The textural features and acidic properties of sulfated mesoporous lanthana‐zirconia solid acids （SO42？/meso‐La0.1Zr0.9Oδ） were efficiently tuned by modifying the conditions used to prepare the meso‐La0.1Zr0.9O...The textural features and acidic properties of sulfated mesoporous lanthana‐zirconia solid acids （SO42？/meso‐La0.1Zr0.9Oδ） were efficiently tuned by modifying the conditions used to prepare the meso‐La0.1Zr0.9Oδcomposites, such as the molar ratio of the template to La and Zr metal ions （Nt/m）, molar ratio of ammonia to La and Zr metal ions （Na/m）, hydrothermal temperature （Thydro）, and hy‐drothermal time （thydro）. The effect of the textural features and acidic properties on the catalytic performance of solid acid catalysts for alkenylation of p‐xylene with phenylacetylene was investi‐gated. Various characterization techniques such as N2 physisorption, X‐ray diffraction, NH3 temper‐ature‐programmed desorption, and thermogravimetric analysis were employed to reveal the rela‐tionship between the nature of catalyst and its catalytic performance. It was found that the catalytic performance significantly depended on the textural features and acidic properties, which were strongly affected by preparation conditions of the meso‐La0.1Zr0.9Oδcomposite. Appropriate acidic sites and high accessibility were required to obtain satisfactory catalytic reactions for this reaction. It was also found that the average crystallite size of t‐ZrO2 affected by the preparation conditions had significant influence on the ultrastrong acidic sites of the catalysts. The optimized SO42？/meso‐La0.1Zr0.9Oδcatalyst exhibited much superior catalytic activity and coke‐resistant stabil‐ity. Moreover, the developed SO42？/meso‐La0.1Zr0.9Oδcatalyst demonstrated excellent catalytic per‐formance for alkenylation of diverse aromatics with phenylacetylene to their correspondingα‐arylstyrenes. Combining the previously established complete regeneration of used catalysts by a facile calcination process with the improved catalytic properties, the developed SO42？/meso‐La0.1Zr0.9Oδ solid acid could be a potential catalyst for industrial production ofα‐arylstyrenes through clean and atom efficient solid‐acid‐mediated Friedel‐Crafts alkenylation of diverse aromatics with phenylacetylene.展开更多
A ceria‐modified hierarchical Hβzeolite was prepared by a desilication‐dealumination procedure followed by ceria modification.The catalytic performance of the ceria‐modified and unmodified hierarchical Hβzeolite ...A ceria‐modified hierarchical Hβzeolite was prepared by a desilication‐dealumination procedure followed by ceria modification.The catalytic performance of the ceria‐modified and unmodified hierarchical Hβzeolite catalysts for alkenylation of p‐xylene with phenylacetylene was investigated.Various characterization techniques,including X‐ray diffraction,X‐ray fluorescence,nitrogen adsorption‐desorption,and NH3temperature‐programmed desorption,were used to examine the structure‐performance relationships.Our results show that the optimized ceria‐modified hierarchical Hβzeolite catalyst demonstrated higher catalytic activity,selectivity,and stability for alkenylation of p‐xylene with phenylacetylene than those of pristine Hβzeolite.This performance was attributed to more acidic sites and improved accessibility to active sites through larger pores,together with a higher mesoporous surface area and volume resulting from the hierarchical pore architecture and ceria modification.Thus,our5wt%CeO2‐Hβ‐B0.2A0.2catalyst shows great potential for producing alkenyl aromatics through solid acid catalyzed alkenylation.?2018,Dalian Institute of Chemical Physics,Chinese Academy of Sciences.Published by Elsevier B.V.All rights reserved展开更多
Alkenyl succinic anhydride(ASA) is a popular paper-sizing agent that is generally added to papermaking systems as an aqueous emulsion. Herein, we reviewed the recent work focusing on ASA emulsions stabilized by solid ...Alkenyl succinic anhydride(ASA) is a popular paper-sizing agent that is generally added to papermaking systems as an aqueous emulsion. Herein, we reviewed the recent work focusing on ASA emulsions stabilized by solid particles. Solid particle-stabilized ASA emulsions generally possess high ASA content and exhibit good sizing performance. The particles that have been used to stabilize ASA emulsions typically include montmorillonite, laponite, alumina, TiO_2, Fe_3O_4, polyaluminum sulfate(PAS), and cellulose nanocrystals(CNCs). Montmorillonite is the first extensively studied particle stabilizer for ASA emulsions. Laponite is undoubtedly the most competent particle stabilizer for preparing ASA emulsions with high sizing efficiency. Montmorillonite and laponite can be used individually as stabilizers after modification or as co-stabilizers with other particles or polymers. TiO_2, alumina, PAS, and CNCs are commonly used as stabilizers either individually or with other particles.展开更多
5-Alkenyl-2,2-butylidene-1,3-dioxane-4,6-diones were synthesized by the Knoevenagel condensation reaction of aromatic aldehydes with 2,2-butylidene-1,3-dioxane-4,6-dione using o-phthalimide-N-sulfonic acid as catalyst...5-Alkenyl-2,2-butylidene-1,3-dioxane-4,6-diones were synthesized by the Knoevenagel condensation reaction of aromatic aldehydes with 2,2-butylidene-1,3-dioxane-4,6-dione using o-phthalimide-N-sulfonic acid as catalyst, without solvent under ultrasonic irradiation. The present method has some notable advantages such as mild reaction conditions, short reaction times, less catalyst dosage and high yields with the green aspects by avoiding toxic catalysts and solvents. Further, the catalyst can be reused for five times without any noticeable decrease in the catalytic activity.展开更多
