Sm/TiCl4 system could well integrate the high reactivity of samarium（Ⅱ） and high deoxygenation capacity of low valent titanium within one system. In this paper, the intermolecular and intramolecular reductive coupl...Sm/TiCl4 system could well integrate the high reactivity of samarium（Ⅱ） and high deoxygenation capacity of low valent titanium within one system. In this paper, the intermolecular and intramolecular reductive coupling reactions of ketones with esters mediated by metallic samarium （Sm） and a catalytic amount of titanium tetrachloride （TiCl4） were successfully developed. A series of substituted ketones and cyclic β-keto-esters were prepared in moderate to good yields under reflux and neutral conditions.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.
The synthesis methods ofα-fluoro-arylketones were well-established through electrophilic/nucleophilic fluorination and transition metal catalyzed cross-coupling.However,due to the site selectivity and substrate restr...The synthesis methods ofα-fluoro-arylketones were well-established through electrophilic/nucleophilic fluorination and transition metal catalyzed cross-coupling.However,due to the site selectivity and substrate restriction,only a few cases have been developed to affordα-alkyl-α-fluoro-alkylketones.Herein,we report a general and efficient method of preparing diverseα-alkyl-α-fluoro-alkylketones via nickelcatalyzed reductive coupling reaction of monofluoroalkyl triflates with low-cost industrial raw material alkyl carboxylic acids.These transformations demonstrate high efficiency,mild conditions,and excellent functional group compatibility.This strategy provides a general and efficient method for the synthesis ofα-alkyl-α-fluoro-alkylketones。展开更多
The reductive coupling reactions of aryl sulfonyl chloride induced by (TiCl4-Zn) reagent affords diaryl disulfide. However, reaction of aryl sulfonyl chloride with α,β-unsaturated ester under the same condition affo...The reductive coupling reactions of aryl sulfonyl chloride induced by (TiCl4-Zn) reagent affords diaryl disulfide. However, reaction of aryl sulfonyl chloride with α,β-unsaturated ester under the same condition affords β-arylsulfo ester.展开更多
Compared with rare and expensive late-transition metals,rare-earth photocatalysts are much less investigated in synthetic chemistry,particularly concerning redox-inactive rare-earth metals.Herein,we describe a general...Compared with rare and expensive late-transition metals,rare-earth photocatalysts are much less investigated in synthetic chemistry,particularly concerning redox-inactive rare-earth metals.Herein,we describe a general strategy to realize the redox-inactive rare-earth photocatalysis by grafting a light-absorbing scaffold onto common ligands in rare-earth organometallics.Three guanidinate rare-earth complexes with photocatalytic functions were synthesized and found to exhibit higher catalytic efficiency than phenothiazine in the reductive homocoupling of benzyl bromides.These preliminary results illustrated that our“grafting”strategy could serve as a facile methodology for the construction of redox-inactive rare-earth photocatalysis systems.展开更多
The construction of secondary alkylsilanes is a challenging subject in the synthetic community.The cross-coupling provides a practical solution to address this problem,but it typically relies on organometallic species...The construction of secondary alkylsilanes is a challenging subject in the synthetic community.The cross-coupling provides a practical solution to address this problem,but it typically relies on organometallic species.Herein,we report an Mn-mediated reductive C(sp^(3))-Si coupling to synthesize these compounds from alkyl and silyl electrophiles.This approach avoids the requirement for activation of Si-Cl by transition metals and thus allows for the coupling of various common chlorosilanes.The reaction proceeds under mild conditions and shows good functional group compatibility.The method offers access toα-silylated organophosphorus and sulfones with a scope that is complementary to those obtained from the established methods.展开更多
Herein we report a method for highly diastereoselective and enantioselective nickel-catalyzed reductive coupling of imines and unactivated alkenes.A monodentate chiral spiro phosphoramidite ligand is the key to contro...Herein we report a method for highly diastereoselective and enantioselective nickel-catalyzed reductive coupling of imines and unactivated alkenes.A monodentate chiral spiro phosphoramidite ligand is the key to controlling the enantioselectivity.This efficient,straightforward method allows for the construction of chiral benzocyclic and indole-fused cyclic amines with two contiguous stereogenic centers in good yields from readily accessible starting materials.展开更多
The intermolecular reductive coupling cyclization reactions of 1,1-dicyanoalkenes promoted by Sm-0/cat. HgCl2 were studied. A possible reaction mechanism was proposed.
