Pub Date : 2026-03-01Epub Date: 2026-01-02DOI: 10.1016/j.tetlet.2025.155958
Jianlong Chen , Caihe Sun , Yilin Bu , Xiaoyu Wang , Xia Zhao , Kui Lu
A visible-light-induced trifluoromethylation of alkenes was accomplished by using trifluoromethylsulfonylpyridinium salt, accompanied by the insertion of SO2 molecules. This reaction proceeded under the catalysis of Ir(ppy)3, resulting in the formation of trifluoromethylated 4H-benzo[e][1,2,4]thiadiazine-1,1-dioxides. The readily available reagents and the mild reaction conditions make this approach an efficient and cost effective method for the synthesis of these compounds.
{"title":"Photochemical trifluoromethylation of alkenes with trifluoromethylsulfonyl-pyridinium salt accompanied by SO₂ insertion: Synthesis of trifluoromethylated 4H-benzo[e][1,2,4]thiadiazine 1,1-dioxides","authors":"Jianlong Chen , Caihe Sun , Yilin Bu , Xiaoyu Wang , Xia Zhao , Kui Lu","doi":"10.1016/j.tetlet.2025.155958","DOIUrl":"10.1016/j.tetlet.2025.155958","url":null,"abstract":"<div><div>A visible-light-induced trifluoromethylation of alkenes was accomplished by using trifluoromethylsulfonylpyridinium salt, accompanied by the insertion of SO<sub>2</sub> molecules. This reaction proceeded under the catalysis of Ir(ppy)<sub>3</sub>, resulting in the formation of trifluoromethylated 4<em>H</em>-benzo[<em>e</em>][1,2,4]thiadiazine-1,1-dioxides. The readily available reagents and the mild reaction conditions make this approach an efficient and cost effective method for the synthesis of these compounds.</div></div>","PeriodicalId":438,"journal":{"name":"Tetrahedron Letters","volume":"176 ","pages":"Article 155958"},"PeriodicalIF":1.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145922023","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The catalytic transformation of 2-(2-aminophenyl)ethanol with arylmethanols has emerged as a versatile and atom-economical route for constructing indole-based heterocycles. Over the past decade, systematic advances have revealed that catalyst design and reaction conditions critically dictate product selectivity, enabling access to C3-alkylated, N-alkylated, bis(indolyl)methanes (BIMs), formylated indoles, and 3-hydroxyindolin-2-ones. Early reports predominantly yielded C3-alkylated indoles, while subsequent developments employing rationally designed pincer-type complexes of Ru(II), Zn(II), Fe(II), Co(II), Mn(I), and Ni(II) have demonstrated a remarkable divergence in reactivity. Notably, Ni–dcype catalysis enabled a selective N-alkylation pathway, whereas the Co(II)–NNSe complex achieved the first one-pot synthesis of 2-aryl-3-formylindoles. Furthermore, variation in catalyst design, such as Ru–NNN pincer systems, afforded structurally complex 3-hydroxyindolin-2-ones under controlled oxidation conditions. These examples highlight how subtle modifications in the electronic and structural features of catalysts direct mechanistic routes through imine formation, hydrogen transfer, or oxidative cyclization. This review underscores the interplay between catalyst architecture, base selection, and reaction environment in governing chemoselectivity and provides mechanistic insights guiding the design of sustainable, earth-abundant metal catalysts for selective indole synthesis.
