Multiple myeloma(MM)is the second most prevalent hematological malignancy.Current MM treatment strategies are hampered by systemic toxicity and suboptimal therapeutic efficacy.This study addressed these limitations th...Multiple myeloma(MM)is the second most prevalent hematological malignancy.Current MM treatment strategies are hampered by systemic toxicity and suboptimal therapeutic efficacy.This study addressed these limitations through the development of a potent MM-targeting chemotherapy strategy,which capitalized on the high binding affinity of alendronate for hydroxyapatite in the bone matrix and the homologous targeting of myeloma cell membranes,termed T-PB@M.The results from our investigations highlight the considerable bone affinity of T-PB@M,both in vitro and in vivo.Additionally,this material demonstrated a capability for drug release triggered by low pH conditions.Moreover,T-PB@M induced the generation of reactive oxygen species and triggered cell apoptosis through the poly(ADP-ribose)polymerase 1(PARP1)-Caspase-3-B-cell lymphoma-2(Bcl-2)pathway in MM cells.Notably,T-PB@M preferentially targeted bone-involved sites,thereby circumventing systemic toxic side effects and leading to prolonged survival of MM orthotopic mice.Therefore,this designed target-MM nanocarrier presents a promising and potentially effective platform for the precise treatment of MM.展开更多
The shape parameter of the Gamma size distribution plays a key role in the evolution of the cloud droplet spectrum in the bulk parameterization schemes. However, due to the inaccurate specification of the shape parame...The shape parameter of the Gamma size distribution plays a key role in the evolution of the cloud droplet spectrum in the bulk parameterization schemes. However, due to the inaccurate specification of the shape parameter in the commonly used bulk double-moment schemes, the cloud droplet spectra cannot reasonably be described during the condensation process. Therefore, a newly-developed triple-parameter condensation scheme with the shape parameter diagnosed through the number concentration, cloud water content, and reflectivity factor of cloud droplets can be applied to improve the evolution of the cloud droplet spectrum. The simulation with the new parameterization scheme was compared to those with a high-resolution Lagrangian bin scheme, the double-moment schemes in a parcel model, and the observation in a 1.5D Eulerian model that consists of two cylinders. The new scheme with the shape parameter varying with time and space can accurately simulate the evolution of the cloud droplet spectrum. Furthermore, the volume-mean radius and cloud water content simulated with the new scheme match the Lagrangian analytical solutions well, and the errors are steady, within approximately 0.2%.展开更多
A Lagrangian advection scheme(LAS)for solving cloud drop diffusion growth was previously proposed(in 2020)and validated with simulations of cloud droplet spectra with a one-and-a-half dimensional(1.5D)cloud bin model ...A Lagrangian advection scheme(LAS)for solving cloud drop diffusion growth was previously proposed(in 2020)and validated with simulations of cloud droplet spectra with a one-and-a-half dimensional(1.5D)cloud bin model for a deep convection case.The simulation results were improved with the new scheme over the original Eulerian scheme.In the present study,the authors simulated rain embryo formation with the LAS for a maritime shallow cumulus cloud case from the RICO(Rain in Cumulus over the Ocean)campaign.The model used to simulate the case was the same 1.5D cloud bin model coupled with the LAS.Comparing the model simulation results with aircraft observation data,the authors conclude that both the general microphysical properties and the detailed cloud droplet spectra are well captured.The LAS is robust and reliable for the simulation of rain embryo formation.展开更多
We herein reported a sustainable synthesis of 3,3-disubstituted oxindoles via a Michael-type reaction based on the CuBr-catalysed capture of carboxylic oxonium ylides with isatylidene malononitrile.The reaction is cha...We herein reported a sustainable synthesis of 3,3-disubstituted oxindoles via a Michael-type reaction based on the CuBr-catalysed capture of carboxylic oxonium ylides with isatylidene malononitrile.The reaction is characterized by a high atom economy and low economic constraints.The catalyst CuBr could be conveniently recyclized.The products of the reaction were found to be inhibitory against Na ion channels.We expect the reaction to shed the light on synthesis of biologically interesting molecules directed by principles of green chemistry.展开更多