Herein,we report a borane-promoted reductive deoxygenation coupling reaction to synthesize sulfides.This reaction features excellent functional group compatibility,high efficiency,broad substrate scope,and application...Herein,we report a borane-promoted reductive deoxygenation coupling reaction to synthesize sulfides.This reaction features excellent functional group compatibility,high efficiency,broad substrate scope,and application in late-stage functionalization of biomolecules.Preliminary mechanistic studies suggest diaryl sulfides are the intermediates of this reaction.Moreover,the real active aryl sulfide anions may be generated in situ with the aid of B2pin2 and react with alkyl tosylates through a concerted SN2 pathway.展开更多
A new cooperative nickel reductive catalysis and N,N-dimethylformamide-mediated strategy for umpolung C–S radical reductive cross coupling of S-(trifluoromethyl)arylsulfonothioates with alkyl halides to produce alkyl...A new cooperative nickel reductive catalysis and N,N-dimethylformamide-mediated strategy for umpolung C–S radical reductive cross coupling of S-(trifluoromethyl)arylsulfonothioates with alkyl halides to produce alkyl aryl thioethers is described. This reaction features excellent selectivity, wide functionality tolerance, broad substrate scope, and facile late-stage modification of biologically relevant molecules.Mechanistic studies recognize initial generation of an amidyl radical anion via thermoinduced reduction of DMF with Sn, followed by umpolung reduction and single electron transfer of the nucleophilic sulfonyl moiety to form a sulphydryl radical and engage the Ni^(0)/Ni^(Ⅰ)/Ni^(Ⅲ)/Ni^(I) catalytic cycle.展开更多
Light-driven CO_(2) reduction reaction(CO_(2)RR)to value-added ethylene(C2H4)holds significant promise for addressing energy and environmental challenges.While the high energy barriers for*CO intermediates hydrogenati...Light-driven CO_(2) reduction reaction(CO_(2)RR)to value-added ethylene(C2H4)holds significant promise for addressing energy and environmental challenges.While the high energy barriers for*CO intermediates hydrogenation and C–C coupling limit the C_(2)H_(4)generation.Herein,CuxP/g-C_(3)N_(4) heterojunction prepared by an in-situ phosphating technique,achieved collaborative photocatalytic CO_(2) and H2O,producing CO and C_(2)H_(4)as the main products.Notably,the selectivity of C_(2)H_(4)produced by CuxP/g-C_(3)N_(4) attained to 64.25%,which was 9.85 times that of CuxP(6.52%).Detailed time-resolution photoluminescence spectra,femtosecond transient absorption spectroscopy tests and density functional theory(DFT)calculation validate the ultra-fast interfacial electron transfer mechanism in CuxP/g-C_(3)N_(4) heterojunction.Successive*H on P sites caused by adsorbed H2O splitting with moderate hydrogenation ability enables the multi-step hydrogenation during CO_(2)RR process over CuxP/g-C_(3)N_(4).With the aid of mediated asymmetric Cu and P dual sites by g-C_(3)N_(4) nanosheet,the produced*CHO shows an energetically favorable for C–C coupling.The coupling formed*CHOCHO further accepts photoexcited efficient e–and*H to deeply produce C_(2)H_(4)according to the C^(2+)intermediates,which has been detected by in-situ diffuse reflectance infrared Fourier transform spectroscopy and interpreted by DFT calculation.The novel insight mechanism offers an essential understanding for the development of CuxP-based heterojunctions for photocatalytic CO_(2) to C^(2+)value-added fuels.展开更多
Aromatic aldehydes are the most fundamentally important compounds used in organic synthesis.The development of new synthetic methods for introduction of a formyl group into an organic scaffold is highly desirable.In t...Aromatic aldehydes are the most fundamentally important compounds used in organic synthesis.The development of new synthetic methods for introduction of a formyl group into an organic scaffold is highly desirable.In this report,a nickel-catalyzed reductive coupling between aryl halides andα–chloro N-methoxyphthalimide has been documented for the synthesis of a diverse array of aromatic aldehydes.Because of mild reductive coupling conditions,excellent functional group tolerance,especially for substrates containing free-OH and-NH_(2),was observed.Due to the simple operation mode,a large library of aromatic aldehydes can be quickly constructed by this process.Moreover,the present protocol is amenable for late-stage functionalization of bioactive compound.A combined computational and experimental investigation suggested the reaction may undergo a reaction mechanism of active Ni(I)catalyst formation and the formation of key formyl radical intermediate under zinc reductive conditions.展开更多
