Pub Date : 2025-10-04DOI: 10.1016/j.tet.2025.134981
An-Xi Zhou , Jie-Tiao Chen , Zhuo-Yu Yang , Xian-Hong Zhu , Liu-Liang Mao , Cong-Bin Ji , Qiang Xiao , Xian-Rong Song
Herein we report a novel, efficient gold-catalyzed tandem reaction of alkynols with TMSN3 as a nitrogen source to yield alkenylnitrile derivatives in the presence of TFA. The reaction proceeds under mild conditions and exhibits broad functional group tolerance. The synthetic utility of this reaction has been reflected by its applicability to a wide range of alkynol substrates.
{"title":"Gold-catalyzed directed transformation of alkynols with trimethylsilyl azide for the efficient construction of alkenylnitrile derivatives","authors":"An-Xi Zhou , Jie-Tiao Chen , Zhuo-Yu Yang , Xian-Hong Zhu , Liu-Liang Mao , Cong-Bin Ji , Qiang Xiao , Xian-Rong Song","doi":"10.1016/j.tet.2025.134981","DOIUrl":"10.1016/j.tet.2025.134981","url":null,"abstract":"<div><div>Herein we report a novel, efficient gold-catalyzed tandem reaction of alkynols with TMSN<sub>3</sub> as a nitrogen source to yield alkenylnitrile derivatives in the presence of TFA. The reaction proceeds under mild conditions and exhibits broad functional group tolerance. The synthetic utility of this reaction has been reflected by its applicability to a wide range of alkynol substrates.</div></div>","PeriodicalId":437,"journal":{"name":"Tetrahedron","volume":"188 ","pages":"Article 134981"},"PeriodicalIF":2.2,"publicationDate":"2025-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145263950","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 : 2025-10-03DOI: 10.1016/j.tet.2025.134980
Sharmin Afroz, Nurabul Mondal, Lokman H. Choudhury
Herein, we report an efficient, one-pot, metal and additive-free multicomponent reaction of amines, carbon disulfide, and maleimides in water medium for the synthesis of succinimide-linked dithiocarbamates. The method operates at room temperature and yields results ranging from good to very good. Both aliphatic and aromatic amines were found suitable for this methodology. The salient features of this methodology include metal- and catalyst-free conditions, operational simplicity, short reaction time, room-temperature reactions, the use of water as a green solvent, easy purification, and a wide substrate scope.
{"title":"Synthesis of dithiocarbamate-succinimide hybrids by room temperature multicomponent reactions in aqueous media","authors":"Sharmin Afroz, Nurabul Mondal, Lokman H. Choudhury","doi":"10.1016/j.tet.2025.134980","DOIUrl":"10.1016/j.tet.2025.134980","url":null,"abstract":"<div><div>Herein, we report an efficient, one-pot, metal and additive-free multicomponent reaction of amines, carbon disulfide, and maleimides in water medium for the synthesis of succinimide-linked dithiocarbamates. The method operates at room temperature and yields results ranging from good to very good. Both aliphatic and aromatic amines were found suitable for this methodology. The salient features of this methodology include metal- and catalyst-free conditions, operational simplicity, short reaction time, room-temperature reactions, the use of water as a green solvent, easy purification, and a wide substrate scope.</div></div>","PeriodicalId":437,"journal":{"name":"Tetrahedron","volume":"188 ","pages":"Article 134980"},"PeriodicalIF":2.2,"publicationDate":"2025-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145263942","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 : 2025-10-03DOI: 10.1016/j.tet.2025.134978
Muhammad Haroon , Razia Noreen , Ameer Fawad Zahoor , Muhammad Irfan , Atta ul Haq , Shahla Faisal , Sajjad Ahmad , Mariusz Mojzych , Freeha Hafeez , Mashooq Ahmad Bhat
The synthesis of novel and effective monoamine oxidase B inhibitors is indispensable for the treatment of Parkinson's disease. In the present study, novel piperazine based triazole derivatives 11a-11k were synthesized in good to excellent yields (81–95 %) through an ultrasound-assisted CetylTrimethylAmmonium Bromide (CTAB) catalyzed synthetic method. All the synthesized hybrids were screened against MAO-B by using in-silico modelling approach. The compounds 11a-11k were subjected to molecular docking to probe key interactions against MonoAmine Oxidase-B (MAO-B) active site. Most of the synthesized hybrids exhibited selectivity against MAO-B enzyme. Notably, 11g and 11i displayed higher potency with binding affinities −14.1 and −14.4 kcal/mol respectively, as compared to reference compounds melatonin (−8.1 kcal/mol) and safinamide (−9.7 kcal/mol), against the target protein. The validation of docking results was achieved by conducting 500 ns Molecular Dynamic (MD) simulation of potent compounds 11g and 11i. The findings of the MD simulation highlighted the prominent stability of 11g and 11i relative to safinamide under physiological conditions. The structure optimization, energy-gap, and NCI (non-covalent interactions) were determined through DFT calculations at B3LYP level by using 631g basis set. Additionally, the correlated movements, dynamic stability and binding free energies of complexes 11g and 11i were calculated through DCCM, PCA and MMPBSA analysis.