A series of novel 3,4-dichloroisothiazole based 1,2,4-triazole derivatives were rationally designed and synthesized. Their structures were confirmed by IH NMR, 13C NMR, HRMS or elemental analysis; the typical crystal ...A series of novel 3,4-dichloroisothiazole based 1,2,4-triazole derivatives were rationally designed and synthesized. Their structures were confirmed by IH NMR, 13C NMR, HRMS or elemental analysis; the typical crystal structure was determined by X-ray diffraction for validation. All target compounds were evaluated for their in vitro fungicidal and in vivo anti-TMV activities. The bioassay results indicated that compound 6b, namely 1-(3,4-dichloroisothiazol-5-yo)-o-(4-ouorophenyo)-2-(OH-o,2o4-triazol-o-yl)ethanol, exhibited excellent growth inhibition against B. cinerea, C. arachldico;a and P. piricola with median effective concentrations (EC50) of 6.98, 2.73 and 3.07μg/mL, respectively, and good in vivo anti-TMV activity of over 60% of inactivation and induction activity at 100 μg/mL. These data demonstrate that compound 6b is both a fungicide and an anti-TMV lead, deserving further studies.展开更多
Vibrio parahaemolyticus is a major pathogen frequently found in seafood.Rapid and accurate detection of this pathogen is important for the control of bacterial foodborne diseases and to ensure food safety.In this stud...Vibrio parahaemolyticus is a major pathogen frequently found in seafood.Rapid and accurate detection of this pathogen is important for the control of bacterial foodborne diseases and to ensure food safety.In this study,we established a one-pot system that combines uracil-DNA glycosylase(UDG),loopmediated isothermal amplification(LAMP),and clustered regularly interspaced short palindromic repeats(CRISPR)/CRISPR-associated protein 12b(Cas12b)for detecting V.parahaemolyticus in seafood.This detection system can effectively perform identification using a single tube and avoid the risk of carryover contamination.展开更多
An unprecedented gold-catalyzed ketene C=O/C=C bifunctionalization method has been developed.Mechanistic studies and density function theory(DFT)calculations indicate that the reaction is initiated by gold-catalyzed W...An unprecedented gold-catalyzed ketene C=O/C=C bifunctionalization method has been developed.Mechanistic studies and density function theory(DFT)calculations indicate that the reaction is initiated by gold-catalyzed Wolff rearrangement of diazoketone to form the ketene intermediate,followed by intermolecular nucleophilic addition and terminated with two divergent cyclization processes via enol intermediates.In the case with alcohols as the nucleophiles,the reaction goes through a C-5-endodig carbocyclization to give the indene products;whereas,O-7-endo-dig cyclization occurs dominantly when indoles/pyrroles are used as the nucleophiles,delivering the 7-membered benzo[d]oxepines.In comparison with the well-documented cycloaddition and nucleophilic addition reactions,this cascade reaction features a novel reaction pattern for the ketene dual functionalization through addition with nucleophile and electrophile in sequence.展开更多
A chiral dirhodium complex is an effective and robust catalyst for asymmetric carbene transformations.However,dirhodiumcatalyzed asymmetric ylide interception processes are rare,mainly because of the dissociation of t...A chiral dirhodium complex is an effective and robust catalyst for asymmetric carbene transformations.However,dirhodiumcatalyzed asymmetric ylide interception processes are rare,mainly because of the dissociation of the metal catalyst before the stereo-determining step.Herein,we report a chiral dirhodium(Ⅱ)-catalyzed asymmetric annulation of vinyl diazoesters withα-hydroxyl ketones,which provides an efficient way to form chiral 2,3-dihydropyrans in good yields with excellent diastereoselectivities and enantioselectivities.This article is the first example of the chiral dirhodium complex–controlled asymmetric aldol-type interception of an in situ–formed oxonium ylide.The origin of the high stereoselectivity is well expounded via experimental and computational studies.These generated chiral products exhibit potent antiproliferation activity in three tested cancer cell lines,namely HCT116(colon cancer),A549(lung adenocarcinoma),and SJSA-1(osteosarcoma cancer).展开更多
