Pub Date : 2024-10-10DOI: 10.1016/j.tet.2024.134295
Erick M.C. Pinheiro , Rafael P.R.F. Oliveira , Sandro J. Greco , Sergio Pinheiro
Azaflavanones are synthetic aza analogues of natural flavanones that have received attention in medicine. More recently, some alpha-ylidene azaflavanones have emerged as promising bioactive compounds. In the last decades, several approaches to synthesizing azaflavanones and alpha-ylidene azaflavanones have been described. These include intramolecular cyclizations of 2′-aminochalcones and analogues, coupling of 2-aminoacetophenones with aromatic aldehydes, metal-catalyzed coupling reactions of ortho-iodoanilines and the condensations of N-protected 2-aminoacetophenones and N-protected 2′-aminochalcones with aromatic aldehydes. This review discusses the different approaches in the racemic synthesis of azaflavanones and alpha-ylidene azaflavanones.
氮杂黄烷酮是天然黄烷酮的人工合成氮杂类似物，在医学领域备受关注。最近，一些α-亚基氮杂黄烷酮作为有前景的生物活性化合物出现。在过去的几十年中，人们已经描述了几种合成氮杂黄烷酮和α-亚基氮杂黄烷酮的方法。这些方法包括 2′-氨基查耳酮及其类似物的分子内环化反应、2-氨基苯乙酮与芳香醛的偶联反应、金属催化的邻碘苯胺偶联反应以及 N 保护的 2-氨基苯乙酮和 N 保护的 2′-氨基查耳酮与芳香醛的缩合反应。本综述讨论了外消旋合成氮杂黄烷酮和α-亚基氮杂黄烷酮的不同方法。
{"title":"Synthesis of azaflavanones and alpha-ylidene azaflavanones","authors":"Erick M.C. Pinheiro , Rafael P.R.F. Oliveira , Sandro J. Greco , Sergio Pinheiro","doi":"10.1016/j.tet.2024.134295","DOIUrl":"10.1016/j.tet.2024.134295","url":null,"abstract":"<div><div>Azaflavanones are synthetic aza analogues of natural flavanones that have received attention in medicine. More recently, some alpha-ylidene azaflavanones have emerged as promising bioactive compounds. In the last decades, several approaches to synthesizing azaflavanones and alpha-ylidene azaflavanones have been described. These include intramolecular cyclizations of 2′-aminochalcones and analogues, coupling of 2-aminoacetophenones with aromatic aldehydes, metal-catalyzed coupling reactions of <em>ortho</em>-iodoanilines and the condensations of N-protected 2-aminoacetophenones and N-protected 2′-aminochalcones with aromatic aldehydes. This review discusses the different approaches in the racemic synthesis of azaflavanones and alpha-ylidene azaflavanones.</div></div>","PeriodicalId":437,"journal":{"name":"Tetrahedron","volume":"167 ","pages":"Article 134295"},"PeriodicalIF":2.1,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142441068","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 : 2024-10-09DOI: 10.1016/j.tet.2024.134297
Adriana Galván , Guadalupe Flores-Gallegos , Orlando O. Hernández-Ramírez , Yolanda Alcaraz-Contreras , Selene Laguna-Rivera , Merced Martínez , Jorge Alberto Mendoza-Pérez , Eduardo Peña-Cabrera , Miguel A. Vázquez
Click chemistry reactions transformed organic synthesis by creating enormous compound libraries connecting almost any chemical entity. The copper-catalyzed alkyne-azide cycloaddition (CuAAC) was the most versatile and efficient and transcended diverse scientific fields such as biology and materials science. Thus, the development of new methodologies based on CuAAC keeps growing. A green approach was envisioned by stabilizing the air and water-sensitive CuI over an ordered mesoporous silica/ionic liquid matrix (MIM-SBA-15). The best catalyst performance was in the water as solvent under ultrasound irradiation, which reached quantitative transformation in a short time. Then, the scope was extended to 24 compounds primarily synthesized with high yields (75–99 %); the methodology tolerated different alkynes and azides with aromatic and alkyl groups. This methodology was also successfully tested in high yields in the multicomponent synthesis of 1,4-disubstituted 1,2,3-triazoles from organic bromides, alkynes, and KN3. The hybrid catalyst recovery and reuse were evaluated along ten reaction cycles; there was no significant loss in activity up to cycle number six (94 % yield).
