The amide moiety plays an important role as a powerful bioactive backbone,and as the synthetic chemistry community moves toward more sp^(3)-rich scaffolds,alkyl halides have become the feedstock of choice for obtainin...The amide moiety plays an important role as a powerful bioactive backbone,and as the synthetic chemistry community moves toward more sp^(3)-rich scaffolds,alkyl halides have become the feedstock of choice for obtaining carbonylation products.With the development of photoredox catalysis,several aminocarbonylation systems for alkyl halides were developed which usually require transition metal catalysis.Considering the demands for green sustainable chemical synthesis,here we report a metal-free,exogenous catalyst-free aminocarbonylation reaction of alkyl iodides under atmospheric pressure of carbon monoxide.Through a combination of EDA and XAT strategies,the reaction occurs efficiently under only light irradiation at room temperature.展开更多
A visible light-promoted fast photochemical Wolff rearrangement was developed toward synthesis ofα-substituted amides in continuous flow with the use of a photochemical oscillatory flow reactor(POFR).The control expe...A visible light-promoted fast photochemical Wolff rearrangement was developed toward synthesis ofα-substituted amides in continuous flow with the use of a photochemical oscillatory flow reactor(POFR).The control experiment indicates that a fast process of the Wolff rearrangement(<40 s)is involved.Notably,this protocol does not require excess use of any reactants,and the resultingα-substituted amides could be isolated by recrystallization in good to excellent yields.展开更多
Chiral N-substituted amino amides and esters are ubiquitous scaffolds in pesticides and pharmaceutical chemicals,but their asymmetric synthesis remains challenging especially for those with multiple chiral centers.In ...Chiral N-substituted amino amides and esters are ubiquitous scaffolds in pesticides and pharmaceutical chemicals,but their asymmetric synthesis remains challenging especially for those with multiple chiral centers.In this study,IR104 from Streptomyces aureocirculatus was identified from 157 wild-type imine reductases for the synthesis of(S)-2-((R)-2-oxo-4-propylpyrrolidin-1-yl)butanamide(antiepileptic drug Brivaracetam)via dynamic kinetic resolution reductive amination from ethyl 3-formylhexanoate and(S)-2-aminobutylamide with high diastereoselectivity.To further improve the catalytic efficiency of IR104,its mutant D191E/L195I/E253S/M258A(M3)was identified by saturation mutagenesis and iterative combinatorial mutagenesis,which exhibited a 102-fold increase in the catalytic efficiency relative to that of wild-type enzyme and high diastereoselectivity(98:2 d.r.).Crystal structural analysis and molecular dynamics simulations provided some insights into the molecular basis for the improved activity of the mutant enzyme.The imine reductase identified in this study could accept chiral amino amides/esters as amino donors for the dynamic kinetic resolution reductive amination of racemicα-substituted aldehydo-esters,expanding the substrate scope of imine reductases in the dynamic kinetic resolution-reductive amination.Finally,IR104-M3 was successfully used for the preparation of Brivaracetam at gram scale.Using this mutant,various N-substituted amino amides/esters with two chiral centers were also synthesized with up to 99:1 d.r.and 96%yields and subsequently converted intoγ-andδ-lactams,providing an efficient protocol for the synthesis of these important compounds via enzymatic dynamic kinetic resolution-reductive amination from simple building blocks.展开更多
The coupling reaction of phenylurea with different functionalized aryl halides in the presence of air stable CuI,N,N-dimethylethylenediamine as a ligand,and K_3PO_4 as a base gives symmetrical and unsymmetrical diaryl...The coupling reaction of phenylurea with different functionalized aryl halides in the presence of air stable CuI,N,N-dimethylethylenediamine as a ligand,and K_3PO_4 as a base gives symmetrical and unsymmetrical diarylureas in relatively high yields.This method is milder than the palladium catalyzed arylation and avoids the use of toxic phosphine ligands.展开更多