Homogeneous gold catalysis has demonstrated the preponderant capability of realizing a broad range of synthetically versatile alkyne functionalization over the last two decades.Though catalytic asymmetric alkyne trans...Homogeneous gold catalysis has demonstrated the preponderant capability of realizing a broad range of synthetically versatile alkyne functionalization over the last two decades.Though catalytic asymmetric alkyne transformation has focused on the principle of using gold catalysts either associated with chiral phosphine ligand or combined with chiral counterion,a variety of breakthroughs have been reported with the application of gold-complex and chiral organocatalyst cooperative catalysis strategy,which could enable the challenging transformations that cannot be realized by mono-catalysis with excellent stereoselectivity.This review will cover two general protocols in this field,including relay catalysis and synergistic catalysis,with emphasis on the detailed cooperative catalysts models to illustrate the roles of the two catalysts and highlight the potential synthetic opportunities offered by asymmetric cooperative catalysis.展开更多
Enantioenrichedγ-butenolides are valuable structural cores in many pharmaceuticals and natural products,but their direct and catalytically asymmetric assembly remains rare.Here,we report an efficient,atom-economic sy...Enantioenrichedγ-butenolides are valuable structural cores in many pharmaceuticals and natural products,but their direct and catalytically asymmetric assembly remains rare.Here,we report an efficient,atom-economic synthetic strategy for enantioenrichedγ-butenolides via a unique enantioselective reaction of cyclopropene carboxylic acids with imines under the synergistic catalysis of Rh2(esp)2/chiral Brønsted acid system.The reaction involved trapping of carboxylic oxonium ylides,generated from cyclopropene carboxylic acids,which presented as the first asymmetric trapping reactive intermediate in the process.展开更多
An enantioselective three-component propargyloxylation reaction of propargyl alcohols,pyridotriazoles,and imines has been realized by cooperative catalysis with dirhodium complex and chiral phosphoric acid under mild ...An enantioselective three-component propargyloxylation reaction of propargyl alcohols,pyridotriazoles,and imines has been realized by cooperative catalysis with dirhodium complex and chiral phosphoric acid under mild conditions.This is the first example of a catalytic asymmetric three-component propargyloxylation reaction,which provides practical access to chiral polyfunctionalized succinate derivatives with adjacent quaternary and tertiary stereocenters in good to high yields with excellent enantioselectivity.In addition to the alkyne motif,pyridyl,alkoxy,amino,and alkenyl species are all tolerated under the reaction conditions.Notably,the utility of the current method is demonstrated by catalytic cyclization of the product alkyne into a variety of heterocyclic structures without loss of enantiomeric purity.展开更多
Paclitaxel(Taxol^(@))as a cornerstone of chemotherapy remains in high demand.The semi-synthesis of paclitaxel via coupling of Taxus leaf-produced baccatin III and manually synthesized isoserine(C-13 side chain)is one ...Paclitaxel(Taxol^(@))as a cornerstone of chemotherapy remains in high demand.The semi-synthesis of paclitaxel via coupling of Taxus leaf-produced baccatin III and manually synthesized isoserine(C-13 side chain)is one of the solutions to avoid environmental damage caused by the sacrifice of the whole Taxus brevifolia.A green synthesis of the C-13 side chain is pivotal to the green production of paclitaxel.We herein report a green synthesis of isoserine derivatives and the semi-synthesis of paclitaxel via a straightforward assembly of isoserines based on an Rh2(TPA)3(OAc)/CPA1 co-catalyzed asymmetric multi-component reaction of ethyl diazoacetate,triethyl silanol and N-(anthrancen-9-ylmethyl)benzaldimine.The method is featured by improved atom economy,effective mass yield,and environmental factors compared to our previous racemic method and BMS company's semi-synthesis method.And the method allows for rapid access to paclitaxel derivatives with varied C-13 side chains.展开更多
In this study,we employed a three-dimensional mesoscale cold-cloud seeding model to simulate the microphysical impacts of artificial ice crystals used as cloud seeding catalysts.Our objective was to elucidate the mech...In this study,we employed a three-dimensional mesoscale cold-cloud seeding model to simulate the microphysical impacts of artificial ice crystals used as cloud seeding catalysts.Our objective was to elucidate the mechanism of snowfall enhancement in stratiform clouds in the Bayanbulak test area of Xinjiang,China.The results indicated that the optimal seeding time was the early stages of weather system development.In this case,the optimal seeding zone was identified as the northwest of the test