{"title":"CuI@MIM-SBA-15 hybrid catalyst in the ultrasound-assisted synthesis of 1,4-disubstituted 1,2,3-triazoles in water","authors":"Adriana Galván , Guadalupe Flores-Gallegos , Orlando O. Hernández-Ramírez , Yolanda Alcaraz-Contreras , Selene Laguna-Rivera , Merced Martínez , Jorge Alberto Mendoza-Pérez , Eduardo Peña-Cabrera , Miguel A. Vázquez","doi":"10.1016/j.tet.2024.134297","DOIUrl":"10.1016/j.tet.2024.134297","url":null,"abstract":"<div><div>Click chemistry reactions transformed organic synthesis by creating enormous compound libraries connecting almost any chemical entity. The copper-catalyzed alkyne-azide cycloaddition (CuAAC) was the most versatile and efficient and transcended diverse scientific fields such as biology and materials science. Thus, the development of new methodologies based on CuAAC keeps growing. A green approach was envisioned by stabilizing the air and water-sensitive CuI over an ordered mesoporous silica/ionic liquid matrix (MIM-SBA-15). The best catalyst performance was in the water as solvent under ultrasound irradiation, which reached quantitative transformation in a short time. Then, the scope was extended to 24 compounds primarily synthesized with high yields (75–99 %); the methodology tolerated different alkynes and azides with aromatic and alkyl groups. This methodology was also successfully tested in high yields in the multicomponent synthesis of 1,4-disubstituted 1,2,3-triazoles from organic bromides, alkynes, and KN<sub>3</sub>. The hybrid catalyst recovery and reuse were evaluated along ten reaction cycles; there was no significant loss in activity up to cycle number six (94 % yield).</div></div>","PeriodicalId":437,"journal":{"name":"Tetrahedron","volume":"167 ","pages":"Article 134297"},"PeriodicalIF":2.1,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142425571","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 : 2024-10-09DOI: 10.1016/j.tet.2024.134292
Mark V. Sigalov , Bagrat A. Shainyan , Nina N. Chipanina , Larisa P. Oznobikhina
The Knoevenagel reaction of 2-acetyl-1,3-indandione, dehydroacetic acid, 3-acetyl-4-hydroxy-coumarin and acetyl-barbituric acid with pyrrol-2-carbaldehyde affords 2-(1-hydroxy-3-(1H-pyrrol-2-yl)allylidene)-1H-indene-1,3(2H)-dione 5, 3-(3-(1H-pyrrol-2-yl)acryloyl)-4-hydroxy-6-methyl-2H-pyran-2-one 6, 3-(3-(1H-pyrrol-2-yl)acryloyl)-4-hydroxy-2H-chromen-2-one 7 and 5-(1-hydroxy-3-(1H-pyrrol-2-yl)allylidene)-1,3-dimethylpyrimidine-2,4,6(1H,3H,5H)-trione 8. The UV-induced E→Z isomerization, intra and intermolecular H-bonding is studied by NMR, IR, UV spectroscopy and theoretical calculations. The driving force for the E→Z isomerization is the formation of a bifurcate O–H⋯O⋯H–N hydrogen bond in the latter. The position of the E⇆Z equilibrium strongly depends on the solvent (CH2Cl2, acetone, EtOH, DMSO). According to QTAIM analysis, the formed OH⋯O bonds are strong or moderate in energy (from 7.6 to 10.2 kcal/mol), while the NH⋯O bonds are weak (from 4.8 to 6.4 kcal/mol).
