3-CF3 S substituted thioflavones and benzothiophenes were achieved via the reactions of AgSCF3 with methylthiolated alkynones and alkynylthioanisoles,respectively,promoted by persulfate.This protocol possesses good fu...3-CF3 S substituted thioflavones and benzothiophenes were achieved via the reactions of AgSCF3 with methylthiolated alkynones and alkynylthioanisoles,respectively,promoted by persulfate.This protocol possesses good functional group tolerance and high yields.Mechanistic studies suggested that a classic two-step radical process was involved,which includes addition of CF3 S radical to triple bond and cyclization with SMe moiety.展开更多
Stereoselective functionalization at C-2 and C-3 of the gibberellin skeleton was achieved via an intramolecular free radical cyclization approach using a tethered C-19 halomethyl ester as the radical precursor.
An efficient method for the synthesis of functionalized chroman-4-ones induced by visible light via the radical cyclization reaction of sulfinic acids and o-(allyloxy)arylaldehydes at room temperature was described.Th...An efficient method for the synthesis of functionalized chroman-4-ones induced by visible light via the radical cyclization reaction of sulfinic acids and o-(allyloxy)arylaldehydes at room temperature was described.The corresponding products were isolated with moderate to good yields.Radical mechanism was proposed fo r this trans formation.Anti-microbial activity of some desired compounds we re screened.展开更多
We herein described an efficient and practical protocol for radical cyclization of aryl alkynoates to access 3-fluoroalkyl-substituted coumarins using readily available,easy-to-handle and low-cost fluoroalkyl carboxyl...We herein described an efficient and practical protocol for radical cyclization of aryl alkynoates to access 3-fluoroalkyl-substituted coumarins using readily available,easy-to-handle and low-cost fluoroalkyl carboxylic anhydride as fluoroalkyl source.This method is featured by its generally applicable to several kinds of fluoroalkyl carboxylic anhydrides including difluoromethy1,trifluoromethyl,pentafluoroethyl,heptafluoropropyl and chlorodifluoromethyl,as well as a good functional group tolerance with respect to a wide variety of aryl alkynoates.This reaction was triggered by addition of fluoroalkyl radical to the triple bond of alkynoates,followed by a cascade 5-exo cyclization/oxidization/1,2-ester migration/rearomatization process.展开更多
Conventional heme enzymes utilize iron-oxygen intermediates to activate substrates and drive reactions.Re-cently,Chen et al.discovered a novel NADPH-independent superoxide mechanism of heme catalase EasC,which facilit...Conventional heme enzymes utilize iron-oxygen intermediates to activate substrates and drive reactions.Re-cently,Chen et al.discovered a novel NADPH-independent superoxide mechanism of heme catalase EasC,which facilitates an O_(2)-dependent radical oxidative cyclization reaction during ergot alkaloid biosynthesis.This en-zyme coordinates superoxide-mediated catalysis by connecting spatially distinct NADPH-binding pocket and heme pocket via a slender tunnel,offering a novel perspective on the catalytic mechanisms of heme enzymes in nature.展开更多
Visible-light photoredox catalysis is a powerful and attractive strategy for organic molecule activation and new reaction design owing to its environmental-friendly characteristics and unique catalytic mechanisms,and ...Visible-light photoredox catalysis is a powerful and attractive strategy for organic molecule activation and new reaction design owing to its environmental-friendly characteristics and unique catalytic mechanisms,and has found wide applications in organic synthesis.This catalytic strategy enables controllable generation of diverse nitrogen-centered radicals(NCRs)under mild conditions,providing access to construction of diverse nitrogencontaining compounds.In this review,we critically illustrate the recent advances in the field of visible-light photoredox-catalyzed cyclization of nitrogen-centered radicals,based on the different radical precursors and activation modes.Wherever possible,particular emphasis is also put on working models and synthetic applications.展开更多
