A series of novel amidine derivatives of doxifluridine were synthesized using acid amide as the starting material,and their antitumor activity was evaluated in A549 cells.Compounds 10 and 11 demonstrated were more pot...A series of novel amidine derivatives of doxifluridine were synthesized using acid amide as the starting material,and their antitumor activity was evaluated in A549 cells.Compounds 10 and 11 demonstrated were more potent than 5-Fu,which was used as a positive control.Compound 10,which were found to be the most potent one with IC_(50) of 3.2μmol/L,was 16 times more potent than 5-Fu with IC_(50) of 52μmol/L to the A549 cells.A new route was designed to synthesize 5 -deoxy-5-fluorocytidine.All compounds were c...展开更多
The intermolecular reductive coupling of nitrites with azobenzene induced by SmI2 was studied. Amidine derivatives were prepared in good yields under neutral and mild conditions.
A direct metal-free C-H amination reaction of cinnamaldehydes and amidines to realize the synthesis of polysubstituted pyrimidines was developed in the presence of base. This greener synthetic methodology provides a s...A direct metal-free C-H amination reaction of cinnamaldehydes and amidines to realize the synthesis of polysubstituted pyrimidines was developed in the presence of base. This greener synthetic methodology provides a straightforward approach to the synthesis of a variety of pyrimidine derivatives under mild reaction condition using oxygen as sole oxidants.展开更多
A lipoplex （i.e., pDNA#1/lipid complex and transfection reagent for pDNA delivery） containing galactosylceramide （GalCer） and an amidine-bearing lipid （TRX） was examined whether the bound pDNA was specifically i...A lipoplex （i.e., pDNA#1/lipid complex and transfection reagent for pDNA delivery） containing galactosylceramide （GalCer） and an amidine-bearing lipid （TRX） was examined whether the bound pDNA was specifically ingested by hepatocyte via asialoglycoprotein receptor （ASGPR） and then expressed protein. Gel electrophoresis and small-angle X-ray scattering （SAXS） confirmed that the TRX-GalCer liposome#2 complexed with pDNA and the resultant lipoplex took a hexagonally packed inverted cylinder structure when the GalCer composition was less than 20 wt.% of the total lipid. When the lipoplex carrying pGL3 （luciferase-cording pDNA） was administrated to HepG2, the luciferase activity was increased with increasing the GalCer composition until it reached 3 wt.% and then decreased upon further addition of GalCer. When we added galactose itself as a competitor, the luciferase activity was decreased, while glucose did not show such decrease, suggesting that HepG2 ingested the lipoplex via ASGPR-mediated endocytosis. This paper indicated that the hexagonally packed inverted cylinder structures of lipoplex may not always provide excellent transfection and presented a possibility that the TRX lipoplex#3 can obtain a cellulartargeting ability through the receptors for oligosaccharide.展开更多
The electrooxidative[3+2]annulation of amidines with 2-arylideneindane-1,3-diones or 4-alkylidene pyrazolones is reported using NaI as a redox catalyst and electrolyte under constant current electrolysis in an undivid...The electrooxidative[3+2]annulation of amidines with 2-arylideneindane-1,3-diones or 4-alkylidene pyrazolones is reported using NaI as a redox catalyst and electrolyte under constant current electrolysis in an undivided cell.The current strategy features excellent functional group tolerance,simple operation,and mild conditions,thus providing an environmentally benign and efficient access to spiroimidazolines in moderate to good yields.展开更多
A flexible polydentate bis(amidine)ligand LH_(2),LH_(2)={CH_(2)NH(tBu)CvN-2-(6-MePy)}_(2),operates as a molecular lock for various coinage metal fragments and forms the dinuclear complexes[LH_(2)(MCl)_(2)],M=Cu(1),Au(...A flexible polydentate bis(amidine)ligand LH_(2),LH_(2)={CH_(2)NH(tBu)CvN-2-(6-MePy)}_(2),operates as a molecular lock for various coinage metal fragments and forms the dinuclear complexes[LH_(2)(MCl)_(2)],M=Cu(1),Au(2),the coordination polymer[{(LH_(2))_(2)(py)_(2)(AgCl)_(3)}(py)_(3)]_(n)(3),and the dimesityl-digold complex[LH_(2)(AuMes)_(2)](4)by formal insertion of MR fragments(M=Cu,Ag,Au;R=Cl,Mes)into the N–H⋯N hydrogen bonds of LH_(2)in yields of 43–95%.Complexes 1,2,and 4 adopt