{"title":"Divergent catalytic routes to indoles from 2-(aminophenyl)ethanol and arylmethanols: insights into mechanism and selectivity","authors":"Sohan Singh , Suman Mahala , Harsh Sharma, Mayank Shekhawat, Hemant Joshi","doi":"10.1016/j.tetlet.2025.155951","DOIUrl":"10.1016/j.tetlet.2025.155951","url":null,"abstract":"<div><div>The catalytic transformation of 2-(2-aminophenyl)ethanol with arylmethanols has emerged as a versatile and atom-economical route for constructing indole-based heterocycles. Over the past decade, systematic advances have revealed that catalyst design and reaction conditions critically dictate product selectivity, enabling access to <em>C3-</em>alkylated, <em>N</em>-alkylated, bis(indolyl)methanes (BIMs), formylated indoles, and 3-hydroxyindolin-2-ones. Early reports predominantly yielded <em>C3-</em>alkylated indoles, while subsequent developments employing rationally designed pincer-type complexes of Ru(II), Zn(II), Fe(II), Co(II), Mn(I), and Ni(II) have demonstrated a remarkable divergence in reactivity. Notably, Ni–dcype catalysis enabled a selective <em>N</em>-alkylation pathway, whereas the Co(II)–NNSe complex achieved the first one-pot synthesis of 2-aryl-3-formylindoles. Furthermore, variation in catalyst design, such as Ru–NNN pincer systems, afforded structurally complex 3-hydroxyindolin-2-ones under controlled oxidation conditions. These examples highlight how subtle modifications in the electronic and structural features of catalysts direct mechanistic routes through imine formation, hydrogen transfer, or oxidative cyclization. This review underscores the interplay between catalyst architecture, base selection, and reaction environment in governing chemoselectivity and provides mechanistic insights guiding the design of sustainable, earth-abundant metal catalysts for selective indole synthesis.</div></div>","PeriodicalId":438,"journal":{"name":"Tetrahedron Letters","volume":"176 ","pages":"Article 155951"},"PeriodicalIF":1.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145837874","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2025-12-17DOI: 10.1016/j.tetlet.2025.155928
Han-Chi Wang, Zhi-Xue Song, Na-Na Sun, Bo Sun
A Ru(II)-catalyzed ortho allylation of N-aryl-7-azaindoles with readily accessible vinylcyclopropanes has been developed. This methodology facilitates the efficient construction of C(sp2)-C(sp3) bonds through sequential CH and CC activation, providing a concise and highly efficient route (up to 93 % yield) to valuable 7-azaindole derivatives. Furthermore, the strategy has been successfully extended to the allylation of isoquinolones with vinylcyclopropanes, underscoring the broad applicability and practical value of this synthetic approach.
{"title":"Ru(II)-catalyzed ortho CH allylation of N-aryl-7-azaindoles with vinylcyclopropanes","authors":"Han-Chi Wang, Zhi-Xue Song, Na-Na Sun, Bo Sun","doi":"10.1016/j.tetlet.2025.155928","DOIUrl":"10.1016/j.tetlet.2025.155928","url":null,"abstract":"<div><div>A Ru(II)-catalyzed <em>ortho</em> allylation of <em>N</em>-aryl-7-azaindoles with readily accessible vinylcyclopropanes has been developed. This methodology facilitates the efficient construction of C(sp<sup>2</sup>)-C(sp<sup>3</sup>) bonds through sequential C<img>H and C<img>C activation, providing a concise and highly efficient route (up to 93 % yield) to valuable 7-azaindole derivatives. Furthermore, the strategy has been successfully extended to the allylation of isoquinolones with vinylcyclopropanes, underscoring the broad applicability and practical value of this synthetic approach.</div></div>","PeriodicalId":438,"journal":{"name":"Tetrahedron Letters","volume":"176 ","pages":"Article 155928"},"PeriodicalIF":1.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145837875","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2025-12-21DOI: 10.1016/j.tetlet.2025.155944
Yiping Huang , Changhai Yue , Dan Wu , Yufan Ji , Kai Zhu , Lei Fan , Wenyu Zhang , Hong Qin , Zheng Fang
An efficient one-pot heptafluoroisopropyl iodide/silver(I)-mediated cross-dehydrogenative N–H/benzylic C(sp3)–H coupling of benzimidazoles with simple benzylic hydrocarbons has been developed. This protocol enables the direct construction of CN bonds from readily available substrates without prefunctionalization under mild conditions. Under the optimized conditions (Ag₂O as the oxidant and i-C₃F₇I as a radical precursor, 100 °C, air), a broad range of N-alkylated benzimidazoles and related azoles are obtained in moderate to good yields with good tolerance to various functional groups. Mechanistic studies, including radical inhibition experiments and a kinetic isotope effect (k_H/k_D = 2.1), support a radical pathway in which benzylic and N-centered radicals are generated under fluorinated radical/silver(I) initiation and undergo radical–radical cross-coupling to form the CN bond. This straightforward and operationally simple strategy provides a practical and complementary approach for the synthesis of benzimidazole derivatives via direct benzylic C(sp3)–H amination.
