Four ＂picket fence＂ porphyrin atropisomers were respectively synthesized from the four corresponding atropisomers of meso-tetra（o-aminophenyl）porphyrin that had been chromatographed on a column eluted with petrole...Four ＂picket fence＂ porphyrin atropisomers were respectively synthesized from the four corresponding atropisomers of meso-tetra（o-aminophenyl）porphyrin that had been chromatographed on a column eluted with petroleum ether and ethyl acetate. Results show that each atropisomer could be successfully synthesized by controlling the acylation temperature at 0 ℃. They were characterized by 1H NMR, HRMS, IR, UV-Vis and Langmuir-Blodgett（LB） film analyses. Although the results of HRMS, IR, UV-Vis analyses indicate there is no remarkable difference among the atropisomers, the results of the 1H NMR and the mean molecular areas obtained by LB film technique imply that the atropisomers are significantly discrepant. The former shows that the chemical shifts of the methyl and amide protons of each atropisomer are distinct, while the later presents that the different atropisomer molecules can occupy the different surface areas at the air/water interface.展开更多
In the pharmaceutical industry, the analysis of atropisomers is of considerable interest from both scientific and regulatory perspectives. The compound of interest contains two stereogenic axes due to the hindered rot...In the pharmaceutical industry, the analysis of atropisomers is of considerable interest from both scientific and regulatory perspectives. The compound of interest contains two stereogenic axes due to the hindered rotation around the single bonds connecting the aryl groups, which results in four potential configurational isomers(atropisomers). The separation of the four atropisomers was achieved on a derivatized β-cyclodextrin bonded stationary phase. Further investigation showed that low temperature conditions, including sample preparation(-70 °C), sample storage(-70 °C), and chromatographic separation(6 °C), were critical to preventing interconversion. LC-UV-laser polarimetric analysis identified peaks 1 and 2 as a pair of enantiomers and peaks3 and 4 as another. Thermodynamic analysis of the retention data indicated that the separation of the pairs of enantiomers is primarily enthalpy controlled as indicated by the positive slope of the van't Huff plot. The difference in absolute Δ(Δ H), ranged from 2.20 k J/mol to 2.42 k J/mol.展开更多
By using a perylene diimine(PDI)syn-atropisomer as highly preorganized precursor,we successfully constructed a visible-light-active organic macrocycle PDI-M.The formation of macrocyclic structure effectively avoids se...By using a perylene diimine(PDI)syn-atropisomer as highly preorganized precursor,we successfully constructed a visible-light-active organic macrocycle PDI-M.The formation of macrocyclic structure effectively avoids self-aggregation of PDI cores and enhances the absorption in visible region.As a photocatalyst,PDI-M exhibits excellent activity on aerobic selective oxidation of sulfide into sulfoxide under visible light irradiation at room temperature.Mechanism studies show that both superoxide and singlet oxygen act as reactive oxygen species.This work provides a typical case toward the maximum utilization of photosensitive groups under mild conditions.展开更多
Many therapeutic drugs are racemates;i.e. they are chiral molecules consisting of “left”- and “right-handed” enantiomers (stereoisomers that are mirror images of each other, and are non-superimposable). In some ca...Many therapeutic drugs are racemates;i.e. they are chiral molecules consisting of “left”- and “right-handed” enantiomers (stereoisomers that are mirror images of each other, and are non-superimposable). In some cases, both enantiomers of the drug contribute to some extent (or equally) to the therapeutic effect;in other cases they contribute not at all. The same is true for the adverse effects of racemate drugs: the adverse effects of a racemate drug can be greater-than, less-than, or equal to one or the other enantiomer. An unusual situation arises when a drug consists of “atropisomers”, stereoisomers arising because of hindered rotation about a single chemical bond. We summarize the concept of atropisomerism, and give examples.展开更多
Herein,the de novo synthesis of atropisomeric benzofurans through the Cu/spirocyclic-pyrrolidine-oxazoline(SPDO)complex catalyze asymmetric formal[3+2]cycloaddition between quinones and ynamides is explored,producing ...Herein,the de novo synthesis of atropisomeric benzofurans through the Cu/spirocyclic-pyrrolidine-oxazoline(SPDO)complex catalyze asymmetric formal[3+2]cycloaddition between quinones and ynamides is explored,producing a range of structurally diverse axially chiral benzofurans in satisfactory yields with good to excellent enantioselectivities.Furthermore,density functional theory calculations were applied to explain the possible reaction mechanism.展开更多