C_(2)-symmetrical structures in the solid state featuring two interconnected 11-membered rings that are locked by two intramolecular N–H⋯R–M hydrogen bonds.QTAIM analyses of the computational geometry-optimized structures 1a,2a,and 4a reveal 13,11,and 22 additional bond critical points,respectively,all of which are related to weak intramolecular attractive interactions,predominantly representing dispersion forces,contributing to the conformational stabilization of the C_(2)-symmetrical stereoisomers in the solid state.Variable-temperature ^(1)H NMR spectroscopy in combination with DFT calculations indicate a dynamic conformational interconversion between two C_(2)-symmetrical ground state structures in solution(ΔG_(c)^(‡)=11.1–13.8 kcal mol^(-1)),which is accompanied by the formation of an intermediate possessing Cᵢsymmetry that retains the hydrogen bonds.展开更多
A novel generation of oxazole vlide and interception with sulfonamide have been well developed to construct fully substituted amidines. This copper-catalyzed four-component reaction incorporates two diazo molecules to...A novel generation of oxazole vlide and interception with sulfonamide have been well developed to construct fully substituted amidines. This copper-catalyzed four-component reaction incorporates two diazo molecules to target amidines and shows broad substrate scope, excellent functional groups tolerance and good to excellent yields.展开更多
In the presence of Cu（I） and triethyl amine, one-pot three-component reaction of fluoroalkanesulfonyl azides, alkynes and iminophosphoranes in CH2Cl2 at room temperature gave a novel class of fluorinated phosphorus ...In the presence of Cu（I） and triethyl amine, one-pot three-component reaction of fluoroalkanesulfonyl azides, alkynes and iminophosphoranes in CH2Cl2 at room temperature gave a novel class of fluorinated phosphorus amidines in good yields.展开更多
Polymers with metal coordination ability are outstanding precursors of nanocatalysts,attracting numerous attention in nanocatalysis area.It has been rarely reported for the poly(N-sulfonyl amidines)as macromolecular l...Polymers with metal coordination ability are outstanding precursors of nanocatalysts,attracting numerous attention in nanocatalysis area.It has been rarely reported for the poly(N-sulfonyl amidines)as macromolecular ligands for nanocatalysis.Herein,a catalyst-free multicomponent polymerization(MCP)strategy is developed to facilely prepare a library of amphiphilic poly(Nsulfonyl amidines)with zwitterionic properties starting from disulfonyl azide,hydrophilic dialdehyde and cyclic amino acids including proline and pipecolinic acid.Metals or additives can be thorougly avoided through this method.All the obtained polymers have well-defined structures,high yields and weight-average molecular weights(M_(w)s,up to 99,300 g/mol).The unique zwitterionic property,amphiphilicity and Cu(Ⅰ)coordination ability of the obtained poly(N-sulfonyl amidines)endow them to form the polymer-Cu(Ⅰ)complexes as nanocatalysts.Such nanocatalysts exhibit high catalytic efficiency in aqueous Cucatalyzed azide-alkyne cycloaddition(CuAAC)reaction at a low Cu(Ⅰ)loading of 50 ppm.Nanocatalysts with a high ratio of polymers to Cu(Ⅰ)have also been demonstrated with Cu(Ⅰ)stabilization ability.This work provides a“green”MCP method toward zwitterionic and amphiphilic poly(N-sulfonyl amidines),and highlights their unique potentials for nanocatalysis.展开更多
An iron-catalyzed[4+2]annulation of amidines with α,β-unsaturated ketoxime acetates is described.This strategy employs amidines as CN units and provides a new protocol for the construction of 2,4,6-trisubstituted py...An iron-catalyzed[4+2]annulation of amidines with α,β-unsaturated ketoxime acetates is described.This strategy employs amidines as CN units and provides a new protocol for the construction of 2,4,6-trisubstituted pyrimidines under batch and continuous flow conditions in moderate to good yields,exhibiting good functional group tolerance,scalability and operational simplicity.展开更多