area,especially near the cloud top(altitudes between 3500 and 4000 m,temperatures range−11 to−15℃),and the ideal concentration of catalyst was with ice crystal density of 1.0×10^(7)kg^(−1)within the target area.Under such conditions,the total precipitation rate in the seeding-affected area increased to 50.1 mm h^(−1).The results also showed that the favorable seeding region was featured by high content of supercooled water and low population of natural ice crystals,where artificial ice crystals could substantially increase the snowfall.This augmentation typically appeared in a unimodal pattern,with the peak formed within 2–3 h after seeding.Seeding in the ice–water mixed zone of a supercooled cloud facilitated rapid ice crystal growth to snow-flake pieces via the Bergeron process,which in turn consumed more supercooled water via collision–coalescence with cloud water droplets.Simultaneously,the intensive consumption of supercooled water impeded the riming process and reduced the formation of graupel particles within the cloud.The dispersion of artificial ice crystals extended over tens of kilometers horizontally;however,in the vertical direction most particles remained approximately 1 km below the seeding layer,due to limited vertical ascent rate in the stratiform clouds restricting upward movement of artificial ice crystals.The above results help better understand the snowfall enhancement mechanism in stratiform clouds and facilitate related weather modification practice.展开更多
基金supported by the National Natural Science Foundation of China(52073145 and 82004081)the Jiangsu Talent Professor Program,Jiangsu Innovation Project of Graduate Student(KYCX23-2192)+1 种基金the National Natural Science Foundation of Nanjing University of Chinese Medicine(NZY82004081)the Special Grants of China Postdoctoral Science Foundation(2021T140792).
文摘Multiple myeloma(MM)is the second most prevalent hematological malignancy.Current MM treatment strategies are hampered by systemic toxicity and suboptimal therapeutic efficacy.This study addressed these limitations through the development of a potent MM-targeting chemotherapy strategy,which capitalized on the high binding affinity of alendronate for hydroxyapatite in the bone matrix and the homologous targeting of myeloma cell membranes,termed T-PB@M.The results from our investigations highlight the considerable bone affinity of T-PB@M,both in vitro and in vivo.Additionally,this material demonstrated a capability for drug release triggered by low pH conditions.Moreover,T-PB@M induced the generation of reactive oxygen species and triggered cell apoptosis through the poly(ADP-ribose)polymerase 1(PARP1)-Caspase-3-B-cell lymphoma-2(Bcl-2)pathway in MM cells.Notably,T-PB@M preferentially targeted bone-involved sites,thereby circumventing systemic toxic side effects and leading to prolonged survival of MM orthotopic mice.Therefore,this designed target-MM nanocarrier presents a promising and potentially effective platform for the precise treatment of MM.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41275147 and 41875173)the STS Program of Inner Mongolia Meteorological Service, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences and Institute of Atmospheric Physics, Chinese Academy of Sciences (Grant No. 2021CG0047)
文摘The shape parameter of the Gamma size distribution plays a key role in the evolution of the cloud droplet spectrum in the bulk parameterization schemes. However, due to the inaccurate specification of the shape parameter in the commonly used bulk double-moment schemes, the cloud droplet spectra cannot reasonably be described during the condensation process. Therefore, a newly-developed triple-parameter condensation scheme with the shape parameter diagnosed through the number concentration, cloud water content, and reflectivity factor of cloud droplets can be applied to improve the evolution of the cloud droplet spectrum. The simulation with the new parameterization scheme was compared to those with a high-resolution Lagrangian bin scheme, the double-moment schemes in a parcel model, and the observation in a 1.5D Eulerian model that consists of two cylinders. The new scheme with the shape parameter varying with time and space can accurately simulate the evolution of the cloud droplet spectrum. Furthermore, the volume-mean radius and cloud water content simulated with the new scheme match the Lagrangian analytical solutions well, and the errors are steady, within approximately 0.2%.
基金This research was funded by the National Natural Science Foundation of China[grant number 41705119]a basic research project[grant number xxx0109-301].