A visible light accelerated C-H functionalization reaction in palladium-catalyzed arylation of vinyl arenes with diaryliodonium salts is reported in the absence of additional photosensitizer. The kinetic isotope effe...A visible light accelerated C-H functionalization reaction in palladium-catalyzed arylation of vinyl arenes with diaryliodonium salts is reported in the absence of additional photosensitizer. The kinetic isotope effect （kH/kD） was changed from 3.6 （under darkness） to 1.1 when irradiated by visible light, which indicated that the C-H functionalization step was the rate determining step under darkness and significantly accelerated by the irradia- tion of visible light. Finally the synthesis of ortho tetra-substituted vinylarene atropisomers with high enantiospecificity was realized via this protocol.展开更多
Chiral organosulfur compounds are not only widely distributed in bioactive natural products and pharmaceuticals,but also play a significant role in chiral ligands/catalysts.Throughout the history of synthetic organic ...Chiral organosulfur compounds are not only widely distributed in bioactive natural products and pharmaceuticals,but also play a significant role in chiral ligands/catalysts.Throughout the history of synthetic organic chemistry,chemists have been absorbed in the construction of centrally chiral organosulfur compounds.Nevertheless,there are relatively few reports on installing sulfur functional groups into axially chiral compounds.Atropisomerism is one of the fundamental phenomena in nature,which ubiquitously exists in natural products.After more than a century of development,atropisomers have been designed and extensively applied to pharmaceuticals,functional materials and chiral ligands/catalysts.Due to the importance of chiral sulfurcontaining atropisomers,there is an increasing demand for enantioselective synthesis of them.Recently,a diversity of approaches by C-S bond formations have been established for the construction of enantioenriched sulfur-containing atropisomers,however,there is no comprehensive review to summarize this great progress.In this mini-review,we summarize recent progress in catalytic asymmetric synthesis of sulfur-containing atropisomers by C-S bond formations,which includes sulfur nucleophilic reactions,sulfur electrophilic reactions and sulfur radical reactions.Furthermore,the reaction mechanisms are also discussed.We hope that this mini-review will enable more researchers to further explore this field.展开更多
A highly efficient kinetic resolution of racemic thioanilide atropisomers via C(sp^(3))-H arylation has been achieved by a hybrid palladium catalyst bearing an anionic chiral Co^(Ⅲ)-complex and a phosphoramidite liga...A highly efficient kinetic resolution of racemic thioanilide atropisomers via C(sp^(3))-H arylation has been achieved by a hybrid palladium catalyst bearing an anionic chiral Co^(Ⅲ)-complex and a phosphoramidite ligand,leading to both enantioenriched atropisomeric arylation thioanilides(up to 99%ee)and N-Me atropisomeric thioanilides(up to 99%ee),simultaneously.The remained enantioenriched substrates can be arylated again by using an achiral anionic ligand to give the enantiomer with the opposite configuration.展开更多
Atropisomeric C-N compounds belong to an important class of axially chiral compounds.However,whereas the asymmetric synthesis of biaryl atropisomers have been well established,general and efficient strategies to acces...Atropisomeric C-N compounds belong to an important class of axially chiral compounds.However,whereas the asymmetric synthesis of biaryl atropisomers have been well established,general and efficient strategies to access single enantiomers of C-N atropisomers are still rare.Until recently,innovative methods have been developed,providing new opportunities for the highly stereoselective synthesis of this vital class of atropisomers.Herein,we comprehensively summarize the development in this emerging field and give some insights into future advance.Emphasis is placed on the synthetic strategies.展开更多
Construction of axially chiral 1-azafluorenes via nickel-catalyzed[2+2+2]cycloaddition of alkynes and(o-alkynyl)benzyl nitriles is described.This strategy enables enantioselective discrimination of two sterically simi...Construction of axially chiral 1-azafluorenes via nickel-catalyzed[2+2+2]cycloaddition of alkynes and(o-alkynyl)benzyl nitriles is described.This strategy enables enantioselective discrimination of two sterically similar ortho substituents,such as H and F,during the construction of tri-ortho-substituted biaryl atropisomers.Mechanistic studies including the stereochemistry model and the stability of the atropenantiomers toward racemization are provided.The unique steric hindrance provided by 1-azafluorene skeleton and the fine chiral cavity of the nickel catalyst are key to achieving high enantioselectivity.展开更多
Atroposelective synthesis of N-N atropisomers is an emerging area but remains underexplored;in particular,the synthesis of N-N benzimidazole atropisomers is still unprecedented.Herein,the first enantioselective synthe...Atroposelective synthesis of N-N atropisomers is an emerging area but remains underexplored;in particular,the synthesis of N-N benzimidazole atropisomers is still unprecedented.Herein,the first enantioselective synthesis of N-N benzimidazole atropisomers via the palladium-catalyzed de novo construction of benzimidazole skeleton is presented.With readily available palladium catalyst and biphosphine ligand,a broad range of nonbiaryl benzimidazole and indole-benzimidazole atropisomers were conveniently ac-cessed in high yields and with excellent enantioselectivities.Significantly,these N-N benzimidazole atropisomers showed great anti-tumor activity and selectivity to breast cancer MCF-7 cells.The simple catalytic system,broad substrate scope,high enantioselectivi-ty,and good bioactivity make this approach highly attractive.展开更多