The management of neurological disorders have huge and increasing human and economic costs. Despite this, there is a scarcity of effective therapeutics, and there is an extreme urgency for new and real treatments. In ...The management of neurological disorders have huge and increasing human and economic costs. Despite this, there is a scarcity of effective therapeutics, and there is an extreme urgency for new and real treatments. In this short review we analyze some promising advancements in the search of new bioactive molecules targeting neuronal nitric oxide synthase （nNOS）, an enzyme deputed to the biosynthesis of nitric oxide （NO）. In different conditions of neuronal damages, this molecule is overproduced, contributing to the pathogenesis and progression of neuronal diseases. Two main approaches to modulate nNOS are discussed： a first one consisting in the direct inhibition of the enzyme by means of small organic molecules, which can be also active against other different targets involved in such diseases. A second section is dedicated to molecules able to prevent the formation of the ternary complex N-methyl-D-aspartate （NMDA）type glutamate receptors, postsynaptic density-95 （PSD95） protein-nNOS, which is necessary to activate the latter for the biosynthesis of NO.展开更多
Chiral organobases occupy a significant position in asymmetric organocatalysis. The general types of chiral organobases include tertiary amines, amidines, guanidines, cyclopropenimines, and iminophosphoranes, etc. The...Chiral organobases occupy a significant position in asymmetric organocatalysis. The general types of chiral organobases include tertiary amines, amidines, guanidines, cyclopropenimines, and iminophosphoranes, etc. These organobases are demonstrated to be effective organocatalysts to promote divers kinds of base-initiated reactions in excellent yields and stereoselectivities. In previous reports, several groups have summarized each kind of chiral organobases in different reviews. To the aim of understanding the whole of them in one review, herein, we provide a brief introduction of these chiral organobases in asymmetric catalysis.展开更多
The intermolecular coupling of a nitro group with a cyano group mediated by a Sm(Hg) amalgam prepared from metal samarium powder and catalytic mercury dichloride was studied.
Terminal rare-earth imido complexes containing metal-nitrogen double bonds have received more attention in recent years due to their importance in group transformation and catalytic reactions.However,due to the large ...Terminal rare-earth imido complexes containing metal-nitrogen double bonds have received more attention in recent years due to their importance in group transformation and catalytic reactions.However,due to the large difference in the orbital energy between rare-earth metals and nitrogen,their synthesis is difficult and the product is easy to polymerize.Here,we use the combination of Cp*and amidinate ligands to inhibit the tetramerization and provide exclusively the first anionic rare-earth(Ⅲ)terminal imido complexes with both electron-donating and electron-withdrawing groups.Chemical bond analysis further confirms the double-bond character,and the strong polarity of the REvN bond,which could be described as three orbital interactions,is primarily derived from the imido nitrogen,while the contribution from the rare-earth metal is limited.The mechanistic study using DFT calculations shows that the formation of the REvN bond involves the activation of two N-H bonds.Furthermore,the anionic rare-earth(Ⅲ)terminal imido complex shows some interesting and unique reactivity towards isocyanates,isonitriles,phenylsilanes,and W(CO)6.The work extends the multiple-bond chemistry between rare-earth metals and main group elements,and is expected to inspire the development of rare-earth organometallic chemistry and related fields.展开更多
Reduced arene complexes of rare-earth metals are of great interest and importance because of their unique reactivity mimicking low-valence rare-earth metal species.Here,we present the synthesis and structural characte...Reduced arene complexes of rare-earth metals are of great interest and importance because of their unique reactivity mimicking low-valence rare-earth metal species.Here,we present the synthesis and structural characterization of a series of reduced naphthalene or anthracene complexes of mononuclear scandium with mixed C_(5)Me_(5)(Cp^(*))and amidinate ligands.Among them,the reduced anthracene complexes of mononuclear scandium have been found for the first time to undergo a rapid inter-ring rearrangement.Significantly,a reduced anthracene complex with a scandium center attached to the terminal six-membered ring of anthracene was synthesized by modulating the substituents on the amidinate ligand.The diversified two-electron redox reactions of the reduced naphthalene complex of mononuclear scandium toward cyclooctatetraene(COT),dibenzo[a,e]cyclooctene,benzophenone,1,4-diazabutadiene(DAD),isothiocyanate,and selenium were examined.The scope of two-electron redox reactions via the trivalent scandium complex with the mixed Cp^(*)/amidinate/arene ligand system is significantly expanded,and thus,these results remedy the shortcomings where it is difficult for rare-earth complexes to undergo the two-electron redox process.展开更多