文摘A Lagrangian advection scheme(LAS)for solving cloud drop diffusion growth was previously proposed(in 2020)and validated with simulations of cloud droplet spectra with a one-and-a-half dimensional(1.5D)cloud bin model for a deep convection case.The simulation results were improved with the new scheme over the original Eulerian scheme.In the present study,the authors simulated rain embryo formation with the LAS for a maritime shallow cumulus cloud case from the RICO(Rain in Cumulus over the Ocean)campaign.The model used to simulate the case was the same 1.5D cloud bin model coupled with the LAS.Comparing the model simulation results with aircraft observation data,the authors conclude that both the general microphysical properties and the detailed cloud droplet spectra are well captured.The LAS is robust and reliable for the simulation of rain embryo formation.
基金the National Natural Science Foundation of China(Nos.82003592(TS),92056201(WH)and 82201376(SC))Key-Area Research and Development Program of Guangdong Province(No.2022B1111050003)(WH)+1 种基金Shenzhen Science and Technology Innovation Project(No.20200812143116001)(SC)Basic Research Foundation of Guangdong province(No.2021A1515011129)(SC).
文摘We herein reported a sustainable synthesis of 3,3-disubstituted oxindoles via a Michael-type reaction based on the CuBr-catalysed capture of carboxylic oxonium ylides with isatylidene malononitrile.The reaction is characterized by a high atom economy and low economic constraints.The catalyst CuBr could be conveniently recyclized.The products of the reaction were found to be inhibitory against Na ion channels.We expect the reaction to shed the light on synthesis of biologically interesting molecules directed by principles of green chemistry.
基金This work was supported in part by the National Key Research & Development Plan (No. 2017YFD0200900 for Zhijin Fan), the National Natural Science Foundation of China (Grant Nos. 31571991 and 21372132 for Zhijin Fan), the Fundamental Research Funds for the Central Universities (No. 020/63171311), and the China Postdoctoral Science Foundation (2017M611156, for Zhao Bin), the Russian Science Foundation (Grant No 16-16-04022 for Tatiana Glukhareva).
文摘A series of novel 3,4-dichloroisothiazole based 1,2,4-triazole derivatives were rationally designed and synthesized. Their structures were confirmed by IH NMR, 13C NMR, HRMS or elemental analysis; the typical crystal structure was determined by X-ray diffraction for validation. All target compounds were evaluated for their in vitro fungicidal and in vivo anti-TMV activities. The bioassay results indicated that compound 6b, namely 1-(3,4-dichloroisothiazol-5-yo)-o-(4-ouorophenyo)-2-(OH-o,2o4-triazol-o-yl)ethanol, exhibited excellent growth inhibition against B. cinerea, C. arachldico;a and P. piricola with median effective concentrations (EC50) of 6.98, 2.73 and 3.07μg/mL, respectively, and good in vivo anti-TMV activity of over 60% of inactivation and induction activity at 100 μg/mL. These data demonstrate that compound 6b is both a fungicide and an anti-TMV lead, deserving further studies.
基金supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions of China,the Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX2021-038)the Lianyungang Science and Technology Program(No.CG2232).
文摘Vibrio parahaemolyticus is a major pathogen frequently found in seafood.Rapid and accurate detection of this pathogen is important for the control of bacterial foodborne diseases and to ensure food safety.In this study,we established a one-pot system that combines uracil-DNA glycosylase(UDG),loopmediated isothermal amplification(LAMP),and clustered regularly interspaced short palindromic repeats(CRISPR)/CRISPR-associated protein 12b(Cas12b)for detecting V.parahaemolyticus in seafood.This detection system can effectively perform identification using a single tube and avoid the risk of carryover contamination.
基金This work was supported by the National Natural Science Foundation of China(21971262,92056201)the National Postdoctoral Program for Innovative Talents(BX20190399)+3 种基金Guangdong Provincial Key Laboratory of Chiral Molecule and Drug Discovery(2019B030301005)the National Mega-project for Innovative Drugs(2019ZX09721001-006-001)the Program for Guangdong Introducing Innovative and Entrepreneurial Teams(2016ZT06Y337)the Fundamental Research Funds for the Central Universities(20ykpy113,18843407).