{"title":"UV-induced E/Z isomerization of the electron-rich pyrrole ring containing diketoenols: Theoretical and experimental study","authors":"Mark V. Sigalov , Bagrat A. Shainyan , Nina N. Chipanina , Larisa P. Oznobikhina","doi":"10.1016/j.tet.2024.134292","DOIUrl":"10.1016/j.tet.2024.134292","url":null,"abstract":"<div><div>The Knoevenagel reaction of 2-acetyl-1,3-indandione, dehydroacetic acid, 3-acetyl-4-hydroxy-coumarin and acetyl-barbituric acid with pyrrol-2-carbaldehyde affords 2-(1-hydroxy-3-(1<em>H</em>-pyrrol-2-yl)allylidene)-1<em>H</em>-indene-1,3(2<em>H</em>)-dione <strong>5</strong>, 3-(3-(1<em>H</em>-pyrrol-2-yl)acryloyl)-4-hydroxy-6-methyl-2<em>H</em>-pyran-2-one <strong>6</strong>, 3-(3-(1<em>H</em>-pyrrol-2-yl)acryloyl)-4-hydroxy-2<em>H</em>-chromen-2-one <strong>7</strong> and 5-(1-hydroxy-3-(1<em>H</em>-pyrrol-2-yl)allylidene)-1,3-dimethylpyrimidine-2,4,6(1<em>H</em>,3<em>H</em>,5<em>H</em>)-trione <strong>8</strong>. The UV-induced <em>E</em>→<em>Z</em> isomerization, intra and intermolecular H-bonding is studied by NMR, IR, UV spectroscopy and theoretical calculations. The driving force for the <em>E</em>→<em>Z</em> isomerization is the formation of a bifurcate O–H⋯O⋯H–N hydrogen bond in the latter. The position of the <em>E</em>⇆<em>Z</em> equilibrium strongly depends on the solvent (CH<sub>2</sub>Cl<sub>2</sub>, acetone, EtOH, DMSO). According to QTAIM analysis, the formed OH⋯O bonds are strong or moderate in energy (from 7.6 to 10.2 kcal/mol), while the NH⋯O bonds are weak (from 4.8 to 6.4 kcal/mol).</div></div>","PeriodicalId":437,"journal":{"name":"Tetrahedron","volume":"168 ","pages":"Article 134292"},"PeriodicalIF":2.1,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142445919","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 : 2024-10-09DOI: 10.1016/j.tet.2024.134298
Sinuhé Galván-Gómez , Gabriela Rodríguez-García , Antonio J. Oliveros-Ortiz , Rosa E. del Río , Carlos M. Cerda-García-Rojas , Verónica Reyes-Olivares , Pedro Joseph-Nathan , Mario A. Gómez-Hurtado
<div><div>The exciton coupling (EC) phenomenon becomes a valuable tool for the absolute configuration (AC) determination of organic molecules when an interaction between two strategically located chromophores in a molecule is evidenced by circularly polarized radiation. Besides the widely used exciton chirality method in electronic circular dichroism, the technique has been also developed for vibrational circular dichroism (VCD). Notably, the information provided by C<img>O stretching vibrations (1680−1800 cm<sup>−1</sup>) in VCD have demonstrated high applicability. However, reported theoretical approaches have warned about the adequate interpretations of the EC phenomenon since analyzed bisignate bands could be associated with other vibrations. The current paper experimentally addresses the problem to expand the criteria for using EC data in AC determinations. Herein, the VCD exciton coupling (VCDEC) methodology is extended to the analysis of C–O stretching vibrations (1100–1300 cm<sup>−1</sup>) to uncover their possible use in AC determinations, as well as to reveal the specific contribution of the EC related to C–O vibrations when experimental parameters are considered. To this aim, naturally occurring <em>p</em>-menthene alcohols <strong>1</strong>–<strong>4</strong> isolated from <em>Ageratina glabrata</em> were previously used to prepare acetates <strong>5</strong> and <strong>6</strong>, and acetonides <strong>7</strong> and <strong>8</strong>, and now, to prepare carbonates <strong>9</strong>–<strong>11</strong>. Density functional theory (DFT) calculations, including the IR and VCD spectra of the seven derivatives (<strong>5</strong>–<strong>11</strong>), were carried out to reinforce the conformational and configurational analysis, while the experimental VCD spectra of <strong>5</strong>–<strong>7</strong>, <strong>9</strong>, and <strong>11</strong> demonstrated the presence of C–O couplets. A systematic analysis of these bands, including the Δ<em>ε</em> value at alpha and beta state (Δ<em>ε</em><sub><em>α</em></sub>, Δ<em>ε</em><sub><em>β</em></sub>, respectively), the amplitude of EC (A = <span><math><mrow><mo>∑</mo><mi>ǀ</mi><mo>Δ</mo><mi>ε</mi><mi>ǀ</mi></mrow></math></span>) value, the couplet period (<em>L =</em> <span><math><mrow><mover><mi>v</mi><mo>‾</mo></mover><mo>Δ</mo><msub><mi>ε</mi><mi>β</mi></msub></mrow></math></span> − <span><math><mrow><mover><mi>v</mi><mo>‾</mo></mover></mrow></math></span> <em>Δε</em><sub><em>α</em></sub>) value, the specific area of C–O at couplet (S = <em>Σf(x)</em>(u<sup>2</sup>)), and the percentage of area related to EC from C–O (S<sub>%</sub>) were considered. These experimental results were directly related to dihedral angles (<em>θ</em>) from simplistic models to establish the AC. The results suggested that A, Cp, S, and S<sub>%</sub> parameters are deeply related to the nature of the chromophores. Thereby, adequate molecular structural moieties should be chosen for AC determination when u
