Low-valent titanium reagent prepared from titanium tetrachloride and zinc was empolyed to induce the coupling reaction of thiocyanates with tetrahydrofuran yield alkyl 4-hydroxy butyl sulfide and isocyanate yield subs...Low-valent titanium reagent prepared from titanium tetrachloride and zinc was empolyed to induce the coupling reaction of thiocyanates with tetrahydrofuran yield alkyl 4-hydroxy butyl sulfide and isocyanate yield substituted urea.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
Treatment of acyl chlorides and diaryl ketones with an activated Ti(o)reagent,prepared by reduction of TiCl_4 with Zn powder,effects an intermolecular reductive cross-coupling reaction leading to ketones.
The intramolecular reductive coupling reaction of 1,6-bis(subshtuted indolyl)hexane-1,6-dione using zero-valent titanium reagent as catalyst proderes the novel photochromic 1,2-diheterocyclic cyclohexenes 2, together ...The intramolecular reductive coupling reaction of 1,6-bis(subshtuted indolyl)hexane-1,6-dione using zero-valent titanium reagent as catalyst proderes the novel photochromic 1,2-diheterocyclic cyclohexenes 2, together with unexpected compounds 3展开更多
We report the concise and protecting-group-free enantioselective total syntheses of circumdatins F and H.In view of the extreme importance of analogs of quinazolinone alkaloids in drug research and discovery,four anal...We report the concise and protecting-group-free enantioselective total syntheses of circumdatins F and H.In view of the extreme importance of analogs of quinazolinone alkaloids in drug research and discovery,four analogs of bioactive quinazolinobenzodiazepine alkaloids,including demethoxycircumdatin H(12)and N-demethyl-benzomalvin A(13),have been synthesized.The method is based on the low-valent titanium-promoted intra-molecular reductive coupling of imides with o-nitrobenzimides,which yielded quinazolino[3,2-a][1,4]benzodi-azepines under mild conditions.In addition,heptacyclic dehydraasperlicin E(16)has been synthesized from asper-licin C by a NCS-mediated dehydra-cyclization reaction.展开更多
The electroreduction of CO_(2)(CO_(2)RR)into value-added chemicals is a sustainable strategy for mitigating global warming and managing the global carbon balance.However,developing an efficient and selective catalyst ...The electroreduction of CO_(2)(CO_(2)RR)into value-added chemicals is a sustainable strategy for mitigating global warming and managing the global carbon balance.However,developing an efficient and selective catalyst is still the central challenge.Here,we developed a simple two-step pyrolysis method to confine low-valent Ni-based nanoparticles within nitrogen-doped carbon(Ni-NC).As a result,such Ni-based nanoparticles can effectively reduce CO_(2)to CO,with a maximum CO Faradaic efficiency(FE)of 98%at an overpotential of 0.8 V,as long as good stability.Experimental and the density functional theory(DFT)calculation results reveal that low-valent Ni plays a key role in activity and selectivity enhancement.This study presents a new understanding of Ni-based CO_(2)RR,and provides a simple,scalable approach to the synthesis of low-valent catalysts towards efficient CO_(2)RR.展开更多
A short and facile synthesis of a series of 1,2-dihydroquiazolin-4(3H)-ones was accomplished in good yields via novel reductive cyclization of o-nitrobenzamides with ketones promoted by TiCl4/Zn system. The structure ...A short and facile synthesis of a series of 1,2-dihydroquiazolin-4(3H)-ones was accomplished in good yields via novel reductive cyclization of o-nitrobenzamides with ketones promoted by TiCl4/Zn system. The structure was established on the basis of elemental analysis, IR, 1H NMR and confirmed by a single-crystal X-ray diffraction analysis. This method has the advantages of easily accessible starting materials, convenient manipulation and moderate to high yields.展开更多
Low-valence transition metallic complexes have drawn longstanding attention due to their high reactivity toward catalytic transformation of various small molecules.Among these known complexes,the low-valence metal cen...Low-valence transition metallic complexes have drawn longstanding attention due to their high reactivity toward catalytic transformation of various small molecules.Among these known complexes,the low-valence metal centres are commonly stabilized by neutral bulky ligands with strong electron-donating capacity.However,low-valence bimetallic complexes supported by anionic sulfur and cyclopentadienyl ligands are still difficult to obtain in high isolated yield.Herein,we report the synthesis and characteri-zation of two scarce thiolate-bridged Co^(I)Co^(II)and Co^(I)Co^(I)complexes bearing sterically demanding ligands through two stepwise one-electron reduction processes.Interestingly,the Co^(I)Co^(II)complex can facilely promote the homolytic cleavage of dihydrogen across the short Co−Co metallic bond to give a Co^(II)Co III dihydride bridged complex,which is capable of serving as a competent hydrogen atom transfer agent.Moreover,the anionic Co^(I)Co^(I)complex can trigger a stepwise hydrogen generation cycle involving several isolated and structurally well-characterized intermediates.展开更多
文摘Low-valent titanium reagent prepared from titanium tetrachloride and zinc was empolyed to induce the coupling reaction of thiocyanates with tetrahydrofuran yield alkyl 4-hydroxy butyl sulfide and isocyanate yield substituted urea.
