Control of enantioselectivity in radical reactions was a formidable challenge for organic chemists for decades. Thanks to the key role of transition metal complexes both in promoting and highly enantioselectively cont...Control of enantioselectivity in radical reactions was a formidable challenge for organic chemists for decades. Thanks to the key role of transition metal complexes both in promoting and highly enantioselectively controlling sophisticated synthetic routes, great improvements in this filed have been achieved by merging transition-metal asymmetric catalysis with radical chemistry. Herein we provide a perspective of some of the most significant contributions in the field during the past decades. Accordingly, the major advances are classified based on different strategies for controlling stereoselectivity including: (1) chiral metal complex chelation, (2) chiral metal complex combined with radical species and reductive elimination, (3) chiral metal complex outer-sphere substitution by radical intermediate. Brief discussion of mechanism is presented whenever relevant.展开更多
The formation of·CCl3 radicals in liver nuclei was suggested by spin trapping of them with N-t-butyl-α-phenylnitrone followed by GC/MS detection of the resulting adduct. Comparison of its formation in microsomal...The formation of·CCl3 radicals in liver nuclei was suggested by spin trapping of them with N-t-butyl-α-phenylnitrone followed by GC/MS detection of the resulting adduct. Comparison of its formation in microsomal biotransformation of CCl4 was made. In aerobic nuclear activation mixtures containing NADPH and CCl4, significant decrease in the arachidonic acid content of nuclear lipids was observed (27. 8%, compared to control), the intensity of this decrease was lower than that occurring in the corresponding microsomal incubation mixtures (29.1%). Significant decreases in arachidonic acid content of nuclear and endoplasmic reticulum lipids were also observed in animals at 6 hours of poisoning with the haloalkane. During aerobic nuclear metabolism of CCl4 or CBrCl3, cholesterol oxidation products were detected: a ketocholesterol, an epoxide like structure and 7-ketocholesterol. Nuclear protein carbonyl formation was not promoted during nuclear CCl4 biotransformation. NADPH by itself may lead to protein carbonyl formation during prolonged periods of incubation. CBrCl3 in contrast, led to decreased protein carbonyl formation. No increase in nuclear protein carbonyl formation was observed in CCl4 intoxicated animals during periods of time between 1 to 6 hours after treatment. The results indicate that during nuclear biotransformation of CCl4 or CBrCl3 reactive free radicals, PUFA degradation, reactive aldehydes and cholesterol oxidation products are formed, nearby DNA and regulatory proteins.展开更多
Bimolecular interactions play crucial roles in lignin pyrolysis.The tautomerization of key intermediates has a significant impact on the formation of stable products,whereas bimolecular tautomerization has been rarely...Bimolecular interactions play crucial roles in lignin pyrolysis.The tautomerization of key intermediates has a significant impact on the formation of stable products,whereas bimolecular tautomerization has been rarely clarified.In the present work,the bimolecular tautomerization mechanism induced by both concerted and radical interactions was proposed and carefully confirmed.A characteristicβ-O-4 lignin dimer,2-phenoxy-1-phenylethanol(α-OH-PPE),was used as the model compound to reveal two representative keto-phenol and enol-keto tautomerism mechanisms,based on theoretical calculations combined with pyrolysis experiments.The results indicate that the unimolecular tautomerism as the rate-determining step limits product generation,due to fairly high energy barriers.While the free hydroxy compounds and radicals derived from initial pyrolysis can further initiate bimolecular tautomerism reactions through the one-step concerted hydroxyl-assisted hydrogen transfer(hydroxylAHT)and two-step radical hydrogen abstraction interactions,respectively.By alleviating and even avoiding the large ring tension of tautomerism,the unstable tautomers(2,4-cyclohexadienone and1-hydroxy styrene)can be rapidly tautomerized into stable phenol and acetophenone with the help of intermolecular interaction.Benefitting from the significant advantage of retro-ene fragmentation in breaking theβ-O-4 bond to form tautomers,a large amount of stable phenolic and ketone products can be generated following bimolecular tautomerization in the pyrolysis ofβ-O-4 linked lignin.展开更多