{"title":"Heptafluoroisopropyl iodide/silver(I)-mediated benzylic C(sp3)–H amination: direct access to N-alkylated benzimidazoles from simple hydrocarbons","authors":"Yiping Huang , Changhai Yue , Dan Wu , Yufan Ji , Kai Zhu , Lei Fan , Wenyu Zhang , Hong Qin , Zheng Fang","doi":"10.1016/j.tetlet.2025.155944","DOIUrl":"10.1016/j.tetlet.2025.155944","url":null,"abstract":"<div><div>An efficient one-pot heptafluoroisopropyl iodide/silver(I)-mediated cross-dehydrogenative N–H/benzylic C(sp<sup>3</sup>)–H coupling of benzimidazoles with simple benzylic hydrocarbons has been developed. This protocol enables the direct construction of C<img>N bonds from readily available substrates without prefunctionalization under mild conditions. Under the optimized conditions (Ag₂O as the oxidant and i-C₃F₇I as a radical precursor, 100 °C, air), a broad range of N-alkylated benzimidazoles and related azoles are obtained in moderate to good yields with good tolerance to various functional groups. Mechanistic studies, including radical inhibition experiments and a kinetic isotope effect (k_H/k_D = 2.1), support a radical pathway in which benzylic and N-centered radicals are generated under fluorinated radical/silver(I) initiation and undergo radical–radical cross-coupling to form the C<img>N bond. This straightforward and operationally simple strategy provides a practical and complementary approach for the synthesis of benzimidazole derivatives via direct benzylic C(sp<sup>3</sup>)–H amination.</div></div>","PeriodicalId":438,"journal":{"name":"Tetrahedron Letters","volume":"176 ","pages":"Article 155944"},"PeriodicalIF":1.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145837939","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2025-12-23DOI: 10.1016/j.tetlet.2025.155952
Wei Jiang , Guanghui Fan , Zhijiang Ma , Zhaozhi Zhu , Gege Zhao , Pengpeng Gao , Peiwen Yang , Jiangang Gan , Hongbo Wei , Weiqing Xie
Arcutine diterpenoid alkaloids are a subclass of C20-diterpenoid alkaloids characterized by a unique tetracyclo[5.3.3.04,9.04,12]tridecane framework. Herein, we report a facile strategy for constructing this scaffold through a tandem Diels–Alder/retro-Diels–Alder/Diels–Alder sequence using 2H-pyran-2-one derivatives bearing two terminal alkenes. DFT studies were also conducted to elucidate the reaction mechanism, revealing that CO2 extrusion plays a crucial role in driving the formation of the diene intermediate, which smoothly undergoes the second Diels–Alder cycloaddition.
{"title":"Synthetic study of arcutine diterpenoid alkaloids: rapid construction of tetracyclo[5.3.3.04,9.04,12]tridecane framework via intramolecular Diels–Alder/retro-Diels–Alder/Diels–Alder cascade","authors":"Wei Jiang , Guanghui Fan , Zhijiang Ma , Zhaozhi Zhu , Gege Zhao , Pengpeng Gao , Peiwen Yang , Jiangang Gan , Hongbo Wei , Weiqing Xie","doi":"10.1016/j.tetlet.2025.155952","DOIUrl":"10.1016/j.tetlet.2025.155952","url":null,"abstract":"<div><div>Arcutine diterpenoid alkaloids are a subclass of C20-diterpenoid alkaloids characterized by a unique tetracyclo[5.3.3.0<sup>4,9</sup>.0<sup>4,12</sup>]tridecane framework. Herein, we report a facile strategy for constructing this scaffold through a tandem Diels–Alder/<em>retro</em>-Diels–Alder/Diels–Alder sequence using 2<em>H</em>-pyran-2-one derivatives bearing two terminal alkenes. DFT studies were also conducted to elucidate the reaction mechanism, revealing that CO<sub>2</sub> extrusion plays a crucial role in driving the formation of the diene intermediate, which smoothly undergoes the second Diels–Alder cycloaddition.</div></div>","PeriodicalId":438,"journal":{"name":"Tetrahedron Letters","volume":"176 ","pages":"Article 155952"},"PeriodicalIF":1.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145881189","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2025-12-31DOI: 10.1016/j.tetlet.2025.155953
Xu Chen , Haojie Ge , Jie Li
A novel synthesis of β-ketonitriles via base-promoted tandem reaction is presented herein. Simply combining N-acylpiperidin-2-one with NaN(SiMe3)2 enabled the preparation of a series of ketonitriles. This protocol is efficient, transition metal-free, mild, and operationally simple.
