Alkyl chlorides are abundant and easily accessible starting materials.However,due to the high reduction potentials associated with unactivated alkyl chlorides,achieving their single electron reduction remains a persis...Alkyl chlorides are abundant and easily accessible starting materials.However,due to the high reduction potentials associated with unactivated alkyl chlorides,achieving their single electron reduction remains a persistent challenge.This challenge has spurred the exploration of efficient activation methods to overcome this issue.In recent years,photocatalysis has emerged as a mild and potent tool for the single electron reduction of unactivated alkyl chlorides,opening up new possibilities in this field.Considering the rapid advancements in this area,a comprehensive review that provides a conceptual understanding of this emerging field,with a specific focus on reaction design and catalytic mechanisms,would be timely and highly valuable.Hence,we present an overview of various synthetic techniques for photoinduced single electron reduction of unactivated alkyl chlorides.Furthermore,we also discuss the limitations of the present methods and future directions that lie ahead in this field.展开更多
Single electron transition reactions between amines(Lewis base)and B(C_(6)F_(5))_(3)(Lewis acid)in cooperation with benzoquinones gave rise to a frustrated radical pair 3 and a nonfrustrated radical pair 4.Both of the...Single electron transition reactions between amines(Lewis base)and B(C_(6)F_(5))_(3)(Lewis acid)in cooperation with benzoquinones gave rise to a frustrated radical pair 3 and a nonfrustrated radical pair 4.Both of them were isolated as stable crystals and studied by single-crystal X-ray diffraction,superconducting quantum interference device measurements,electron paramagnetic resonance,nuclear magnetic resonance,and UV–vis spectroscopy.Antiferromagnetic exchange coupling was observed among both 3 and 4.Radical anion and cation are basically separated in 3,while 4 featured a relatively strong anion-cationπ–πstacking interaction.This work demonstrated that the Lewis acid coupled electron transfer is an efficient way to prepare stable radical ion pairs.展开更多
The emergence of metal nanoclusters with atomically precise compositions and structures provides an opportunity for in-depth investigation of catalysis mechanisms and structure−property correlations at the nanoscale.H...The emergence of metal nanoclusters with atomically precise compositions and structures provides an opportunity for in-depth investigation of catalysis mechanisms and structure−property correlations at the nanoscale.However,a serious problem for metal nanocluster catalysts is that the ligands inhibit the catalytic activity through deactivating the surface of the nanoclusters.Here,we introduce a novel catalytic mode for metal nanoclusters,in which the nanoclusters initiate the catalysis via single electron transfer(SET)without destroying the integrity of nanoclusters,providing a solution for the contradiction between activity and stability of metal nanoclusters.We illustrated that the novel activation mode featured low catalyst loading(0.01 mol%),high TOF,mild reaction conditions,and easy recycling of catalyst in alkyne hydroborylation,which often suffered from poor selectivity,low functional group tolerance,etc.Furthermore,the catalyst[Au_(1)Cu_(14)(TBBT)_(12)(PPh_(3))_(6)]^(+)(TBBTH:p-tert-butylthiophenol)can be applied in highly efficient tandem processes such as hydroborylation−deuteration and hydroborylation−isomerization,demonstrating the utility of the introduced activation mode for metal nanoclusters.展开更多
Treatment of ICF2CF2OCF2CF2SC2F (1) with organic halides in the presence of copper powder in a co-solvent DMF/HMPA( V/V= 1:1) gave the corresponding trifluoromethylated compounds in good to excellent yields. A copper ...Treatment of ICF2CF2OCF2CF2SC2F (1) with organic halides in the presence of copper powder in a co-solvent DMF/HMPA( V/V= 1:1) gave the corresponding trifluoromethylated compounds in good to excellent yields. A copper induced single electron transfer reaction mechanism is proposed.展开更多
In this paper a projectile ion-recoil ion coincidence technique is used to investigate the transfer ionization processes in collisions of 0.22-6.30 MeV Cq+ ions and 0.25-6.35 MeV 0q+ ions (q=1, 2, 3, 4) with the H...In this paper a projectile ion-recoil ion coincidence technique is used to investigate the transfer ionization processes in collisions of 0.22-6.30 MeV Cq+ ions and 0.25-6.35 MeV 0q+ ions (q=1, 2, 3, 4) with the He atom separately. The cross section ratio f of transfer ionization to single electron transfer is measured, and the dependence of f on both charge state q and energy E of the projectiles is investigated. The electron-structure and the mechanisms leading to transfer ionization affect the dependence of f on q and E. Our measurements, along with other data published previously, suggest a similar dependence of f on charge state and energy of projectile for partially stripped ions over a large energy range. The maximum value of f is approximately 0.17q^0.60; the energy corresponding to maximum f is about 160q^0.60 keV/u.展开更多
