Comprehensive Summary,A convenient approach for the construction of 2-aminobenzothiazoles via I2-catalyzed tandem cyclization reaction of amines and carbon disulfide has been developed.The present approach starts from...Comprehensive Summary,A convenient approach for the construction of 2-aminobenzothiazoles via I2-catalyzed tandem cyclization reaction of amines and carbon disulfide has been developed.The present approach starts from simple and readily available starting materials,affording a series of 2-aminobenzothiazoles in up to 89%yields under metal-free conditions.In this work,C—H/N—H functionalization was achieved and multiple C-hetero bonds were successfully constructed in one pot.展开更多
Herein, we report a novel synthesis of 1,3-oxazin-6-ones from enamides with CO2 through C--H carboxylation and one-pot cyclization. This transition-metal-free and redox-neutral process features broad substrate scope, ...Herein, we report a novel synthesis of 1,3-oxazin-6-ones from enamides with CO2 through C--H carboxylation and one-pot cyclization. This transition-metal-free and redox-neutral process features broad substrate scope, good functional group tolerance and facile product derivatization. The nucleophilic attack to CO2 from the electron-rich alkene is demonstrated for this reaction.展开更多
Iodomethane is usually used as an electrophilic methylation reagent.Herein,we report its use as a C1 organocatalyst for the aerobic ortho-selective trifluoromethylation of pyridines in the absence of a transition meta...Iodomethane is usually used as an electrophilic methylation reagent.Herein,we report its use as a C1 organocatalyst for the aerobic ortho-selective trifluoromethylation of pyridines in the absence of a transition metal.Trifluoroacetic acid(TFA)was employed as an inexpensive,readily available trifluoromethyl source.The reaction efficiently produced a variety of trifluoromethylation products,with good functional group compatibility.Pyridine-containing drug molecules could also be selectively trifluoromethylated for late-stage functionalizations.Mechanistic studies showed that iodomethane selectively reacted with the pyridine starting material,rather than the pyridine product,to generate the corresponding N-methylpyridinium iodide.The decarboxylation of trifluoroacetic acid produced a trifluoromethyl anion,which added to the methylpyridinium iodide,and the subsequent aerobic rearomatization led to the generation of the ortho-trifluoromethylated product.展开更多
Due to the increasing demand for the sustainability of modern organic chemistry, the development of green and powerful methods for C-C and C-B bond formation is highly desired. Among them, the transition-metal-free co...Due to the increasing demand for the sustainability of modern organic chemistry, the development of green and powerful methods for C-C and C-B bond formation is highly desired. Among them, the transition-metal-free coupling reactions of gem–diborylalkanes emerge as one valuable tool for organic chemists in the last decade. The review covers selected representative examples. A comparison of these reactions with transition-metal-catalyzed reactions is provided. The recent example of α-boryl radical formation from gem–diborylalkanes is also briefly discussed.展开更多
The unique properties of fluorine-containing organic compounds make fluorine substitution attractive for the development of pharmaceuticals and various specialty materials,which have inspired the evolution of diverse ...The unique properties of fluorine-containing organic compounds make fluorine substitution attractive for the development of pharmaceuticals and various specialty materials,which have inspired the evolution of diverse C–F bond activation techniques.Although many advances have been made in functionalizations of activated C–F bonds utilizing transition metal complexes,there are fewer approaches available for nonactivated C–F bonds due to the difficulty in oxidative addition of transition metals to the inert C–F bonds.In this regard,using Lewis acid to abstract the fluoride and light/radical initiator to generate the radical intermediate have emerged as powerful tools for activating those inert C–F bonds.Meanwhile,these transition-metal-free processes are greener,economical,and for the pharmaceutical industry,without heavy metal residues.This review provides an overview of recent C–F bond activations and functionalizations under transition-metal-free conditions.The key mechanisms involved are demonstrated and discussed in detail.Finally,a brief discussion on the existing limitations of this field and our perspective are presented.展开更多
A facile synthesis of 1,3,4-oxadiazoles and 1,3,4-oxadiazoles-d_(5) via[4+1]cyclization of ClCF_(2)COONa with non-amine compounds containing amino groups is developed.Of note,this is the first time that halofluorinate...A facile synthesis of 1,3,4-oxadiazoles and 1,3,4-oxadiazoles-d_(5) via[4+1]cyclization of ClCF_(2)COONa with non-amine compounds containing amino groups is developed.Of note,this is the first time that halofluorinated compounds are used as C1 synthon to construct deuterated nitrogen-heterocyclic compounds.The current protocol features simple operation,readily accessible raw materials,wide substrate scope and valuable products.展开更多