{"title":"NaN(SiMe3)2 promoted synthesis of β-ketonitriles with N-acylpiperidin-2-one and their cytotoxic activity on U87MG cells","authors":"Xu Chen , Haojie Ge , Jie Li","doi":"10.1016/j.tetlet.2025.155953","DOIUrl":"10.1016/j.tetlet.2025.155953","url":null,"abstract":"<div><div>A novel synthesis of β-ketonitriles via base-promoted tandem reaction is presented herein. Simply combining <em>N</em>-acylpiperidin-2-one with NaN(SiMe<sub>3</sub>)<sub>2</sub> enabled the preparation of a series of ketonitriles. This protocol is efficient, transition metal-free, mild, and operationally simple.</div></div>","PeriodicalId":438,"journal":{"name":"Tetrahedron Letters","volume":"176 ","pages":"Article 155953"},"PeriodicalIF":1.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145922021","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2025-12-26DOI: 10.1016/j.tetlet.2025.155934
Yuta Inagaki, Shinnosuke Wakamori, Ryo Katsuta, Ken Ishigami
Efficient synthesis of the cyclic depsipeptide n-C14-surfactin was achieved using hydrophobic tag-assisted liquid-phase peptide synthesis (LPPS). Two linear synthetic routes, made possible by attaching the tag to the side-chain carboxyl group of either an aspartic acid or a glutamic acid residue, were examined, where both peptide elongation and macrocyclization proceeded with tag assistance. In addition to this prominent approach, an improved one-pot sequential coupling/deprotection protocol enabled decagram-scale synthesis, affording n-C14-surfactin with high chemical purity. The present strategy afforded significantly improved synthetic efficiency, with an excellent overall yield of 72 % over 13 steps, compared to previous solution- or solid-phase syntheses lacking support-based macrocyclization.
{"title":"Efficient synthesis of the cyclic lipopeptide n-C14-surfactin using soluble hydrophobic tag-assisted liquid-phase peptide synthesis","authors":"Yuta Inagaki, Shinnosuke Wakamori, Ryo Katsuta, Ken Ishigami","doi":"10.1016/j.tetlet.2025.155934","DOIUrl":"10.1016/j.tetlet.2025.155934","url":null,"abstract":"<div><div>Efficient synthesis of the cyclic depsipeptide <em>n</em>-C<sub>14</sub>-surfactin was achieved using hydrophobic tag-assisted liquid-phase peptide synthesis (LPPS). Two linear synthetic routes, made possible by attaching the tag to the side-chain carboxyl group of either an aspartic acid or a glutamic acid residue, were examined, where both peptide elongation and macrocyclization proceeded with tag assistance. In addition to this prominent approach, an improved one-pot sequential coupling/deprotection protocol enabled decagram-scale synthesis, affording <em>n</em>-C<sub>14</sub>-surfactin with high chemical purity. The present strategy afforded significantly improved synthetic efficiency, with an excellent overall yield of 72 % over 13 steps, compared to previous solution- or solid-phase syntheses lacking support-based macrocyclization.</div></div>","PeriodicalId":438,"journal":{"name":"Tetrahedron Letters","volume":"176 ","pages":"Article 155934"},"PeriodicalIF":1.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145837872","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2026-01-02DOI: 10.1016/j.tetlet.2025.155957
Chihiro Sonoda, Takashi Hayashi
We report the synthesis and characterization of three new electron-deficient iron porphyrins bearing trifluoromethyl group substituents; FePormCF3, FePorβMe2(CF3)4 and FePorβEt2(CF3)4. FePormCF3, substituted with a CF3 group at the meso-position, and FePorβMe2(CF3)4, substituted with four CF3 and two methyl groups at the pyrrole β-positions, were synthesized via coupling of two dipyrromethane molecules, while FePorβEt2(CF3)4, where two methyl groups of FePorβMe2(CF3)4 were replaced with ethyl groups, was obtained through a biladiene-ac precursor route involving copper-templated cyclization. The corresponding free-base porphyrins were characterized by NMR and mass spectrometry, revealing clear electronic effects caused by the CF3 substituents. The 1H and 19F NMR spectra indicate downfield shifts of inner NHs, suggesting that the electron-withdrawing CF3 groups decrease the electron density of the porphyrin π-system and weaken the aromatic ring current. Differential pulse voltammetry measurements demonstrated positive