The reaction of HCN with O(^1D, ^3p) radical has been investigated by density functional theory (DFT) and ab initio methods. The stationary points on the reaction paths (reactants, intermediates and products) we...The reaction of HCN with O(^1D, ^3p) radical has been investigated by density functional theory (DFT) and ab initio methods. The stationary points on the reaction paths (reactants, intermediates and products) were optimized at the (U)B3LYP/aug-cc-pVTZ level. Single-point calculations were performed at the (U)QCISD(T)/aug-cc-pVTZ level for the optimized structures and all the total energies were corrected by zero-point energy. It is shown that there exist three competing mechanisms of oxygen attacking nitrogen O→N, oxygen attacking carbon O→C and oxygen attacking hydrogen O→H. The rate constants were obtained via Eyring transition-state theory in the temperature range of 600~2000 K. The linear relationship between lnk and 1/T was presented. The results show that path 1 is the main reaction channel and the product of NCO + H is predominant.展开更多
An asymmetric total synthesis of(+)-21-epi-eburnamonine has been achieved.Key features of the synthesis include a visible-light photocatalytic intra-/intramolecular radical cascade reaction to assemble the tetracyclic...An asymmetric total synthesis of(+)-21-epi-eburnamonine has been achieved.Key features of the synthesis include a visible-light photocatalytic intra-/intramolecular radical cascade reaction to assemble the tetracyclic ABCD ring system,and a highly diastereoselective Johnson-Claisen rearrangement to establish the C20 all-carbon quaternary stereocenter.展开更多
The anion of heterocyclic ketene aminals reacted with 2,4-dini- tro-halobenzenes to give an arylated product through the radical nucleo- philic substitution confirmed by ESR spectroscopy,ESR-spin trapping techni- que,...The anion of heterocyclic ketene aminals reacted with 2,4-dini- tro-halobenzenes to give an arylated product through the radical nucleo- philic substitution confirmed by ESR spectroscopy,ESR-spin trapping techni- que,and depression of the reaction rate by the addition of inhibitor.展开更多
The transition state(TS) and Intrinsic Reaction Coordinate (IRC) for the titled reaction were traced by means of MCSCF/6-31G (210 configurations). The reaction activation energy of this reaction is 140.2KJ/mol. The re...The transition state(TS) and Intrinsic Reaction Coordinate (IRC) for the titled reaction were traced by means of MCSCF/6-31G (210 configurations). The reaction activation energy of this reaction is 140.2KJ/mol. The reaction rate constants of five temperetures were calculated by CVT involving the tunneling effects.展开更多
Alkynes are one of the most significant functional groups in organic chemistry and great efforts have been made to explore efficient approach for the construction of chiral alkynes.The asymmetric C(sp^(3))–C(sp)cross...Alkynes are one of the most significant functional groups in organic chemistry and great efforts have been made to explore efficient approach for the construction of chiral alkynes.The asymmetric C(sp^(3))–C(sp)cross-coupling provides a significant complementary strategy through radical-initiated process.However,the stereocontrol of highly reactive and unstable radical intermediate has been a challenge for decades.To address this problem,a variety of chiral ligands are developed for initiating the reaction and achieving enantiocontrol of alkyl radicals.This review summarizes recent developments in copper-catalyzed enantioselective alkynylation of prochiral alkyl radicals and their brief mechanistic studies.展开更多
Functionalized free radical addition/cyclization reactions represent an efficient way for introducing new functionality or coupling fragments to molecules.Ynones are good regional selectivity radical acceptors in orga...Functionalized free radical addition/cyclization reactions represent an efficient way for introducing new functionality or coupling fragments to molecules.Ynones are good regional selectivity radical acceptors in organic synthesis,and many of bio-relevant cyclic compounds could be easily obtained by direct radical cyclization reaction.Here,we report a photocatalytic cascade radical addition of biaryl ynones,for the divergent synthesis of privileged carbon cycles.Additionally,further transformation of the multi-functional group product into a variety of other derivatives demonstrates the synthetic value of this developed method.展开更多
