New methods for dehydrogenation of steroidal 2,5(10)-dienes with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) or pyridinium hydrobromide perbromide(PHP,Py·HBr·Br_2) to aromatic A ring steroid in quantitat...New methods for dehydrogenation of steroidal 2,5(10)-dienes with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) or pyridinium hydrobromide perbromide(PHP,Py·HBr·Br_2) to aromatic A ring steroid in quantitative yield in short time are described.展开更多
The reaction mechanisms of diene polymerization with homogeneous rare earth catalyst are studied by means of the spectra of ~1H-NMR, one-and two-dimensions ^(13)C-NMR. Based on the data of above NMR spectra, it is pro...The reaction mechanisms of diene polymerization with homogeneous rare earth catalyst are studied by means of the spectra of ~1H-NMR, one-and two-dimensions ^(13)C-NMR. Based on the data of above NMR spectra, it is proposed that the polymerization reaction proceeds according to the following mechanism: η~4-diene (cis-trans-)and η~3-allyl (syn-anti-).展开更多
With the increasing demand for homoallylic silanes and allylic silanes,the highly efficient and regioselective hydrosilylations of conjugated dienes are urgently needed.Herein,we developed a Ni-catalyzed regiodivergen...With the increasing demand for homoallylic silanes and allylic silanes,the highly efficient and regioselective hydrosilylations of conjugated dienes are urgently needed.Herein,we developed a Ni-catalyzed regiodivergent hydrosilylation of aromatic conjugated dienes by adjusting the temperature and ligands.Under low temperature(-30℃),an eternal-ligand-free system(Ni/t-BuOk)can efficiently facilitate the 3,4-anti-Markovnikov hydrosilylation to provide homoallylic silanes via electrophilic activation process;under room temperature(25℃),a ligand-controlled system(Ni/t-BuOk/PPh3)can eventuate the 3,4-Markovnikov hydrosilylation to produce allylic silanes via Chalk-Harrod process.Both systems are compatible with various conjugated dienes and primary silanes in excellent yields andregioselectivities.展开更多
Hydrocarbonylation of conjugated dienes is one of the most promising yet challenging methods for the synthesis of carbonyl compounds.Herein,we reported the development of an unprecedented palladium-catalyzed branched ...Hydrocarbonylation of conjugated dienes is one of the most promising yet challenging methods for the synthesis of carbonyl compounds.Herein,we reported the development of an unprecedented palladium-catalyzed branched selective 3,4-hydroaminocarbonylation of 1,3-dienes with CO and amines hydrochloride to affordβ,γ-unsaturated amides.This reaction employs readily available starting materials(including anilines,amines,amino acids,peptides,aryl-1,3-dienes,alyl-1,3-dienes)and tolerates a wide range of functional groups,thus providing a facile and effective approach to access a diverse array ofα-substitutedβ,γ-unsaturated amides.Mechanistic investigations suggested that the hydropalladation of dienes is irreversible,and the insertion of CO into the allyl-Pd species is probably the rate-limiting step.展开更多
Olefins are very easily accessible compounds which are both popular substrates in synthetic chemistry and good ligands in the organometallic complexes.This dual character makes olefins a rich source of chiral ligands ...Olefins are very easily accessible compounds which are both popular substrates in synthetic chemistry and good ligands in the organometallic complexes.This dual character makes olefins a rich source of chiral ligands and catalysts for asymmetric catalysis.Herein,we willbriefly summarize our studies on the development of chiral diene ligands for transition-metal catalyzed asymmetric reactions and chiral FLP catalysts for asymmetric metal-free hydrogenations and hydrosilylations.Several acyclic chiral diene ligands as well as P/olefin and S/olefin hybrid ligands were developed for Rh or Pd-catalyzed asymmetric reactions.With these ligands in hand,we further put forward a novel strategy for acquiring chiral FLP catalysts via the in situ hydroboration of chiral dienes with Piers'borane.These catalysts proved to be highly ffective for asymmetric metal-free hydrogenations and hydrosilylations of imines,ilyl enol ethers,ketones,and aromatic N-heterocycles.展开更多