In this paper, an ultra-compact single negative（SNG） electric waveguided metamaterial（WG-MTM） is first investigated and used to reduce the mutual coupling in E ＆ H planes of a dual-band microstrip antenna array. ...In this paper, an ultra-compact single negative（SNG） electric waveguided metamaterial（WG-MTM） is first investigated and used to reduce the mutual coupling in E ＆ H planes of a dual-band microstrip antenna array. The proposed SNG electric WG-MTM unit cell is designed by etching two different symmetrical spiral lines on the ground, and has two stopbands operating at 1.86 GHz and 2.40 GHz. The circuit size is very compact, which is only λ_0/33.6 ×λ_0/15.1（where λ_0 is the wavelength at 1.86 GHz in free space）. Taking advantage of the dual-stopband property of the proposed SNG electric WG-MTM, a dual-band microstrip antenna array operating at 1.86 GHz and 2.40 GHz with very low mutual coupling is designed by embedding a cross shaped array of the proposed SNG electric WG-MTM. The measured and simulated results of the designed dual-band antenna array are in good agreement with each other, indicating that the mutual coupling of the fabricated dual-band antenna array realizes 9.8/11.1 d B reductions in the H plane, 8.5/7.9 d B reductions in the E plane at1.86 GHz and 2.40 GHz, respectively. Besides, the distance of the antenna elements in the array is only 0.35 λ_0（where λ_0 is the wavelength at 1.86 GHz in free space）. The proposed strategy is used for the first time to reduce the mutual coupling in E ＆ H planes of the dual-band microstrip antenna array by using ultra-compact SNG electric WG-MTM.展开更多
Divergent synthesis of valuable molecules through common starting materials and metal catalysis represents a longstanding challenge and a significant research goal.We here describe chemodivergent,highly enantio-and re...Divergent synthesis of valuable molecules through common starting materials and metal catalysis represents a longstanding challenge and a significant research goal.We here describe chemodivergent,highly enantio-and regioselective nickel-catalyzed reductive and dehydrogenative coupling reactions of alkynes,aldehydes,and silanes.A single chiral Ni-based catalyst is leveraged to directly prepare three distinct enantioenriched products(silyl-protected trisubstituted chiral allylic alcohols,oxasilacyclopentenes,and silicon-stereogenic oxasilacyclopentenes)in a single chemical operation.The use of a bulky C2-symmetric N-heterocyclic carbene(NHC)ligand for nickel catalyst is the key to enable simultaneous exceptional control of stereo-and regioselectivity(up to 99%enantiomeric excess(ee),>99:1 regiomeric ratio(rr),>99:1 E/Z)and high efficiency(up to 99%yield).Computational studies elucidate the origin of chemodivergency and reveal the critical role of NHC in the enantioselectivity-and rate-determining oxidative cyclization step via anη2-aldehydeη2-alkyne Ni five-centered transition state.We expected that the enantioselectiveη2-activation mode be widely applicable in other Ni-catalyzed carbonyl couplings.展开更多
In recent years, there have been a number of reports on the phenomenon in which ferric iron（Fe（Ⅲ）） is reduced to ferrous iron [Fe（Ⅱ）] in anaerobic environments, accompanied by simultaneous oxidation of ammonia...In recent years, there have been a number of reports on the phenomenon in which ferric iron（Fe（Ⅲ）） is reduced to ferrous iron [Fe（Ⅱ）] in anaerobic environments, accompanied by simultaneous oxidation of ammonia to NO2-, NO3-, or N2.However, studies on the relevant reaction characteristics and mechanisms are rare. Recently, in research on the effect of Fe（Ⅲ） on the activity of Anammox sludge, excess ammonia oxidization has also been found.Hence, in the present study, Fe（Ⅲ） was used to serve as the electron acceptor instead of NO2-,and the feasibility and characteristics of Anammox coupled to Fe（Ⅲ） reduction（termed Feammox） were investigated. After 160 days of cultivation, the conversion rate of ammonia in the reactor was above 80%, accompanied by the production of a large amount of NO3-and a small amount of NO2-. The total nitrogen removal rate was up to 71.8%. Furthermore,quantities of Fe（Ⅱ） were detected in the sludge fluorescence in situ hybridization（FISH） and denaturated gradient gel electrophoresis（DGGE） analyses further revealed that in the sludge, some Anammox bacteria were retained, and some microbes were enriched during the acclimatization process. We thus deduced that in Anammox sludge, Fe（Ⅲ） reduction takes place together with ammonia oxidation to NO2-and NO3-along with the Anammox process.展开更多