Reduction of chlorogermylene MsFluindtBu-GeCl 1 with potassium graphite(KC8)afforded putative germylyne radical MsFluindtBu-Ge 2 as confirmed by electron paramagnetic resonance(EPR)spectroscopy.However,it slowly decay...Reduction of chlorogermylene MsFluindtBu-GeCl 1 with potassium graphite(KC8)afforded putative germylyne radical MsFluindtBu-Ge 2 as confirmed by electron paramagnetic resonance(EPR)spectroscopy.However,it slowly decayed via C—H bond activation at the fluorenyl moiety to yield a bis(germylene)3 at room temperature.By using a Lewis base to stabilize the unoccupied p orbital at the GeⅠradical center,acyclic two-coordinate GeⅠradicals MsFluindtBu-Ge(IMe4)4(IMe4=1,3,4,5-tetramethyl-imidazolin-2-ylidene),MsFluindtBu-Ge(IiPr)5(IiPr=1,3-diisopropyl-4,5-dimethyl-imidazolin-2-ylidene),MsFluindtBu-Ge(PMe3)6 were isolated in crystalline forms.The unpaired electron in 4-6 mainly resides at the Ge 4p orbital as revealed by EPR spectroscopic studies and theoretical calculations.Interestingly,facile ligand exchange of PMe3 in 6 with IMe4 and IiPr was observed to afford 4 and 5,respectively.Moreover,phosphinogermylyne 6 reacted with PhEEPh(E=S,Se),4-tetrabutylphenylacetylene(Ar'CCH),[CpMo(CO)3]2 and nBu3SnH to furnish germylenes MsFluindtBu-GeEPh(E=S 7,Se 8),MsFluindtBu-GeCH=CHAr'9,a germylyne complex MsFluindtBu-Ge≡Mo(CO)2Cp 10 and a Ge(Ⅳ)compound MsFluindtBu-GeH2SnnBu311,respectively.The reactivity studies demonstrate that 6 can act as a synthon of one-coordinate germylyne radical attributing to labile coordination of trimethylphosphine.展开更多
Construction of C-F bonds is a direct and efficient method for introducing fluorine into pharmaceuticals,agrochemicals,and materials.Strategies such as nucleophilic,electrophilic,radical,and transition-metal catalyzed...Construction of C-F bonds is a direct and efficient method for introducing fluorine into pharmaceuticals,agrochemicals,and materials.Strategies such as nucleophilic,electrophilic,radical,and transition-metal catalyzed fluorination have been developed to meet the demand of diverse C-F bond formation.Among them,radical fluorination has been witnessed with substantial advancement in a recent decade.Herein,we reviewed methods for formation of C-F bonds with carbon-centered radicals as key intermediates,especially in recent five years.We introduce in the paper with different fluorinating reagents,strategies for radical generation,and application in late-stage functionalization and synthesis of PET tracers.We also indicate the current limitations and propose the direction of the field for the future development.展开更多
The frequent detection of pharmaceutical compounds in the environment has led to a growing awareness,which may pose a major threat to the aquatic environment.In this study,photodegradation(direct and indirect photolys...The frequent detection of pharmaceutical compounds in the environment has led to a growing awareness,which may pose a major threat to the aquatic environment.In this study,photodegradation(direct and indirect photolysis)of two different dissociation states of fluoxetine(FLU)was investigated in water,mainly including the determination of photolytic transition states and products,and the mechanisms of indirect photodegradation with·OH,CO_(3)^(*-)and NO_(3)^(*).The main direct photolysis pathways are defluorination and C–C bond cleavage.In addition,the indirect photodegradation of FLU in water is mainly through the reactions with·OH and NO_(3)^(*),and the photodegradation reaction with CO_(3)^(*-)is relatively difficult to occur in the water environment.Our results provide a theoretical basis for understanding the phototransformation process of FLU in the water environment and assessing its potential risk.展开更多
The chemistry of alkoxy radicals was extensively explored during the period of 1960s to 1990s,but it has remained dormant for the past few decades.Recently,alkoxy radicals attract the attentions again,because new meth...The chemistry of alkoxy radicals was extensively explored during the period of 1960s to 1990s,but it has remained dormant for the past few decades.Recently,alkoxy radicals attract the attentions again,because new methods for generating alkoxy radical species have emerged.These newly developed methods are mainly based on the photolysis by visible light under mild conditions,thus allowing for new transformations of the carbon-centered radical species that are generated from theβ-scission or hydrogen abstraction of the alkoxy radicals.展开更多