Comprehensive Summary The development of switchable solvent-free multicomponent reactions to build high-value-added products is an important demand for organic synthesis.Herein,we detailed the successful implementatio...Comprehensive Summary The development of switchable solvent-free multicomponent reactions to build high-value-added products is an important demand for organic synthesis.Herein,we detailed the successful implementation of a switchable strategy for the construction of diverse 4-fluoroalkyl-1,4-dihydropyrimidines and 4-fluoroalkyl-pyrimidines via a solvent/additive-free[3+2+1]annulation,starting from readily available enamines,trifluoroacetaldehyde hydrate or 1-ethoxy-2,2-difluoroethanol and amidines hydrochloride.This reaction conforms to the concept of green synthesis,and provides a new avenue to access valuable fluorinated heterocycles.展开更多
Sensitivity to structure and composition is very challenging to establish in nanocatalysis due to inadequate definition of structures that are very close in composition.We synthesized a pair of atomically precise copp...Sensitivity to structure and composition is very challenging to establish in nanocatalysis due to inadequate definition of structures that are very close in composition.We synthesized a pair of atomically precise copper clusters that are very close in composition,[Cu_(20)H_(9)(Tf-dpf)_(10)]·BF4(Cu_(20)H_(9))and[Cu_(20)H_(8)(Tf-dpf)_(10)]·(BF_(4))_(2)(Cu_(20)H_(8)),by using a pyridyl-functionalized flexible amidinate ligand,N,N′-di(5-trifluoromethyl-2-pyridyl)formamidinate.The one-hydride difference in their composition leads to significant variation in geometric and electronic structures and,consequently,distinctly different optical and catalytic properties.Cu_(20)H_(8)exhibits 25 times higher catalytic activity than Cu_(20)H_(9)(96.7%vs 3.7%in yield)in the selective hydrogenation of anα,β-unsaturated aldehyde(cinnamaldehyde)to saturated aldehyde(3-phenylpropanal).Electrospray ionization mass spectrometry combined with density functional theory calculations reveal that the greater ease of dissociation of one Tf-dpf ligand compared to Cu_(20)H_(8)is the key to its higher activity.This work demonstrates a clear case of structure and composition sensitivity in nanocatalysis and that one hydride,out of∼330 atoms in the nanoclusters,can make a huge difference in the catalytic activity.These insights will be useful in the design and synthesis of atomically precise nanocatalysts.展开更多
1 Results Search for catalysts which can control the regio- and stereoselectivity for olefin polymerization is a very important research subject.For the polymerization of isoprene,we have recently achieved,for the fir...1 Results Search for catalysts which can control the regio- and stereoselectivity for olefin polymerization is a very important research subject.For the polymerization of isoprene,we have recently achieved,for the first time,the isospecific 3,4 polymerization by using a cationic rare earth metal alkyl catalyst bearing a silylene-linked cyclopentadieny-phosphido ligand[1], and the cis-1,4 living polymerization by a bis(phosphinophenyl)amido-ligated rare earth metal catalyst[2]. In addition to these ligan...展开更多
文摘A series of novel amidine derivatives of doxifluridine were synthesized using acid amide as the starting material,and their antitumor activity was evaluated in A549 cells.Compounds 10 and 11 demonstrated were more potent than 5-Fu,which was used as a positive control.Compound 10,which were found to be the most potent one with IC_(50) of 3.2μmol/L,was 16 times more potent than 5-Fu with IC_(50) of 52μmol/L to the A549 cells.A new route was designed to synthesize 5 -deoxy-5-fluorocytidine.All compounds were c...