{"title":"The vibrational circular dichroism exciton coupling in single-bond C–O stretching vibrations of p-menthene derivatives","authors":"Sinuhé Galván-Gómez , Gabriela Rodríguez-García , Antonio J. Oliveros-Ortiz , Rosa E. del Río , Carlos M. Cerda-García-Rojas , Verónica Reyes-Olivares , Pedro Joseph-Nathan , Mario A. Gómez-Hurtado","doi":"10.1016/j.tet.2024.134298","DOIUrl":"10.1016/j.tet.2024.134298","url":null,"abstract":"<div><div>The exciton coupling (EC) phenomenon becomes a valuable tool for the absolute configuration (AC) determination of organic molecules when an interaction between two strategically located chromophores in a molecule is evidenced by circularly polarized radiation. Besides the widely used exciton chirality method in electronic circular dichroism, the technique has been also developed for vibrational circular dichroism (VCD). Notably, the information provided by C<img>O stretching vibrations (1680−1800 cm<sup>−1</sup>) in VCD have demonstrated high applicability. However, reported theoretical approaches have warned about the adequate interpretations of the EC phenomenon since analyzed bisignate bands could be associated with other vibrations. The current paper experimentally addresses the problem to expand the criteria for using EC data in AC determinations. Herein, the VCD exciton coupling (VCDEC) methodology is extended to the analysis of C–O stretching vibrations (1100–1300 cm<sup>−1</sup>) to uncover their possible use in AC determinations, as well as to reveal the specific contribution of the EC related to C–O vibrations when experimental parameters are considered. To this aim, naturally occurring <em>p</em>-menthene alcohols <strong>1</strong>–<strong>4</strong> isolated from <em>Ageratina glabrata</em> were previously used to prepare acetates <strong>5</strong> and <strong>6</strong>, and acetonides <strong>7</strong> and <strong>8</strong>, and now, to prepare carbonates <strong>9</strong>–<strong>11</strong>. Density functional theory (DFT) calculations, including the IR and VCD spectra of the seven derivatives (<strong>5</strong>–<strong>11</strong>), were carried out to reinforce the conformational and configurational analysis, while the experimental VCD spectra of <strong>5</strong>–<strong>7</strong>, <strong>9</strong>, and <strong>11</strong> demonstrated the presence of C–O couplets. A systematic analysis of these bands, including the Δ<em>ε</em> value at alpha and beta state (Δ<em>ε</em><sub><em>α</em></sub>, Δ<em>ε</em><sub><em>β</em></sub>, respectively), the amplitude of EC (A = <span><math><mrow><mo>∑</mo><mi>ǀ</mi><mo>Δ</mo><mi>ε</mi><mi>ǀ</mi></mrow></math></span>) value, the couplet period (<em>L =</em> <span><math><mrow><mover><mi>v</mi><mo>‾</mo></mover><mo>Δ</mo><msub><mi>ε</mi><mi>β</mi></msub></mrow></math></span> − <span><math><mrow><mover><mi>v</mi><mo>‾</mo></mover></mrow></math></span> <em>Δε</em><sub><em>α</em></sub>) value, the specific area of C–O at couplet (S = <em>Σf(x)</em>(u<sup>2</sup>)), and the percentage of area related to EC from C–O (S<sub>%</sub>) were considered. These experimental results were directly related to dihedral angles (<em>θ</em>) from simplistic models to establish the AC. The results suggested that A, Cp, S, and S<sub>%</sub> parameters are deeply related to the nature of the chromophores. Thereby, adequate molecular structural moieties should be chosen for AC determination when u","PeriodicalId":437,"journal":{"name":"Tetrahedron","volume":"167 ","pages":"Article 134298"},"PeriodicalIF":2.1,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142437741","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}
Mavintramycin A is a new aminohexopyranose nucleoside antibiotic with potent anti-Mycobacterium avium complex (MAC) activity against M. avium and M. intracellulare. Herein, we report the total syntheses of mavintramycin A and its structural analog cytosaminomycin C, which is a known anticoccidial antibiotic. Furthermore, the anti-MAC activities of mavintramycin A, cytosaminomycin C, and their corresponding p-methoxybenzyl-protected analogs were evaluated. Notably, the developed synthetic route enables ready access to various analogs of mavintramycin A for structure-activity relationship studies.