{"title":"Novel piperazine derivatives as MAO-B inhibitors: Design, synthesis and computational exploration through molecular docking, MD simulations, MM-PBSA and DFT studies","authors":"Muhammad Haroon , Razia Noreen , Ameer Fawad Zahoor , Muhammad Irfan , Atta ul Haq , Shahla Faisal , Sajjad Ahmad , Mariusz Mojzych , Freeha Hafeez , Mashooq Ahmad Bhat","doi":"10.1016/j.tet.2025.134978","DOIUrl":"10.1016/j.tet.2025.134978","url":null,"abstract":"<div><div>The synthesis of novel and effective monoamine oxidase B inhibitors is indispensable for the treatment of Parkinson's disease. In the present study, novel piperazine based triazole derivatives <strong>11a-11k</strong> were synthesized in good to excellent yields (81–95 %) through an ultrasound-assisted CetylTrimethylAmmonium Bromide (CTAB) catalyzed synthetic method. All the synthesized hybrids were screened against MAO-B by using <em>in-silico</em> modelling approach. The compounds <strong>11a-11k</strong> were subjected to molecular docking to probe key interactions against MonoAmine Oxidase-B (MAO-B) active site. Most of the synthesized hybrids exhibited selectivity against MAO-B enzyme. Notably, <strong>11g</strong> and <strong>11i</strong> displayed higher potency with binding affinities −14.1 and −14.4 kcal/mol respectively, as compared to reference compounds melatonin (−8.1 kcal/mol) and safinamide (−9.7 kcal/mol), against the target protein. The validation of docking results was achieved by conducting 500 ns Molecular Dynamic (MD) simulation of potent compounds <strong>11g</strong> and <strong>11i</strong>. The findings of the MD simulation highlighted the prominent stability of <strong>11g</strong> and <strong>11i</strong> relative to safinamide under physiological conditions. The structure optimization, energy-gap, and NCI (non-covalent interactions) were determined through DFT calculations at B3LYP level by using 631g basis set. Additionally, the correlated movements, dynamic stability and binding free energies of complexes <strong>11g</strong> and <strong>11i</strong> were calculated through DCCM, PCA and MMPBSA analysis.</div></div>","PeriodicalId":437,"journal":{"name":"Tetrahedron","volume":"188 ","pages":"Article 134978"},"PeriodicalIF":2.2,"publicationDate":"2025-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145263949","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 : 2025-10-03DOI: 10.1016/j.tet.2025.134979
Anastasiya N. Bogdanova, Vadim A. Shiryaev, Marat R. Baimuratov, Yuri N. Klimochkin
The Diels-Alder reaction of adamantane-containing pyridinium dienic salts was studied. The reaction was found to proceed in an unexpected way. The presence of good leaving pyridine, moiety promotes the formation of an additional double bond in the reaction products and can lead to aromatization of the structure. The formation of a dimethylsulfide and pyridine based dienic salts in situ in the reaction with 1,4-naphthoquinone in a basic medium has been demonstrated. The investigation of the mechanisms of mentioned cycloadditions was performed on DFT level of theory with B3LYP functional in 6-311G++(2d,2p) basis set with solvation by ethanol in IEFPCM solvation model. Based on the results of the calculations, it can be assumed that the reaction cannot be stopped at the Diels-Alder stage because it has the highest barrier among all subsequent stages. A previously undescribed rearrangement was found while studying the interaction of a diene-structured pyridinium salt with tetracyanoethylene.