文摘The intermolecular reductive coupling of nitrites with azobenzene induced by SmI2 was studied. Amidine derivatives were prepared in good yields under neutral and mild conditions.
基金the China Postdoctoral Science Foundation Funded Project (No. 2014M562165)Jiangxi Natural Science Foundation (Nos. 20133BCB24011, 20141BBG70070 and 20151BAB203011)the Science Foundation of Jiangxi Provincial Department of Education (No. Gjj4669) for support of this research
文摘A direct metal-free C-H amination reaction of cinnamaldehydes and amidines to realize the synthesis of polysubstituted pyrimidines was developed in the presence of base. This greener synthetic methodology provides a straightforward approach to the synthesis of a variety of pyrimidine derivatives under mild reaction condition using oxygen as sole oxidants.
基金SORST of JST and a Grant-in-Aid for Scientific Research(No.16350068 and 16655048)SAXS was performed at SPring-8 BL40B2(No.2006A1510).
文摘A lipoplex （i.e., pDNA#1/lipid complex and transfection reagent for pDNA delivery） containing galactosylceramide （GalCer） and an amidine-bearing lipid （TRX） was examined whether the bound pDNA was specifically ingested by hepatocyte via asialoglycoprotein receptor （ASGPR） and then expressed protein. Gel electrophoresis and small-angle X-ray scattering （SAXS） confirmed that the TRX-GalCer liposome#2 complexed with pDNA and the resultant lipoplex took a hexagonally packed inverted cylinder structure when the GalCer composition was less than 20 wt.% of the total lipid. When the lipoplex carrying pGL3 （luciferase-cording pDNA） was administrated to HepG2, the luciferase activity was increased with increasing the GalCer composition until it reached 3 wt.% and then decreased upon further addition of GalCer. When we added galactose itself as a competitor, the luciferase activity was decreased, while glucose did not show such decrease, suggesting that HepG2 ingested the lipoplex via ASGPR-mediated endocytosis. This paper indicated that the hexagonally packed inverted cylinder structures of lipoplex may not always provide excellent transfection and presented a possibility that the TRX lipoplex#3 can obtain a cellulartargeting ability through the receptors for oligosaccharide.
基金the National Natural Science Foundation of China (No. 22078150)the Natural Science Foundation of Jiangsu Province, Frontier Project (No. BK20212003)
文摘The electrooxidative[3+2]annulation of amidines with 2-arylideneindane-1,3-diones or 4-alkylidene pyrazolones is reported using NaI as a redox catalyst and electrolyte under constant current electrolysis in an undivided cell.The current strategy features excellent functional group tolerance,simple operation,and mild conditions,thus providing an environmentally benign and efficient access to spiroimidazolines in moderate to good yields.
基金supported by the U.S.Department of Energy,Office of Energy Sciences Materials Sciences Division,under contract DE-AC02-05CH11231support for providing computing resources by the Advanced Computer Services at Kennesaw State University+1 种基金support by the Department of Chemistry and Biochemistry(New Faculty Startup Fund(#08020)as well as the College of Sciences and Mathematics(CSM)at Kennesaw State University(CSM Research Stimulus Program)by Aditya Birla Carbon(Birla Carbon Scholarship for O.U.T.)is acknowledged.This material is based upon work supported by the US National Science Foundation under grant CHE-1800332.