Rana kunyuensis is a species of brown frog that lives exclusively on Kunyu Mountain,Yantai,China.In the current study,a 279-bp cDNA sequence encoding a novel antimicrobial peptide (AMP),designated as amurin-9KY,was cl...Rana kunyuensis is a species of brown frog that lives exclusively on Kunyu Mountain,Yantai,China.In the current study,a 279-bp cDNA sequence encoding a novel antimicrobial peptide (AMP),designated as amurin-9KY,was cloned from synthesized double-strand skin cDNA of R.kunyuensis.The amurin-9KY precursor was composed of 62 amino acid (aa) residues,whereas the mature peptide was composed of 14 aa and contained two cysteines forming a C-terminal heptapeptide ring (Rana box domain) and an amidated C-terminus.These structural characters represent a novel amphibian AMP family.Although amurin-9KY exhibited high similarity to the already identified amurin-9AM from R.amurensis,little is known about the structures and activities of amurin-9 family AMPs so far.Therefore,amurin-9KY and its three derivatives (amurin-9KY1-3) were designed and synthesized.The structures and activities were examined to evaluate the influence of C-terminal amidation and the heptapeptide ring on the activities and structure of amurin-9KY..Results indicated that C-terminal amidation was essential for antimicrobial activity,whereas both C-terminal amidation and the heptapeptide ring played roles in the low hemolytic activity.Circular dichroism (CD) spectra showed that the four peptides adopted an α-helical conformation in THF/H2O (v/v 1∶1) solution,but a random coil in aqueous solution.Elimination of the C-terminal heptapeptide ring generated two free cysteine residues with unpaired thiol groups,which greatly increased the concentration-dependent anti-oxidant activity.Scanning electron microscopy (SEM) was also performed to determine the possible bactericidal mechanisms.展开更多
A potentially versatile procedure for surface modification of nanometer silica is illustrated by N, N-dicyclohexylcarbodiimide (DCC) mediated amidation of stearic acid.
Cu2O and Cul were supported on multiwalled carbon nanotubes （MWCNTs） using a wet impregna- tion method, and the resulting materials were fully characterized by powder X-ray diffraction, Fourier transform infrared sp...Cu2O and Cul were supported on multiwalled carbon nanotubes （MWCNTs） using a wet impregna- tion method, and the resulting materials were fully characterized by powder X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy with energy dispersive X-ray spectroscopy, transmission electron microscopy, and temperature-programmed desorption with ammonia analysis. The results of these experiments revealed that Cu2O and CuI were deposited on the MWCNTs in the cubic and γ phases, respectively. These results also showed that the Cu-containing MWCNTs exhibited weak to strong electron-accepting （Lewis acidic） properties. The catalytic activities of these materials were studied for the synthesis of biologically significant N-（pyridin-2-yl）benzamides via the oxidative amidation of aryl aldehydes with 2-aminopyridines. The yields of the products were in the range 50%-95% with 100% selectivity. Notably, the CuI/MWCNT catalyst was much more effective than the Cu2O/MWCNT catalyst with respect to the isolated yield of the product, although the latter of these two catalysts exhibited much better recyclability. A preferential interaction was observed between the polar nature of the acid-activated MWCNTs and the ionic Cu2O compared with covalent CuL The differences in these interactions had a significant impact on the rate of the nucleophilic attack of the amino group of 2-aminopyridine substrate on the carbonyl group of the aryl aldehyde.展开更多
Amphipathic-type thioesters CH3(CH2)mCOS(CH2)nCOONa (m + n = 12) were synthesized and their reaction with various alkylamines was examined. Compounds having thioester moiety close to carboxylate (m = 10, n = 2) afford...Amphipathic-type thioesters CH3(CH2)mCOS(CH2)nCOONa (m + n = 12) were synthesized and their reaction with various alkylamines was examined. Compounds having thioester moiety close to carboxylate (m = 10, n = 2) afforded the corresponding amides in good yields, while the substrate having thioester moiety distant from carboxylate (m = 2, n = 10) afforded the amides in relatively low yield. In all cases, the difference in yield due to the chain length of amine was not observed. The results indicated that the reaction took place effectively near the surface of micelle. However, the reaction was found to occur not only on micelle surface but also in solution.展开更多
Cp^*Co(Ⅲ)-catalyzed direct C—H amidation of azines has been developed.This co nversion could proceed smoothly in the absence of external oxidants,acids or bases,with excellent regioselectivity and broad functional g...Cp^*Co(Ⅲ)-catalyzed direct C—H amidation of azines has been developed.This co nversion could proceed smoothly in the absence of external oxidants,acids or bases,with excellent regioselectivity and broad functional group tolerance,CO2 was released as the sole byproduct,thus providing an environmentally benign amidation process.The products obtained are important intermediates in organic synthesis.展开更多