On the basis of investigation of cyclic voltammetry, EPR spectroscopy and competition experiments, the nucleophilic substitution reaction of p- dinitrobenzene with the sodium salt of ethyl α-cyanoacetate carbanion in...On the basis of investigation of cyclic voltammetry, EPR spectroscopy and competition experiments, the nucleophilic substitution reaction of p- dinitrobenzene with the sodium salt of ethyl α-cyanoacetate carbanion in dimethyl sulfoxide giving ethyl α-cyano-α- (p-nitrophenyl) acetate is shown to take place via the intermediacy of p-dinitrobenzene radical anion. The reaction rate goes faster than that between p-nitrohalobenzenes and the same sodium salt of ethyl α-cyanoacetate carbanion. There is an evidence for a single electron transfer mechanism.展开更多
The demand and pursuit of chemical entities with UV filtration and antioxidant properties for enhanced photoprotection have been driven in recent times by acute exposure of humans to solar ultraviolet radiations. The ...The demand and pursuit of chemical entities with UV filtration and antioxidant properties for enhanced photoprotection have been driven in recent times by acute exposure of humans to solar ultraviolet radiations. The structural, electronic, antioxidant and UV absorption properties of drometrizole (PBT) and designed ortho-substituted derivatives are reported via DFT and TD-DFT in the gas and aqueous phases. DFT and TD-DFT computations were performed at the M062x-D3Zero/6-311++G(d,p)//B97-3c and PBE0-D3(BJ)/def2-TZVP levels of theory respectively. Reaction enthalpies related to hydrogen atom transfer (HAT), single-electron transfer followed by proton transfer (SET-PT), and sequential proton loss electron transfer (SPLET) mechanisms were computed and compared with those of phenol. Results show that the presence of -NH2 substituent reduces the O-H bond dissociation enthalpy and ionization potential, while that of -CN increases the proton affinity. The HAT and SPLET mechanisms are the most plausible in the gas and aqueous phases respectively. The molecule with the -NH2 substituent (PBT1) was identified to be the compound with the highest antioxidant activity. The UV spectra of the studied compounds are characterized by two bands in the 280 - 400 nm regions. Results from this study provide a better comprehension antioxidant mechanism of drometrizole and present a new perspective for the design of electron-donor antioxidant molecules with enhanced antioxidant-photoprotective efficiencies for applications in commercial sunscreens.展开更多
Spectroscopic investigations discovered that the in-situ generated phenylhydrazone anion was significantly bathochromically shifted to visible light region for photoactivation under irradiation. The photoexcited pheny...Spectroscopic investigations discovered that the in-situ generated phenylhydrazone anion was significantly bathochromically shifted to visible light region for photoactivation under irradiation. The photoexcited phenylhydrazone anion was potential to reduce aryl iodides via single electron transfer process for the subsequent radical chain reaction. A redox-neutral photochemical carbonylation of aryl iodides was developed on basis of the special spectroscopic features of phenylhydrazone anion. This protocol provided a convenient and efficient synthetic tool for accessing carbonylation products under redox neutral conditions without the need of transition-metals.展开更多
Herein, we report the first visible-light photoredox-catalyzed carboxylation of aryl epoxides with CO_(2)to synthesize hydroxy acid derivatives. A variety of valuable β-, γ-, δ-, ε–hydroxy acid derivatives are ob...Herein, we report the first visible-light photoredox-catalyzed carboxylation of aryl epoxides with CO_(2)to synthesize hydroxy acid derivatives. A variety of valuable β-, γ-, δ-, ε–hydroxy acid derivatives are obtained in moderate to high yields under mild conditions. This protocol shows noteworthy functionalgroup compatibility, high chemo-and regioselectivities under transition-metal-free conditions with an inexpensive organo-dye as photosensitizer. Mechanistic studies indicate that the benzylic carbanion is generated as an intermediate via the sequential single electron transfer(SSET) process.展开更多
