing the adsorption capabilities of membranes. Functionalization of polyvinylidene fluoride (PVDF) membranes with CDs addresses the challenges posed by the hydrophobicity of PVDF, such as membrane fouling, permeability, and selectivity. This modification not only improves membrane performance but also expands its potential applications in areas such as water treatment, sensing, and biomaterials. This review provides a detailed examination of the synthetic strategies employed to achieve CD functionalization on PVDF, considering the chemical inertness of the polymer and the stability of the resulting materials. The performance of these CD-functionalized PVDF membranes is critically analyzed and the study highlights the intersection of organic synthesis, supramolecular chemistry, and material science, contributing to the development of advanced functional materials with broad applicability.
环糊精（CD）功能化膜是有机化学领域，尤其是功能材料开发领域的一个很有前途的进步。环糊精独特的环状结构有利于其众所周知的主客体相互作用，从而能够封装各种有机分子并增强膜的吸附能力。用 CD 对聚偏二氟乙烯（PVDF）膜进行功能化处理可解决 PVDF 疏水性带来的难题，如膜堵塞、渗透性和选择性。这种改性不仅能提高膜的性能，还能扩大其在水处理、传感和生物材料等领域的潜在应用。考虑到聚合物的化学惰性和所得材料的稳定性，本综述详细分析了在 PVDF 上实现 CD 功能化所采用的合成策略。本研究对这些 CD 功能化 PVDF 膜的性能进行了批判性分析，强调了有机合成、超分子化学和材料科学之间的交叉，有助于开发具有广泛适用性的先进功能材料。
{"title":"Cyclodextrins functionalized polyvinylidene fluoride membranes: Strategies and diverse applications","authors":"Mohamed Magdi Ahmed , Dominika Nowacka , Anna Maria Skwierawska , Michal Řezanka","doi":"10.1016/j.tet.2024.134385","DOIUrl":"10.1016/j.tet.2024.134385","url":null,"abstract":"<div><div>Cyclodextrin (CD)-functionalized membranes represent a promising advancement in the domain of organic chemistry, particularly in the development of functional materials. The unique toroidal structure of CDs facilitates their well-known host-guest interactions, enabling the encapsulation of various organic molecules and enhancing the adsorption capabilities of membranes. Functionalization of polyvinylidene fluoride (PVDF) membranes with CDs addresses the challenges posed by the hydrophobicity of PVDF, such as membrane fouling, permeability, and selectivity. This modification not only improves membrane performance but also expands its potential applications in areas such as water treatment, sensing, and biomaterials. This review provides a detailed examination of the synthetic strategies employed to achieve CD functionalization on PVDF, considering the chemical inertness of the polymer and the stability of the resulting materials. The performance of these CD-functionalized PVDF membranes is critically analyzed and the study highlights the intersection of organic synthesis, supramolecular chemistry, and material science, contributing to the development of advanced functional materials with broad applicability.</div></div>","PeriodicalId":437,"journal":{"name":"Tetrahedron","volume":"170 ","pages":"Article 134385"},"PeriodicalIF":2.1,"publicationDate":"2024-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142719771","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-19DOI: 10.1016/j.tet.2024.134383
Vahideh Zadsirjan, Fatemeh Soleimani
Azetidines (azacyclobutanes) are found to be a well-known class of heterocyclic molecules. Azetidine framework was identified in various natural products and several pharmacologically significant synthetic compounds. Because of the intrinsic ring strain, the formation of azetidines is a stimulating attempt. Several methods have been established to form various substituted azetidine derivatives. The two typical methods to make azetidine scaffold are cyclization reaction and cycloaddition reaction of appropriate substrates. In addition, various substituted azetidines are retrieved by conversions of functional groups on azetidine motif. The azetidine ring contains characteristic reactivity and also act as ligands in asymmetric catalysis. Significantly, various azetidines find applications in medicinal chemistry as pharmacological tools in peptidomimetics as unnatural amino acids. In this mini review, we want to show recent advances in the synthesis of azetidines from 2021 to 2024.