This paper reports that the split ring resonators and complementary split ring resonators are compounded to construct a novel compact composite metamaterial. The composite metamaterial exhibits a unique property of bl...This paper reports that the split ring resonators and complementary split ring resonators are compounded to construct a novel compact composite metamaterial. The composite metamaterial exhibits a unique property of blocking electromagnetic wave propagating in two directions near the resonant frequency. An example of two-element microstrip antenna array demonstrates that the developed metamaterial enables array performance that is an improvement in comparison with the traditional one, including mutual coupling suppression of 9.07 dB, remarkable side lobe suppression and gain improvement of 2.14 dB. The mechanism of performance enhancement is analysed based on the electric field and Poynting vector distributions in array. The present work not only is a meaningful exploration of new type composite metamaterial design, but also opens up possibilities for extensive metamaterial applications to antenna engineer.展开更多
The C–Ge cross-coupling offers a promising approach for the precise synthesis of organogermanes. However, the current methods are primarily effective in the germylation of organo(pseudo)halides. This work demonstrate...The C–Ge cross-coupling offers a promising approach for the precise synthesis of organogermanes. However, the current methods are primarily effective in the germylation of organo(pseudo)halides. This work demonstrates the possibility of transferring low-cost and easily available ester groups into organogermanes through the cleavage of stable C–O bonds. Primary,secondary, and even tertiary benzylic pivalates were coupled well with chlorogermanes. The reactions proceed under mild conditions. The scalability of this reaction and derivatization of the formed benzylgermanes are demonstrated.展开更多
Cross C–C bond formation of two vinyl electrophiles is a long-standing challenge in synthetic chemistry.Herein,we report a nickel-catalyzed reductive vinyl–vinyl coupling between vinyl triflates and boron-substitute...Cross C–C bond formation of two vinyl electrophiles is a long-standing challenge in synthetic chemistry.Herein,we report a nickel-catalyzed reductive vinyl–vinyl coupling between vinyl triflates and boron-substituted vinyl bromides.This new protocol offers facile access to dienylboronates with high structural complexity and molecular diversity.The reaction proceeds with a broad substrate scope under very mild conditions.The synthetic utility of the method is highlighted by its gram-scale reaction,modification of complex molecules,and diverse transformation of the products.展开更多
Zinc-promoted umpolung thiolation of alkyl electrophiles with masked sulfur transfer reagents in the absence of nickel or copper catalysis is described. This protocol proceeds via a SET process of Zn to electrophilic ...Zinc-promoted umpolung thiolation of alkyl electrophiles with masked sulfur transfer reagents in the absence of nickel or copper catalysis is described. This protocol proceeds via a SET process of Zn to electrophilic sulfur reagent followed by insertion of Zn into disulfide and nucleophilic thiolation, providing straightforward access to a wide range of alkyl sulfides with broad substrate scope. A neutral TMEDA-ligated four-coordinated zinc thiolate with tetrahedra geometry was synthesized, isolated and fully characterized by NMR, IR and X-ray analysis. More importantly, the chemical reactivity of this active intermediate has been investigated, enabling the construction of C-Se, C-Te, Sb-S and Bi-S bonds to prepare valuable sulfur-containing molecules and beyond.展开更多
基金Project (No. 2004C21032) supported by the Key Technologies R &D Program of Zhejiang Province, China
文摘Sm/TiCl4 system could well integrate the high reactivity of samarium（Ⅱ） and high deoxygenation capacity of low valent titanium within one system. In this paper, the intermolecular and intramolecular reductive coupling reactions of ketones with esters mediated by metallic samarium （Sm） and a catalytic amount of titanium tetrachloride （TiCl4） were successfully developed. A series of substituted ketones and cyclic β-keto-esters were prepared in moderate to good yields under reflux and neutral conditions.