Z)-a-Selanyl alkenyl Grignard reagents 2 were prepared conveniently by treatment of a-bromovinylselenides 1 with magnesium filings in THF. Intermediates 2 were reacted with alkyl iodides in the presence of CuI or Pd(...Z)-a-Selanyl alkenyl Grignard reagents 2 were prepared conveniently by treatment of a-bromovinylselenides 1 with magnesium filings in THF. Intermediates 2 were reacted with alkyl iodides in the presence of CuI or Pd(PPh3)4 to afford (Z)-1,2-disubstituted vinylselenides 3, which were cross-coupled with Grignard reagents in the presence of (PPh3)2NiCl2 to give trisubstituted alkenes 4 stereoselectively in good yields.展开更多
<i><span style="font-family:Verdana;">Lithraea</span></i><span style="font-family:;" "=""> <i><span style="font-family:Verdana;">m...<i><span style="font-family:Verdana;">Lithraea</span></i><span style="font-family:;" "=""> <i><span style="font-family:Verdana;">molleoides</span></i><span style="font-family:Verdana;"> (Anacardiaceae) is a tree that grows in South America including Southern Brazil, Southern, and Eastern Bolivia, Southern Paraguay, Northern, and Central Argentina. Infusions, decoctions, or tinctures from its aerial parts (leaves, buds, and young stems) are employed in ethnomedicine mainly against respiratory, and digestive inflammations and illnesses. Antibacterial, antiviral, antioxidant, anti-inflammatory, and antinociceptive activities, among others, have been reported for </span><i><span style="font-family:Verdana;">L.</span></i> <i><span style="font-family:Verdana;">molleoides</span></i><span style="font-family:Verdana;">. Many of its biological activities have been associated with the reported presence of 5-alkenyl resorcinols. Alkyl/alkenyl catechols and alkyl/alkenyl resorcinols are very common in members of the Anacardiaceae family and several activities have been attributed to them. This work describes the isolation and the structural elucidation of three new 5-alkenyl resorcinols isolated from </span><i><span style="font-family:Verdana;">Lithraea</span></i> <i><span style="font-family:Verdana;">molleoides</span></i><span style="font-family:Verdana;"> reported in nature for the first time.</span></span>展开更多
Two novel Acetophenones, 4-(1'-geranyloxy)-2,6-dihydroxyacetophenone 1 and 4-(1'-farnesyl)-2,6-dihydroxyacetophenone 2 isolated from the fruit of Evodia merrillii and from the aerial parts of Borronia ramosa r...Two novel Acetophenones, 4-(1'-geranyloxy)-2,6-dihydroxyacetophenone 1 and 4-(1'-farnesyl)-2,6-dihydroxyacetophenone 2 isolated from the fruit of Evodia merrillii and from the aerial parts of Borronia ramosa respectively, have been synthesized by starting from 2,4,6-trihydroxyacetophenone 3.展开更多
The conversion of commercially available chiral sulfinamides into pharmaceutically useful chiral sulfoximines via direct SIVfunctionalization is synthetically attractive but challenging due to the competitive reaction...The conversion of commercially available chiral sulfinamides into pharmaceutically useful chiral sulfoximines via direct SIVfunctionalization is synthetically attractive but challenging due to the competitive reaction of N-functionalization. Herein, we disclose a novel strain-release strategy to access stereospecific and chemoselective SIV-arylation and alkenylation of sulfinamides using arynes and strained cyclic alkynes. This method tolerates an unprecedented chemical diversity of functional groups attached to the nitrogen center(N-R). The origin of the high SIV-selectivity is elucidated by density functional theory calculations, suggesting a stepwise mechanism for the aryne substrates and a concerted mechanism for the cyclic alkynes.展开更多
By rational modification of electronic and steric properties of pincer ligands,a Co/Fe dual catalyst system is developed for one-pot sequential Markovnikov alkyne hydrosilylation and stereoselective alkene isomerizati...By rational modification of electronic and steric properties of pincer ligands,a Co/Fe dual catalyst system is developed for one-pot sequential Markovnikov alkyne hydrosilylation and stereoselective alkene isomerization.The protocol provides an atom-economical and efficient approach to trisubstituted(E)-alkenyl silanes from widely accessible terminal alkynes with high regio-and stereoselectivities under mild conditions.The utility of this reaction was demonstrated by gram-scale synthesis and derivatization of bioactive molecules.The radical clock and trapping experiments indicated that radical pathway might be operative in the alkene isomerization step.展开更多
Chemoselective,living/controlled polymerizations of allyl methacrylate(AMA) and vinyl methacrylate(VMA) with/without methyl methacrylate(MMA) by using the phosphonium ylide/organoaluminum based Lewis pairs(LPs) have b...Chemoselective,living/controlled polymerizations of allyl methacrylate(AMA) and vinyl methacrylate(VMA) with/without methyl methacrylate(MMA) by using the phosphonium ylide/organoaluminum based Lewis pairs(LPs) have been realized.The P-ylide-2/AIMe(BHT)_(2)(Pylide-2=Ph_(3)P=CHMe and BHT=2,6-iBu_(2)-4-MeC_(6)H_(2)O) was demonstrated to be superior by which homopolymers PAMAs(M_(n)=27.6-111.5kg/mol and ■=1.14-1.25) and PVMAs(M_(n)=28.4-78.4 kg/mol and ■=1.12-1.18) and block copolymers PMMA-b-PAMA,PAMA-b-PVMA,PAMA-bPMMA,PMMA-b-PAMA-b-PMMA,PAMA-b-PMMA-b-PAMA,and PAMA-b-PVMA-b-PAMA were synthesized.In the polymerizations,all of the monomers were reacted by the conjugated ester vinyl groups leaving intactly the nonconjugated acryloxy groups.The pendant acryloxy groups attached to the main chain enable further to post-functionalization by the AIBN-induced radical "thiol-ene" reaction using PhCH_(2)SH.The thiolether side group-containing polymers PAMA-SCH_(2)Ph and PAMA-SCH_(2)Ph-b-PMMA-b-PAMA-SCH_(2)Ph were thus prepared.展开更多