Catalytic Michael addition reaction represents a fundamental importance in organic synthetic chemistry.Whereas corresponding conversions toward intrinsically low reactive enamide remains an ongoing challenging.We here...Catalytic Michael addition reaction represents a fundamental importance in organic synthetic chemistry.Whereas corresponding conversions toward intrinsically low reactive enamide remains an ongoing challenging.We herein report a copper-catalyzed conjugate addition of allenes toβ-substituted alkenyl amides,one of the most challenging Michael acceptors.The present method utilizes readily available allenes as the latent carbon-based nucleophiles and simple,commonβ-substituted alkenyl amides as starting materials,unlike previous methods that usually preinstall an activating group to improve the reactivity of amide or uses highly reactive stoichiometric quantities of organometallics.Hence,this approach shows good functional group compatibility and can be implemented under mild reaction conditions with excellent level of chemo-and regioselectivities.展开更多
Selective molecular recognition in water is routine for bioreceptors,but remains challenging for synthetic hosts.This is principally because noncovalent interactions are usually less efficient in aqueous environments....Selective molecular recognition in water is routine for bioreceptors,but remains challenging for synthetic hosts.This is principally because noncovalent interactions are usually less efficient in aqueous environments.By mimicking the cavity feature of bioreceptors,Prof.Wei Jiang proposed and clarified the concept of“endo-functionalized cavity”.Through situating polar binding sites into a deep hydrophobic cavity,we designed and synthesized several macrocyclic hosts,among which amide naphthotubes are the most representative.The hosts can selectively recognize various polar molecules including organic micropollutants,drug molecules,and chiral molecules in water by employing the hydrophobic effect and shielded hydrogen bonding.In addition,these biomimetic hosts have been applied in spectroscopic analysis,adsorptive separation and self-assembly.In this review,we provide an overview of recent advances on amide naphthotubes with special emphasis on the efforts of Jiang's group.We are convinced that these biomimetic macrocycles will make further contributions to supramolecular chemistry and beyond.展开更多
Colorectal cancer is a common cancer worldwide.Traditional chemotherapeutic drugs often face limitations such as poor aqueous solubility and high systemic toxicity,which can lead to adverse side effects and limited th...Colorectal cancer is a common cancer worldwide.Traditional chemotherapeutic drugs often face limitations such as poor aqueous solubility and high systemic toxicity,which can lead to adverse side effects and limited therapeutic efficacy.In this study,a library of one kind of biodegradable and biocompatible polymer,leucine based-poly(ester amide)s(Leu-PEAs)was developed and utilized as drug carrier.The structure of Leu-PEAs can be tuned to alter their physicochemical properties,enhancing drug loading capacity and delivery efficiency.Leu-PEAs can self-assemble into nanoparticles by nanoprecipitation and load paclitaxel(PTX)with the diameter of~108 nm and PTX loading capacity of~8.5%.PTX-loaded Leu-PEAs nanoparticles(PTX@Leu-PEAs)demonstrated significant inhibition of CT26 cell growth in vitro.In vivo,these nanoparticles exhibited prolonged tumor accumulation and antitumor effects,with no observed toxicity to normal organs.Furthermore,blank Leu-PEAs nanoparticles also showed antitumor effects in vitro and in vivo,which may be attributed to the activation of the mammalian target of rapamycin(m TOR)pathway by leucine.Consequently,this biocompatible Leu-PEAs nano-drug delivery system shows potential as a promising strategy for colorectal cancer treatment,warranting further investigation.展开更多
An atom economicβ-C(sp^(3))−H chlorination of amide derivatives has been developed.This mild protocol employs CuCl_(2) instead of palladium catalysts with atom-economic HCl as chlorine sources and enables the late-st...An atom economicβ-C(sp^(3))−H chlorination of amide derivatives has been developed.This mild protocol employs CuCl_(2) instead of palladium catalysts with atom-economic HCl as chlorine sources and enables the late-stage functionalization of medicine derivatives.Mechanism studies suggest a plausible visible light triggered ligand-to-metal charge transfer(LMCT)/1,4-hydrogen atom transfer(HAT)cascade.展开更多