The widespread applications of atropisomeric compounds have led to an increasing demand for their synthesis.Rather than synthesizing different functionalized atropisomers individually,an attractive alternative is to i...The widespread applications of atropisomeric compounds have led to an increasing demand for their synthesis.Rather than synthesizing different functionalized atropisomers individually,an attractive alternative is to identify a key intermediate or precursor that can be readily elaborated and functionalized to realize divergent synthesis of this class of compounds.Building on our previous research on asymmetric ring-opening of cyclic diaryliodoniums,in this work we developed a copper-catalyzed enantioselective ring-opening reaction of ortho,ortho’-dibromo substituted cyclic diaryliodonium with lithium iodide.The resulting optically active product 2,2'-dibromo-6,6'-diiodo-1,1'-biphenyl,possessing two C—Br bonds and two C—I bonds,can be selectively advanced to form different functionalities.Remarkably,the utilities of the product were highlighted by successively demonstrating C—I and C—Br metalation,followed by carboxylation,boroylation,oxygenation,allylation,phosphinylation,etc.,all of which provide a new and convenient approach to synthesizing a range of functionalized axially chiral biphenyls.展开更多
Planar chiral cyclophanes are a type of structurally intriguing organic molecules,which have found increasingly applications in the field of biologically active compounds,asymmetric catalysis,and optically pure materi...Planar chiral cyclophanes are a type of structurally intriguing organic molecules,which have found increasingly applications in the field of biologically active compounds,asymmetric catalysis,and optically pure materials.As such,significant efforts in the development of new methods to build up enantioenriched cyclophanes in a precise manner have attracted increased attention in recent years.Among the plethora of reported synthetic strategies,catalytic enantioselective method has emerged as one of the most straightforward and efficient ways to deliver optically pure planar chiral cyclophanes.In this review,the recent progress in catalytic enantioselective reactions for the synthesis of planar chiral cyclophanes will be discussed,which would stimulate the research interest of chemists for the discovery of novel asymmetric strategies for the preparation of valuable and previously difficult-to-access chiral molecules.展开更多
Axially chiral binaphthol have achieved great success in asymmetric catalysis.Compared toα-binaphthol,axially chiral aryl-β-naphthol are far less reported.Here,we report a method of asymmetric catalysis to construct...Axially chiral binaphthol have achieved great success in asymmetric catalysis.Compared toα-binaphthol,axially chiral aryl-β-naphthol are far less reported.Here,we report a method of asymmetric catalysis to constructβ-naphthol with up to 99%yield,95.5:4.5 enantiomeric ratio,using alkynyl esters as precursors and chiral phosphonic acid(CPA)/Lewis acid as catalysts.Key steps involve oxygen transfer and de novo arene formation to set up the chiral axis.Moreover,this methodology provides a versatile platform for structurally divergent synthesis of atroposelectiveβ-naphthol analogs,which are widely found in bioactive molecules and asymmetric catalysts.展开更多
在采用区域选择性硝化方法合成β-硝基-5,10,15,20-四芳基卟啉铜、镍配合物的过程中,发现并通过核磁等方法分析了5,10,15,20-四(2-甲氧基苯基)卟啉及其相应β-硝基取代物的阻旋异构现象。图谱分析表明,与其结构类似的5,10,15,20-四(2-...在采用区域选择性硝化方法合成β-硝基-5,10,15,20-四芳基卟啉铜、镍配合物的过程中,发现并通过核磁等方法分析了5,10,15,20-四(2-甲氧基苯基)卟啉及其相应β-硝基取代物的阻旋异构现象。图谱分析表明,与其结构类似的5,10,15,20-四(2-羟基苯基)卟啉及5,10,15,20-四(4-甲氧基苯基)卟啉系列化合物没有该阻旋异构现象,说明邻位甲氧基阻碍了苯环与芳环之间C-C单键的旋转。进一步通过Chemdraw 3D Ultra软件能量最小化计算,讨论了阻转异构体可能的方式。展开更多
基金Supported by the National Natural Science Foundation of China(No.20806025)
文摘Four ＂picket fence＂ porphyrin atropisomers were respectively synthesized from the four corresponding atropisomers of meso-tetra（o-aminophenyl）porphyrin that had been chromatographed on a column eluted with petroleum ether and ethyl acetate. Results show that each atropisomer could be successfully synthesized by controlling the acylation temperature at 0 ℃. They were characterized by 1H NMR, HRMS, IR, UV-Vis and Langmuir-Blodgett（LB） film analyses. Although the results of HRMS, IR, UV-Vis analyses indicate there is no remarkable difference among the atropisomers, the results of the 1H NMR and the mean molecular areas obtained by LB film technique imply that the atropisomers are significantly discrepant. The former shows that the chemical shifts of the methyl and amide protons of each atropisomer are distinct, while the later presents that the different atropisomer molecules can occupy the different surface areas at the air/water interface.