Herein,we report an asymmetric two-component alkenyl Catellani reaction for the construction of C—N axial chirality through a palladium/chiral norbornene cooperative catalysis and an axial-to-axial chirality transfer...Herein,we report an asymmetric two-component alkenyl Catellani reaction for the construction of C—N axial chirality through a palladium/chiral norbornene cooperative catalysis and an axial-to-axial chirality transfer process.Various partially aromatic iodinated 2-pyridones,quinolones,coumarin and uracil substrates react with 2,6-disubstituted aryl bromides with a tethered amide group,to afford a wide variety of polycyclic C—N atropisomers(38 examples,up to 97%e.e.).The obtained C—N axial chirality originates from the preformed transient C—C axial chirality with high fidelity.The synthetic utility of this chemistry is demonstrated by facile prepa-ration of complex quinoline and pyridine based C—N atropisomers through a N-deprotection and aromatization sequence.In addi-tion,a remote axial-to-central diastereoinduction process dictated by C—N axial chirality is observed with excellent diastereocontrol.展开更多
Heterocycle-braced cyclic peptides have demonstrated enhanced metabolic stability,increased potency and selectivity.Here,we present a rapid synthesis method for constructing Trp(C7)-alkene(E)-crosslinked cyclic peptid...Heterocycle-braced cyclic peptides have demonstrated enhanced metabolic stability,increased potency and selectivity.Here,we present a rapid synthesis method for constructing Trp(C7)-alkene(E)-crosslinked cyclic peptides with potent anti-proliferative activities against cancer cells,through C-H alkenylation and macrolactamization.This report addresses critical challenges associated with the installation and removal of the directing group N-Piv,configuration selectivity of the olefin,and intramolecular cyclization.No-tably,this method exhibits mild reaction conditions,traceless removal of the directing group,and high configuration selectivity.展开更多
Catalytic enantioselective alkenylation is an efficient method to construct chiral alkene molecules,but the asymmetric alkenylation of simple alkenes catalyzed by metal-free catalysts remains an elusive challenge.Here...Catalytic enantioselective alkenylation is an efficient method to construct chiral alkene molecules,but the asymmetric alkenylation of simple alkenes catalyzed by metal-free catalysts remains an elusive challenge.Herein,we reported an asymmetric alkenylation of benzoxazinones with diarylethylenes by utilizing a B(C_(6)F_(5))_(3)/chiral phosphoric acid catalyst.A broad of benzoxazinones and diarylethylenes with electron-withdrawing and electron-donating groups were tolerated(up to 95%yield and 97.5:2.5 e.r.)in the methodology under mild reaction conditions.Moreover,the synthetic utility was confirmed by the scaled-up reaction and transformations of the products.The mechanism was preliminarily explored by control reactions,nonlinear effect experiment and DFT calculations.展开更多
Catalyst innovation lies at the heart of transition-metal-catalyzed reaction development. In this article, we have explored the C(sp2)–H alkenylation activity with novel spirocyclic N-heterocyclic carbene(NHC)-based ...Catalyst innovation lies at the heart of transition-metal-catalyzed reaction development. In this article, we have explored the C(sp2)–H alkenylation activity with novel spirocyclic N-heterocyclic carbene(NHC)-based cyclometalated ruthenium pincer catalyst system, SNRu-X. After screening catalyst and condition, a high valent Ru(Ⅳ) dioxide(X = O_(2)) species has demonstrated superior reactivity in the catalytic alkenylation of aromatic and olefinic C–H bonds with unactivated alkenyl bromides and triflates. This reaction has achieved the easy construction of a wide range of(hetero)aromatic alkenes and dienes, in good to excellent yields with exclusive selectivity. Preliminary mechanistic studies indicate that this reaction may proceed through a single electron transfer(SET) triggered oxidative addition, by doing so, providing valuable complementary to classical alkenylation reactions that are dependent on activated alkenyl precursors.展开更多
Main observation and conclusion A new Rh(Ⅲ)-catalyzed direct C—H alkenylation of 2,3-unsubstitued indoles with alkenyl borates through C—H activation followed by transmetallation was described.This protocol provide...Main observation and conclusion A new Rh(Ⅲ)-catalyzed direct C—H alkenylation of 2,3-unsubstitued indoles with alkenyl borates through C—H activation followed by transmetallation was described.This protocol provides an efficient method for the synthesis of terminal C2-alkenylindoles under mild conditions,and also shows broad substrate scope and high functional group tolerance with respect to both components.Furthermore,the C2-alkenylated indole can be easily transformed into carboline derivative,which is an important polycyclic indole moiety in natural products and drug molecules.展开更多