{"title":"Diels-Alder reaction of 1-butadienyl pyridinium salts. A new approach to adamantane-based carbocyclic compounds","authors":"Anastasiya N. Bogdanova, Vadim A. Shiryaev, Marat R. Baimuratov, Yuri N. Klimochkin","doi":"10.1016/j.tet.2025.134979","DOIUrl":"10.1016/j.tet.2025.134979","url":null,"abstract":"<div><div>The Diels-Alder reaction of adamantane-containing pyridinium dienic salts was studied. The reaction was found to proceed in an unexpected way. The presence of good leaving pyridine, moiety promotes the formation of an additional double bond in the reaction products and can lead to aromatization of the structure. The formation of a dimethylsulfide and pyridine based dienic salts <em>in situ</em> in the reaction with 1,4-naphthoquinone in a basic medium has been demonstrated. The investigation of the mechanisms of mentioned cycloadditions was performed on DFT level of theory with B3LYP functional in 6-311G++(2d,2p) basis set with solvation by ethanol in IEFPCM solvation model. Based on the results of the calculations, it can be assumed that the reaction cannot be stopped at the Diels-Alder stage because it has the highest barrier among all subsequent stages. A previously undescribed rearrangement was found while studying the interaction of a diene-structured pyridinium salt with tetracyanoethylene.</div></div>","PeriodicalId":437,"journal":{"name":"Tetrahedron","volume":"188 ","pages":"Article 134979"},"PeriodicalIF":2.2,"publicationDate":"2025-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145263948","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 : 2025-10-01DOI: 10.1016/j.tet.2025.134977
Manijeh Nematpour
In line with recent research on the synthesis of five-membered heterocyclic compounds, the synthesis of novel derivatives of 2-(1,3-selenazol-2-ylidene) malononitrile and 2-(thiazol-2-ylidene) malononitrile was carried out via the ring opening of nitroepoxide as an efficient starting material in this study. This reaction was carried out via the formation of malononitrile-isothiocyanate (or isoselenocyanate) adducts, followed by the addition of nitroepoxide to synthesize the products with easy purification. The effectiveness of this process was demonstrated through a gram-scale experiment, performing the four-component reaction, without the addition of a catalyst, at room temperature and in acetone solvent. 18 new heterocyclic compounds from the new 1,3-selenazoles and thiazoles family were synthesized and identified, and confirmed by IR, Mass, and NMR analyses.
{"title":"Synthesis of new 2-(thiazol-2-ylidene) malononitrile, and 2-(1,3-selenazol-2-ylidene) malononitrile derivatives via nitroepoxide ring opening with malononitrile-isothiocyanate (or isoselenocyanate) adducts","authors":"Manijeh Nematpour","doi":"10.1016/j.tet.2025.134977","DOIUrl":"10.1016/j.tet.2025.134977","url":null,"abstract":"<div><div>In line with recent research on the synthesis of five-membered heterocyclic compounds, the synthesis of novel derivatives of 2-(1,3-selenazol-2-ylidene) malononitrile and 2-(thiazol-2-ylidene) malononitrile was carried out <em>via</em> the ring opening of nitroepoxide as an efficient starting material in this study. This reaction was carried out <em>via</em> the formation of malononitrile-isothiocyanate (or isoselenocyanate) adducts, followed by the addition of nitroepoxide to synthesize the products with easy purification. The effectiveness of this process was demonstrated through a gram-scale experiment, performing the four-component reaction, without the addition of a catalyst, at room temperature and in acetone solvent. 18 new heterocyclic compounds from the new 1,3-selenazoles and thiazoles family were synthesized and identified, and confirmed by IR, Mass, and NMR analyses.</div></div>","PeriodicalId":437,"journal":{"name":"Tetrahedron","volume":"188 ","pages":"Article 134977"},"PeriodicalIF":2.2,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145227819","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 visible-light promoted triazole ring C(5)-H bond direct imidization to efficient construction of isoquinoline- and quinazoline-fused 1,2,3-triazoles was discovered. Employing easily available N(1)-(o-acetylaryl)-1,2,3-triazoles and O-(4-(trifluoromethyl)benzoyl)hydroxylamine as substrates, the designed products were obtained in moderate to excellent yields with a broad substrate scope by a one-pot two-step procedure, through an oxime ester intermediate generated in situ. This protocol features mild conditions, operational simplicity, good functional group tolerance, and easy scale-up. Preliminary mechanistic studies suggested that a radical route might be involved in the reaction.