马文曲霉素 A 是一种新的氨基己吡喃糖核苷类抗生素，对阿维菌素分枝杆菌和细胞内分枝杆菌具有很强的抗分枝杆菌复合体（MAC）活性。在此，我们报告了马文曲霉素 A 及其结构类似物胞嘧啶霉素 C 的全合成，后者是一种已知的抗球菌抗生素。此外，我们还评估了马文曲霉素 A、胞氨霉素 C 及其相应的对甲氧基苄基保护类似物的抗 MAC 活性。值得注意的是，所开发的合成路线可随时获得各种马文霉素 A 类似物，用于结构-活性关系研究。
{"title":"Total syntheses of mavintramycin A and its structural analog, cytosaminomycin C, and evaluation of their antibacterial activities against Mycobacterium avium and Mycobacterium intracellulare","authors":"Hanaka Satoh , Daiki Lee , Shiho Arima , Kanji Hosoda , Satoru Shigeno , Hiroshi Tomoda , Taichi Ohshiro , Tohru Nagamitsu","doi":"10.1016/j.tet.2024.134299","DOIUrl":"10.1016/j.tet.2024.134299","url":null,"abstract":"<div><div>Mavintramycin A is a new aminohexopyranose nucleoside antibiotic with potent anti-<em>Mycobacterium avium</em> complex (MAC) activity against <em>M. avium</em> and <em>M. intracellulare</em>. Herein, we report the total syntheses of mavintramycin A and its structural analog cytosaminomycin C, which is a known anticoccidial antibiotic. Furthermore, the anti-MAC activities of mavintramycin A, cytosaminomycin C, and their corresponding <em>p</em>-methoxybenzyl-protected analogs were evaluated. Notably, the developed synthetic route enables ready access to various analogs of mavintramycin A for structure-activity relationship studies.</div></div>","PeriodicalId":437,"journal":{"name":"Tetrahedron","volume":"168 ","pages":"Article 134299"},"PeriodicalIF":2.1,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142533896","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 : 2024-10-05DOI: 10.1016/j.tet.2024.134294
Guo-Zhen Wei, Xiao-Han Qiu, Lei Guo, Ming Bian, Hui-Yu Chen, Yu-Ning Gao, Zhen-Jiang Liu
An efficient decarboxylative difluoroalkylation method of cyclic N-sulfonyl ketimines with difluoroalkyl carboxylates has been developed through visible light-mediated photoredox catalysis process. This protocol provides a straightforward route for the synthesis of difluoroalkylated Cα-tetrasubstituted α-amino acid derivatives in moderate to good yields with excellent functional group tolerance under mild and simple conditions.
{"title":"Visible light mediated decarboxylative difluoroalkylations of cyclic N-sulfonyl ketimines: Efficient synthesis of difluoroalkylated Cα-tetrasubstituted α-amino acid derivatives","authors":"Guo-Zhen Wei, Xiao-Han Qiu, Lei Guo, Ming Bian, Hui-Yu Chen, Yu-Ning Gao, Zhen-Jiang Liu","doi":"10.1016/j.tet.2024.134294","DOIUrl":"10.1016/j.tet.2024.134294","url":null,"abstract":"<div><div>An efficient decarboxylative difluoroalkylation method of cyclic <em>N</em>-sulfonyl ketimines with difluoroalkyl carboxylates has been developed through visible light-mediated photoredox catalysis process. This protocol provides a straightforward route for the synthesis of difluoroalkylated C<sup>α</sup>-tetrasubstituted α-amino acid derivatives in moderate to good yields with excellent functional group tolerance under mild and simple conditions.</div></div>","PeriodicalId":437,"journal":{"name":"Tetrahedron","volume":"167 ","pages":"Article 134294"},"PeriodicalIF":2.1,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142425570","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 : 2024-10-04DOI: 10.1016/j.tet.2024.134293
Pushpa V. Malekar , Ganesh V. More , Chepuri V. Ramana
The enantioselective transfer hydrogenation of racemic β-keto γ-lactams via dynamic kinetic resolution using a chiral Ru(II) catalyst has been developed for the synthesis of optically active β-hydroxyl lactams with excellent conversion (up to 99 %), high diastereomeric ratio (dr 93:07) and enantiomeric selectivity (89 % ee). The reaction proceeded by using HCO2H/Et3N as hydrogen donor and features mild, additive free reaction conditions, fast crystallization, broad substrate scope, and an operationally simpler setup than that for molecular hydrogenation.