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.
文摘Treatment of acyl chlorides and diaryl ketones with an activated Ti(o)reagent,prepared by reduction of TiCl_4 with Zn powder,effects an intermolecular reductive cross-coupling reaction leading to ketones.
文摘The intramolecular reductive coupling reaction of 1,6-bis(subshtuted indolyl)hexane-1,6-dione using zero-valent titanium reagent as catalyst proderes the novel photochromic 1,2-diheterocyclic cyclohexenes 2, together with unexpected compounds 3
基金support from the National Natural Science Foundation of China(Nos.21332007 and 21472153)the Program for Changjiang Scholars and Innovative Research Team in University(PCSIRT)of Ministry of Education.
文摘We report the concise and protecting-group-free enantioselective total syntheses of circumdatins F and H.In view of the extreme importance of analogs of quinazolinone alkaloids in drug research and discovery,four analogs of bioactive quinazolinobenzodiazepine alkaloids,including demethoxycircumdatin H(12)and N-demethyl-benzomalvin A(13),have been synthesized.The method is based on the low-valent titanium-promoted intra-molecular reductive coupling of imides with o-nitrobenzimides,which yielded quinazolino[3,2-a][1,4]benzodi-azepines under mild conditions.In addition,heptacyclic dehydraasperlicin E(16)has been synthesized from asper-licin C by a NCS-mediated dehydra-cyclization reaction.
基金the financial support from the Shenzhen Science and Technology Research Grant(No.JCYJ20200109140416788,China)the Chemistry and Chemical Engineering Guangdong Laboratory(No.1922018,China)National Key R&D Program of China(No.2020YFB0704500)。
文摘The electroreduction of CO_(2)(CO_(2)RR)into value-added chemicals is a sustainable strategy for mitigating global warming and managing the global carbon balance.However,developing an efficient and selective catalyst is still the central challenge.Here,we developed a simple two-step pyrolysis method to confine low-valent Ni-based nanoparticles within nitrogen-doped carbon(Ni-NC).As a result,such Ni-based nanoparticles can effectively reduce CO_(2)to CO,with a maximum CO Faradaic efficiency(FE)of 98%at an overpotential of 0.8 V,as long as good stability.Experimental and the density functional theory(DFT)calculation results reveal that low-valent Ni plays a key role in activity and selectivity enhancement.This study presents a new understanding of Ni-based CO_(2)RR,and provides a simple,scalable approach to the synthesis of low-valent catalysts towards efficient CO_(2)RR.
基金Project supported by the Natural Science Foundation of Education Committee of Jiangsu Province (No. 03KJB150136).
文摘A short and facile synthesis of a series of 1,2-dihydroquiazolin-4(3H)-ones was accomplished in good yields via novel reductive cyclization of o-nitrobenzamides with ketones promoted by TiCl4/Zn system. The structure was established on the basis of elemental analysis, IR, 1H NMR and confirmed by a single-crystal X-ray diffraction analysis. This method has the advantages of easily accessible starting materials, convenient manipulation and moderate to high yields.
基金supported by the National Natural Science Foun-dation of China(Nos.21690064,22001031)Key Laboratory of Bio-based Chemicals of Liaoning Province of China,the“111”project of the Ministry of Education of China and the Fundamental Research Funds for the Central Universities(No.DUT19RC(3)013).
文摘Low-valence transition metallic complexes have drawn longstanding attention due to their high reactivity toward catalytic transformation of various small molecules.Among these known complexes,the low-valence metal centres are commonly stabilized by neutral bulky ligands with strong electron-donating capacity.However,low-valence bimetallic complexes supported by anionic sulfur and cyclopentadienyl ligands are still difficult to obtain in high isolated yield.Herein,we report the synthesis and characteri-zation of two scarce thiolate-bridged Co^(I)Co^(II)and Co^(I)Co^(I)complexes bearing sterically demanding ligands through two stepwise one-electron reduction processes.Interestingly,the Co^(I)Co^(II)complex can facilely promote the homolytic cleavage of dihydrogen across the short Co−Co metallic bond to give a Co^(II)Co III dihydride bridged complex,which is capable of serving as a competent hydrogen atom transfer agent.Moreover,the anionic Co^(I)Co^(I)complex can trigger a stepwise hydrogen generation cycle involving several isolated and structurally well-characterized intermediates.
基金Project supported by the National Natural Science Foundation of China （No. 21072144） and the Major Basic Research Project of the Natural Science Foundation of the Jiangsu Higher Education Institutions （No. 10KJAI50049）.