{"title":"Recent advances in the synthesis of azetidines","authors":"Vahideh Zadsirjan, Fatemeh Soleimani","doi":"10.1016/j.tet.2024.134383","DOIUrl":"10.1016/j.tet.2024.134383","url":null,"abstract":"<div><div>Azetidines (azacyclobutanes) are found to be a well-known class of heterocyclic molecules. Azetidine framework was identified in various natural products and several pharmacologically significant synthetic compounds. Because of the intrinsic ring strain, the formation of azetidines is a stimulating attempt. Several methods have been established to form various substituted azetidine derivatives. The two typical methods to make azetidine scaffold are cyclization reaction and cycloaddition reaction of appropriate substrates. In addition, various substituted azetidines are retrieved by conversions of functional groups on azetidine motif. The azetidine ring contains characteristic reactivity and also act as ligands in asymmetric catalysis. Significantly, various azetidines find applications in medicinal chemistry as pharmacological tools in peptidomimetics as unnatural amino acids. In this mini review, we want to show recent advances in the synthesis of azetidines from 2021 to 2024.</div></div>","PeriodicalId":437,"journal":{"name":"Tetrahedron","volume":"169 ","pages":"Article 134383"},"PeriodicalIF":2.1,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142705627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-19DOI: 10.1016/j.tet.2024.134370
Biyun Su , Qi Zhang , Paison Faida , Dou Yang , Liqin Ding , Boli Hou
The Schiff base condensation reaction was adopted to synthesize a series of pyridine-based quinoxaline ligands (L1, L2, L3, L4) using 2-acetylpyridine and 1,2-phenylenediamine aromatic amines with different substituents of –OCH3, –F, -Cl, -Br. Then, four symmetrical dinuclear metal complexes (1–4) were obtained by coordination reaction of the synthesized ligands with CoCl2·6H2O, and six unexpectedly systematic and novel solvent-involved asymmetric mononuclear metal complexes (1A-4A, 3B, 4B) were obtained during single crystals cultivating by solvent diffusion method. The microscopic composition of the complexes were proved by a series of characterizations such as elemental analysis, IR and UV–vis. At the same time, by improving the single crystal culture technology, full crystal sample of compounds was obtained and X-ray single crystal diffraction showed a rare single crystal to single crystal structure transition (SCSC) phenomenon in this study. Furthermore, the catalytic properties of the complexes for MMA polymerization was explored, it was found that the catalytic activity of complexes 1–4 containing different types of substituents on pyridyl quinoxaline ligand was in the order of 1 < 2 < 3 < 4, indicating that the complex with an electron-withdrawing substituent showed the higher activity than that of electron-donating substituent. Complexes 1A-4A, 3B and 4B showed higher catalytic activity in MMA polymerization than 1–4, which confirmed that the catalytic activity of mononuclear complexes were generally higher than that of binuclear complexes.