文摘In the pharmaceutical industry, the analysis of atropisomers is of considerable interest from both scientific and regulatory perspectives. The compound of interest contains two stereogenic axes due to the hindered rotation around the single bonds connecting the aryl groups, which results in four potential configurational isomers(atropisomers). The separation of the four atropisomers was achieved on a derivatized β-cyclodextrin bonded stationary phase. Further investigation showed that low temperature conditions, including sample preparation(-70 °C), sample storage(-70 °C), and chromatographic separation(6 °C), were critical to preventing interconversion. LC-UV-laser polarimetric analysis identified peaks 1 and 2 as a pair of enantiomers and peaks3 and 4 as another. Thermodynamic analysis of the retention data indicated that the separation of the pairs of enantiomers is primarily enthalpy controlled as indicated by the positive slope of the van't Huff plot. The difference in absolute Δ(Δ H), ranged from 2.20 k J/mol to 2.42 k J/mol.
基金supported by the National Natural Science Foundation of China(No.22171021)Yanjing Young Scholar Candidate Program of Capital Normal University,Capacity Building for SciTech Innovation-Fundamental Scientific Research Funds.
文摘By using a perylene diimine(PDI)syn-atropisomer as highly preorganized precursor,we successfully constructed a visible-light-active organic macrocycle PDI-M.The formation of macrocyclic structure effectively avoids self-aggregation of PDI cores and enhances the absorption in visible region.As a photocatalyst,PDI-M exhibits excellent activity on aerobic selective oxidation of sulfide into sulfoxide under visible light irradiation at room temperature.Mechanism studies show that both superoxide and singlet oxygen act as reactive oxygen species.This work provides a typical case toward the maximum utilization of photosensitive groups under mild conditions.
文摘Many therapeutic drugs are racemates;i.e. they are chiral molecules consisting of “left”- and “right-handed” enantiomers (stereoisomers that are mirror images of each other, and are non-superimposable). In some cases, both enantiomers of the drug contribute to some extent (or equally) to the therapeutic effect;in other cases they contribute not at all. The same is true for the adverse effects of racemate drugs: the adverse effects of a racemate drug can be greater-than, less-than, or equal to one or the other enantiomer. An unusual situation arises when a drug consists of “atropisomers”, stereoisomers arising because of hindered rotation about a single chemical bond. We summarize the concept of atropisomerism, and give examples.
基金supported by the National Natural Science Foundation of China(22278200,21971095,21502080,21772019,21772076,21871117,91956203)the National Key R&D Program of China(2023YFA1506400)+3 种基金the Science and Technology Major Program of Gansu Province of China(22ZD6FA006,23ZDFA015)the“111”Program of Ministry of Education of Chinathe Major Project of the Ministry of Science and Technology of China(2018ZX09711001-005-002)the Science and Technology Commission of Shanghai Municipality(19JC1430100)。
文摘Herein,the de novo synthesis of atropisomeric benzofurans through the Cu/spirocyclic-pyrrolidine-oxazoline(SPDO)complex catalyze asymmetric formal[3+2]cycloaddition between quinones and ynamides is explored,producing a range of structurally diverse axially chiral benzofurans in satisfactory yields with good to excellent enantioselectivities.Furthermore,density functional theory calculations were applied to explain the possible reaction mechanism.