{"title":"Visible-light promoted triazole C(5)-H imidization: An efficient access to quinazoline- and isoquinoline-fused 1,2,3-triazoles","authors":"Wenxiang Zhu, Yan Liang, Yanting Wu, Tiebo Xiao, Guiping Qin, Yubo Jiang","doi":"10.1016/j.tet.2025.134960","DOIUrl":"10.1016/j.tet.2025.134960","url":null,"abstract":"<div><div>A visible-light promoted triazole ring C(5)-H bond direct imidization to efficient construction of isoquinoline- and quinazoline-fused 1,2,3-triazoles was discovered. Employing easily available <em>N</em>(1)-(<em>o</em>-acetylaryl)-1,2,3-triazoles and <em>O</em>-(4-(trifluoromethyl)benzoyl)hydroxylamine as substrates, the designed products were obtained in moderate to excellent yields with a broad substrate scope by a one-pot two-step procedure, through an oxime ester intermediate generated in situ. This protocol features mild conditions, operational simplicity, good functional group tolerance, and easy scale-up. Preliminary mechanistic studies suggested that a radical route might be involved in the reaction.</div></div>","PeriodicalId":437,"journal":{"name":"Tetrahedron","volume":"188 ","pages":"Article 134960"},"PeriodicalIF":2.2,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145263943","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 : 2025-09-29DOI: 10.1016/j.tet.2025.134975
Saikat Dogra, Samim Sahaji, Anup Kumar Misra
Concise synthesis of the acidic pentasaccharide corresponding to the cell wall O-antigen of Shigella boydii type 16 has been achieved in very good yield by stereoselective glycosylations of judiciously functionalized monosaccharide intermediates. The construction of two 1,2-cis D-mannosidic linkages were achieved using a d-mannosyl thioglycoside donor with a picoloyl group placed at C-3 position enabling the potential of H-bond mediated aglycone delivery under conventional thiophilic activation conditions. The α-glycosylated d-galactose moiety was incorporated in the pentasaccharide by carrying out the glycosylation reaction in an ether based solvent using a donor with non-participating group present at C-2 position. The primary benzyloxy group was removed without affecting the benzylidene acetal and secondary benzyloxy groups using triethylsilane as hydrogen source under a time dependent catalytic transfer hydrogenation condition. A late stage TEMPO mediated BAIB oxidation of the primary hydroxyl group was carried out to convert the d-glucose moiety to the d-glucuronic acid component in the target compound.
{"title":"Synthesis of the pentasaccharide repeating unit corresponding to the cell wall O-antigen of Shigella boydii type 16","authors":"Saikat Dogra, Samim Sahaji, Anup Kumar Misra","doi":"10.1016/j.tet.2025.134975","DOIUrl":"10.1016/j.tet.2025.134975","url":null,"abstract":"<div><div>Concise synthesis of the acidic pentasaccharide corresponding to the cell wall <em>O</em>-antigen of <em>Shigella boydii type 16</em> has been achieved in very good yield by stereoselective glycosylations of judiciously functionalized monosaccharide intermediates. The construction of two 1,2-<em>cis</em> D-mannosidic linkages were achieved using a <span>d</span>-mannosyl thioglycoside donor with a picoloyl group placed at C-3 position enabling the potential of <em>H</em>-bond mediated aglycone delivery under conventional thiophilic activation conditions. The α-glycosylated <span>d</span>-galactose moiety was incorporated in the pentasaccharide by carrying out the glycosylation reaction in an ether based solvent using a donor with non-participating group present at C-2 position. The primary benzyloxy group was removed without affecting the benzylidene acetal and secondary benzyloxy groups using triethylsilane as hydrogen source under a time dependent catalytic transfer hydrogenation condition. A late stage TEMPO mediated BAIB oxidation of the primary hydroxyl group was carried out to convert the <span>d</span>-glucose moiety to the <span>d</span>-glucuronic acid component in the target compound.</div></div>","PeriodicalId":437,"journal":{"name":"Tetrahedron","volume":"188 ","pages":"Article 134975"},"PeriodicalIF":2.2,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145263941","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 : 2025-09-27DOI: 10.1016/j.tet.2025.134962
Appasaheb K. Nirpal, Shyam Sathyamoorthi
We have explored an interesting rearrangement of protected epoxy-alcohols into tetrahydrofuran derivatives. Our protocol is operationally simple and involves treatment of a substrate with catalytic quantities of boron trifluoride diethyl etherate in methylene chloride without any special precautions to exclude air or ambient moisture. The nature of the protecting group dictates the stereochemical outcome of the cyclization. For example, with trans-di-substituted epoxides bearing pendant esters or carbamates, the rearrangement gives tetrahydrofurans with contiguous stereocenters in a syn configuration. With these substrates, we hypothesize that the transformation initiates upon attack of the epoxide by the carbonyl oxygen of the ester or carbamate. Conversely, with trans-di-substituted epoxides bearing free alcohols or ethers, cyclization gives tetrahydrofurans with contiguous stereocenters in an anti configuration. Here, we believe that a simple SN2 attack on the epoxide is taking place. We also examined the cyclization with aziridine alcohols and their derivatives and with oxetane esters and found that some of these substrates were compatible with the reaction conditions.