Pseudolaric acids are a family of diterpenoid natural products that exhibit a broad spectrum of biological activities.The main structural feature of their framework is a trans-fused perhydroazulene bearing a bridged l...Pseudolaric acids are a family of diterpenoid natural products that exhibit a broad spectrum of biological activities.The main structural feature of their framework is a trans-fused perhydroazulene bearing a bridged lactone positioned at the junction of the rings.Herein,we have developed a radical cyclization strategy that allows flexible tuning of the cyclization process through diverse silicon substitutions on the substrates.This strategy can assist in constructing a series of skeletons with structural resemblance to pseudolaric acids and expedites the construction of the bridged lactone.Finally,it facilitates the synthesis of the entire skeletal structure of the pseudolaric acidfamily of natural products,excludingthe B-ringfunctionalization.展开更多
Due to the innate highly reactive properties and short life-time,organic free radicals can often serve as promoters or intermediates to engage in various radical transformations,which are often otherwise difficult to ...Due to the innate highly reactive properties and short life-time,organic free radicals can often serve as promoters or intermediates to engage in various radical transformations,which are often otherwise difficult to access by ionic pathway-based mechanisms.With the evolvement of radical chemistry,chiral radical catalyzed-transformations have recently emerged as an attractive and robust platform for synthesis of chiral molecules of interest.Herein,we highlight several creative and strategic advances in chiral radical catalyst design,cyclization reaction achievements,and future challenges.展开更多
Houpolignols A-C(1-3),unprecedented oligomers of dearomatized obovatol with tetracyclo[9.3.1.0^(2,7).0^(9,14)]pentadecane(1 and 2)and 8,18-dioxapentacyclo[13.3.1.1^(5,9).0^(4,16).0^(13,20)]icosane(3)core structures,to...Houpolignols A-C(1-3),unprecedented oligomers of dearomatized obovatol with tetracyclo[9.3.1.0^(2,7).0^(9,14)]pentadecane(1 and 2)and 8,18-dioxapentacyclo[13.3.1.1^(5,9).0^(4,16).0^(13,20)]icosane(3)core structures,together with their biosynthetic congener houpolignol D(4),were isolated from the cortex of Magnolia officinalis var.biloba.Their structures were determined by spectroscopic analyses,Xray crystallography data,and quantum chemical calculations.Radical cascade cyclizations were proposed as crucial biosynthetic steps of 1-4.(±)-1 showed anti-nonalcoholic steatohepatitis(NASH)effect by promoting fatty acid beta-oxidation.展开更多
The generation of variousβ-chiral sulfones bearing chiral cyclic sulfinamides through photoredox-catalyzed sulfur dioxide insertion with asymmetric radical cyclization is described.This method features a broad substr...The generation of variousβ-chiral sulfones bearing chiral cyclic sulfinamides through photoredox-catalyzed sulfur dioxide insertion with asymmetric radical cyclization is described.This method features a broad substrate scope and excellent stereospecificity.Computational studies reveal that the dispersion interaction between sulfinyl group and CH_(2)SO_(2)Ph group plays a crucial role in the stereoselectivity control.展开更多
A series of novel cyclic derivatives have been synthesized by utilizing a nickel powder mediated radical cyclization as the key step. The structures of the new compounds were confirmed by 1H-NMR and MS.