α-Fluoroalkyl (Rf) alcohols are privileged motifs in drugs and pharmaceutically active compounds.As such,it is highly desirable to develop efficient methods for assembling these scaffolds.Herein,a visible-light-induc...α-Fluoroalkyl (Rf) alcohols are privileged motifs in drugs and pharmaceutically active compounds.As such,it is highly desirable to develop efficient methods for assembling these scaffolds.Herein,a visible-light-induced cascade radical cyclization of alkenyl fluoroalkyl ketones is developed,producing a variety of decorate α-Rf cycloalkanols in promising yields with up to >20 : 1 dr selectivity.A radical chain mechanism involving an intramolecular radical addition to the α-Rf carbonyl group and a subsequent intermolecular hydrogen atom transfer (HAT) has been proposed.Density functional theory (DFT) calculations indicate that a fluorine effect contributes to the radical addition to carbonyls by lowering the π* (C=O) orbital energy of CORf and energy barrier of the HAT between alkoxy radicals and THF,which may be valuable for controllable transformations of fluorinated molecules.展开更多
A copper-catalyzed enantioconvergent radical C-(sp^(3))-N cross-coupling of racemic tertiaryα-bromo-β-lactams with aromatic amines is developed under mild thermal reaction conditions.The use of a sterically demanded...A copper-catalyzed enantioconvergent radical C-(sp^(3))-N cross-coupling of racemic tertiaryα-bromo-β-lactams with aromatic amines is developed under mild thermal reaction conditions.The use of a sterically demanded oxazoline-derived sulfonamide N,N,N-ligand is crucial for the reaction initiation and effective enantio-discrimination of the azetidinone-derived cyclic alkyl radicals.The strategy provides an attractive approach to access chiralα-amino-β-lactams,an important structural motif in many biologically active molecules.Preliminary mechanistic studies support the formation of azetidinone-derived alkyl radicals from the L*Cu(I)-amido complex andα-bromo-β-lactams.展开更多
Using galvinoxyl as catalyst, the phase transfer catalyzed method of oxidation of primary amines to symmetrical azobenzenes with a saturated solution of potassium ferricyanide in 2 mom aqueous potassium hydroxide and ...Using galvinoxyl as catalyst, the phase transfer catalyzed method of oxidation of primary amines to symmetrical azobenzenes with a saturated solution of potassium ferricyanide in 2 mom aqueous potassium hydroxide and dichloromethane is described. The reaction has intimate relation with Hammett substituent constants. This report offers an efficient and rapid method to prepare azobenzenes and a possible mechanism is also suggested.展开更多
Polyacrylic acid particles in nano-scale were synthesized using an inverse (W/O) emulsion polymerization method. The particle size and size change of inverse micelles which solubilize a part of monomer solution was mo...Polyacrylic acid particles in nano-scale were synthesized using an inverse (W/O) emulsion polymerization method. The particle size and size change of inverse micelles which solubilize a part of monomer solution was monitored by PCS (photon correlation spectroscopy) and the particles of polyacrylic acid were viewed in scanning electron microscope for the first time. It was concluded that the inverse micelles were primarily the polymerization reaction sites.展开更多
The gas phase reaction mechanism of F2 + 2HBr = 2HF + Br2 has been investigated by (U)MP2 at 6-311G** level, and a series of four-center and three-center transition states have been obtained. The reaction mechan...The gas phase reaction mechanism of F2 + 2HBr = 2HF + Br2 has been investigated by (U)MP2 at 6-311G** level, and a series of four-center and three-center transition states have been obtained. The reaction mechanism was achieved by comparing the activation energy of seven reaction paths, i.e. the dissociation energy of F2 is less than the activation energy of the bimolecular elementary reaction F2 + HBr → HF + BrF. Thus it is theoretically proved that the title reaction occurs more easily in the free radical reaction with three medium steps.展开更多
基金Acknowledgement Financial support from the "1000-Youth Talents Plan" and the National Natural Science Foundation of China (No. 21702149)is greatly appreciated.