An SN2-based photochemical strategy using dithiocarbamate anion as catalyst was developed for the activation of benzyl halides,which are extremely challenging to be applied as radical precursors in visible light photo...An SN2-based photochemical strategy using dithiocarbamate anion as catalyst was developed for the activation of benzyl halides,which are extremely challenging to be applied as radical precursors in visible light photocatalysis.With this transition-metal-free and oxidant-free protocol,the benzylation(or cyanomethylation)of various heterocycles including quinoxalin-2(1H)-ones,coumarin,2-phenyl-2H-indazole,1-methyl-5-phenylpyrazin-2(1H)-one,1-(fluoromethyl)cinnolin-4(1H)-one,and 2,4-dibenzyl-1,2,4-triazine-3,5(2H,4H)-dione could be realized(46 examples,up to 98%yield).Importantly,some biologically relevant 3-benzylquinoxalin-2(1H)-ones were also be synthesized under mild conditions.展开更多
2,2,6,6-Tetramethyl-l-piperidinyl-N-oxyl(TEMPO)and its derivatives as stable radicals can participate in many reactions.During the process,TEMPO and its derivatives could act not only as the substrates to capture or i...2,2,6,6-Tetramethyl-l-piperidinyl-N-oxyl(TEMPO)and its derivatives as stable radicals can participate in many reactions.During the process,TEMPO and its derivatives could act not only as the substrates to capture or initiate new radical intermediates to provide new compounds but also as organic catalysts or oxidants for transformations of alkenes,alcohols,aldehydes and so on to synthesize various high valueadded compounds.In this review,we would introduce recent advances of the transformations of different substrates mediated by TEMPO and its derivatives under transition-metal-free conditions.展开更多
A general transition-metal-free visible-light-promoted 3-acetalation reaction of quinoxaline-2(1H)-ones was developed under mild conditions.By employing 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene(4CzIPN)as an ...A general transition-metal-free visible-light-promoted 3-acetalation reaction of quinoxaline-2(1H)-ones was developed under mild conditions.By employing 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene(4CzIPN)as an inexpensive photocatalyst,and glyoxylic acid acetal as a radical source,various acetalated quinoxaline-2(1H)-ones were constructed in moderate to good yields.Moreover,the versatility of this protocol is highlighted by the successful application in the late-stage modification of drug molecules and the various functionality transformations.The excellent antitumor activity of the acetalated product demonstrated that this streamlined and sustainable approach could have emerged as a powerful strategy for structural modification in medicinal chemistry.展开更多
基金Financial support from the National Natural Science Foundation of China(Nos.22271244,22201240,and 21871226)the Hunan Provincial Natural Science Foundation of China(No.2020JJ5531)+1 种基金Open Research Fund of School of Chemistry and Chemical Engineering,Henan Normal University(2022C02)the Undergraduate Investigated Study and Innovated Experiment Plan from Ministry of Education of China and the Science and Technology Innovation Program of Hunan Province(2020RC1009)is gratefully acknowledged.
文摘Comprehensive Summary,A convenient approach for the construction of 2-aminobenzothiazoles via I2-catalyzed tandem cyclization reaction of amines and carbon disulfide has been developed.The present approach starts from simple and readily available starting materials,affording a series of 2-aminobenzothiazoles in up to 89%yields under metal-free conditions.In this work,C—H/N—H functionalization was achieved and multiple C-hetero bonds were successfully constructed in one pot.
文摘Herein, we report a novel synthesis of 1,3-oxazin-6-ones from enamides with CO2 through C--H carboxylation and one-pot cyclization. This transition-metal-free and redox-neutral process features broad substrate scope, good functional group tolerance and facile product derivatization. The nucleophilic attack to CO2 from the electron-rich alkene is demonstrated for this reaction.
基金supported by the National Natural Science Foundation of China(21971093)the Fundamental Research Funds for the Central Universities(lzujbky-2021-sp53)+1 种基金the International Joint Research Centre for Green Catalysis and Synthesis(2016B01017)the 111 Project。
文摘Iodomethane is usually used as an electrophilic methylation reagent.Herein,we report its use as a C1 organocatalyst for the aerobic ortho-selective trifluoromethylation of pyridines in the absence of a transition metal.Trifluoroacetic acid(TFA)was employed as an inexpensive,readily available trifluoromethyl source.The reaction efficiently produced a variety of trifluoromethylation products,with good functional group compatibility.Pyridine-containing drug molecules could also be selectively trifluoromethylated for late-stage functionalizations.Mechanistic studies showed that iodomethane selectively reacted with the pyridine starting material,rather than the pyridine product,to generate the corresponding N-methylpyridinium iodide.The decarboxylation of trifluoroacetic acid produced a trifluoromethyl anion,which added to the methylpyridinium iodide,and the subsequent aerobic rearomatization led to the generation of the ortho-trifluoromethylated product.