A new synthesis of the bridged [6-6-6] ABE tricyclic ring analogues of methyllycaconitine with the C-1 oxygenated substituents has been developed using an efficient aza-annulation of β-enamino ketone followed by a fa...A new synthesis of the bridged [6-6-6] ABE tricyclic ring analogues of methyllycaconitine with the C-1 oxygenated substituents has been developed using an efficient aza-annulation of β-enamino ketone followed by a facile decarboxylation to form BE rings.Subsequent elaboration to form the A ring was achieved by a transannular acyl radical cyclization with concomitant equipment of the key C-1 oxygen functionality.展开更多
In the past decades,diazaphospholene hydrides(DAP-H)have emerged as powerful catalysts for a variety of reductive transformations.However,the radical processes with DAPs as catalysts are extremely rare.Herein,a DAP-ca...In the past decades,diazaphospholene hydrides(DAP-H)have emerged as powerful catalysts for a variety of reductive transformations.However,the radical processes with DAPs as catalysts are extremely rare.Herein,a DAP-catalyzed radical process of aryl halides to accessγ-spirolactams through a XAT/1,5-HAT/radical addition/HAT process is presented.This reaction features metal-free conditions and broad functional group tolerance,leading toγ-spirolactams in good yields.展开更多
Salimabromide,a unique and scarce marine tetracyclic polyketide,was synthesized in both racemic and optically active forms.A novel carboxylic acid-directed method for tandem oxidative difunctionalization of olefins wa...Salimabromide,a unique and scarce marine tetracyclic polyketide,was synthesized in both racemic and optically active forms.A novel carboxylic acid-directed method for tandem oxidative difunctionalization of olefins was developed,whereby the formation of bridged butyrolactone and enone moieties occurs concurrently.Density functional theory(DFT)calculations indicate that this reaction follows a[3+2]process rather than the[2+2]process.In the meantime,the distinctive benzo-fused[4.3.1]carbon skeleton and highly hindered vicinal quaternary stereocenters were simultaneously constructed through a challenging intramolecular Giese-Baran radical cyclization.Furthermore,deuterium kinetic isotopic effects were utilized to enhance the efficacy of this pivotal step.This represents a new illustration of the application of kinetic isotope effects in natural product synthesis.Then,the short asymmetric synthesis of(+)-salimabromide(13 or 15 steps)was accomplished by combing this method with rhodium-catalyzed enantioselective hydrogenation of a cycloheptenone derivative(97%ee)or conjugate addition of an aryl boronic acid with 2-cyclohepten-1-one(>99%ee).展开更多
基金the National Natural Science Foundation of China(Nos.21991123,21677094)for financial support。
文摘3-CF3 S substituted thioflavones and benzothiophenes were achieved via the reactions of AgSCF3 with methylthiolated alkynones and alkynylthioanisoles,respectively,promoted by persulfate.This protocol possesses good functional group tolerance and high yields.Mechanistic studies suggested that a classic two-step radical process was involved,which includes addition of CF3 S radical to triple bond and cyclization with SMe moiety.
文摘Stereoselective functionalization at C-2 and C-3 of the gibberellin skeleton was achieved via an intramolecular free radical cyclization approach using a tethered C-19 halomethyl ester as the radical precursor.
基金the National Natural Science Foundation of China(No.21772107)Shandong Province Key Research and Development Plan(No.2019GSF108017)。
文摘An efficient method for the synthesis of functionalized chroman-4-ones induced by visible light via the radical cyclization reaction of sulfinic acids and o-(allyloxy)arylaldehydes at room temperature was described.The corresponding products were isolated with moderate to good yields.Radical mechanism was proposed fo r this trans formation.Anti-microbial activity of some desired compounds we re screened.
基金supported by the Natural Science Foundation of Fujian Province(No.2022J01500)the National Natural Science Foundation of China(No.22071241)the Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China(No.2021ZZ105).
文摘We herein described an efficient and practical protocol for radical cyclization of aryl alkynoates to access 3-fluoroalkyl-substituted coumarins using readily available,easy-to-handle and low-cost fluoroalkyl carboxylic anhydride as fluoroalkyl source.This method is featured by its generally applicable to several kinds of fluoroalkyl carboxylic anhydrides including difluoromethy1,trifluoromethyl,pentafluoroethyl,heptafluoropropyl and chlorodifluoromethyl,as well as a good functional group tolerance with respect to a wide variety of aryl alkynoates.This reaction was triggered by addition of fluoroalkyl radical to the triple bond of alkynoates,followed by a cascade 5-exo cyclization/oxidization/1,2-ester migration/rearomatization process.