The pursuit of incorporating eco-friendly reinforcing agents in polymer composites has accentuated the exploration of various natural biomass-derived materials.The burgeoning environmental crisis spurred by the discha...The pursuit of incorporating eco-friendly reinforcing agents in polymer composites has accentuated the exploration of various natural biomass-derived materials.The burgeoning environmental crisis spurred by the discharge of synthetic dyes into wastewater has catalyzed the search for effective and sustainable treatment technologies.Among the various sorbent materials explored,biochar,being renewable,has gained prominence due to its excellent adsorption properties and environmental sustainability.It has also emerged as a focal point for its potential to replace other conventional reinforcing agents,viz.,fumed silica,aluminum oxide,treated clays,etc.This study introduces a novel class of polymer nanocomposites comprising of lignin-based biochar particles and poly(ester amide urethane)matrix via a feasible method.The structural evaluation of these nanocomposites was accomplished using Fourier-transform infrared spectroscopy,X-ray photoelectron spectroscopy,and powder X-ray diffraction.The polymer nanocomposites exhibited superior mechanical properties with an increment in tensile strength factor by 45%in comparison to its pristine matrix,along with an excellent toughness value of 90.22 MJm^(−3)at a low loading amount of only 1 wt%.The composites showed excellent improvement in thermal properties with a sharp rise in the glass transition temperature(Tg)value from−28.15℃to 84℃,while also championing sustainability through inherent biodegradability attributes.Beyond their structural prowess,these polymer nanocomposites demonstrated excellent potential as adsorbents,displaying efficient removal of malachite green and tartrazine dyes from aqueous systems with a removal efficiency of 87.25%and 73.98%,respectively.The kinetics study revealed the pseudo second order model to be the precision tool to assess the dye removal study.Complementing this,the Langmuir adsorption isotherm provided a framework to assess the sorption features of the polymer nanocomposites.Overall,these renewable biochar integrated polymer matrices boast remarkable recovery capabilities up to seven cycles of usage with an excellent dye recovery percentage of 95.21%for the last cycle,thereby defining sustainability as well as economic feasibility.展开更多
目的 探讨三维酰胺质子转移加权(three-dimensions amide proton transfer weighted,3D-APTw)成像在评估肝细胞癌(hepatocellular carcinoma,HCC)病理分级中的价值。材料与方法 前瞻性招募2020年10月至2023年4月经手术病理证实为HCC并进...目的 探讨三维酰胺质子转移加权(three-dimensions amide proton transfer weighted,3D-APTw)成像在评估肝细胞癌(hepatocellular carcinoma,HCC)病理分级中的价值。材料与方法 前瞻性招募2020年10月至2023年4月经手术病理证实为HCC并进行Edmondson-Steiner四级(Ⅰ~Ⅳ)分级的患者共43例。将Ⅰ级和Ⅱ级HCC定为低级别HCC,Ⅲ级和Ⅳ级病变定为高级别HCC。采用飞利浦3.0 T MRI设备在术前对患者进行扫描,分别采集T1WI、T2WI、弥散加权成像、酰胺质子转移加权(amide proton transfer weighted,APTw)及多期增强图像。由两位经验丰富的放射科医生独立测量HCC及正常肝实质的APTw值。采用Mann-Whitney U非参数检验分析组间差异。采用受试者工作特征(receiver operating characteristic,ROC)曲线分析APTw值的诊断效能,计算曲线下面积(area under the curve,AUC)、阈值及其敏感度和特异度。采用Spearman相关分析,评估APTw与HCC的组织学分级之间的相关性。结果 低级别HCC的APTw值(2.15%±0.13%)低于高级别HCC(2.63%±0.13%),差异具有统计学意义(P=0.03)。APTw值鉴别高级别及低级别HCC的AUC为0.69(95%CI:0.53~0.82),最佳阈值为1.85%时,敏感度和特异度分别为90.00%和42.31%。Spearman相关性分析结果显示APTw值与HCC病理分级呈正相关,相关系数r=0.43(P=0.003)。结论 APTw值可用于鉴别高级别及低级别HCC,3D-APTw成像在术前预测HCC病理分级中有一定的价值。展开更多
基金supported by National Key R&D Program of China(No.2023YFA1507500)the International Partnership Program of Chinese Academy of Sciences(No.028GJHZ2023045FN)。
文摘The amide moiety plays an important role as a powerful bioactive backbone,and as the synthetic chemistry community moves toward more sp^(3)-rich scaffolds,alkyl halides have become the feedstock of choice for obtaining carbonylation products.With the development of photoredox catalysis,several aminocarbonylation systems for alkyl halides were developed which usually require transition metal catalysis.Considering the demands for green sustainable chemical synthesis,here we report a metal-free,exogenous catalyst-free aminocarbonylation reaction of alkyl iodides under atmospheric pressure of carbon monoxide.Through a combination of EDA and XAT strategies,the reaction occurs efficiently under only light irradiation at room temperature.