文摘Control of enantioselectivity in radical reactions was a formidable challenge for organic chemists for decades. Thanks to the key role of transition metal complexes both in promoting and highly enantioselectively controlling sophisticated synthetic routes, great improvements in this filed have been achieved by merging transition-metal asymmetric catalysis with radical chemistry. Herein we provide a perspective of some of the most significant contributions in the field during the past decades. Accordingly, the major advances are classified based on different strategies for controlling stereoselectivity including: (1) chiral metal complex chelation, (2) chiral metal complex combined with radical species and reductive elimination, (3) chiral metal complex outer-sphere substitution by radical intermediate. Brief discussion of mechanism is presented whenever relevant.
文摘The formation of·CCl3 radicals in liver nuclei was suggested by spin trapping of them with N-t-butyl-α-phenylnitrone followed by GC/MS detection of the resulting adduct. Comparison of its formation in microsomal biotransformation of CCl4 was made. In aerobic nuclear activation mixtures containing NADPH and CCl4, significant decrease in the arachidonic acid content of nuclear lipids was observed (27. 8%, compared to control), the intensity of this decrease was lower than that occurring in the corresponding microsomal incubation mixtures (29.1%). Significant decreases in arachidonic acid content of nuclear and endoplasmic reticulum lipids were also observed in animals at 6 hours of poisoning with the haloalkane. During aerobic nuclear metabolism of CCl4 or CBrCl3, cholesterol oxidation products were detected: a ketocholesterol, an epoxide like structure and 7-ketocholesterol. Nuclear protein carbonyl formation was not promoted during nuclear CCl4 biotransformation. NADPH by itself may lead to protein carbonyl formation during prolonged periods of incubation. CBrCl3 in contrast, led to decreased protein carbonyl formation. No increase in nuclear protein carbonyl formation was observed in CCl4 intoxicated animals during periods of time between 1 to 6 hours after treatment. The results indicate that during nuclear biotransformation of CCl4 or CBrCl3 reactive free radicals, PUFA degradation, reactive aldehydes and cholesterol oxidation products are formed, nearby DNA and regulatory proteins.
基金the National Natural Science Foundation of China(52276189,52106241)Natural Science Foundation of Jiangsu Province(BK20221248)for financial support。
文摘Bimolecular interactions play crucial roles in lignin pyrolysis.The tautomerization of key intermediates has a significant impact on the formation of stable products,whereas bimolecular tautomerization has been rarely clarified.In the present work,the bimolecular tautomerization mechanism induced by both concerted and radical interactions was proposed and carefully confirmed.A characteristicβ-O-4 lignin dimer,2-phenoxy-1-phenylethanol(α-OH-PPE),was used as the model compound to reveal two representative keto-phenol and enol-keto tautomerism mechanisms,based on theoretical calculations combined with pyrolysis experiments.The results indicate that the unimolecular tautomerism as the rate-determining step limits product generation,due to fairly high energy barriers.While the free hydroxy compounds and radicals derived from initial pyrolysis can further initiate bimolecular tautomerism reactions through the one-step concerted hydroxyl-assisted hydrogen transfer(hydroxylAHT)and two-step radical hydrogen abstraction interactions,respectively.By alleviating and even avoiding the large ring tension of tautomerism,the unstable tautomers(2,4-cyclohexadienone and1-hydroxy styrene)can be rapidly tautomerized into stable phenol and acetophenone with the help of intermolecular interaction.Benefitting from the significant advantage of retro-ene fragmentation in breaking theβ-O-4 bond to form tautomers,a large amount of stable phenolic and ketone products can be generated following bimolecular tautomerization in the pyrolysis ofβ-O-4 linked lignin.