基金supported by the National Natural Science Foundation of China(32025001,32300021,32200017).
文摘Conventional heme enzymes utilize iron-oxygen intermediates to activate substrates and drive reactions.Re-cently,Chen et al.discovered a novel NADPH-independent superoxide mechanism of heme catalase EasC,which facilitates an O_(2)-dependent radical oxidative cyclization reaction during ergot alkaloid biosynthesis.This en-zyme coordinates superoxide-mediated catalysis by connecting spatially distinct NADPH-binding pocket and heme pocket via a slender tunnel,offering a novel perspective on the catalytic mechanisms of heme enzymes in nature.
基金The authors’works in this area have been sponsored by the National Natural Science Foundation of China(Nos.91856119,21971081,21622201,21820102003,91956201 and 21772053)the Program of Introducing Talents of Discipline to Universities of China(111 Program,No.B17019).
文摘Visible-light photoredox catalysis is a powerful and attractive strategy for organic molecule activation and new reaction design owing to its environmental-friendly characteristics and unique catalytic mechanisms,and has found wide applications in organic synthesis.This catalytic strategy enables controllable generation of diverse nitrogen-centered radicals(NCRs)under mild conditions,providing access to construction of diverse nitrogencontaining compounds.In this review,we critically illustrate the recent advances in the field of visible-light photoredox-catalyzed cyclization of nitrogen-centered radicals,based on the different radical precursors and activation modes.Wherever possible,particular emphasis is also put on working models and synthetic applications.
基金the National Natural Science Foundation of China(Nos.22071205,22301251 and 21772164)China Postdoctoral Science Foundation(2023M732942),NFFTBS(J1310024)+1 种基金NCETFJ,and PCSIRT is acknowledgedthe financial support(No.202005)from State Key Laboratory of Elemento-Organic Chemistry,Nankai University.
文摘Pseudolaric acids are a family of diterpenoid natural products that exhibit a broad spectrum of biological activities.The main structural feature of their framework is a trans-fused perhydroazulene bearing a bridged lactone positioned at the junction of the rings.Herein,we have developed a radical cyclization strategy that allows flexible tuning of the cyclization process through diverse silicon substitutions on the substrates.This strategy can assist in constructing a series of skeletons with structural resemblance to pseudolaric acids and expedites the construction of the bridged lactone.Finally,it facilitates the synthesis of the entire skeletal structure of the pseudolaric acidfamily of natural products,excludingthe B-ringfunctionalization.
基金support from the National Natural Science Foundation of China(Nos.22301109 and 22171099)the Research Funds for Talent Introduction of Jiangsu Ocean University(No.KQ23065)+1 种基金Lianyungang Haiyan Project(No.KK24005)Postgraduate Research&Practice Innovation Program of JiangsuProvince.
文摘Due to the innate highly reactive properties and short life-time,organic free radicals can often serve as promoters or intermediates to engage in various radical transformations,which are often otherwise difficult to access by ionic pathway-based mechanisms.With the evolvement of radical chemistry,chiral radical catalyzed-transformations have recently emerged as an attractive and robust platform for synthesis of chiral molecules of interest.Herein,we highlight several creative and strategic advances in chiral radical catalyst design,cyclization reaction achievements,and future challenges.
基金Financial support for this study is from the National Natural Science Foundation of China(No.32170406)the Social Development Special Projects-Key Research and Development Plan of Science and Technology Department of Yunnan Province(No.202303AC100025)the 111 Project from Ministry of Education of China and the State Administration of Foreign Export Affairs of China(No.B18056).