shifts of the Fe(II)/Fe(III) redox potentials to −715 mV and −355 mV vs. Fc/Fc+ for FePormCF3 and FePorβMe2(CF3)4, respectively, confirming that introduction of the CF3 substituents effectively stabilizes the ferrous state. These results highlight how CF3 substitution modulates the electronic structure and redox properties of metalloporphyrins. In addition, it has been confirmed that these iron complexes can be incorporated into the myoglobin heme pocket. The present study establishes versatile synthetic approaches for introducing strong electron-withdrawing groups into heme analogues, in our efforts to develop useful attractive artificial cofactors with controlled redox potentials and unique reactivity.
{"title":"Synthesis and chemical properties of electron-deficient porphyrin cofactors with trifluoromethyl groups","authors":"Chihiro Sonoda, Takashi Hayashi","doi":"10.1016/j.tetlet.2025.155957","DOIUrl":"10.1016/j.tetlet.2025.155957","url":null,"abstract":"<div><div>We report the synthesis and characterization of three new electron-deficient iron porphyrins bearing trifluoromethyl group substituents; FePormCF<sub>3</sub>, FePorβMe<sub>2</sub>(CF<sub>3</sub>)<sub>4</sub> and FePorβEt<sub>2</sub>(CF<sub>3</sub>)<sub>4</sub>. FePormCF<sub>3</sub>, substituted with a CF<sub>3</sub> group at the <em>meso</em>-position, and FePorβMe<sub>2</sub>(CF<sub>3</sub>)<sub>4</sub>, substituted with four CF<sub>3</sub> and two methyl groups at the pyrrole β-positions, were synthesized via coupling of two dipyrromethane molecules, while FePorβEt<sub>2</sub>(CF<sub>3</sub>)<sub>4</sub>, where two methyl groups of FePorβMe<sub>2</sub>(CF<sub>3</sub>)<sub>4</sub> were replaced with ethyl groups, was obtained through a biladiene-<em>ac</em> precursor route involving copper-templated cyclization. The corresponding free-base porphyrins were characterized by NMR and mass spectrometry, revealing clear electronic effects caused by the CF<sub>3</sub> substituents. The <sup>1</sup>H and <sup>19</sup>F NMR spectra indicate downfield shifts of inner NHs, suggesting that the electron-withdrawing CF<sub>3</sub> groups decrease the electron density of the porphyrin π-system and weaken the aromatic ring current. Differential pulse voltammetry measurements demonstrated positive shifts of the Fe(II)/Fe(III) redox potentials to −715 mV and −355 mV vs. Fc/Fc<sup>+</sup> for FePormCF<sub>3</sub> and FePorβMe<sub>2</sub>(CF<sub>3</sub>)<sub>4</sub>, respectively, confirming that introduction of the CF<sub>3</sub> substituents effectively stabilizes the ferrous state. These results highlight how CF<sub>3</sub> substitution modulates the electronic structure and redox properties of metalloporphyrins. In addition, it has been confirmed that these iron complexes can be incorporated into the myoglobin heme pocket. The present study establishes versatile synthetic approaches for introducing strong electron-withdrawing groups into heme analogues, in our efforts to develop useful attractive artificial cofactors with controlled redox potentials and unique reactivity.</div></div>","PeriodicalId":438,"journal":{"name":"Tetrahedron Letters","volume":"176 ","pages":"Article 155957"},"PeriodicalIF":1.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145922022","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2026-01-07DOI: 10.1016/j.tetlet.2026.155959
Yichen Li, Lin Pu
A BINOL-pyridine-based chiral unsymmetric dialdehyde was synthesized. This compound in combination with Zn2+ has exhibited highly chemoselective as well as enantioselective fluorescent response toward lysine, an essential amino acid. It was found that this compound undergoes regioselective macrocyclization with l-lysine but generates a more complex mixture with d-lysine. This difference in reactivity should contribute to the observed chemo- and enantioselectivty in the fluorescence response. This molecular probe can be used at 20 times lower concentration than a previously reported analog for lysine recognition. It has also displayed significantly enhanced enantioselectivity over the previously reported analog with the enantioselective fluorescence intensity ratio (ef) increased from 16.9 to 60.0 [ef = (IL-I0)/(ID-I0). I0: the fluorescence intensity of the probe in the absence of the amino acid].