{"title":"Ru-catalyzed asymmetric transfer hydrogenation of racemic β-keto γ-lactams via dynamic kinetic resolution","authors":"Pushpa V. Malekar , Ganesh V. More , Chepuri V. Ramana","doi":"10.1016/j.tet.2024.134293","DOIUrl":"10.1016/j.tet.2024.134293","url":null,"abstract":"<div><div>The enantioselective transfer hydrogenation of racemic <em>β</em>-keto <em>γ</em>-lactams <em>via</em> dynamic kinetic resolution using a chiral Ru(II) catalyst has been developed for the synthesis of optically active <em>β</em>-hydroxyl lactams with excellent conversion (up to 99 %), high diastereomeric ratio (<em>dr</em> 93:07) and enantiomeric selectivity (89 % <em>ee</em>). The reaction proceeded by using HCO<sub>2</sub>H/Et<sub>3</sub>N as hydrogen donor and features mild, additive free reaction conditions, fast crystallization, broad substrate scope, and an operationally simpler setup than that for molecular hydrogenation.</div></div>","PeriodicalId":437,"journal":{"name":"Tetrahedron","volume":"167 ","pages":"Article 134293"},"PeriodicalIF":2.1,"publicationDate":"2024-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142425574","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}
A series of spirocyclic pyrrolidine derivatives with quaternary stereocenters was constructed via asymmetric [3 + 2] cycloaddition reactions between imino esters and 2-oxindole. By ingenious use of ligands on the silver catalyst allows stereoselectivity to either endo-isomers (ee up to 98 %, yields up to 96 %) with (R, Rp)-Ph-Phosferrox or exo-isomers (ee up to 99 %, yields up to 87 %) with (R)-BINAP. This work is notable for its high yields, broad substrate adaptability and excellent enantioselectivity.
{"title":"Diastereoselective Stereo-Divergent Synthesis of Spiroindolines via Ligand-Controlled Silver(I)-Catalyzed Asymmetric [3 + 2] cycloadditions","authors":"Yangmin Ma, Xuemei Zhang, Gege Dang, Miao Xia, Zhaoyang Sun, Siyue Ma, Wenting Zhang","doi":"10.1016/j.tet.2024.134291","DOIUrl":"10.1016/j.tet.2024.134291","url":null,"abstract":"<div><div>A series of spirocyclic pyrrolidine derivatives with quaternary stereocenters was constructed via asymmetric [3 + 2] cycloaddition reactions between imino esters and 2-oxindole. By ingenious use of ligands on the silver catalyst allows stereoselectivity to either <em>endo</em>-isomers (ee up to 98 %, yields up to 96 %) with (<em>R</em>, <em>Rp</em>)-Ph-Phosferrox or <em>exo</em>-isomers (ee up to 99 %, yields up to 87 %) with (<em>R</em>)-BINAP. This work is notable for its high yields, broad substrate adaptability and excellent enantioselectivity.</div></div>","PeriodicalId":437,"journal":{"name":"Tetrahedron","volume":"167 ","pages":"Article 134291"},"PeriodicalIF":2.1,"publicationDate":"2024-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142425575","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 : 2024-10-03DOI: 10.1016/j.tet.2024.134289
Tina Abbasi , Mohammad Bagher Teimouri , Issa Yavari , Rahman Bikas , Tadeusz Lis
A green one-pot reaction involving cyclic secondary amines, activated alkynes, and alloxan derivatives in water has been established, offering a cost-effective and selective route to (enamino)hydroxybarbiturates and 3-amino-5-hydroxycyclopent-2-enone-derived carbonylureas with high yields. This method utilizes readily available starting materials to produce valuable compounds for medicinal chemistry and organic synthesis through a three-component cascade reaction under mild conditions.