文摘A visible light accelerated C-H functionalization reaction in palladium-catalyzed arylation of vinyl arenes with diaryliodonium salts is reported in the absence of additional photosensitizer. The kinetic isotope effect （kH/kD） was changed from 3.6 （under darkness） to 1.1 when irradiated by visible light, which indicated that the C-H functionalization step was the rate determining step under darkness and significantly accelerated by the irradia- tion of visible light. Finally the synthesis of ortho tetra-substituted vinylarene atropisomers with high enantiospecificity was realized via this protocol.
基金supported by the National Natural Science Foundation of China (22071149,21871178)the Natural Science Foundation of Shanghai (23ZR1428200)the Program for Professor of Special Appointment (Eastern Scholar)at Shanghai Institutions of Higher Learning。
文摘Chiral organosulfur compounds are not only widely distributed in bioactive natural products and pharmaceuticals,but also play a significant role in chiral ligands/catalysts.Throughout the history of synthetic organic chemistry,chemists have been absorbed in the construction of centrally chiral organosulfur compounds.Nevertheless,there are relatively few reports on installing sulfur functional groups into axially chiral compounds.Atropisomerism is one of the fundamental phenomena in nature,which ubiquitously exists in natural products.After more than a century of development,atropisomers have been designed and extensively applied to pharmaceuticals,functional materials and chiral ligands/catalysts.Due to the importance of chiral sulfurcontaining atropisomers,there is an increasing demand for enantioselective synthesis of them.Recently,a diversity of approaches by C-S bond formations have been established for the construction of enantioenriched sulfur-containing atropisomers,however,there is no comprehensive review to summarize this great progress.In this mini-review,we summarize recent progress in catalytic asymmetric synthesis of sulfur-containing atropisomers by C-S bond formations,which includes sulfur nucleophilic reactions,sulfur electrophilic reactions and sulfur radical reactions.Furthermore,the reaction mechanisms are also discussed.We hope that this mini-review will enable more researchers to further explore this field.
基金We are grateful for the financial support from NSFC(Grant No.21831007).
文摘A highly efficient kinetic resolution of racemic thioanilide atropisomers via C(sp^(3))-H arylation has been achieved by a hybrid palladium catalyst bearing an anionic chiral Co^(Ⅲ)-complex and a phosphoramidite ligand,leading to both enantioenriched atropisomeric arylation thioanilides(up to 99%ee)and N-Me atropisomeric thioanilides(up to 99%ee),simultaneously.The remained enantioenriched substrates can be arylated again by using an achiral anionic ligand to give the enantiomer with the opposite configuration.
基金Financial support from the National Natural Science Foundation of China(Nos.21925109 and 21772170)the Open Research Fund of School Chemistry and Chemical Engineering,Henan Normal University and the Center of Chemistry for Frontier Technologies of Zhejiang University is gratefully acknowledged.
文摘Atropisomeric C-N compounds belong to an important class of axially chiral compounds.However,whereas the asymmetric synthesis of biaryl atropisomers have been well established,general and efficient strategies to access single enantiomers of C-N atropisomers are still rare.Until recently,innovative methods have been developed,providing new opportunities for the highly stereoselective synthesis of this vital class of atropisomers.Herein,we comprehensively summarize the development in this emerging field and give some insights into future advance.Emphasis is placed on the synthetic strategies.
基金supported by the National Key Research and Development Program of China(2022YFA1502902)the National Natural Science Foundation of China(22371215,22222111,21971198)+2 种基金the Guangdong Basic and Applied Basic Research Foundation(2022A1515012614)the Large-scale Instrument and Equipment Sharing Foundation of Wuhan UniversityChina Postdoctoral Science Foundation(2022M722451)for the financial support。
文摘Construction of axially chiral 1-azafluorenes via nickel-catalyzed[2+2+2]cycloaddition of alkynes and(o-alkynyl)benzyl nitriles is described.This strategy enables enantioselective discrimination of two sterically similar ortho substituents,such as H and F,during the construction of tri-ortho-substituted biaryl atropisomers.Mechanistic studies including the stereochemistry model and the stability of the atropenantiomers toward racemization are provided.The unique steric hindrance provided by 1-azafluorene skeleton and the fine chiral cavity of the nickel catalyst are key to achieving high enantioselectivity.
基金supported by Taishan Scholar Youth Expert Program in Shandong Province (tsqn201909096)National Natural Science Foundation of China (22371152)+1 种基金Shandong Provincial Natural Science Foundation Project (ZR2023JQ006,ZR2022MB021)the startup fund from Qingdao University.