Catalyst innovation lies at the heart of transition-metal-catalyzed reaction development. In this article, we have explored the C(sp2)–H alkenylation activity with novel spirocyclic N-heterocyclic carbene(NHC)-based ...Catalyst innovation lies at the heart of transition-metal-catalyzed reaction development. In this article, we have explored the C(sp2)–H alkenylation activity with novel spirocyclic N-heterocyclic carbene(NHC)-based cyclometalated ruthenium pincer catalyst system, SNRu-X. After screening catalyst and condition, a high valent Ru(Ⅳ) dioxide(X = O_(2)) species has demonstrated superior reactivity in the catalytic alkenylation of aromatic and olefinic C–H bonds with unactivated alkenyl bromides and triflates. This reaction has achieved the easy construction of a wide range of(hetero)aromatic alkenes and dienes, in good to excellent yields with exclusive selectivity. Preliminary mechanistic studies indicate that this reaction may proceed through a single electron transfer(SET) triggered oxidative addition, by doing so, providing valuable complementary to classical alkenylation reactions that are dependent on activated alkenyl precursors.展开更多
Organosilicon compounds play an important role in the fields of materials science,pharmacy,and organic synthesis.The development of effective approaches for the preparation of these compounds have also become a resear...Organosilicon compounds play an important role in the fields of materials science,pharmacy,and organic synthesis.The development of effective approaches for the preparation of these compounds have also become a research focus in organic synthesis.In recent years,free radical synthesis of organosilicons has been vigorously developed,which generally has the advantages of milder synthesis conditions,higher yields and selectivity,and free of precious metal catalysts compared with traditional strategies.This article reviews research progresses in the synthesis of organosilico n compounds by free radical pathways since 2016.In most cases,the radical silylation is achieved based on the reaction of silyl radicals,which are triggered by four routes including peroxide,transition-metal-induced peroxide decomposition,alkali,photocatalysis.The alkyl radicals can also initiate the radical silylation for the generation of C(sp^(3))—Si bonds.展开更多
Comprehensive Summary The conversion of CF3-alkenes to gem-difluoroalkenes using reductive cross-coupling strategy has received much attention in recent years,however,the use of green and readily available reducing sa...Comprehensive Summary The conversion of CF3-alkenes to gem-difluoroalkenes using reductive cross-coupling strategy has received much attention in recent years,however,the use of green and readily available reducing salt to mediate these reactions remains to be explored.In this work,a concise construction of gem-difluoroalkenes,which requires neither a catalyst nor a metal reducing agent,was established.Rongalite,a safe and inexpensive industrial product,was employed as both a radical initiator and reductant.This procedure was compatible with both linear and cyclic diaryliodonium salts,enabling a wide variety of substrates(>70 examples).The utility of this approach was demonstrated through gram-scale synthesis and efficient late-stage functionalizations of anti-inflammatory drugs.展开更多
基金supported by the National Natural Science Foundation of China (22001248)the Fundamental Research Funds for the Central Universitiesthe University of the Chinese Academy of Sciences。
文摘Alkyl chlorides are abundant and easily accessible starting materials.However,due to the high reduction potentials associated with unactivated alkyl chlorides,achieving their single electron reduction remains a persistent challenge.This challenge has spurred the exploration of efficient activation methods to overcome this issue.In recent years,photocatalysis has emerged as a mild and potent tool for the single electron reduction of unactivated alkyl chlorides,opening up new possibilities in this field.Considering the rapid advancements in this area,a comprehensive review that provides a conceptual understanding of this emerging field,with a specific focus on reaction design and catalytic mechanisms,would be timely and highly valuable.Hence,we present an overview of various synthetic techniques for photoinduced single electron reduction of unactivated alkyl chlorides.Furthermore,we also discuss the limitations of the present methods and future directions that lie ahead in this field.
基金the National Key R&D Program of China(grant no.2018YFA0306004)the National Natural Science Foundation of China(grant no.21525102)for their financial support.
文摘Single electron transition reactions between amines(Lewis base)and B(C_(6)F_(5))_(3)(Lewis acid)in cooperation with benzoquinones gave rise to a frustrated radical pair 3 and a nonfrustrated radical pair 4.Both of them were isolated as stable crystals and studied by single-crystal X-ray diffraction,superconducting quantum interference device measurements,electron paramagnetic resonance,nuclear magnetic resonance,and UV–vis spectroscopy.Antiferromagnetic exchange coupling was observed among both 3 and 4.Radical anion and cation are basically separated in 3,while 4 featured a relatively strong anion-cationπ–πstacking interaction.This work demonstrated that the Lewis acid coupled electron transfer is an efficient way to prepare stable radical ion pairs.