文摘An unprecedented gold-catalyzed ketene C=O/C=C bifunctionalization method has been developed.Mechanistic studies and density function theory(DFT)calculations indicate that the reaction is initiated by gold-catalyzed Wolff rearrangement of diazoketone to form the ketene intermediate,followed by intermolecular nucleophilic addition and terminated with two divergent cyclization processes via enol intermediates.In the case with alcohols as the nucleophiles,the reaction goes through a C-5-endodig carbocyclization to give the indene products;whereas,O-7-endo-dig cyclization occurs dominantly when indoles/pyrroles are used as the nucleophiles,delivering the 7-membered benzo[d]oxepines.In comparison with the well-documented cycloaddition and nucleophilic addition reactions,this cascade reaction features a novel reaction pattern for the ketene dual functionalization through addition with nucleophile and electrophile in sequence.
基金supported by the National Natural Science Foundation of China(22001268,21973113,81973176)the Guangdong Provincial Key Laboratory of Chiral Molecule and Drug Discovery(2019B030301005)+2 种基金the Program for Guangdong Introducing Innovative and Entrepreneurial Teams(2016ZT06Y337)the Guangdong Natural Science Fund(2020A1515010614)Key-Area Research and Development Program of Guangdong Province(2022B1111050003)。
文摘A chiral dirhodium complex is an effective and robust catalyst for asymmetric carbene transformations.However,dirhodiumcatalyzed asymmetric ylide interception processes are rare,mainly because of the dissociation of the metal catalyst before the stereo-determining step.Herein,we report a chiral dirhodium(Ⅱ)-catalyzed asymmetric annulation of vinyl diazoesters withα-hydroxyl ketones,which provides an efficient way to form chiral 2,3-dihydropyrans in good yields with excellent diastereoselectivities and enantioselectivities.This article is the first example of the chiral dirhodium complex–controlled asymmetric aldol-type interception of an in situ–formed oxonium ylide.The origin of the high stereoselectivity is well expounded via experimental and computational studies.These generated chiral products exhibit potent antiproliferation activity in three tested cancer cell lines,namely HCT116(colon cancer),A549(lung adenocarcinoma),and SJSA-1(osteosarcoma cancer).
基金Support for this research from the National Natural Science Foundation of China (Nos. 21971262, 81702255)National Postdoctoral Program for Innovative Talents (No. BX20190399)+1 种基金Guangdong Provincial Key Laboratory of Chiral Molecule and Drug Discovery (No. 2019B030301005)The Program for Guangdong Introducing Innovative and Entrepreneurial Teams (No. 2016ZT06Y337)
文摘Homogeneous gold catalysis has demonstrated the preponderant capability of realizing a broad range of synthetically versatile alkyne functionalization over the last two decades.Though catalytic asymmetric alkyne transformation has focused on the principle of using gold catalysts either associated with chiral phosphine ligand or combined with chiral counterion,a variety of breakthroughs have been reported with the application of gold-complex and chiral organocatalyst cooperative catalysis strategy,which could enable the challenging transformations that cannot be realized by mono-catalysis with excellent stereoselectivity.This review will cover two general protocols in this field,including relay catalysis and synergistic catalysis,with emphasis on the detailed cooperative catalysts models to illustrate the roles of the two catalysts and highlight the potential synthetic opportunities offered by asymmetric cooperative catalysis.
基金supported by National Natural Science Foundation of China(no.21901259)Guangdong Basic and Applied Basic Research Foundation(no.2020A1515011116)+1 种基金the Program for Guangdong Introducing Innovative and Entrepreneurial Teams(no.2016ZT06Y337)the National Science&Technology Major Project“Key New Drug Creation and Manufacturing Program”of China(no.2018ZX09711002-006).
文摘Enantioenrichedγ-butenolides are valuable structural cores in many pharmaceuticals and natural products,but their direct and catalytically asymmetric assembly remains rare.Here,we report an efficient,atom-economic synthetic strategy for enantioenrichedγ-butenolides via a unique enantioselective reaction of cyclopropene carboxylic acids with imines under the synergistic catalysis of Rh2(esp)2/chiral Brønsted acid system.The reaction involved trapping of carboxylic oxonium ylides,generated from cyclopropene carboxylic acids,which presented as the first asymmetric trapping reactive intermediate in the process.
基金supported by the National Natural Science Foundation of China(nos.21971262 and 81973176)the Guangdong Provincial Key Laboratory of Chiral Molecule and Drug Discovery(no.2019B030301005)+1 种基金the National Mega-Project for Innovative Drugs(no.2019ZX09721001-006-001)the Program for Guangdong Introducing Innovative and Entrepreneurial Teams(no.2016ZT06Y337).