基金supported by the Youth Fund Project of Anhui Normal University (No. 2006xqn65)
文摘The reaction of HCN with O(^1D, ^3p) radical has been investigated by density functional theory (DFT) and ab initio methods. The stationary points on the reaction paths (reactants, intermediates and products) were optimized at the (U)B3LYP/aug-cc-pVTZ level. Single-point calculations were performed at the (U)QCISD(T)/aug-cc-pVTZ level for the optimized structures and all the total energies were corrected by zero-point energy. It is shown that there exist three competing mechanisms of oxygen attacking nitrogen O→N, oxygen attacking carbon O→C and oxygen attacking hydrogen O→H. The rate constants were obtained via Eyring transition-state theory in the temperature range of 600~2000 K. The linear relationship between lnk and 1/T was presented. The results show that path 1 is the main reaction channel and the product of NCO + H is predominant.
基金surpport from National Natural Science Foundation of China(21921002 and 21991114)National Science and Technology Major Projects for“Major New Drugs Innovation and Development”(2018ZX09711003-015 and 2018ZX09711001-005-004).
文摘An asymmetric total synthesis of(+)-21-epi-eburnamonine has been achieved.Key features of the synthesis include a visible-light photocatalytic intra-/intramolecular radical cascade reaction to assemble the tetracyclic ABCD ring system,and a highly diastereoselective Johnson-Claisen rearrangement to establish the C20 all-carbon quaternary stereocenter.
文摘The anion of heterocyclic ketene aminals reacted with 2,4-dini- tro-halobenzenes to give an arylated product through the radical nucleo- philic substitution confirmed by ESR spectroscopy,ESR-spin trapping techni- que,and depression of the reaction rate by the addition of inhibitor.
文摘The transition state(TS) and Intrinsic Reaction Coordinate (IRC) for the titled reaction were traced by means of MCSCF/6-31G (210 configurations). The reaction activation energy of this reaction is 140.2KJ/mol. The reaction rate constants of five temperetures were calculated by CVT involving the tunneling effects.
基金We are grateful to the National Natural Science Foundation of China(22071073,22271112,21772218,and 21821002)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB20000000)State Key Laboratory of Organometallic Chemistry,Shanghai Institute of Organic Chemistry,Chinese Academy of Sciences and the Central China Normal University(CCNU).
文摘Alkynes are one of the most significant functional groups in organic chemistry and great efforts have been made to explore efficient approach for the construction of chiral alkynes.The asymmetric C(sp^(3))–C(sp)cross-coupling provides a significant complementary strategy through radical-initiated process.However,the stereocontrol of highly reactive and unstable radical intermediate has been a challenge for decades.To address this problem,a variety of chiral ligands are developed for initiating the reaction and achieving enantiocontrol of alkyl radicals.This review summarizes recent developments in copper-catalyzed enantioselective alkynylation of prochiral alkyl radicals and their brief mechanistic studies.
基金the Natural Science Foundation of Zhejiang Province(LY22B020001)the Zhejiang Public Welfare Public Research Program(LGC22B010001)the National Natural Science Foundation of China(32201238)is greatly acknowledged.
文摘Functionalized free radical addition/cyclization reactions represent an efficient way for introducing new functionality or coupling fragments to molecules.Ynones are good regional selectivity radical acceptors in organic synthesis,and many of bio-relevant cyclic compounds could be easily obtained by direct radical cyclization reaction.Here,we report a photocatalytic cascade radical addition of biaryl ynones,for the divergent synthesis of privileged carbon cycles.Additionally,further transformation of the multi-functional group product into a variety of other derivatives demonstrates the synthetic value of this developed method.
基金National Natural Science Foundation of China (Grants:22322112 and 22071164)Fundamental Research Funds for the Central Universities,Sun Yat-sen University (23qnpy35)+2 种基金the Suzhou Science&Technology NOVA Program (Grant:ZXL2022445)for generous financial supportL.Z.thanks Guangxi University of Science and Technology (03190227 and 03190228)the Guangxi Department of Science and Technology (2021GXNSFBA220021)for financial support.