{"title":"Regioselective synthesis of functionalized cyclopent-2-enone-derived carbonylureas and enaminohydroxybarbiturates from alloxans in water","authors":"Tina Abbasi , Mohammad Bagher Teimouri , Issa Yavari , Rahman Bikas , Tadeusz Lis","doi":"10.1016/j.tet.2024.134289","DOIUrl":"10.1016/j.tet.2024.134289","url":null,"abstract":"<div><div>A green one-pot reaction involving cyclic secondary amines, activated alkynes, and alloxan derivatives in water has been established, offering a cost-effective and selective route to (enamino)hydroxybarbiturates and 3-amino-5-hydroxycyclopent-2-enone-derived carbonylureas with high yields. This method utilizes readily available starting materials to produce valuable compounds for medicinal chemistry and organic synthesis through a three-component cascade reaction under mild conditions.</div></div>","PeriodicalId":437,"journal":{"name":"Tetrahedron","volume":"167 ","pages":"Article 134289"},"PeriodicalIF":2.1,"publicationDate":"2024-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142425569","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 : 2024-10-03DOI: 10.1016/j.tet.2024.134290
Rachana Upadhyay, Amit B. Patel
Herein, a novel approach of bimetallic Pd(OAc)2/CuI-catalyzed alkynylation of 3-chloroazetidin-2-one (β-lactam derivative) with terminal alkyne via tandem C–C bond activation/Sonogashira-type cross-coupling reaction is developed. This synthesis encompasses a sequence of inert Csp3–X/Csp–H functionalization processes involving the coupling of the C(sp3) adjacent to the 3-chloroazetidin-2-one with the C(sp) of a terminal alkyne. The final analogs are synthesized by means of the indole-benzothiazole Schiff base formation, cyclization of the Schiff base to generate the β-lactam derivative, and Sonogashira coupling to afford a C(sp3)–C(sp) bond. In addition, indole, benzothiazole, and azetidine-2-one have been identified to be highly efficient heterocyclic scaffolds with a range of pharmacological benefits. It encouraged us to discover a hybrid compound that had each of these moieties. Cooperation between two different metals is essential for the successful implementation of this approach. Specifically, the interaction between the Pd and Cu centers in the transmetallation step is depicted through a plausible mechanistic route. The reaction conditions have been optimized by varying catalyst and ligand loadings, bases, temperatures, and solvents. The reaction is highly efficient, yielding alkynylated products in up to 84 % yield with a wide range of substrates and functional group tolerance, thereby serving as a functional model for the Sonogashira coupling reaction.
{"title":"Synergistic Pd(OAc)2/CuI-catalyzed alkynylation of β-lactam derivative via Sonogashira coupling","authors":"Rachana Upadhyay, Amit B. Patel","doi":"10.1016/j.tet.2024.134290","DOIUrl":"10.1016/j.tet.2024.134290","url":null,"abstract":"<div><div>Herein, a novel approach of bimetallic Pd(OAc)<sub>2</sub>/CuI-catalyzed alkynylation of 3-chloroazetidin-2-one (<em>β</em>-lactam derivative) with terminal alkyne <em>via</em> tandem C–C bond activation/Sonogashira-type cross-coupling reaction is developed. This synthesis encompasses a sequence of inert Csp<sup>3</sup>–X/Csp–H functionalization processes involving the coupling of the C(sp<sup>3</sup>) adjacent to the 3-chloroazetidin-2-one with the C(sp) of a terminal alkyne. The final analogs are synthesized by means of the indole-benzothiazole Schiff base formation, cyclization of the Schiff base to generate the <em>β</em>-lactam derivative, and Sonogashira coupling to afford a C(sp<sup>3</sup>)–C(sp) bond. In addition, indole, benzothiazole, and azetidine-2-one have been identified to be highly efficient heterocyclic scaffolds with a range of pharmacological benefits. It encouraged us to discover a hybrid compound that had each of these moieties. Cooperation between two different metals is essential for the successful implementation of this approach. Specifically, the interaction between the Pd and Cu centers in the transmetallation step is depicted through a plausible mechanistic route. The reaction conditions have been optimized by varying catalyst and ligand loadings, bases, temperatures, and solvents. The reaction is highly efficient, yielding alkynylated products in up to 84 % yield with a wide range of substrates and functional group tolerance, thereby serving as a functional model for the Sonogashira coupling reaction.</div></div>","PeriodicalId":437,"journal":{"name":"Tetrahedron","volume":"167 ","pages":"Article 134290"},"PeriodicalIF":2.1,"publicationDate":"2024-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142425566","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