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the financial support of the National Key R&D Program of China(No.2021YFF0701700)the National Science Foundation of China(Nos.22271264,21971228)。
文摘The synthesis methods ofα-fluoro-arylketones were well-established through electrophilic/nucleophilic fluorination and transition metal catalyzed cross-coupling.However,due to the site selectivity and substrate restriction,only a few cases have been developed to affordα-alkyl-α-fluoro-alkylketones.Herein,we report a general and efficient method of preparing diverseα-alkyl-α-fluoro-alkylketones via nickelcatalyzed reductive coupling reaction of monofluoroalkyl triflates with low-cost industrial raw material alkyl carboxylic acids.These transformations demonstrate high efficiency,mild conditions,and excellent functional group compatibility.This strategy provides a general and efficient method for the synthesis ofα-alkyl-α-fluoro-alkylketones。
文摘The reductive coupling reactions of aryl sulfonyl chloride induced by (TiCl4-Zn) reagent affords diaryl disulfide. However, reaction of aryl sulfonyl chloride with α,β-unsaturated ester under the same condition affords β-arylsulfo ester.
基金supported by the National Key R&D Program of China(No.2021YFF0701600)the National Natural Science Foundation of China(Nos.22371006 and 22271001).
文摘Compared with rare and expensive late-transition metals,rare-earth photocatalysts are much less investigated in synthetic chemistry,particularly concerning redox-inactive rare-earth metals.Herein,we describe a general strategy to realize the redox-inactive rare-earth photocatalysis by grafting a light-absorbing scaffold onto common ligands in rare-earth organometallics.Three guanidinate rare-earth complexes with photocatalytic functions were synthesized and found to exhibit higher catalytic efficiency than phenothiazine in the reductive homocoupling of benzyl bromides.These preliminary results illustrated that our“grafting”strategy could serve as a facile methodology for the construction of redox-inactive rare-earth photocatalysis systems.
基金the National Natural Science Foundation of China for its financial support(No.22071084).
文摘The construction of secondary alkylsilanes is a challenging subject in the synthetic community.The cross-coupling provides a practical solution to address this problem,but it typically relies on organometallic species.Herein,we report an Mn-mediated reductive C(sp^(3))-Si coupling to synthesize these compounds from alkyl and silyl electrophiles.This approach avoids the requirement for activation of Si-Cl by transition metals and thus allows for the coupling of various common chlorosilanes.The reaction proceeds under mild conditions and shows good functional group compatibility.The method offers access toα-silylated organophosphorus and sulfones with a scope that is complementary to those obtained from the established methods.
基金the National Natural Science Foundation of China(Nos.21790332,91956000,22188101)the Fundamental Research Funds for the Central Universities,and the Haihe Laboratory of Sustainable Chemical Transformations for their financial support.
文摘Herein we report a method for highly diastereoselective and enantioselective nickel-catalyzed reductive coupling of imines and unactivated alkenes.A monodentate chiral spiro phosphoramidite ligand is the key to controlling the enantioselectivity.This efficient,straightforward method allows for the construction of chiral benzocyclic and indole-fused cyclic amines with two contiguous stereogenic centers in good yields from readily accessible starting materials.
基金ProjectsupportedbytheNationalNaturalScienceFoundationofChina (No .2 0 0 72 0 33)andtheNaturalScienceFoundationofZhejiangProvince (No .2 980 6 7) .
文摘The intermolecular reductive coupling cyclization reactions of 1,1-dicyanoalkenes promoted by Sm-0/cat. HgCl2 were studied. A possible reaction mechanism was proposed.