In this work, a spherical hollow mesoporous silica(SHMS) with high surface area(902 m^2/g) and large mesopore volume(1.31 cm^3/g) was prepared via a facile and scalable two-step soft-hard dual templateassisted sol-gel...In this work, a spherical hollow mesoporous silica(SHMS) with high surface area(902 m^2/g) and large mesopore volume(1.31 cm^3/g) was prepared via a facile and scalable two-step soft-hard dual templateassisted sol-gel approach(OSDSG) by using glucose-derived carbon nano/micro particles(NMCP) as a hard template and cetyltrimethylammonium bromide(CTAB) as a soft template,respectively,in which the size-preselected carbon submicro-particle was used to replace ploymer sphere, and no extra precious additives like n-octadecyltrimethoxysilane(C18TMS). Supported phosphotungstic acid(PTA) catalysts on SHMS(PTA/SHMS) and on previously reported spherical mesoporous silica(PTA/SMS) with 25 wt% of PTA loading were prepared and employed as solid acid catalysts for diverse reactions. Transmission electron microscopy(TEM),N_2 adsorption-desorption, X-ray diffraction(XRD), and NH_3 temperatureprogrammed desorption(NH_3-TPD) techniques were employed to characterize the nature of carriers and supported PTA catalysts for revealing the structure-performance relationship. The developed PTA/SHMS catalyst demonstrates much higher catalytic activity than PTA/SMS for diverse reactions including alkenylation, esterification, alkylation, and benzylation, ascribed to the strengthened mass transfer and enlarged exposure degree of acidic sites to reactants those resulting from unique hollow and mesoporous morphology. Moreover, PTA/SHMS catalyst also exhibits outstanding catalytic performance for the diverse a-arylstyrenes via solid acid-mediated alkenylation. PTA/SHMS could be considered as a practical solid acid catalyst for diverse transformations.展开更多
A high-efficient and stereo-specific approach for the preparation of biologically important （E）-2-styryl-tetra- hydrobenzo[d]thiazoles has been developed via TMSC1 promoted direct sp3 C-H alkenylation of 2-methyl-5,...A high-efficient and stereo-specific approach for the preparation of biologically important （E）-2-styryl-tetra- hydrobenzo[d]thiazoles has been developed via TMSC1 promoted direct sp3 C-H alkenylation of 2-methyl-5,6-di- hydrobenzo[d]thiazol-7（4H）-one under metal-free conditions. Seventeen target compounds were synthesized in ex- cellent yields of 82%--98% under the optimal conditions of 300 mol% TMSCI at 110℃ for 2 h, and their chemical structures were elucidated by IR, NMR, ESI-MS, elemental analyses and X-ray crystallography analysis. A plausible mechanism was also proposed, and this method provided a good functional group conversion for the sp3 C-H substrates.展开更多
Highly dispersed silicotungstic acid-derived WO_(3) composited with ZrO_(2) supported on SBA-_(15) (WZ/SBA-_(15)) as an ordered mesoporous solid acid catalyst was prepared via a facile incipient wetness impregnation (...Highly dispersed silicotungstic acid-derived WO_(3) composited with ZrO_(2) supported on SBA-_(15) (WZ/SBA-_(15)) as an ordered mesoporous solid acid catalyst was prepared via a facile incipient wetness impregnation (IWI) method that active ingredients, ZrO_(2) and WO_(3), were impregnated into the channels of SBA-_(15) simultaneously with a subsequent calcination process. The relationship between catalyst nature and performance was explored by high resolution transmission electron microscopy (HRTEM), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), FT-IR, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), N_(2) adsorption-desorption, NH_(3) temperature-programmed desorption (NH_(3)-TPD), and FT-IR of pyridine adsorption (Py-IR) characterization techniques. The catalytic performance of W_(12)Z_(15)/SBA-_(15) is not only greater than that of single component solid acid catalysts, WO_(3)/SBA-_(15) and ZrO_(2)/SBA-_(15), but also W_(12)/Z_(15)/SBA-_(15) prepared by impregnating active ingredients, ZrO_(2) and WO_(3), into SBA-_(15) in sequence. The outstanding performance of W_(12)Z_(15)/SBA-_(15) is derived from the strong interaction between ZrO_(2) and WO_(3), which results in more acid sites, and relatively high specific surface area, large pore volume, and ordered mesoporous structure of SBA-_(15). The characterization and reaction results clearly demonstrate that the synergy of ZrO_(2) and WO_(3) has a clear boost for the alkenylation. The optimized W_(12)Z_(15)/SBA-_(15)-500 achieves a 99.4% conversion of phenylacetylene and a 92.3% selectivity of main product α-arylstyrene for the alkenylation of p-xylene with phenylacetylene, with very low level of oligomers producing at the same time. Moreover, W_(12)Z_(15)/SBA-_(15)-500 shows excellent catalytic stability and regeneration. Therefore, W_(12)Z_(15)/SBA-_(15)-500 is a promising solid acid catalyst for the alkenylation.展开更多
Main observation and conclusion An efficient Lewis acid enabled ketones phosphonylation to synthesize vinylphosphonates has been developed.This method relays on ketone hydrophosphonylation/α-hydroxy phosphonates unim...Main observation and conclusion An efficient Lewis acid enabled ketones phosphonylation to synthesize vinylphosphonates has been developed.This method relays on ketone hydrophosphonylation/α-hydroxy phosphonates unimolecular elimination(E1)dehydration cascade reaction sequence.展开更多