基金financial support from the National Natural Science Foundation of China(No.22208279)Financial support from the Fuzhou University(No.0041/511095)。
文摘A visible light-promoted fast photochemical Wolff rearrangement was developed toward synthesis ofα-substituted amides in continuous flow with the use of a photochemical oscillatory flow reactor(POFR).The control experiment indicates that a fast process of the Wolff rearrangement(<40 s)is involved.Notably,this protocol does not require excess use of any reactants,and the resultingα-substituted amides could be isolated by recrystallization in good to excellent yields.
文摘Chiral N-substituted amino amides and esters are ubiquitous scaffolds in pesticides and pharmaceutical chemicals,but their asymmetric synthesis remains challenging especially for those with multiple chiral centers.In this study,IR104 from Streptomyces aureocirculatus was identified from 157 wild-type imine reductases for the synthesis of(S)-2-((R)-2-oxo-4-propylpyrrolidin-1-yl)butanamide(antiepileptic drug Brivaracetam)via dynamic kinetic resolution reductive amination from ethyl 3-formylhexanoate and(S)-2-aminobutylamide with high diastereoselectivity.To further improve the catalytic efficiency of IR104,its mutant D191E/L195I/E253S/M258A(M3)was identified by saturation mutagenesis and iterative combinatorial mutagenesis,which exhibited a 102-fold increase in the catalytic efficiency relative to that of wild-type enzyme and high diastereoselectivity(98:2 d.r.).Crystal structural analysis and molecular dynamics simulations provided some insights into the molecular basis for the improved activity of the mutant enzyme.The imine reductase identified in this study could accept chiral amino amides/esters as amino donors for the dynamic kinetic resolution reductive amination of racemicα-substituted aldehydo-esters,expanding the substrate scope of imine reductases in the dynamic kinetic resolution-reductive amination.Finally,IR104-M3 was successfully used for the preparation of Brivaracetam at gram scale.Using this mutant,various N-substituted amino amides/esters with two chiral centers were also synthesized with up to 99:1 d.r.and 96%yields and subsequently converted intoγ-andδ-lactams,providing an efficient protocol for the synthesis of these important compounds via enzymatic dynamic kinetic resolution-reductive amination from simple building blocks.
基金Authors are thankful to Head of Department of Chemistry V.G.Vaze College,Mulund(E),Mumbai-81(MS),India and Head of Department of Organic Research Laboratory,S.C.S.College,Omerga-413 606(MS),India for providing the necessary laboratory facilities
文摘The coupling reaction of phenylurea with different functionalized aryl halides in the presence of air stable CuI,N,N-dimethylethylenediamine as a ligand,and K_3PO_4 as a base gives symmetrical and unsymmetrical diarylureas in relatively high yields.This method is milder than the palladium catalyzed arylation and avoids the use of toxic phosphine ligands.