文摘A flexible polydentate bis(amidine)ligand LH_(2),LH_(2)={CH_(2)NH(tBu)CvN-2-(6-MePy)}_(2),operates as a molecular lock for various coinage metal fragments and forms the dinuclear complexes[LH_(2)(MCl)_(2)],M=Cu(1),Au(2),the coordination polymer[{(LH_(2))_(2)(py)_(2)(AgCl)_(3)}(py)_(3)]_(n)(3),and the dimesityl-digold complex[LH_(2)(AuMes)_(2)](4)by formal insertion of MR fragments(M=Cu,Ag,Au;R=Cl,Mes)into the N–H⋯N hydrogen bonds of LH_(2)in yields of 43–95%.Complexes 1,2,and 4 adopt C_(2)-symmetrical structures in the solid state featuring two interconnected 11-membered rings that are locked by two intramolecular N–H⋯R–M hydrogen bonds.QTAIM analyses of the computational geometry-optimized structures 1a,2a,and 4a reveal 13,11,and 22 additional bond critical points,respectively,all of which are related to weak intramolecular attractive interactions,predominantly representing dispersion forces,contributing to the conformational stabilization of the C_(2)-symmetrical stereoisomers in the solid state.Variable-temperature ^(1)H NMR spectroscopy in combination with DFT calculations indicate a dynamic conformational interconversion between two C_(2)-symmetrical ground state structures in solution(ΔG_(c)^(‡)=11.1–13.8 kcal mol^(-1)),which is accompanied by the formation of an intermediate possessing Cᵢsymmetry that retains the hydrogen bonds.
文摘A novel generation of oxazole vlide and interception with sulfonamide have been well developed to construct fully substituted amidines. This copper-catalyzed four-component reaction incorporates two diazo molecules to target amidines and shows broad substrate scope, excellent functional groups tolerance and good to excellent yields.
基金Project supported by the National Natural Science Foundation of China （Nos. 21032006, 20972178） and Shanghai Natural Science Council.
文摘In the presence of Cu（I） and triethyl amine, one-pot three-component reaction of fluoroalkanesulfonyl azides, alkynes and iminophosphoranes in CH2Cl2 at room temperature gave a novel class of fluorinated phosphorus amidines in good yields.
基金supported by the National Natural Science Foundation of China(21978039)the Natural Science Foundation of Jiangsu Province(BK20221265,BK20211100)the Fundamental Research Funds for the Central Universities(DUT21YG133,DUT22YG224)。
文摘Polymers with metal coordination ability are outstanding precursors of nanocatalysts,attracting numerous attention in nanocatalysis area.It has been rarely reported for the poly(N-sulfonyl amidines)as macromolecular ligands for nanocatalysis.Herein,a catalyst-free multicomponent polymerization(MCP)strategy is developed to facilely prepare a library of amphiphilic poly(Nsulfonyl amidines)with zwitterionic properties starting from disulfonyl azide,hydrophilic dialdehyde and cyclic amino acids including proline and pipecolinic acid.Metals or additives can be thorougly avoided through this method.All the obtained polymers have well-defined structures,high yields and weight-average molecular weights(M_(w)s,up to 99,300 g/mol).The unique zwitterionic property,amphiphilicity and Cu(Ⅰ)coordination ability of the obtained poly(N-sulfonyl amidines)endow them to form the polymer-Cu(Ⅰ)complexes as nanocatalysts.Such nanocatalysts exhibit high catalytic efficiency in aqueous Cucatalyzed azide-alkyne cycloaddition(CuAAC)reaction at a low Cu(Ⅰ)loading of 50 ppm.Nanocatalysts with a high ratio of polymers to Cu(Ⅰ)have also been demonstrated with Cu(Ⅰ)stabilization ability.This work provides a“green”MCP method toward zwitterionic and amphiphilic poly(N-sulfonyl amidines),and highlights their unique potentials for nanocatalysis.