基金financially supported by the National Natural Science Foundation of China(Nos.92061110,21925303,21829501,21771186,21222301,21528303,and 21171170)the Anhui Provincial Natural Science Foundation(2108085Y05 and 2108085MB56)+1 种基金Collaborative Innovation Program of Hefei Science Center,CAS(Nos.2020HSCCIP005 and 2022HSC-CIP018)the Hefei National Laboratory for Physical Sciences at the Microscale(KF2020102).
文摘The emergence of metal nanoclusters with atomically precise compositions and structures provides an opportunity for in-depth investigation of catalysis mechanisms and structure−property correlations at the nanoscale.However,a serious problem for metal nanocluster catalysts is that the ligands inhibit the catalytic activity through deactivating the surface of the nanoclusters.Here,we introduce a novel catalytic mode for metal nanoclusters,in which the nanoclusters initiate the catalysis via single electron transfer(SET)without destroying the integrity of nanoclusters,providing a solution for the contradiction between activity and stability of metal nanoclusters.We illustrated that the novel activation mode featured low catalyst loading(0.01 mol%),high TOF,mild reaction conditions,and easy recycling of catalyst in alkyne hydroborylation,which often suffered from poor selectivity,low functional group tolerance,etc.Furthermore,the catalyst[Au_(1)Cu_(14)(TBBT)_(12)(PPh_(3))_(6)]^(+)(TBBTH:p-tert-butylthiophenol)can be applied in highly efficient tandem processes such as hydroborylation−deuteration and hydroborylation−isomerization,demonstrating the utility of the introduced activation mode for metal nanoclusters.
基金Project supported by the National Natural Science Foundation of China.
文摘Treatment of ICF2CF2OCF2CF2SC2F (1) with organic halides in the presence of copper powder in a co-solvent DMF/HMPA( V/V= 1:1) gave the corresponding trifluoromethylated compounds in good to excellent yields. A copper induced single electron transfer reaction mechanism is proposed.
文摘In this paper a projectile ion-recoil ion coincidence technique is used to investigate the transfer ionization processes in collisions of 0.22-6.30 MeV Cq+ ions and 0.25-6.35 MeV 0q+ ions (q=1, 2, 3, 4) with the He atom separately. The cross section ratio f of transfer ionization to single electron transfer is measured, and the dependence of f on both charge state q and energy E of the projectiles is investigated. The electron-structure and the mechanisms leading to transfer ionization affect the dependence of f on q and E. Our measurements, along with other data published previously, suggest a similar dependence of f on charge state and energy of projectile for partially stripped ions over a large energy range. The maximum value of f is approximately 0.17q^0.60; the energy corresponding to maximum f is about 160q^0.60 keV/u.
文摘On the basis of investigation of cyclic voltammetry, EPR spectroscopy and competition experiments, the nucleophilic substitution reaction of p- dinitrobenzene with the sodium salt of ethyl α-cyanoacetate carbanion in dimethyl sulfoxide giving ethyl α-cyano-α- (p-nitrophenyl) acetate is shown to take place via the intermediacy of p-dinitrobenzene radical anion. The reaction rate goes faster than that between p-nitrohalobenzenes and the same sodium salt of ethyl α-cyanoacetate carbanion. There is an evidence for a single electron transfer mechanism.
文摘The demand and pursuit of chemical entities with UV filtration and antioxidant properties for enhanced photoprotection have been driven in recent times by acute exposure of humans to solar ultraviolet radiations. The structural, electronic, antioxidant and UV absorption properties of drometrizole (PBT) and designed ortho-substituted derivatives are reported via DFT and TD-DFT in the gas and aqueous phases. DFT and TD-DFT computations were performed at the M062x-D3Zero/6-311++G(d,p)//B97-3c and PBE0-D3(BJ)/def2-TZVP levels of theory respectively. Reaction enthalpies related to hydrogen atom transfer (HAT), single-electron transfer followed by proton transfer (SET-PT), and sequential proton loss electron transfer (SPLET) mechanisms were computed and compared with those of phenol. Results show that the presence of -NH2 substituent reduces the O-H bond dissociation enthalpy and ionization potential, while that of -CN increases the proton affinity. The HAT and SPLET mechanisms are the most plausible in the gas and aqueous phases respectively. The molecule with the -NH2 substituent (PBT1) was identified to be the compound with the highest antioxidant activity. The UV spectra of the studied compounds are characterized by two bands in the 280 - 400 nm regions. Results from this study provide a better comprehension antioxidant mechanism of drometrizole and present a new perspective for the design of electron-donor antioxidant molecules with enhanced antioxidant-photoprotective efficiencies for applications in commercial sunscreens.