文摘An enantioselective three-component propargyloxylation reaction of propargyl alcohols,pyridotriazoles,and imines has been realized by cooperative catalysis with dirhodium complex and chiral phosphoric acid under mild conditions.This is the first example of a catalytic asymmetric three-component propargyloxylation reaction,which provides practical access to chiral polyfunctionalized succinate derivatives with adjacent quaternary and tertiary stereocenters in good to high yields with excellent enantioselectivity.In addition to the alkyne motif,pyridyl,alkoxy,amino,and alkenyl species are all tolerated under the reaction conditions.Notably,the utility of the current method is demonstrated by catalytic cyclization of the product alkyne into a variety of heterocyclic structures without loss of enantiomeric purity.
基金Support for this research from the National Natural Science Foundation of China(Nos.92056201 and 82003592)Guangdong Provincial Key Laboratory of Chiral Molecule and Drug Discovery(No.2019B030301005)The Program for Guangdong Introducing Innovative and Entrepreneurial Teams(No.2016ZT06Y337)and Zhujiang Talent Program Postdoctoral Funding Project is greatly acknowledged。
文摘Paclitaxel(Taxol^(@))as a cornerstone of chemotherapy remains in high demand.The semi-synthesis of paclitaxel via coupling of Taxus leaf-produced baccatin III and manually synthesized isoserine(C-13 side chain)is one of the solutions to avoid environmental damage caused by the sacrifice of the whole Taxus brevifolia.A green synthesis of the C-13 side chain is pivotal to the green production of paclitaxel.We herein report a green synthesis of isoserine derivatives and the semi-synthesis of paclitaxel via a straightforward assembly of isoserines based on an Rh2(TPA)3(OAc)/CPA1 co-catalyzed asymmetric multi-component reaction of ethyl diazoacetate,triethyl silanol and N-(anthrancen-9-ylmethyl)benzaldimine.The method is featured by improved atom economy,effective mass yield,and environmental factors compared to our previous racemic method and BMS company's semi-synthesis method.And the method allows for rapid access to paclitaxel derivatives with varied C-13 side chains.
基金Supported by the Scientific Research Project of the Bayingol Mongolian Autonomous Prefecture in Xinjiang(202318)China Meteorological Administration(CMA)Weather Modification Centre Innovation Team Project(WMC2023IT01)CMA Key Innovation Team Project(CMA2022ZD10).
文摘In this study,we employed a three-dimensional mesoscale cold-cloud seeding model to simulate the microphysical impacts of artificial ice crystals used as cloud seeding catalysts.Our objective was to elucidate the mechanism of snowfall enhancement in stratiform clouds in the Bayanbulak test area of Xinjiang,China.The results indicated that the optimal seeding time was the early stages of weather system development.In this case,the optimal seeding zone was identified as the northwest of the test area,especially near the cloud top(altitudes between 3500 and 4000 m,temperatures range−11 to−15℃),and the ideal concentration of catalyst was with ice crystal density of 1.0×10^(7)kg^(−1)within the target area.Under such conditions,the total precipitation rate in the seeding-affected area increased to 50.1 mm h^(−1).The results also showed that the favorable seeding region was featured by high content of supercooled water and low population of natural ice crystals,where artificial ice crystals could substantially increase the snowfall.This augmentation typically appeared in a unimodal pattern,with the peak formed within 2–3 h after seeding.Seeding in the ice–water mixed zone of a supercooled cloud facilitated rapid ice crystal growth to snow-flake pieces via the Bergeron process,which in turn consumed more supercooled water via collision–coalescence with cloud water droplets.Simultaneously,the intensive consumption of supercooled water impeded the riming process and reduced the formation of graupel particles within the cloud.The dispersion of artificial ice crystals extended over tens of kilometers horizontally;however,in the vertical direction most particles remained approximately 1 km below the seeding layer,due to limited vertical ascent rate in the stratiform clouds restricting upward movement of artificial ice crystals.The above results help better understand the snowfall enhancement mechanism in stratiform clouds and facilitate related weather modification practice.