基金the National Natural Science Foundation of China(No.22078150)the National Key R&D Program of China(No.2021YFC2101904)+1 种基金the Jiangsu Province Industrial Prospects and Key Core Technologies-Competitive Projects(No.BE2021083)the Nanjing International Joint R&D Project(No.202002037)for their financial support。
文摘An iron-catalyzed[4+2]annulation of amidines with α,β-unsaturated ketoxime acetates is described.This strategy employs amidines as CN units and provides a new protocol for the construction of 2,4,6-trisubstituted pyrimidines under batch and continuous flow conditions in moderate to good yields,exhibiting good functional group tolerance,scalability and operational simplicity.
文摘The management of neurological disorders have huge and increasing human and economic costs. Despite this, there is a scarcity of effective therapeutics, and there is an extreme urgency for new and real treatments. In this short review we analyze some promising advancements in the search of new bioactive molecules targeting neuronal nitric oxide synthase （nNOS）, an enzyme deputed to the biosynthesis of nitric oxide （NO）. In different conditions of neuronal damages, this molecule is overproduced, contributing to the pathogenesis and progression of neuronal diseases. Two main approaches to modulate nNOS are discussed： a first one consisting in the direct inhibition of the enzyme by means of small organic molecules, which can be also active against other different targets involved in such diseases. A second section is dedicated to molecules able to prevent the formation of the ternary complex N-methyl-D-aspartate （NMDA）type glutamate receptors, postsynaptic density-95 （PSD95） protein-nNOS, which is necessary to activate the latter for the biosynthesis of NO.
基金the National Natural Science Foundation of China (Nos. 21625205 and 21332003)the National Program for Support of Top-Notch Young Professionals for financial support
文摘Chiral organobases occupy a significant position in asymmetric organocatalysis. The general types of chiral organobases include tertiary amines, amidines, guanidines, cyclopropenimines, and iminophosphoranes, etc. These organobases are demonstrated to be effective organocatalysts to promote divers kinds of base-initiated reactions in excellent yields and stereoselectivities. In previous reports, several groups have summarized each kind of chiral organobases in different reviews. To the aim of understanding the whole of them in one review, herein, we provide a brief introduction of these chiral organobases in asymmetric catalysis.
基金National Natural Science Foundation of China (Project No. 20072033) and Natural Science Foundation of Zhejiang province for financial support.
文摘The intermolecular coupling of a nitro group with a cyano group mediated by a Sm(Hg) amalgam prepared from metal samarium powder and catalytic mercury dichloride was studied.
基金supported by the National Key R&D Program of China(no.2021YFF0701600)the National Natural Science Foundation of China(no.22371006 and 22131001)the Beijing National Laboratory for Molecular Sciences(BNLMS-CXXM-202401).
文摘Terminal rare-earth imido complexes containing metal-nitrogen double bonds have received more attention in recent years due to their importance in group transformation and catalytic reactions.However,due to the large difference in the orbital energy between rare-earth metals and nitrogen,their synthesis is difficult and the product is easy to polymerize.Here,we use the combination of Cp*and amidinate ligands to inhibit the tetramerization and provide exclusively the first anionic rare-earth(Ⅲ)terminal imido complexes with both electron-donating and electron-withdrawing groups.Chemical bond analysis further confirms the double-bond character,and the strong polarity of the REvN bond,which could be described as three orbital interactions,is primarily derived from the imido nitrogen,while the contribution from the rare-earth metal is limited.The mechanistic study using DFT calculations shows that the formation of the REvN bond involves the activation of two N-H bonds.Furthermore,the anionic rare-earth(Ⅲ)terminal imido complex shows some interesting and unique reactivity towards isocyanates,isonitriles,phenylsilanes,and W(CO)6.The work extends the multiple-bond chemistry between rare-earth metals and main group elements,and is expected to inspire the development of rare-earth organometallic chemistry and related fields.
基金work was supported by the National Key R&D Program of China(No.2021YFF0701600)the National Natural Science Foundation of China(No.21725201,21890721,and 22131001).