基金supported by grants from the National Natural Science Foundation of China(31772455)Natural Science Foundation of Jiangsu Province(BK20160336and BK20171214)+1 种基金Natural Science Foundation of College in Jiangsu Province(16KJB350004)Suzhou Science and Technology Development Project(SYN201504 and SNG2017045)
文摘Rana kunyuensis is a species of brown frog that lives exclusively on Kunyu Mountain,Yantai,China.In the current study,a 279-bp cDNA sequence encoding a novel antimicrobial peptide (AMP),designated as amurin-9KY,was cloned from synthesized double-strand skin cDNA of R.kunyuensis.The amurin-9KY precursor was composed of 62 amino acid (aa) residues,whereas the mature peptide was composed of 14 aa and contained two cysteines forming a C-terminal heptapeptide ring (Rana box domain) and an amidated C-terminus.These structural characters represent a novel amphibian AMP family.Although amurin-9KY exhibited high similarity to the already identified amurin-9AM from R.amurensis,little is known about the structures and activities of amurin-9 family AMPs so far.Therefore,amurin-9KY and its three derivatives (amurin-9KY1-3) were designed and synthesized.The structures and activities were examined to evaluate the influence of C-terminal amidation and the heptapeptide ring on the activities and structure of amurin-9KY..Results indicated that C-terminal amidation was essential for antimicrobial activity,whereas both C-terminal amidation and the heptapeptide ring played roles in the low hemolytic activity.Circular dichroism (CD) spectra showed that the four peptides adopted an α-helical conformation in THF/H2O (v/v 1∶1) solution,but a random coil in aqueous solution.Elimination of the C-terminal heptapeptide ring generated two free cysteine residues with unpaired thiol groups,which greatly increased the concentration-dependent anti-oxidant activity.Scanning electron microscopy (SEM) was also performed to determine the possible bactericidal mechanisms.
基金This project was supported by China Postdoctoral Science Foundation and Tsinghua-Zhongda Postdoctoral Science Foundation.
文摘A potentially versatile procedure for surface modification of nanometer silica is illustrated by N, N-dicyclohexylcarbodiimide (DCC) mediated amidation of stearic acid.
基金DST-SERB for the financial support for this research work(Project number:SERB/F/3690/2013-14)
文摘Cu2O and Cul were supported on multiwalled carbon nanotubes （MWCNTs） using a wet impregna- tion method, and the resulting materials were fully characterized by powder X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy with energy dispersive X-ray spectroscopy, transmission electron microscopy, and temperature-programmed desorption with ammonia analysis. The results of these experiments revealed that Cu2O and CuI were deposited on the MWCNTs in the cubic and γ phases, respectively. These results also showed that the Cu-containing MWCNTs exhibited weak to strong electron-accepting （Lewis acidic） properties. The catalytic activities of these materials were studied for the synthesis of biologically significant N-（pyridin-2-yl）benzamides via the oxidative amidation of aryl aldehydes with 2-aminopyridines. The yields of the products were in the range 50%-95% with 100% selectivity. Notably, the CuI/MWCNT catalyst was much more effective than the Cu2O/MWCNT catalyst with respect to the isolated yield of the product, although the latter of these two catalysts exhibited much better recyclability. A preferential interaction was observed between the polar nature of the acid-activated MWCNTs and the ionic Cu2O compared with covalent CuL The differences in these interactions had a significant impact on the rate of the nucleophilic attack of the amino group of 2-aminopyridine substrate on the carbonyl group of the aryl aldehyde.
文摘Amphipathic-type thioesters CH3(CH2)mCOS(CH2)nCOONa (m + n = 12) were synthesized and their reaction with various alkylamines was examined. Compounds having thioester moiety close to carboxylate (m = 10, n = 2) afforded the corresponding amides in good yields, while the substrate having thioester moiety distant from carboxylate (m = 2, n = 10) afforded the amides in relatively low yield. In all cases, the difference in yield due to the chain length of amine was not observed. The results indicated that the reaction took place effectively near the surface of micelle. However, the reaction was found to occur not only on micelle surface but also in solution.
基金the Ministry of Science and Technology of China(No.2016YFE0132600)Henan Center for Outstanding Overseas Scientists(No.GZS2020001)。
文摘Cp^*Co(Ⅲ)-catalyzed direct C—H amidation of azines has been developed.This co nversion could proceed smoothly in the absence of external oxidants,acids or bases,with excellent regioselectivity and broad functional group tolerance,CO2 was released as the sole byproduct,thus providing an environmentally benign amidation process.The products obtained are important intermediates in organic synthesis.