{"title":"Chemoselective and enantioselective fluorescent recognition of lysine by a BINOL-pyridine-based chiral dialdehyde","authors":"Yichen Li, Lin Pu","doi":"10.1016/j.tetlet.2026.155959","DOIUrl":"10.1016/j.tetlet.2026.155959","url":null,"abstract":"<div><div>A BINOL-pyridine-based chiral unsymmetric dialdehyde was synthesized. This compound in combination with Zn<sup>2+</sup> has exhibited highly chemoselective as well as enantioselective fluorescent response toward lysine, an essential amino acid. It was found that this compound undergoes regioselective macrocyclization with <span>l</span>-lysine but generates a more complex mixture with <span>d</span>-lysine. This difference in reactivity should contribute to the observed chemo- and enantioselectivty in the fluorescence response. This molecular probe can be used at 20 times lower concentration than a previously reported analog for lysine recognition. It has also displayed significantly enhanced enantioselectivity over the previously reported analog with the enantioselective fluorescence intensity ratio (ef) increased from 16.9 to 60.0 [ef = (I<sub>L</sub>-I<sub>0</sub>)/(I<sub>D</sub>-I<sub>0</sub>). I<sub>0</sub>: the fluorescence intensity of the probe in the absence of the amino acid].</div></div>","PeriodicalId":438,"journal":{"name":"Tetrahedron Letters","volume":"176 ","pages":"Article 155959"},"PeriodicalIF":1.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145922020","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2025-12-20DOI: 10.1016/j.tetlet.2025.155945
Jacob C. Hood, Douglas A. Klumpp
A series of N-heterocyclic-substituted cyclopropyl ethanols were prepared and shown to give excellent product conversions in Friedel-Crafts reactions with benzene in trifluoromethanesulfonic acid (triflic acid). With protonation of the N-heterocycle and ionization of the cyclopropylcarbinol, dicationic species are generated. These provide homoallyl products (93–99 % yields) and with heating give substituted-tetralin products (84–97 % yields).
{"title":"Temperature-controlled Friedel-Crafts reactions of cyclopropyl ethanols via dicationic bicyclobutonium ion intermediates","authors":"Jacob C. Hood, Douglas A. Klumpp","doi":"10.1016/j.tetlet.2025.155945","DOIUrl":"10.1016/j.tetlet.2025.155945","url":null,"abstract":"<div><div>A series of <em>N</em>-heterocyclic-substituted cyclopropyl ethanols were prepared and shown to give excellent product conversions in Friedel-Crafts reactions with benzene in trifluoromethanesulfonic acid (triflic acid). With protonation of the N-heterocycle and ionization of the cyclopropylcarbinol, dicationic species are generated. These provide homoallyl products (93–99 % yields) and with heating give substituted-tetralin products (84–97 % yields).</div></div>","PeriodicalId":438,"journal":{"name":"Tetrahedron Letters","volume":"176 ","pages":"Article 155945"},"PeriodicalIF":1.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145881320","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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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