基金support from Natural Science Foundation of Sichuan(No.2021YJ0413)Sichuan Key Laboratory of Medical Imaging(North Sichuan Medical College,No.SKLMI201901)+2 种基金Strategic Cooperation of Science and Technology between Nanchong City and North Sichuan Medical College(Nos.19SXHZ0441,19SXHZ0227)Chongqing Postdoctoral Science Foundation(No.cstc2020jcyj-bshX0052)China Postdoctoral Science Foundation(No.2020M673121).
文摘Herein,we report a borane-promoted reductive deoxygenation coupling reaction to synthesize sulfides.This reaction features excellent functional group compatibility,high efficiency,broad substrate scope,and application in late-stage functionalization of biomolecules.Preliminary mechanistic studies suggest diaryl sulfides are the intermediates of this reaction.Moreover,the real active aryl sulfide anions may be generated in situ with the aid of B2pin2 and react with alkyl tosylates through a concerted SN2 pathway.
基金the National Natural Science Foundation of China(No.22271245)the Jiangxi Province Science and Technology Project(Nos.20212AEI91002 and 20202ACBL213002)the Open Research Fund of School of Chemistry and Chemical Engineering,Henan Normal University(No.2021ZD01)for financial support.
文摘A new cooperative nickel reductive catalysis and N,N-dimethylformamide-mediated strategy for umpolung C–S radical reductive cross coupling of S-(trifluoromethyl)arylsulfonothioates with alkyl halides to produce alkyl aryl thioethers is described. This reaction features excellent selectivity, wide functionality tolerance, broad substrate scope, and facile late-stage modification of biologically relevant molecules.Mechanistic studies recognize initial generation of an amidyl radical anion via thermoinduced reduction of DMF with Sn, followed by umpolung reduction and single electron transfer of the nucleophilic sulfonyl moiety to form a sulphydryl radical and engage the Ni^(0)/Ni^(Ⅰ)/Ni^(Ⅲ)/Ni^(I) catalytic cycle.
文摘Light-driven CO_(2) reduction reaction(CO_(2)RR)to value-added ethylene(C2H4)holds significant promise for addressing energy and environmental challenges.While the high energy barriers for*CO intermediates hydrogenation and C–C coupling limit the C_(2)H_(4)generation.Herein,CuxP/g-C_(3)N_(4) heterojunction prepared by an in-situ phosphating technique,achieved collaborative photocatalytic CO_(2) and H2O,producing CO and C_(2)H_(4)as the main products.Notably,the selectivity of C_(2)H_(4)produced by CuxP/g-C_(3)N_(4) attained to 64.25%,which was 9.85 times that of CuxP(6.52%).Detailed time-resolution photoluminescence spectra,femtosecond transient absorption spectroscopy tests and density functional theory(DFT)calculation validate the ultra-fast interfacial electron transfer mechanism in CuxP/g-C_(3)N_(4) heterojunction.Successive*H on P sites caused by adsorbed H2O splitting with moderate hydrogenation ability enables the multi-step hydrogenation during CO_(2)RR process over CuxP/g-C_(3)N_(4).With the aid of mediated asymmetric Cu and P dual sites by g-C_(3)N_(4) nanosheet,the produced*CHO shows an energetically favorable for C–C coupling.The coupling formed*CHOCHO further accepts photoexcited efficient e–and*H to deeply produce C_(2)H_(4)according to the C^(2+)intermediates,which has been detected by in-situ diffuse reflectance infrared Fourier transform spectroscopy and interpreted by DFT calculation.The novel insight mechanism offers an essential understanding for the development of CuxP-based heterojunctions for photocatalytic CO_(2) to C^(2+)value-added fuels.
基金financial support from the National Natural Science Foundation of China(No.22001147)Taishan Scholars Project of Shandong Province(No.tsqn202103027)+1 种基金Distinguished Young Scholars of Shandong Province(Overseas)(No.2022HWYQ-001)Qilu Youth Scholar Funding of Shandong University。
文摘Aromatic aldehydes are the most fundamentally important compounds used in organic synthesis.The development of new synthetic methods for introduction of a formyl group into an organic scaffold is highly desirable.In this report,a nickel-catalyzed reductive coupling between aryl halides andα–chloro N-methoxyphthalimide has been documented for the synthesis of a diverse array of aromatic aldehydes.Because of mild reductive coupling conditions,excellent functional group tolerance,especially for substrates containing free-OH and-NH_(2),was observed.Due to the simple operation mode,a large library of aromatic aldehydes can be quickly constructed by this process.Moreover,the present protocol is amenable for late-stage functionalization of bioactive compound.A combined computational and experimental investigation suggested the reaction may undergo a reaction mechanism of active Ni(I)catalyst formation and the formation of key formyl radical intermediate under zinc reductive conditions.