{"title":"Structural optimization of pyridine quinoxaline cobalt (II) catalysts for MMA polymerization based on systematical SCSC transformation study","authors":"Biyun Su , Qi Zhang , Paison Faida , Dou Yang , Liqin Ding , Boli Hou","doi":"10.1016/j.tet.2024.134370","DOIUrl":"10.1016/j.tet.2024.134370","url":null,"abstract":"<div><div>The Schiff base condensation reaction was adopted to synthesize a series of pyridine-based quinoxaline ligands (<strong>L1, L2, L3, L4</strong>) using 2-acetylpyridine and 1,2-phenylenediamine aromatic amines with different substituents of –OCH<sub>3</sub>, –F, -Cl, -Br. Then, four symmetrical dinuclear metal complexes (<strong>1–4</strong>) were obtained by coordination reaction of the synthesized ligands with CoCl<sub>2</sub>·6H<sub>2</sub>O, and six unexpectedly systematic and novel solvent-involved asymmetric mononuclear metal complexes (<strong>1A-4A, 3B, 4B</strong>) were obtained during single crystals cultivating by solvent diffusion method. The microscopic composition of the complexes were proved by a series of characterizations such as elemental analysis, IR and UV–vis. At the same time, by improving the single crystal culture technology, full crystal sample of compounds was obtained and X-ray single crystal diffraction showed a rare single crystal to single crystal structure transition (SCSC) phenomenon in this study. Furthermore, the catalytic properties of the complexes for MMA polymerization was explored, it was found that the catalytic activity of complexes <strong>1–4</strong> containing different types of substituents on pyridyl quinoxaline ligand was in the order of <strong>1 < 2</strong> < <strong>3 < 4</strong>, indicating that the complex with an electron-withdrawing substituent showed the higher activity than that of electron-donating substituent. Complexes <strong>1A-4A, 3B</strong> and <strong>4B</strong> showed higher catalytic activity in MMA polymerization than <strong>1–4</strong>, which confirmed that the catalytic activity of mononuclear complexes were generally higher than that of binuclear complexes.</div></div>","PeriodicalId":437,"journal":{"name":"Tetrahedron","volume":"170 ","pages":"Article 134370"},"PeriodicalIF":2.1,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142719774","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-18DOI: 10.1016/j.tet.2024.134382
Brett M. Lucht , Richard J. Monsky , Michael C. Rosko , Joseph M. Tanski , Jocelyn M. Nadeau
Structure-property relationship studies of fluorescent molecules containing donor-acceptor units are important for informing the design of organic materials for custom applications. We report the synthesis and characterization of a series of novel thiophene-substituted quinoxaline donor-acceptor dyes with varied substituent positioning. The dyes were synthesized using microwave-assisted methods in one or two steps from commercially available precursors. In solution, proton NMR spectroscopy studies revealed significant upfield shifts for certain thiophene ring protons in the o-disubstituted quinoxaline derivatives compared to their monosubstituted analogs. The upfield shifts resulted from restricted rotation about the thiophene-quinoxaline C–C bonds due to steric congestion leading to some protons being shielded by neighboring aromatic rings. In the solid state, single-crystal X-ray diffraction studies of the o-disubstituted derivatives showed that they exhibit thiophene ring disorder. These dyes are weakly emissive in solution, and their photophysical characterization using UV–vis and fluorescence spectroscopy in solvents of varying polarity revealed slight to moderate emission solvatochromism, with Lippert-Mataga analysis estimated Δμ values between 3 and 6 D. The dyes with thiophene rings attached to the benzene side of the quinoxaline ring exhibited a higher degree of solvatochromism than those with thiophene rings attached to the pyrazine side, illustrating the impact that substituent positioning can have on a molecule's photophysical properties. DFT and TD-DFT computational results were consistent with the observed photophysical properties and electronic structures of the dyes and aided in rationalization of the trends.