基金supported by the National Natural Science Foundation of China (Nos.22271246 and 22101251)Yunling Scholar Project of "Yunnan Revitalization Talent Support Program" for financial support。
文摘Spectroscopic investigations discovered that the in-situ generated phenylhydrazone anion was significantly bathochromically shifted to visible light region for photoactivation under irradiation. The photoexcited phenylhydrazone anion was potential to reduce aryl iodides via single electron transfer process for the subsequent radical chain reaction. A redox-neutral photochemical carbonylation of aryl iodides was developed on basis of the special spectroscopic features of phenylhydrazone anion. This protocol provided a convenient and efficient synthetic tool for accessing carbonylation products under redox neutral conditions without the need of transition-metals.
基金the National Natural Science Foundation of China (Nos. 22225106, 22301193)Fundamental Research Funds from Sichuan University (No. 2020SCUNL102)the Fundamental Research Funds for the Central Universities。
文摘Herein, we report the first visible-light photoredox-catalyzed carboxylation of aryl epoxides with CO_(2)to synthesize hydroxy acid derivatives. A variety of valuable β-, γ-, δ-, ε–hydroxy acid derivatives are obtained in moderate to high yields under mild conditions. This protocol shows noteworthy functionalgroup compatibility, high chemo-and regioselectivities under transition-metal-free conditions with an inexpensive organo-dye as photosensitizer. Mechanistic studies indicate that the benzylic carbanion is generated as an intermediate via the sequential single electron transfer(SSET) process.
基金suported by the National Natural Science Foundation of China (2187,1117, 91956203)the “111” Program of Minister of Education, Beijing National Laboratory for Molecular Sciences (BNLMS202109)the Science and Technology Commission of Shanghai Municipality (19JC1430100)。
文摘Catalyst innovation lies at the heart of transition-metal-catalyzed reaction development. In this article, we have explored the C(sp2)–H alkenylation activity with novel spirocyclic N-heterocyclic carbene(NHC)-based cyclometalated ruthenium pincer catalyst system, SNRu-X. After screening catalyst and condition, a high valent Ru(Ⅳ) dioxide(X = O_(2)) species has demonstrated superior reactivity in the catalytic alkenylation of aromatic and olefinic C–H bonds with unactivated alkenyl bromides and triflates. This reaction has achieved the easy construction of a wide range of(hetero)aromatic alkenes and dienes, in good to excellent yields with exclusive selectivity. Preliminary mechanistic studies indicate that this reaction may proceed through a single electron transfer(SET) triggered oxidative addition, by doing so, providing valuable complementary to classical alkenylation reactions that are dependent on activated alkenyl precursors.
基金the Fundamental Research Funds for the Central Universities(No.30920021120)Key Laboratory of Biomass Energy and Material,Jiangsu Province(No.JSBEM201912)+1 种基金the National Natural Science Foundation of China(No.21905089)the Chinese Postdoctoral Science Foundation(No.2019M662775)for financial support。
文摘Organosilicon compounds play an important role in the fields of materials science,pharmacy,and organic synthesis.The development of effective approaches for the preparation of these compounds have also become a research focus in organic synthesis.In recent years,free radical synthesis of organosilicons has been vigorously developed,which generally has the advantages of milder synthesis conditions,higher yields and selectivity,and free of precious metal catalysts compared with traditional strategies.This article reviews research progresses in the synthesis of organosilico n compounds by free radical pathways since 2016.In most cases,the radical silylation is achieved based on the reaction of silyl radicals,which are triggered by four routes including peroxide,transition-metal-induced peroxide decomposition,alkali,photocatalysis.The alkyl radicals can also initiate the radical silylation for the generation of C(sp^(3))—Si bonds.
基金supported by the National Natural Science Foundation of China(Grants 21971080,21971079,21772051)This work was also supported by the 111 Project B17019.
文摘Comprehensive Summary The conversion of CF3-alkenes to gem-difluoroalkenes using reductive cross-coupling strategy has received much attention in recent years,however,the use of green and readily available reducing salt to mediate these reactions remains to be explored.In this work,a concise construction of gem-difluoroalkenes,which requires neither a catalyst nor a metal reducing agent,was established.Rongalite,a safe and inexpensive industrial product,was employed as both a radical initiator and reductant.This procedure was compatible with both linear and cyclic diaryliodonium salts,enabling a wide variety of substrates(>70 examples).The utility of this approach was demonstrated through gram-scale synthesis and efficient late-stage functionalizations of anti-inflammatory drugs.