基金financially supported by the National Natural Science Foundation of China (21276041)the Program for New Century Excellent Talents in University of Ministry of Education (NCET-12-0079)+1 种基金the Natural Science Foundation of Liaoning Province (2015020200)the Fundamental Research Funds for the Central Universities (DUT15LK41)~~
文摘The textural features and acidic properties of sulfated mesoporous lanthana‐zirconia solid acids （SO42？/meso‐La0.1Zr0.9Oδ） were efficiently tuned by modifying the conditions used to prepare the meso‐La0.1Zr0.9Oδcomposites, such as the molar ratio of the template to La and Zr metal ions （Nt/m）, molar ratio of ammonia to La and Zr metal ions （Na/m）, hydrothermal temperature （Thydro）, and hy‐drothermal time （thydro）. The effect of the textural features and acidic properties on the catalytic performance of solid acid catalysts for alkenylation of p‐xylene with phenylacetylene was investi‐gated. Various characterization techniques such as N2 physisorption, X‐ray diffraction, NH3 temper‐ature‐programmed desorption, and thermogravimetric analysis were employed to reveal the rela‐tionship between the nature of catalyst and its catalytic performance. It was found that the catalytic performance significantly depended on the textural features and acidic properties, which were strongly affected by preparation conditions of the meso‐La0.1Zr0.9Oδcomposite. Appropriate acidic sites and high accessibility were required to obtain satisfactory catalytic reactions for this reaction. It was also found that the average crystallite size of t‐ZrO2 affected by the preparation conditions had significant influence on the ultrastrong acidic sites of the catalysts. The optimized SO42？/meso‐La0.1Zr0.9Oδcatalyst exhibited much superior catalytic activity and coke‐resistant stabil‐ity. Moreover, the developed SO42？/meso‐La0.1Zr0.9Oδcatalyst demonstrated excellent catalytic per‐formance for alkenylation of diverse aromatics with phenylacetylene to their correspondingα‐arylstyrenes. Combining the previously established complete regeneration of used catalysts by a facile calcination process with the improved catalytic properties, the developed SO42？/meso‐La0.1Zr0.9Oδ solid acid could be a potential catalyst for industrial production ofα‐arylstyrenes through clean and atom efficient solid‐acid‐mediated Friedel‐Crafts alkenylation of diverse aromatics with phenylacetylene.
基金supported by the National Natural Science Foundation of China(21276041,U1610104)the Chinese Ministry of Education via the Program for New Century Excellent Talents in University(NCET-12-0079)~~
文摘A ceria‐modified hierarchical Hβzeolite was prepared by a desilication‐dealumination procedure followed by ceria modification.The catalytic performance of the ceria‐modified and unmodified hierarchical Hβzeolite catalysts for alkenylation of p‐xylene with phenylacetylene was investigated.Various characterization techniques,including X‐ray diffraction,X‐ray fluorescence,nitrogen adsorption‐desorption,and NH3temperature‐programmed desorption,were used to examine the structure‐performance relationships.Our results show that the optimized ceria‐modified hierarchical Hβzeolite catalyst demonstrated higher catalytic activity,selectivity,and stability for alkenylation of p‐xylene with phenylacetylene than those of pristine Hβzeolite.This performance was attributed to more acidic sites and improved accessibility to active sites through larger pores,together with a higher mesoporous surface area and volume resulting from the hierarchical pore architecture and ceria modification.Thus,our5wt%CeO2‐Hβ‐B0.2A0.2catalyst shows great potential for producing alkenyl aromatics through solid acid catalyzed alkenylation.?2018,Dalian Institute of Chemical Physics,Chinese Academy of Sciences.Published by Elsevier B.V.All rights reserved
基金funded by the National Natural Science Foundation of China(Grant Nos.31270625 and 21406122)
文摘Alkenyl succinic anhydride(ASA) is a popular paper-sizing agent that is generally added to papermaking systems as an aqueous emulsion. Herein, we reviewed the recent work focusing on ASA emulsions stabilized by solid particles. Solid particle-stabilized ASA emulsions generally possess high ASA content and exhibit good sizing performance. The particles that have been used to stabilize ASA emulsions typically include montmorillonite, laponite, alumina, TiO_2, Fe_3O_4, polyaluminum sulfate(PAS), and cellulose nanocrystals(CNCs). Montmorillonite is the first extensively studied particle stabilizer for ASA emulsions. Laponite is undoubtedly the most competent particle stabilizer for preparing ASA emulsions with high sizing efficiency. Montmorillonite and laponite can be used individually as stabilizers after modification or as co-stabilizers with other particles or polymers. TiO_2, alumina, PAS, and CNCs are commonly used as stabilizers either individually or with other particles.
文摘5-Alkenyl-2,2-butylidene-1,3-dioxane-4,6-diones were synthesized by the Knoevenagel condensation reaction of aromatic aldehydes with 2,2-butylidene-1,3-dioxane-4,6-dione using o-phthalimide-N-sulfonic acid as catalyst, without solvent under ultrasonic irradiation. The present method has some notable advantages such as mild reaction conditions, short reaction times, less catalyst dosage and high yields with the green aspects by avoiding toxic catalysts and solvents. Further, the catalyst can be reused for five times without any noticeable decrease in the catalytic activity.