文摘Reduction of chlorogermylene MsFluindtBu-GeCl 1 with potassium graphite(KC8)afforded putative germylyne radical MsFluindtBu-Ge 2 as confirmed by electron paramagnetic resonance(EPR)spectroscopy.However,it slowly decayed via C—H bond activation at the fluorenyl moiety to yield a bis(germylene)3 at room temperature.By using a Lewis base to stabilize the unoccupied p orbital at the GeⅠradical center,acyclic two-coordinate GeⅠradicals MsFluindtBu-Ge(IMe4)4(IMe4=1,3,4,5-tetramethyl-imidazolin-2-ylidene),MsFluindtBu-Ge(IiPr)5(IiPr=1,3-diisopropyl-4,5-dimethyl-imidazolin-2-ylidene),MsFluindtBu-Ge(PMe3)6 were isolated in crystalline forms.The unpaired electron in 4-6 mainly resides at the Ge 4p orbital as revealed by EPR spectroscopic studies and theoretical calculations.Interestingly,facile ligand exchange of PMe3 in 6 with IMe4 and IiPr was observed to afford 4 and 5,respectively.Moreover,phosphinogermylyne 6 reacted with PhEEPh(E=S,Se),4-tetrabutylphenylacetylene(Ar'CCH),[CpMo(CO)3]2 and nBu3SnH to furnish germylenes MsFluindtBu-GeEPh(E=S 7,Se 8),MsFluindtBu-GeCH=CHAr'9,a germylyne complex MsFluindtBu-Ge≡Mo(CO)2Cp 10 and a Ge(Ⅳ)compound MsFluindtBu-GeH2SnnBu311,respectively.The reactivity studies demonstrate that 6 can act as a synthon of one-coordinate germylyne radical attributing to labile coordination of trimethylphosphine.
基金the National Natural Science Foundation of China(22301224)Wuhan Science and Technology Project(2023020201020273),and Wuhan University for financial support.We thank Prof.Wen-Bo Liu(Wuhan University)for proof reading.
文摘Construction of C-F bonds is a direct and efficient method for introducing fluorine into pharmaceuticals,agrochemicals,and materials.Strategies such as nucleophilic,electrophilic,radical,and transition-metal catalyzed fluorination have been developed to meet the demand of diverse C-F bond formation.Among them,radical fluorination has been witnessed with substantial advancement in a recent decade.Herein,we reviewed methods for formation of C-F bonds with carbon-centered radicals as key intermediates,especially in recent five years.We introduce in the paper with different fluorinating reagents,strategies for radical generation,and application in late-stage functionalization and synthesis of PET tracers.We also indicate the current limitations and propose the direction of the field for the future development.
基金supported by the National Natural Science Foundation of China(No.41601519)。
文摘The frequent detection of pharmaceutical compounds in the environment has led to a growing awareness,which may pose a major threat to the aquatic environment.In this study,photodegradation(direct and indirect photolysis)of two different dissociation states of fluoxetine(FLU)was investigated in water,mainly including the determination of photolytic transition states and products,and the mechanisms of indirect photodegradation with·OH,CO_(3)^(*-)and NO_(3)^(*).The main direct photolysis pathways are defluorination and C–C bond cleavage.In addition,the indirect photodegradation of FLU in water is mainly through the reactions with·OH and NO_(3)^(*),and the photodegradation reaction with CO_(3)^(*-)is relatively difficult to occur in the water environment.Our results provide a theoretical basis for understanding the phototransformation process of FLU in the water environment and assessing its potential risk.
基金The project is supported by NSFC(91956104),BNLMS,and Laboratory for Synthetic Chemistry and Chemical Biology of Health@InnoHK of ITC,HKSAR.