{"title":"Rearrangement of protected epoxy-alcohols into tetrahydrofuran derivatives: The protecting group matters!","authors":"Appasaheb K. Nirpal, Shyam Sathyamoorthi","doi":"10.1016/j.tet.2025.134962","DOIUrl":"10.1016/j.tet.2025.134962","url":null,"abstract":"<div><div>We have explored an interesting rearrangement of protected epoxy-alcohols into tetrahydrofuran derivatives. Our protocol is operationally simple and involves treatment of a substrate with catalytic quantities of boron trifluoride diethyl etherate in methylene chloride without any special precautions to exclude air or ambient moisture. The nature of the protecting group dictates the stereochemical outcome of the cyclization. For example, with <em>trans</em>-di-substituted epoxides bearing pendant esters or carbamates, the rearrangement gives tetrahydrofurans with contiguous stereocenters in a <em>syn</em> configuration. With these substrates, we hypothesize that the transformation initiates upon attack of the epoxide by the carbonyl oxygen of the ester or carbamate. Conversely, with <em>trans</em>-di-substituted epoxides bearing free alcohols or ethers, cyclization gives tetrahydrofurans with contiguous stereocenters in an <em>anti</em> configuration. Here, we believe that a simple S<sub>N</sub>2 attack on the epoxide is taking place. We also examined the cyclization with aziridine alcohols and their derivatives and with oxetane esters and found that some of these substrates were compatible with the reaction conditions.</div></div>","PeriodicalId":437,"journal":{"name":"Tetrahedron","volume":"188 ","pages":"Article 134962"},"PeriodicalIF":2.2,"publicationDate":"2025-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145227815","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 : 2025-09-27DOI: 10.1016/j.tet.2025.134971
Ikuya Fujii , Taihei Mori , Ryo Shintani
Selective functionalization of unactivated C(sp3)–H bonds remains a major synthetic challenge. Herein, we report a visible-light-promoted, phenothiazine-catalyzed cyanoalkylation of silyl enol ethers via structurally tunable aryl radicals as hydrogen atom transfer (HAT) reagents. Upon irradiation, photoexcited phenothiazine generates nucleophilic aryl radicals from aryl iodides, which selectively abstract hydrogen atoms from alkyl nitriles such as acetonitrile via a polarity-matched HAT process, affording cyanomethyl radicals. These radicals subsequently undergo regioselective addition to silyl enol ethers, followed by oxidation and desilylation to furnish γ-ketonitriles under mild, metal-free conditions. Mechanistic investigations, including kinetic isotope effect measurements, radical trapping, and DFT calculations, support a reaction pathway wherein a C–H bond cleavage via HAT constitutes the rate-determining step. This work highlights the utility of structurally tunable aryl radicals in enabling polarity-matched HAT processes for C–H bond functionalization.