文摘Z)-a-Selanyl alkenyl Grignard reagents 2 were prepared conveniently by treatment of a-bromovinylselenides 1 with magnesium filings in THF. Intermediates 2 were reacted with alkyl iodides in the presence of CuI or Pd(PPh3)4 to afford (Z)-1,2-disubstituted vinylselenides 3, which were cross-coupled with Grignard reagents in the presence of (PPh3)2NiCl2 to give trisubstituted alkenes 4 stereoselectively in good yields.
文摘<i><span style="font-family:Verdana;">Lithraea</span></i><span style="font-family:;" "=""> <i><span style="font-family:Verdana;">molleoides</span></i><span style="font-family:Verdana;"> (Anacardiaceae) is a tree that grows in South America including Southern Brazil, Southern, and Eastern Bolivia, Southern Paraguay, Northern, and Central Argentina. Infusions, decoctions, or tinctures from its aerial parts (leaves, buds, and young stems) are employed in ethnomedicine mainly against respiratory, and digestive inflammations and illnesses. Antibacterial, antiviral, antioxidant, anti-inflammatory, and antinociceptive activities, among others, have been reported for </span><i><span style="font-family:Verdana;">L.</span></i> <i><span style="font-family:Verdana;">molleoides</span></i><span style="font-family:Verdana;">. Many of its biological activities have been associated with the reported presence of 5-alkenyl resorcinols. Alkyl/alkenyl catechols and alkyl/alkenyl resorcinols are very common in members of the Anacardiaceae family and several activities have been attributed to them. This work describes the isolation and the structural elucidation of three new 5-alkenyl resorcinols isolated from </span><i><span style="font-family:Verdana;">Lithraea</span></i> <i><span style="font-family:Verdana;">molleoides</span></i><span style="font-family:Verdana;"> reported in nature for the first time.</span></span>
文摘Two novel Acetophenones, 4-(1'-geranyloxy)-2,6-dihydroxyacetophenone 1 and 4-(1'-farnesyl)-2,6-dihydroxyacetophenone 2 isolated from the fruit of Evodia merrillii and from the aerial parts of Borronia ramosa respectively, have been synthesized by starting from 2,4,6-trihydroxyacetophenone 3.
基金supported by the National Natural Science Foundation of China(22001065)the Science and Technology Foundation of Hunan Province(2021JJ30090)+3 种基金Guangdong Provincial Key Laboratory of Catalysis(2020B121201002)Shenzhen Science and Technology Program(KQTD20210811090112004)supported by Center for Computational Science and Engineering at SUSTechthe CHEM high-performance supercomputer cluster(CHEM-HPC)located at the Department of Chemistry,SUSTech。
文摘The conversion of commercially available chiral sulfinamides into pharmaceutically useful chiral sulfoximines via direct SIVfunctionalization is synthetically attractive but challenging due to the competitive reaction of N-functionalization. Herein, we disclose a novel strain-release strategy to access stereospecific and chemoselective SIV-arylation and alkenylation of sulfinamides using arynes and strained cyclic alkynes. This method tolerates an unprecedented chemical diversity of functional groups attached to the nitrogen center(N-R). The origin of the high SIV-selectivity is elucidated by density functional theory calculations, suggesting a stepwise mechanism for the aryne substrates and a concerted mechanism for the cyclic alkynes.
基金the National Key R&D Program of China(2021YFA1500100)the National Natural Science Foundation of China(21825109,21821002,22072178,22293013)+3 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB0610000)CAS Project for Young Scientists in Basic Research(YSBR-094)Science and Technology Commission of Shanghai Municipality(23JC1404400)CAS Youth Interdisciplinary Team(JCTD-2021-11).
文摘By rational modification of electronic and steric properties of pincer ligands,a Co/Fe dual catalyst system is developed for one-pot sequential Markovnikov alkyne hydrosilylation and stereoselective alkene isomerization.The protocol provides an atom-economical and efficient approach to trisubstituted(E)-alkenyl silanes from widely accessible terminal alkynes with high regio-and stereoselectivities under mild conditions.The utility of this reaction was demonstrated by gram-scale synthesis and derivatization of bioactive molecules.The radical clock and trapping experiments indicated that radical pathway might be operative in the alkene isomerization step.
基金financially supported by the National Natural Science Foundation of China (Nos. 21972112 and 22225104)China Postdoctoral Science Foundation (Nos. 2022TQ0115 and 2022M711297)。
文摘Chemoselective,living/controlled polymerizations of allyl methacrylate(AMA) and vinyl methacrylate(VMA) with/without methyl methacrylate(MMA) by using the phosphonium ylide/organoaluminum based Lewis pairs(LPs) have been realized.The P-ylide-2/AIMe(BHT)_(2)(Pylide-2=Ph_(3)P=CHMe and BHT=2,6-iBu_(2)-4-MeC_(6)H_(2)O) was demonstrated to be superior by which homopolymers PAMAs(M_(n)=27.6-111.5kg/mol and ■=1.14-1.25) and PVMAs(M_(n)=28.4-78.4 kg/mol and ■=1.12-1.18) and block copolymers PMMA-b-PAMA,PAMA-b-PVMA,PAMA-bPMMA,PMMA-b-PAMA-b-PMMA,PAMA-b-PMMA-b-PAMA,and PAMA-b-PVMA-b-PAMA were synthesized.In the polymerizations,all of the monomers were reacted by the conjugated ester vinyl groups leaving intactly the nonconjugated acryloxy groups.The pendant acryloxy groups attached to the main chain enable further to post-functionalization by the AIBN-induced radical "thiol-ene" reaction using PhCH_(2)SH.The thiolether side group-containing polymers PAMA-SCH_(2)Ph and PAMA-SCH_(2)Ph-b-PMMA-b-PAMA-SCH_(2)Ph were thus prepared.