文摘Atroposelective synthesis of N-N atropisomers is an emerging area but remains underexplored;in particular,the synthesis of N-N benzimidazole atropisomers is still unprecedented.Herein,the first enantioselective synthesis of N-N benzimidazole atropisomers via the palladium-catalyzed de novo construction of benzimidazole skeleton is presented.With readily available palladium catalyst and biphosphine ligand,a broad range of nonbiaryl benzimidazole and indole-benzimidazole atropisomers were conveniently ac-cessed in high yields and with excellent enantioselectivities.Significantly,these N-N benzimidazole atropisomers showed great anti-tumor activity and selectivity to breast cancer MCF-7 cells.The simple catalytic system,broad substrate scope,high enantioselectivi-ty,and good bioactivity make this approach highly attractive.
基金financial supports from National Natural Science Foundation of China(92056102)the Natural Science Foundation of Fujian Province(2023J011395).
文摘The widespread applications of atropisomeric compounds have led to an increasing demand for their synthesis.Rather than synthesizing different functionalized atropisomers individually,an attractive alternative is to identify a key intermediate or precursor that can be readily elaborated and functionalized to realize divergent synthesis of this class of compounds.Building on our previous research on asymmetric ring-opening of cyclic diaryliodoniums,in this work we developed a copper-catalyzed enantioselective ring-opening reaction of ortho,ortho’-dibromo substituted cyclic diaryliodonium with lithium iodide.The resulting optically active product 2,2'-dibromo-6,6'-diiodo-1,1'-biphenyl,possessing two C—Br bonds and two C—I bonds,can be selectively advanced to form different functionalities.Remarkably,the utilities of the product were highlighted by successively demonstrating C—I and C—Br metalation,followed by carboxylation,boroylation,oxygenation,allylation,phosphinylation,etc.,all of which provide a new and convenient approach to synthesizing a range of functionalized axially chiral biphenyls.
基金financial support provided by Huanghuai University and Hangzhou Medical College.
文摘Planar chiral cyclophanes are a type of structurally intriguing organic molecules,which have found increasingly applications in the field of biologically active compounds,asymmetric catalysis,and optically pure materials.As such,significant efforts in the development of new methods to build up enantioenriched cyclophanes in a precise manner have attracted increased attention in recent years.Among the plethora of reported synthetic strategies,catalytic enantioselective method has emerged as one of the most straightforward and efficient ways to deliver optically pure planar chiral cyclophanes.In this review,the recent progress in catalytic enantioselective reactions for the synthesis of planar chiral cyclophanes will be discussed,which would stimulate the research interest of chemists for the discovery of novel asymmetric strategies for the preparation of valuable and previously difficult-to-access chiral molecules.
基金financial support from the National Natural Science Foundation of China(Nos.22071062,22001077 and 22271096)Guangdong Science and Technology Department(Nos.2021A1515012331,2023A1515011001)+1 种基金the Fundamental Research Funds for the Central Universities(No.2022ZYGXZR016)South China University of Technology for start-up funds。
文摘Axially chiral binaphthol have achieved great success in asymmetric catalysis.Compared toα-binaphthol,axially chiral aryl-β-naphthol are far less reported.Here,we report a method of asymmetric catalysis to constructβ-naphthol with up to 99%yield,95.5:4.5 enantiomeric ratio,using alkynyl esters as precursors and chiral phosphonic acid(CPA)/Lewis acid as catalysts.Key steps involve oxygen transfer and de novo arene formation to set up the chiral axis.Moreover,this methodology provides a versatile platform for structurally divergent synthesis of atroposelectiveβ-naphthol analogs,which are widely found in bioactive molecules and asymmetric catalysts.
文摘在采用区域选择性硝化方法合成β-硝基-5,10,15,20-四芳基卟啉铜、镍配合物的过程中,发现并通过核磁等方法分析了5,10,15,20-四(2-甲氧基苯基)卟啉及其相应β-硝基取代物的阻旋异构现象。图谱分析表明,与其结构类似的5,10,15,20-四(2-羟基苯基)卟啉及5,10,15,20-四(4-甲氧基苯基)卟啉系列化合物没有该阻旋异构现象,说明邻位甲氧基阻碍了苯环与芳环之间C-C单键的旋转。进一步通过Chemdraw 3D Ultra软件能量最小化计算,讨论了阻转异构体可能的方式。