{"title":"Structurally tunable aryl radicals for hydrogen atom transfer: Visible-light-promoted cyanoalkylation of silyl enol ethers enabled by organic photoredox catalysis","authors":"Ikuya Fujii , Taihei Mori , Ryo Shintani","doi":"10.1016/j.tet.2025.134971","DOIUrl":"10.1016/j.tet.2025.134971","url":null,"abstract":"<div><div>Selective functionalization of unactivated C(sp<sup>3</sup>)–H bonds remains a major synthetic challenge. Herein, we report a visible-light-promoted, phenothiazine-catalyzed cyanoalkylation of silyl enol ethers via structurally tunable aryl radicals as hydrogen atom transfer (HAT) reagents. Upon irradiation, photoexcited phenothiazine generates nucleophilic aryl radicals from aryl iodides, which selectively abstract hydrogen atoms from alkyl nitriles such as acetonitrile via a polarity-matched HAT process, affording cyanomethyl radicals. These radicals subsequently undergo regioselective addition to silyl enol ethers, followed by oxidation and desilylation to furnish γ-ketonitriles under mild, metal-free conditions. Mechanistic investigations, including kinetic isotope effect measurements, radical trapping, and DFT calculations, support a reaction pathway wherein a C–H bond cleavage via HAT constitutes the rate-determining step. This work highlights the utility of structurally tunable aryl radicals in enabling polarity-matched HAT processes for C–H bond functionalization.</div></div>","PeriodicalId":437,"journal":{"name":"Tetrahedron","volume":"189 ","pages":"Article 134971"},"PeriodicalIF":2.2,"publicationDate":"2025-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145327265","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 : 2025-09-26DOI: 10.1016/j.tet.2025.134961
Neha Tripathi, Mangalampalli Ravikanth
Three fluorescent phenoxazinophanes, each incorporating two phenoxazine units bridged by two ethene linkers, were synthesized in a three-step sequence starting from commercially available phenoxazine. Substituents such as methyl and phenyl groups were introduced at the ethene bridges for the first time, resulting in significant modulation of the electronic properties of phenoxazinophanes. The X-ray structure revealed that phenoxazine moiety in phenoxazinophane exhibits a butterfly-shaped, non-planar structure with a significant reduction in dihedral angle (36.7°) between the planes of the two benzene rings compared to the angle in free phenoxazine (167°). The spectroscopic, and electrochemical studies revealed that the properties of phenoxazinophanes markedly distinct from those of previously reported phenothiazinophanes and depends on the type of substituents present at the bridged ethene carbons. Remarkably, the phenoxazinophanes exhibit green fluorescence in the solid state with a broad emission in the region of 450–650 nm and quantum yields were in the range of 0.32–0.35. Preliminary studies indicated that phenoxazinophanes exhibit aggregation-induced emission. The electrochemical studies revealed that phenoxazinophanes are highly electron rich and DFT/TD-DFT studies were in agreement with the experimental observations.
{"title":"Phenoxazinophanes: Synthesis, structure, spectral, redox and theoretical studies","authors":"Neha Tripathi, Mangalampalli Ravikanth","doi":"10.1016/j.tet.2025.134961","DOIUrl":"10.1016/j.tet.2025.134961","url":null,"abstract":"<div><div>Three fluorescent phenoxazinophanes, each incorporating two phenoxazine units bridged by two ethene linkers, were synthesized in a three-step sequence starting from commercially available phenoxazine. Substituents such as methyl and phenyl groups were introduced at the ethene bridges for the first time, resulting in significant modulation of the electronic properties of phenoxazinophanes. The X-ray structure revealed that phenoxazine moiety in phenoxazinophane exhibits a butterfly-shaped, non-planar structure with a significant reduction in dihedral angle (36.7°) between the planes of the two benzene rings compared to the angle in free phenoxazine (167°). The spectroscopic, and electrochemical studies revealed that the properties of phenoxazinophanes markedly distinct from those of previously reported phenothiazinophanes and depends on the type of substituents present at the bridged ethene carbons. Remarkably, the phenoxazinophanes exhibit green fluorescence in the solid state with a broad emission in the region of 450–650 nm and quantum yields were in the range of 0.32–0.35. Preliminary studies indicated that phenoxazinophanes exhibit aggregation-induced emission. The electrochemical studies revealed that phenoxazinophanes are highly electron rich and DFT/TD-DFT studies were in agreement with the experimental observations.</div></div>","PeriodicalId":437,"journal":{"name":"Tetrahedron","volume":"188 ","pages":"Article 134961"},"PeriodicalIF":2.2,"publicationDate":"2025-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145227814","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}
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