文摘Herein,we report an asymmetric two-component alkenyl Catellani reaction for the construction of C—N axial chirality through a palladium/chiral norbornene cooperative catalysis and an axial-to-axial chirality transfer process.Various partially aromatic iodinated 2-pyridones,quinolones,coumarin and uracil substrates react with 2,6-disubstituted aryl bromides with a tethered amide group,to afford a wide variety of polycyclic C—N atropisomers(38 examples,up to 97%e.e.).The obtained C—N axial chirality originates from the preformed transient C—C axial chirality with high fidelity.The synthetic utility of this chemistry is demonstrated by facile prepa-ration of complex quinoline and pyridine based C—N atropisomers through a N-deprotection and aromatization sequence.In addi-tion,a remote axial-to-central diastereoinduction process dictated by C—N axial chirality is observed with excellent diastereocontrol.
基金the National Key R&D Program of China(No.2022YFA1302900 to H.Liu)National Natural Science Foundation of China(Nos.82130105,22337003,82121005 to H.Liu+2 种基金and Nos.22177124,82322063 to J.Wang)Program of Shang-hai Academic Research Leader(No.23XD1460300 to J.Wang)the Lingang Laboratory(No.LG-GG-202204-02 to J.Wang)for supporting this work.We would like to acknowledge Shanghai Highline Therapeutics.
文摘Heterocycle-braced cyclic peptides have demonstrated enhanced metabolic stability,increased potency and selectivity.Here,we present a rapid synthesis method for constructing Trp(C7)-alkene(E)-crosslinked cyclic peptides with potent anti-proliferative activities against cancer cells,through C-H alkenylation and macrolactamization.This report addresses critical challenges associated with the installation and removal of the directing group N-Piv,configuration selectivity of the olefin,and intramolecular cyclization.No-tably,this method exhibits mild reaction conditions,traceless removal of the directing group,and high configuration selectivity.
基金National Natural Science Foundation of China(Nos.22193011,21971120 and 21933008)National Science&Technology Fundamental Resource Investigation Program of China(No.2018FY201200)for financial support.
文摘Catalytic enantioselective alkenylation is an efficient method to construct chiral alkene molecules,but the asymmetric alkenylation of simple alkenes catalyzed by metal-free catalysts remains an elusive challenge.Herein,we reported an asymmetric alkenylation of benzoxazinones with diarylethylenes by utilizing a B(C_(6)F_(5))_(3)/chiral phosphoric acid catalyst.A broad of benzoxazinones and diarylethylenes with electron-withdrawing and electron-donating groups were tolerated(up to 95%yield and 97.5:2.5 e.r.)in the methodology under mild reaction conditions.Moreover,the synthetic utility was confirmed by the scaled-up reaction and transformations of the products.The mechanism was preliminarily explored by control reactions,nonlinear effect experiment and DFT calculations.
基金suported by the National Natural Science Foundation of China (2187,1117, 91956203)the “111” Program of Minister of Education, Beijing National Laboratory for Molecular Sciences (BNLMS202109)the Science and Technology Commission of Shanghai Municipality (19JC1430100)。
文摘Catalyst innovation lies at the heart of transition-metal-catalyzed reaction development. In this article, we have explored the C(sp2)–H alkenylation activity with novel spirocyclic N-heterocyclic carbene(NHC)-based cyclometalated ruthenium pincer catalyst system, SNRu-X. After screening catalyst and condition, a high valent Ru(Ⅳ) dioxide(X = O_(2)) species has demonstrated superior reactivity in the catalytic alkenylation of aromatic and olefinic C–H bonds with unactivated alkenyl bromides and triflates. This reaction has achieved the easy construction of a wide range of(hetero)aromatic alkenes and dienes, in good to excellent yields with exclusive selectivity. Preliminary mechanistic studies indicate that this reaction may proceed through a single electron transfer(SET) triggered oxidative addition, by doing so, providing valuable complementary to classical alkenylation reactions that are dependent on activated alkenyl precursors.
基金We are grateful to the National Natural Science Foundation of China(No.21302064)the Natural Science Foundation of Hubei Province(No.2017CFB690).
文摘Main observation and conclusion A new Rh(Ⅲ)-catalyzed direct C—H alkenylation of 2,3-unsubstitued indoles with alkenyl borates through C—H activation followed by transmetallation was described.This protocol provides an efficient method for the synthesis of terminal C2-alkenylindoles under mild conditions,and also shows broad substrate scope and high functional group tolerance with respect to both components.Furthermore,the C2-alkenylated indole can be easily transformed into carboline derivative,which is an important polycyclic indole moiety in natural products and drug molecules.