基金financial support from the National Natural Science Foundation of China (No. 22101261)。
文摘Due to the increasing demand for the sustainability of modern organic chemistry, the development of green and powerful methods for C-C and C-B bond formation is highly desired. Among them, the transition-metal-free coupling reactions of gem–diborylalkanes emerge as one valuable tool for organic chemists in the last decade. The review covers selected representative examples. A comparison of these reactions with transition-metal-catalyzed reactions is provided. The recent example of α-boryl radical formation from gem–diborylalkanes is also briefly discussed.
文摘The unique properties of fluorine-containing organic compounds make fluorine substitution attractive for the development of pharmaceuticals and various specialty materials,which have inspired the evolution of diverse C–F bond activation techniques.Although many advances have been made in functionalizations of activated C–F bonds utilizing transition metal complexes,there are fewer approaches available for nonactivated C–F bonds due to the difficulty in oxidative addition of transition metals to the inert C–F bonds.In this regard,using Lewis acid to abstract the fluoride and light/radical initiator to generate the radical intermediate have emerged as powerful tools for activating those inert C–F bonds.Meanwhile,these transition-metal-free processes are greener,economical,and for the pharmaceutical industry,without heavy metal residues.This review provides an overview of recent C–F bond activations and functionalizations under transition-metal-free conditions.The key mechanisms involved are demonstrated and discussed in detail.Finally,a brief discussion on the existing limitations of this field and our perspective are presented.
基金Financial support from the National Natural Science Foundation of China(Nos.21772046,2193103)the Guangdong Provincial Key Laboratory of Catalysis(No.2020B121201002)Subsidized Project for Cultivating Postgraduates’Innovative Ability in Scientific Research of Huaqiao University。
文摘A facile synthesis of 1,3,4-oxadiazoles and 1,3,4-oxadiazoles-d_(5) via[4+1]cyclization of ClCF_(2)COONa with non-amine compounds containing amino groups is developed.Of note,this is the first time that halofluorinated compounds are used as C1 synthon to construct deuterated nitrogen-heterocyclic compounds.The current protocol features simple operation,readily accessible raw materials,wide substrate scope and valuable products.
基金support from the National Natural Science Foundation of China(Nos.21971224,22071222,22171249)111 Project(No.D20003)+3 种基金the Key Research Projects of Universities in Henan Province(No.21A150053)the Natural Science Foundation of Henan Province(No.202300410375)China Postdoctoral Science Foundation(No.2021M692906)Henan Postdoctoral Foundation(No.202003014).
文摘An SN2-based photochemical strategy using dithiocarbamate anion as catalyst was developed for the activation of benzyl halides,which are extremely challenging to be applied as radical precursors in visible light photocatalysis.With this transition-metal-free and oxidant-free protocol,the benzylation(or cyanomethylation)of various heterocycles including quinoxalin-2(1H)-ones,coumarin,2-phenyl-2H-indazole,1-methyl-5-phenylpyrazin-2(1H)-one,1-(fluoromethyl)cinnolin-4(1H)-one,and 2,4-dibenzyl-1,2,4-triazine-3,5(2H,4H)-dione could be realized(46 examples,up to 98%yield).Importantly,some biologically relevant 3-benzylquinoxalin-2(1H)-ones were also be synthesized under mild conditions.
基金supported by the National Natural Science Foundation of China (No.21303231)Natural Science Foundation of Jiangsu Province (No.BK20161261)+1 种基金Natural Science Foundation of Shandong Province (No.ZR2019MB002)Shandong Agricultural University
文摘2,2,6,6-Tetramethyl-l-piperidinyl-N-oxyl(TEMPO)and its derivatives as stable radicals can participate in many reactions.During the process,TEMPO and its derivatives could act not only as the substrates to capture or initiate new radical intermediates to provide new compounds but also as organic catalysts or oxidants for transformations of alkenes,alcohols,aldehydes and so on to synthesize various high valueadded compounds.In this review,we would introduce recent advances of the transformations of different substrates mediated by TEMPO and its derivatives under transition-metal-free conditions.
基金financial support from the National Natural Science Foundation of China(Nos.82003585,21971224)the Technical innovation Team of Henan Normal University(No.2022TD03)+2 种基金the Postgraduate Education Reform Project of Henan Province(Nos.2019SJGLX008Y,2019SJGLX034Y)the PostgraduateEducation Reformand QualityImprovement Project of Henan Province(No.YJS2021AL079)the Scienceand Technology Research Project(No.222102310244).
文摘A general transition-metal-free visible-light-promoted 3-acetalation reaction of quinoxaline-2(1H)-ones was developed under mild conditions.By employing 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene(4CzIPN)as an inexpensive photocatalyst,and glyoxylic acid acetal as a radical source,various acetalated quinoxaline-2(1H)-ones were constructed in moderate to good yields.Moreover,the versatility of this protocol is highlighted by the successful application in the late-stage modification of drug molecules and the various functionality transformations.The excellent antitumor activity of the acetalated product demonstrated that this streamlined and sustainable approach could have emerged as a powerful strategy for structural modification in medicinal chemistry.