基金Project supported by the National Natural Science Foundation of China(Grant No.61372034)
文摘In this paper, an ultra-compact single negative（SNG） electric waveguided metamaterial（WG-MTM） is first investigated and used to reduce the mutual coupling in E ＆ H planes of a dual-band microstrip antenna array. The proposed SNG electric WG-MTM unit cell is designed by etching two different symmetrical spiral lines on the ground, and has two stopbands operating at 1.86 GHz and 2.40 GHz. The circuit size is very compact, which is only λ_0/33.6 ×λ_0/15.1（where λ_0 is the wavelength at 1.86 GHz in free space）. Taking advantage of the dual-stopband property of the proposed SNG electric WG-MTM, a dual-band microstrip antenna array operating at 1.86 GHz and 2.40 GHz with very low mutual coupling is designed by embedding a cross shaped array of the proposed SNG electric WG-MTM. The measured and simulated results of the designed dual-band antenna array are in good agreement with each other, indicating that the mutual coupling of the fabricated dual-band antenna array realizes 9.8/11.1 d B reductions in the H plane, 8.5/7.9 d B reductions in the E plane at1.86 GHz and 2.40 GHz, respectively. Besides, the distance of the antenna elements in the array is only 0.35 λ_0（where λ_0 is the wavelength at 1.86 GHz in free space）. The proposed strategy is used for the first time to reduce the mutual coupling in E ＆ H planes of the dual-band microstrip antenna array by using ultra-compact SNG electric WG-MTM.
基金National Key R&D Program of China(2021YFF0701600 and 2022YFA1503702)National Natural Science Foundation of China(22325110,92256303,21821002,and 22171280)+3 种基金Strategic Priority Research Program of the Chinese Academy of Sciences(XDB0610000)Ningbo Natural Science Foundation(2022j017)Program of Shanghai Academic/Technology Research Leader(22XD1424900)CAS Youth Interdisciplinary Team(JCTD-2021-11).
文摘Divergent synthesis of valuable molecules through common starting materials and metal catalysis represents a longstanding challenge and a significant research goal.We here describe chemodivergent,highly enantio-and regioselective nickel-catalyzed reductive and dehydrogenative coupling reactions of alkynes,aldehydes,and silanes.A single chiral Ni-based catalyst is leveraged to directly prepare three distinct enantioenriched products(silyl-protected trisubstituted chiral allylic alcohols,oxasilacyclopentenes,and silicon-stereogenic oxasilacyclopentenes)in a single chemical operation.The use of a bulky C2-symmetric N-heterocyclic carbene(NHC)ligand for nickel catalyst is the key to enable simultaneous exceptional control of stereo-and regioselectivity(up to 99%enantiomeric excess(ee),>99:1 regiomeric ratio(rr),>99:1 E/Z)and high efficiency(up to 99%yield).Computational studies elucidate the origin of chemodivergency and reveal the critical role of NHC in the enantioselectivity-and rate-determining oxidative cyclization step via anη2-aldehydeη2-alkyne Ni five-centered transition state.We expected that the enantioselectiveη2-activation mode be widely applicable in other Ni-catalyzed carbonyl couplings.