文摘Houpolignols A-C(1-3),unprecedented oligomers of dearomatized obovatol with tetracyclo[9.3.1.0^(2,7).0^(9,14)]pentadecane(1 and 2)and 8,18-dioxapentacyclo[13.3.1.1^(5,9).0^(4,16).0^(13,20)]icosane(3)core structures,together with their biosynthetic congener houpolignol D(4),were isolated from the cortex of Magnolia officinalis var.biloba.Their structures were determined by spectroscopic analyses,Xray crystallography data,and quantum chemical calculations.Radical cascade cyclizations were proposed as crucial biosynthetic steps of 1-4.(±)-1 showed anti-nonalcoholic steatohepatitis(NASH)effect by promoting fatty acid beta-oxidation.
基金supported by the National Natural Science Foundation of China(22171206)the Natural Science Foundation of Zhejiang Province(LZ23B020001)+1 种基金the Zhejiang Provincial Ten Thousand Talent Program(2023R5244)the Open Research Fund of School of Chemistry and Chemical Engineering,Henan Normal University(2020ZD04)。
文摘The generation of variousβ-chiral sulfones bearing chiral cyclic sulfinamides through photoredox-catalyzed sulfur dioxide insertion with asymmetric radical cyclization is described.This method features a broad substrate scope and excellent stereospecificity.Computational studies reveal that the dispersion interaction between sulfinyl group and CH_(2)SO_(2)Ph group plays a crucial role in the stereoselectivity control.
基金This program was supported by National Key Basic Research Program(973)(No.G1998051125).
文摘A series of novel cyclic derivatives have been synthesized by utilizing a nickel powder mediated radical cyclization as the key step. The structures of the new compounds were confirmed by 1H-NMR and MS.
基金National Natural Science Foundation of China (Nos.21472129 and 21871190) for financial support of this work by grants。
文摘A new synthesis of the bridged [6-6-6] ABE tricyclic ring analogues of methyllycaconitine with the C-1 oxygenated substituents has been developed using an efficient aza-annulation of β-enamino ketone followed by a facile decarboxylation to form BE rings.Subsequent elaboration to form the A ring was achieved by a transannular acyl radical cyclization with concomitant equipment of the key C-1 oxygen functionality.
基金the National Natural Science Foundation of China(No.22201202)the Natural Science Foundation of Zhejiang Province(No.LZ23B020001)+1 种基金Zhejiang Provincial Ten Thousand Talent Program(2023R5244)Open Research Fund of School of Chemistry and Chemical Engineering,Henan Normal University(2020zD04)is gratefully acknowledged.
文摘In the past decades,diazaphospholene hydrides(DAP-H)have emerged as powerful catalysts for a variety of reductive transformations.However,the radical processes with DAPs as catalysts are extremely rare.Herein,a DAP-catalyzed radical process of aryl halides to accessγ-spirolactams through a XAT/1,5-HAT/radical addition/HAT process is presented.This reaction features metal-free conditions and broad functional group tolerance,leading toγ-spirolactams in good yields.
基金Zhejiang Provincial Key Laboratory Construction Project and the National Natural Science Foundation of China(No.22271236)for support of this research.
文摘Salimabromide,a unique and scarce marine tetracyclic polyketide,was synthesized in both racemic and optically active forms.A novel carboxylic acid-directed method for tandem oxidative difunctionalization of olefins was developed,whereby the formation of bridged butyrolactone and enone moieties occurs concurrently.Density functional theory(DFT)calculations indicate that this reaction follows a[3+2]process rather than the[2+2]process.In the meantime,the distinctive benzo-fused[4.3.1]carbon skeleton and highly hindered vicinal quaternary stereocenters were simultaneously constructed through a challenging intramolecular Giese-Baran radical cyclization.Furthermore,deuterium kinetic isotopic effects were utilized to enhance the efficacy of this pivotal step.This represents a new illustration of the application of kinetic isotope effects in natural product synthesis.Then,the short asymmetric synthesis of(+)-salimabromide(13 or 15 steps)was accomplished by combing this method with rhodium-catalyzed enantioselective hydrogenation of a cycloheptenone derivative(97%ee)or conjugate addition of an aryl boronic acid with 2-cyclohepten-1-one(>99%ee).