对含有供体-受体单元的荧光分子进行结构-性质关系研究，对于设计定制应用的有机材料非常重要。我们报告了一系列具有不同取代基位置的新型噻吩取代喹喔啉供体-受体染料的合成和表征。这些染料是采用微波辅助方法，通过一个或两个步骤从市售前体中合成的。在溶液中，质子核磁共振光谱研究显示，与单取代类似物相比，邻二取代喹喔啉衍生物中某些噻吩环质子有明显的上场偏移。这种上场偏移是由于立体拥塞导致噻吩-喹喔啉 C-C 键的旋转受限，从而导致某些质子被邻近的芳香环屏蔽。在固态下，对邻位二取代衍生物进行的单晶 X 射线衍射研究表明，它们表现出噻吩环的无序性。这些染料在溶液中具有微弱的发射性，在不同极性的溶剂中使用紫外-可见光和荧光光谱对其进行光物理表征，发现它们具有轻微到中等程度的发射溶解色度，Lippert-Mataga 分析估计的Δμ 值在 3 到 6 D 之间。噻吩环连接在喹喔啉环苯侧的染料比噻吩环连接在吡嗪侧的染料具有更高的溶色性，这说明了取代基位置对分子光物理特性的影响。DFT 和 TD-DFT 计算结果与观察到的染料光物理特性和电子结构相一致，有助于合理解释这些趋势。
{"title":"Thiophene-substituted quinoxaline donor-acceptor dyes: Synthesis, NMR spectroscopy, X-ray crystallography, and photophysical properties","authors":"Brett M. Lucht , Richard J. Monsky , Michael C. Rosko , Joseph M. Tanski , Jocelyn M. Nadeau","doi":"10.1016/j.tet.2024.134382","DOIUrl":"10.1016/j.tet.2024.134382","url":null,"abstract":"<div><div>Structure-property relationship studies of fluorescent molecules containing donor-acceptor units are important for informing the design of organic materials for custom applications. We report the synthesis and characterization of a series of novel thiophene-substituted quinoxaline donor-acceptor dyes with varied substituent positioning. The dyes were synthesized using microwave-assisted methods in one or two steps from commercially available precursors. In solution, proton NMR spectroscopy studies revealed significant upfield shifts for certain thiophene ring protons in the <em>o</em>-disubstituted quinoxaline derivatives compared to their monosubstituted analogs. The upfield shifts resulted from restricted rotation about the thiophene-quinoxaline C–C bonds due to steric congestion leading to some protons being shielded by neighboring aromatic rings. In the solid state, single-crystal X-ray diffraction studies of the <em>o</em>-disubstituted derivatives showed that they exhibit thiophene ring disorder. These dyes are weakly emissive in solution, and their photophysical characterization using UV–vis and fluorescence spectroscopy in solvents of varying polarity revealed slight to moderate emission solvatochromism, with Lippert-Mataga analysis estimated Δμ values between 3 and 6 D. The dyes with thiophene rings attached to the benzene side of the quinoxaline ring exhibited a higher degree of solvatochromism than those with thiophene rings attached to the pyrazine side, illustrating the impact that substituent positioning can have on a molecule's photophysical properties. DFT and TD-DFT computational results were consistent with the observed photophysical properties and electronic structures of the dyes and aided in rationalization of the trends.</div></div>","PeriodicalId":437,"journal":{"name":"Tetrahedron","volume":"170 ","pages":"Article 134382"},"PeriodicalIF":2.1,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142720377","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-16DOI: 10.1016/j.tet.2024.134381
Manijeh Nematpour
In this study, various benzothiazoles, benzoxazoles, and benzo[1,3]-dithiols derivatives with good yields were obtained using the Ullmann coupling reaction of dihalobenzenes and malononitrile-heterocumulene adducts in the vicinity of copper catalyst, Cs2CO3 as a base under ultrasound irradiation. The use of the popular sonochemical method, short reaction time, simple and available raw materials, mild catalytic copper reaction conditions, simple purification, and good efficiency are some of the notable characteristics of this protocol.
{"title":"Ullmann coupling reaction of dihalobenzenes and malononitrile-heterocumulene adducts under ultrasound-irradiation","authors":"Manijeh Nematpour","doi":"10.1016/j.tet.2024.134381","DOIUrl":"10.1016/j.tet.2024.134381","url":null,"abstract":"<div><div>In this study, various benzothiazoles, benzoxazoles, and benzo[1,3]-dithiols derivatives with good yields were obtained using the Ullmann coupling reaction of dihalobenzenes and malononitrile-heterocumulene adducts in the vicinity of copper catalyst, Cs<sub>2</sub>CO<sub>3</sub> as a base under ultrasound irradiation. The use of the popular sonochemical method, short reaction time, simple and available raw materials, mild catalytic copper reaction conditions, simple purification, and good efficiency are some of the notable characteristics of this protocol.</div></div>","PeriodicalId":437,"journal":{"name":"Tetrahedron","volume":"170 ","pages":"Article 134381"},"PeriodicalIF":2.1,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142719773","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
扫码关注我们
求助内容：
应助结果提醒方式：
京公网安备 11010802042870号