基金supported by the Natural Science Foundation of China(Nos.51408387,51478284)Second Phase Program for Advantageous Characteristic Subject of Jiangsu Province,the Jiangsu Collaborative Innovation Center of Technology and Material of Water Treatment and Suzhou Key Lab of Separation and Purification Materials&Technologies(No.SZS201512)
文摘In recent years, there have been a number of reports on the phenomenon in which ferric iron（Fe（Ⅲ）） is reduced to ferrous iron [Fe（Ⅱ）] in anaerobic environments, accompanied by simultaneous oxidation of ammonia to NO2-, NO3-, or N2.However, studies on the relevant reaction characteristics and mechanisms are rare. Recently, in research on the effect of Fe（Ⅲ） on the activity of Anammox sludge, excess ammonia oxidization has also been found.Hence, in the present study, Fe（Ⅲ） was used to serve as the electron acceptor instead of NO2-,and the feasibility and characteristics of Anammox coupled to Fe（Ⅲ） reduction（termed Feammox） were investigated. After 160 days of cultivation, the conversion rate of ammonia in the reactor was above 80%, accompanied by the production of a large amount of NO3-and a small amount of NO2-. The total nitrogen removal rate was up to 71.8%. Furthermore,quantities of Fe（Ⅱ） were detected in the sludge fluorescence in situ hybridization（FISH） and denaturated gradient gel electrophoresis（DGGE） analyses further revealed that in the sludge, some Anammox bacteria were retained, and some microbes were enriched during the acclimatization process. We thus deduced that in Anammox sludge, Fe（Ⅲ） reduction takes place together with ammonia oxidation to NO2-and NO3-along with the Anammox process.
基金supported partially by the Hi-Tech Research and Development Program of China (Grant No. 2009AA01Z231)partially by Aviation Science Foundation (Grant No. 20090180007)+1 种基金partially by the New-century Talent Program of the Education Department of China (Grant No. NCET070154)partially by National Defence Research Funding (Grant Nos. 08DZ0229 and 09DZ0204)
文摘This paper reports that the split ring resonators and complementary split ring resonators are compounded to construct a novel compact composite metamaterial. The composite metamaterial exhibits a unique property of blocking electromagnetic wave propagating in two directions near the resonant frequency. An example of two-element microstrip antenna array demonstrates that the developed metamaterial enables array performance that is an improvement in comparison with the traditional one, including mutual coupling suppression of 9.07 dB, remarkable side lobe suppression and gain improvement of 2.14 dB. The mechanism of performance enhancement is analysed based on the electric field and Poynting vector distributions in array. The present work not only is a meaningful exploration of new type composite metamaterial design, but also opens up possibilities for extensive metamaterial applications to antenna engineer.
基金supported by the National Natural Science Foundation of China (22071084, 22271127)the Fundamental Research Funds for the Central Universities (lzujbky-2022-ey01)。
文摘The C–Ge cross-coupling offers a promising approach for the precise synthesis of organogermanes. However, the current methods are primarily effective in the germylation of organo(pseudo)halides. This work demonstrates the possibility of transferring low-cost and easily available ester groups into organogermanes through the cleavage of stable C–O bonds. Primary,secondary, and even tertiary benzylic pivalates were coupled well with chlorogermanes. The reactions proceed under mild conditions. The scalability of this reaction and derivatization of the formed benzylgermanes are demonstrated.
基金The authors thank the National Natural Science Foundation of China for financial support(nos.21772072 and 22071084)。
文摘Cross C–C bond formation of two vinyl electrophiles is a long-standing challenge in synthetic chemistry.Herein,we report a nickel-catalyzed reductive vinyl–vinyl coupling between vinyl triflates and boron-substituted vinyl bromides.This new protocol offers facile access to dienylboronates with high structural complexity and molecular diversity.The reaction proceeds with a broad substrate scope under very mild conditions.The synthetic utility of the method is highlighted by its gram-scale reaction,modification of complex molecules,and diverse transformation of the products.
基金the National Science Foundation of China(22001051)Zhejiang Provincial Natural Science Foundation of China(LY23B020002)for financial supportfunding from the STU Scientific Research Foundation for Talents(NTF20022)。
文摘Zinc-promoted umpolung thiolation of alkyl electrophiles with masked sulfur transfer reagents in the absence of nickel or copper catalysis is described. This protocol proceeds via a SET process of Zn to electrophilic sulfur reagent followed by insertion of Zn into disulfide and nucleophilic thiolation, providing straightforward access to a wide range of alkyl sulfides with broad substrate scope. A neutral TMEDA-ligated four-coordinated zinc thiolate with tetrahedra geometry was synthesized, isolated and fully characterized by NMR, IR and X-ray analysis. More importantly, the chemical reactivity of this active intermediate has been investigated, enabling the construction of C-Se, C-Te, Sb-S and Bi-S bonds to prepare valuable sulfur-containing molecules and beyond.