基金the financial support from the National Natural Science Foundation of China(NSFC,Nos.22171042,21831002,and 22193012)the Jilin Province Natural Science Foundation(No.20160520140JH)+1 种基金the Fundamental Research Funds for the Central Universitiesthe Ten Thousand Talents Program for generous financial support。
文摘Catalytic Michael addition reaction represents a fundamental importance in organic synthetic chemistry.Whereas corresponding conversions toward intrinsically low reactive enamide remains an ongoing challenging.We herein report a copper-catalyzed conjugate addition of allenes toβ-substituted alkenyl amides,one of the most challenging Michael acceptors.The present method utilizes readily available allenes as the latent carbon-based nucleophiles and simple,commonβ-substituted alkenyl amides as starting materials,unlike previous methods that usually preinstall an activating group to improve the reactivity of amide or uses highly reactive stoichiometric quantities of organometallics.Hence,this approach shows good functional group compatibility and can be implemented under mild reaction conditions with excellent level of chemo-and regioselectivities.
基金the National Natural Science Foundation of China(Nos.22174059 and 22201128)Hunan Provincial Natural Science Foundation of China(Nos.2022JJ40363 and 2022JJ40365)+1 种基金the Young Science and Technology Innovation Program of Hunan Province(No.2022RC1230)China Postdoctoral Science Foundation(No.2022M721542)for financial support。
文摘Selective molecular recognition in water is routine for bioreceptors,but remains challenging for synthetic hosts.This is principally because noncovalent interactions are usually less efficient in aqueous environments.By mimicking the cavity feature of bioreceptors,Prof.Wei Jiang proposed and clarified the concept of“endo-functionalized cavity”.Through situating polar binding sites into a deep hydrophobic cavity,we designed and synthesized several macrocyclic hosts,among which amide naphthotubes are the most representative.The hosts can selectively recognize various polar molecules including organic micropollutants,drug molecules,and chiral molecules in water by employing the hydrophobic effect and shielded hydrogen bonding.In addition,these biomimetic hosts have been applied in spectroscopic analysis,adsorptive separation and self-assembly.In this review,we provide an overview of recent advances on amide naphthotubes with special emphasis on the efforts of Jiang's group.We are convinced that these biomimetic macrocycles will make further contributions to supramolecular chemistry and beyond.
基金support of the National Natural Science Foundation of China(Nos.52173150,52073313)the Guangzhou Science and Technology Program City-University Joint Funding Project(No.2023A03J0001)the Shenzhen Science and Technology Program(No.KCXFZ 202002011010232)。
文摘Colorectal cancer is a common cancer worldwide.Traditional chemotherapeutic drugs often face limitations such as poor aqueous solubility and high systemic toxicity,which can lead to adverse side effects and limited therapeutic efficacy.In this study,a library of one kind of biodegradable and biocompatible polymer,leucine based-poly(ester amide)s(Leu-PEAs)was developed and utilized as drug carrier.The structure of Leu-PEAs can be tuned to alter their physicochemical properties,enhancing drug loading capacity and delivery efficiency.Leu-PEAs can self-assemble into nanoparticles by nanoprecipitation and load paclitaxel(PTX)with the diameter of~108 nm and PTX loading capacity of~8.5%.PTX-loaded Leu-PEAs nanoparticles(PTX@Leu-PEAs)demonstrated significant inhibition of CT26 cell growth in vitro.In vivo,these nanoparticles exhibited prolonged tumor accumulation and antitumor effects,with no observed toxicity to normal organs.Furthermore,blank Leu-PEAs nanoparticles also showed antitumor effects in vitro and in vivo,which may be attributed to the activation of the mammalian target of rapamycin(m TOR)pathway by leucine.Consequently,this biocompatible Leu-PEAs nano-drug delivery system shows potential as a promising strategy for colorectal cancer treatment,warranting further investigation.