文摘Reduced arene complexes of rare-earth metals are of great interest and importance because of their unique reactivity mimicking low-valence rare-earth metal species.Here,we present the synthesis and structural characterization of a series of reduced naphthalene or anthracene complexes of mononuclear scandium with mixed C_(5)Me_(5)(Cp^(*))and amidinate ligands.Among them,the reduced anthracene complexes of mononuclear scandium have been found for the first time to undergo a rapid inter-ring rearrangement.Significantly,a reduced anthracene complex with a scandium center attached to the terminal six-membered ring of anthracene was synthesized by modulating the substituents on the amidinate ligand.The diversified two-electron redox reactions of the reduced naphthalene complex of mononuclear scandium toward cyclooctatetraene(COT),dibenzo[a,e]cyclooctene,benzophenone,1,4-diazabutadiene(DAD),isothiocyanate,and selenium were examined.The scope of two-electron redox reactions via the trivalent scandium complex with the mixed Cp^(*)/amidinate/arene ligand system is significantly expanded,and thus,these results remedy the shortcomings where it is difficult for rare-earth complexes to undergo the two-electron redox process.
基金the National Natural Science Foundation of China(22071171)the Natural Science Foundation of Zhejiang Province(LZ22B020003)for financial support of this work.
文摘Comprehensive Summary The development of switchable solvent-free multicomponent reactions to build high-value-added products is an important demand for organic synthesis.Herein,we detailed the successful implementation of a switchable strategy for the construction of diverse 4-fluoroalkyl-1,4-dihydropyrimidines and 4-fluoroalkyl-pyrimidines via a solvent/additive-free[3+2+1]annulation,starting from readily available enamines,trifluoroacetaldehyde hydrate or 1-ethoxy-2,2-difluoroethanol and amidines hydrochloride.This reaction conforms to the concept of green synthesis,and provides a new avenue to access valuable fluorinated heterocycles.
基金supported by the National Natural Science Foundation of China(grant nos.91961201 and 21973116)the Beijing Natural Science Foundation(grant no.2234087)the China Postdoctoral Science Foundation(grant nos.2023T160357 and 2022M721797).
文摘Sensitivity to structure and composition is very challenging to establish in nanocatalysis due to inadequate definition of structures that are very close in composition.We synthesized a pair of atomically precise copper clusters that are very close in composition,[Cu_(20)H_(9)(Tf-dpf)_(10)]·BF4(Cu_(20)H_(9))and[Cu_(20)H_(8)(Tf-dpf)_(10)]·(BF_(4))_(2)(Cu_(20)H_(8)),by using a pyridyl-functionalized flexible amidinate ligand,N,N′-di(5-trifluoromethyl-2-pyridyl)formamidinate.The one-hydride difference in their composition leads to significant variation in geometric and electronic structures and,consequently,distinctly different optical and catalytic properties.Cu_(20)H_(8)exhibits 25 times higher catalytic activity than Cu_(20)H_(9)(96.7%vs 3.7%in yield)in the selective hydrogenation of anα,β-unsaturated aldehyde(cinnamaldehyde)to saturated aldehyde(3-phenylpropanal).Electrospray ionization mass spectrometry combined with density functional theory calculations reveal that the greater ease of dissociation of one Tf-dpf ligand compared to Cu_(20)H_(8)is the key to its higher activity.This work demonstrates a clear case of structure and composition sensitivity in nanocatalysis and that one hydride,out of∼330 atoms in the nanoclusters,can make a huge difference in the catalytic activity.These insights will be useful in the design and synthesis of atomically precise nanocatalysts.
文摘1 Results Search for catalysts which can control the regio- and stereoselectivity for olefin polymerization is a very important research subject.For the polymerization of isoprene,we have recently achieved,for the first time,the isospecific 3,4 polymerization by using a cationic rare earth metal alkyl catalyst bearing a silylene-linked cyclopentadieny-phosphido ligand[1], and the cis-1,4 living polymerization by a bis(phosphinophenyl)amido-ligated rare earth metal catalyst[2]. In addition to these ligan...