基金financially supported by the National Natural Science Foundation of China(Nos.21276041 and U1610104)by the Chinese Ministry of Education via the Program for New Century Excellent Talents in University(No. NCET-12-0079)
文摘In this work, a spherical hollow mesoporous silica(SHMS) with high surface area(902 m^2/g) and large mesopore volume(1.31 cm^3/g) was prepared via a facile and scalable two-step soft-hard dual templateassisted sol-gel approach(OSDSG) by using glucose-derived carbon nano/micro particles(NMCP) as a hard template and cetyltrimethylammonium bromide(CTAB) as a soft template,respectively,in which the size-preselected carbon submicro-particle was used to replace ploymer sphere, and no extra precious additives like n-octadecyltrimethoxysilane(C18TMS). Supported phosphotungstic acid(PTA) catalysts on SHMS(PTA/SHMS) and on previously reported spherical mesoporous silica(PTA/SMS) with 25 wt% of PTA loading were prepared and employed as solid acid catalysts for diverse reactions. Transmission electron microscopy(TEM),N_2 adsorption-desorption, X-ray diffraction(XRD), and NH_3 temperatureprogrammed desorption(NH_3-TPD) techniques were employed to characterize the nature of carriers and supported PTA catalysts for revealing the structure-performance relationship. The developed PTA/SHMS catalyst demonstrates much higher catalytic activity than PTA/SMS for diverse reactions including alkenylation, esterification, alkylation, and benzylation, ascribed to the strengthened mass transfer and enlarged exposure degree of acidic sites to reactants those resulting from unique hollow and mesoporous morphology. Moreover, PTA/SHMS catalyst also exhibits outstanding catalytic performance for the diverse a-arylstyrenes via solid acid-mediated alkenylation. PTA/SHMS could be considered as a practical solid acid catalyst for diverse transformations.
基金The authors thank the finance supported by the National Natural Science Foundation of China （No. 21272136）, and Scientific Research Innovation Founda- tion of Graduate School of China Three Gorges Univer- sity.
文摘A high-efficient and stereo-specific approach for the preparation of biologically important （E）-2-styryl-tetra- hydrobenzo[d]thiazoles has been developed via TMSC1 promoted direct sp3 C-H alkenylation of 2-methyl-5,6-di- hydrobenzo[d]thiazol-7（4H）-one under metal-free conditions. Seventeen target compounds were synthesized in ex- cellent yields of 82%--98% under the optimal conditions of 300 mol% TMSCI at 110℃ for 2 h, and their chemical structures were elucidated by IR, NMR, ESI-MS, elemental analyses and X-ray crystallography analysis. A plausible mechanism was also proposed, and this method provided a good functional group conversion for the sp3 C-H substrates.
基金financially supported by the National Natural Science Foundation of China (No. 21276041)Chinese Ministry of Education via the Program for New Century Excellent Talents in University (No. NCET-12-0079)。
文摘Highly dispersed silicotungstic acid-derived WO_(3) composited with ZrO_(2) supported on SBA-_(15) (WZ/SBA-_(15)) as an ordered mesoporous solid acid catalyst was prepared via a facile incipient wetness impregnation (IWI) method that active ingredients, ZrO_(2) and WO_(3), were impregnated into the channels of SBA-_(15) simultaneously with a subsequent calcination process. The relationship between catalyst nature and performance was explored by high resolution transmission electron microscopy (HRTEM), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), FT-IR, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), N_(2) adsorption-desorption, NH_(3) temperature-programmed desorption (NH_(3)-TPD), and FT-IR of pyridine adsorption (Py-IR) characterization techniques. The catalytic performance of W_(12)Z_(15)/SBA-_(15) is not only greater than that of single component solid acid catalysts, WO_(3)/SBA-_(15) and ZrO_(2)/SBA-_(15), but also W_(12)/Z_(15)/SBA-_(15) prepared by impregnating active ingredients, ZrO_(2) and WO_(3), into SBA-_(15) in sequence. The outstanding performance of W_(12)Z_(15)/SBA-_(15) is derived from the strong interaction between ZrO_(2) and WO_(3), which results in more acid sites, and relatively high specific surface area, large pore volume, and ordered mesoporous structure of SBA-_(15). The characterization and reaction results clearly demonstrate that the synergy of ZrO_(2) and WO_(3) has a clear boost for the alkenylation. The optimized W_(12)Z_(15)/SBA-_(15)-500 achieves a 99.4% conversion of phenylacetylene and a 92.3% selectivity of main product α-arylstyrene for the alkenylation of p-xylene with phenylacetylene, with very low level of oligomers producing at the same time. Moreover, W_(12)Z_(15)/SBA-_(15)-500 shows excellent catalytic stability and regeneration. Therefore, W_(12)Z_(15)/SBA-_(15)-500 is a promising solid acid catalyst for the alkenylation.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.21762038 and 21968032)the Fundamental Research Funds for the Central Universities(Nos.31920190077 and 31920190015)+2 种基金the Innovation and Entrepreneurship Talent Project of Lanzhou(No.2019-RC-21)the Scientific Research Foundation of Northwest University for Nationalities(No.xbmuyjrc 201603)the Organic Chemistry Innovation Groups.The authors thank Dr.Gang-Wei Wang for helpful discussions.
文摘Main observation and conclusion An efficient Lewis acid enabled ketones phosphonylation to synthesize vinylphosphonates has been developed.This method relays on ketone hydrophosphonylation/α-hydroxy phosphonates unimolecular elimination(E1)dehydration cascade reaction sequence.