文摘The chemistry of alkoxy radicals was extensively explored during the period of 1960s to 1990s,but it has remained dormant for the past few decades.Recently,alkoxy radicals attract the attentions again,because new methods for generating alkoxy radical species have emerged.These newly developed methods are mainly based on the photolysis by visible light under mild conditions,thus allowing for new transformations of the carbon-centered radical species that are generated from theβ-scission or hydrogen abstraction of the alkoxy radicals.
基金supported by the National Natural Science Foundation of China(22071218 and 22203076)the Natural Science Foundation of Zhejiang Province(LZ20B020001 and LY23B020004)+2 种基金the Ten Thousand Talents Plan of Zhejiang Province(2020R52021)the Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang Province(2022R01007)Key Laboratory of Green Pesticides and Cleaner Production Technology of Zhejiang Province.
文摘α-Fluoroalkyl (Rf) alcohols are privileged motifs in drugs and pharmaceutically active compounds.As such,it is highly desirable to develop efficient methods for assembling these scaffolds.Herein,a visible-light-induced cascade radical cyclization of alkenyl fluoroalkyl ketones is developed,producing a variety of decorate α-Rf cycloalkanols in promising yields with up to >20 : 1 dr selectivity.A radical chain mechanism involving an intramolecular radical addition to the α-Rf carbonyl group and a subsequent intermolecular hydrogen atom transfer (HAT) has been proposed.Density functional theory (DFT) calculations indicate that a fluorine effect contributes to the radical addition to carbonyls by lowering the π* (C=O) orbital energy of CORf and energy barrier of the HAT between alkoxy radicals and THF,which may be valuable for controllable transformations of fluorinated molecules.
基金support from the National Key R&D Program of China(Nos.2021YFF0701604 and 2021YFF0701704)National Natural Science Foundation of China(Nos.22025103,92256301,21831002,and 22271133)+1 种基金Shenzhen Key Labor atory of Cross-Coupling Reactions(ZDSYS20220328104200001)Shenzhen Science and Technology Program(Nos.KQTD20210811090112004,JCYJ20200109141001789,JCYJ20220818100600001,and JCYJ202205300115409020).
文摘A copper-catalyzed enantioconvergent radical C-(sp^(3))-N cross-coupling of racemic tertiaryα-bromo-β-lactams with aromatic amines is developed under mild thermal reaction conditions.The use of a sterically demanded oxazoline-derived sulfonamide N,N,N-ligand is crucial for the reaction initiation and effective enantio-discrimination of the azetidinone-derived cyclic alkyl radicals.The strategy provides an attractive approach to access chiralα-amino-β-lactams,an important structural motif in many biologically active molecules.Preliminary mechanistic studies support the formation of azetidinone-derived alkyl radicals from the L*Cu(I)-amido complex andα-bromo-β-lactams.
文摘Using galvinoxyl as catalyst, the phase transfer catalyzed method of oxidation of primary amines to symmetrical azobenzenes with a saturated solution of potassium ferricyanide in 2 mom aqueous potassium hydroxide and dichloromethane is described. The reaction has intimate relation with Hammett substituent constants. This report offers an efficient and rapid method to prepare azobenzenes and a possible mechanism is also suggested.
文摘Polyacrylic acid particles in nano-scale were synthesized using an inverse (W/O) emulsion polymerization method. The particle size and size change of inverse micelles which solubilize a part of monomer solution was monitored by PCS (photon correlation spectroscopy) and the particles of polyacrylic acid were viewed in scanning electron microscope for the first time. It was concluded that the inverse micelles were primarily the polymerization reaction sites.
基金This work was supported by the China Postdoctoral Science Foundation (No. 2003033486) and the Natural Science Research Fund of University in JiangSu (No. 04KJB150149)
文摘The gas phase reaction mechanism of F2 + 2HBr = 2HF + Br2 has been investigated by (U)MP2 at 6-311G** level, and a series of four-center and three-center transition states have been obtained. The reaction mechanism was achieved by comparing the activation energy of seven reaction paths, i.e. the dissociation energy of F2 is less than the activation energy of the bimolecular elementary reaction F2 + HBr → HF + BrF. Thus it is theoretically proved that the title reaction occurs more easily in the free radical reaction with three medium steps.