基金support from the University Nursing Program for Young Scholars with Creative Talents in Heilongjiang Province(No.UNPYSCT-2017124).
文摘An atom economicβ-C(sp^(3))−H chlorination of amide derivatives has been developed.This mild protocol employs CuCl_(2) instead of palladium catalysts with atom-economic HCl as chlorine sources and enables the late-stage functionalization of medicine derivatives.Mechanism studies suggest a plausible visible light triggered ligand-to-metal charge transfer(LMCT)/1,4-hydrogen atom transfer(HAT)cascade.
文摘The pursuit of incorporating eco-friendly reinforcing agents in polymer composites has accentuated the exploration of various natural biomass-derived materials.The burgeoning environmental crisis spurred by the discharge of synthetic dyes into wastewater has catalyzed the search for effective and sustainable treatment technologies.Among the various sorbent materials explored,biochar,being renewable,has gained prominence due to its excellent adsorption properties and environmental sustainability.It has also emerged as a focal point for its potential to replace other conventional reinforcing agents,viz.,fumed silica,aluminum oxide,treated clays,etc.This study introduces a novel class of polymer nanocomposites comprising of lignin-based biochar particles and poly(ester amide urethane)matrix via a feasible method.The structural evaluation of these nanocomposites was accomplished using Fourier-transform infrared spectroscopy,X-ray photoelectron spectroscopy,and powder X-ray diffraction.The polymer nanocomposites exhibited superior mechanical properties with an increment in tensile strength factor by 45%in comparison to its pristine matrix,along with an excellent toughness value of 90.22 MJm^(−3)at a low loading amount of only 1 wt%.The composites showed excellent improvement in thermal properties with a sharp rise in the glass transition temperature(Tg)value from−28.15℃to 84℃,while also championing sustainability through inherent biodegradability attributes.Beyond their structural prowess,these polymer nanocomposites demonstrated excellent potential as adsorbents,displaying efficient removal of malachite green and tartrazine dyes from aqueous systems with a removal efficiency of 87.25%and 73.98%,respectively.The kinetics study revealed the pseudo second order model to be the precision tool to assess the dye removal study.Complementing this,the Langmuir adsorption isotherm provided a framework to assess the sorption features of the polymer nanocomposites.Overall,these renewable biochar integrated polymer matrices boast remarkable recovery capabilities up to seven cycles of usage with an excellent dye recovery percentage of 95.21%for the last cycle,thereby defining sustainability as well as economic feasibility.
文摘目的 探讨三维酰胺质子转移加权(three-dimensions amide proton transfer weighted,3D-APTw)成像在评估肝细胞癌(hepatocellular carcinoma,HCC)病理分级中的价值。材料与方法 前瞻性招募2020年10月至2023年4月经手术病理证实为HCC并进行Edmondson-Steiner四级(Ⅰ~Ⅳ)分级的患者共43例。将Ⅰ级和Ⅱ级HCC定为低级别HCC,Ⅲ级和Ⅳ级病变定为高级别HCC。采用飞利浦3.0 T MRI设备在术前对患者进行扫描,分别采集T1WI、T2WI、弥散加权成像、酰胺质子转移加权(amide proton transfer weighted,APTw)及多期增强图像。由两位经验丰富的放射科医生独立测量HCC及正常肝实质的APTw值。采用Mann-Whitney U非参数检验分析组间差异。采用受试者工作特征(receiver operating characteristic,ROC)曲线分析APTw值的诊断效能,计算曲线下面积(area under the curve,AUC)、阈值及其敏感度和特异度。采用Spearman相关分析,评估APTw与HCC的组织学分级之间的相关性。结果 低级别HCC的APTw值(2.15%±0.13%)低于高级别HCC(2.63%±0.13%),差异具有统计学意义(P=0.03)。APTw值鉴别高级别及低级别HCC的AUC为0.69(95%CI:0.53~0.82),最佳阈值为1.85%时,敏感度和特异度分别为90.00%和42.31%。Spearman相关性分析结果显示APTw值与HCC病理分级呈正相关,相关系数r=0.43(P=0.003)。结论 APTw值可用于鉴别高级别及低级别HCC,3D-APTw成像在术前预测HCC病理分级中有一定的价值。