Polymerization of 2-(4-halophenyl)-1,3-butadiene(2-XPB) and their copolymerization with isoprene using a yttrium catalyst have been examined. The β-diketiminato yttrium bis(alkyl) complex(1) activated by [Ph_3 C][B(C...Polymerization of 2-(4-halophenyl)-1,3-butadiene(2-XPB) and their copolymerization with isoprene using a yttrium catalyst have been examined. The β-diketiminato yttrium bis(alkyl) complex(1) activated by [Ph_3 C][B(C_(6) F_(5))_(4)] and Ali Bu3 shows high cis-1,4-selectivity(>98%) for the polymerization of 2-XPB(2-XPB = 2-FPB, 2-Cl PB and 2-Br PB) to afford halogenated plastic poly(dienes) with glass transition temperatures of30–55 ℃. Moreover, the copolymerization of 2-XPB with isoprene(IP) has also been achieved by this catalyst, and the insertion ratios of 2-XPB can be facilely tuned in a full range of 0%–100% simply by changing the 2-XPB-to-IP ratio. Quantitative hydrogenation of cis-1,4-poly(2-XPB) results in perfect alternating ethylene-halostyrene copolymers, and an alternating copolymer of 4-vinylbenzoic acid with ethylene is obtained by a consecutive reaction of ethylene-4-bromostyrene copolymer with ^(n)Bu Li, CO_(2) and HCl.展开更多
Regiodivergent 1,2-hydroboration of 1,3-dienes with pinacolborane has been accomplished by well-defined cobalt complexes of different bidentate ligands. The iminopyridine-cobalt system is selective for Markovnikov 1,2...Regiodivergent 1,2-hydroboration of 1,3-dienes with pinacolborane has been accomplished by well-defined cobalt complexes of different bidentate ligands. The iminopyridine-cobalt system is selective for Markovnikov 1,2-hydroboration to form allylboronates, while the FOXAP-cobalt(FOXAP=(S)-1-(diphenylphosphino)-2-[(S)-4-isopropyloxazolin-2-yl]ferrocene) catalyst effects the complementary anti-Markonikv 1,2-hydroboration to afford homoallyboronates with high regioselectivity.展开更多
The deepening of the studies on essentials of rare earth coordination catalyst brings about more and more reports on model compounds as active centre of the catalyst. Among them the most significant researches are tho...The deepening of the studies on essentials of rare earth coordination catalyst brings about more and more reports on model compounds as active centre of the catalyst. Among them the most significant researches are those with identification of the crystal structures of compounds.展开更多
in this work, the phosphine-catalyzed annulation reactions between modified allylic derivatives and polar 1,1-dicyano-1,3-dienes have been studied. In the catalysis of PPh3 （20 mol%）, a [4 ＋ 1 ] annulation reaction...in this work, the phosphine-catalyzed annulation reactions between modified allylic derivatives and polar 1,1-dicyano-1,3-dienes have been studied. In the catalysis of PPh3 （20 mol%）, a [4 ＋ 1 ] annulation reaction is realized between a series of l,l-dicyano-2,4-diaryl-1,3-dienes and ethoxycarbonyl-activated allylic acetate, producing polysubstituted cyclopentenes in modest to excellent yields. It is also observed that the substituents of both 1,3-dienes and allylic derivatives have a significant influence on the annulation mode： under the catalysis of PPh3 or PBu3 （20 mol%）, regioselective [3 ＋ 2] annulation products are formed from differently substituted substratcs.展开更多
Herein,we present a strategy for the formation of 2-fluoro-1,3-diene derivatives via rhodium-catalyzed direct C(sp2)-C(sp2) cross-coupling of gem-difluoroalkenes and acrylamides.By merging Rh(Ⅲ)-catalyzed C(sp2)-H bo...Herein,we present a strategy for the formation of 2-fluoro-1,3-diene derivatives via rhodium-catalyzed direct C(sp2)-C(sp2) cross-coupling of gem-difluoroalkenes and acrylamides.By merging Rh(Ⅲ)-catalyzed C(sp2)-H bond activation and nucleophilic addition/F-elimination of gem-difluoroalkene,an efficient defluorinative vinylation reaction is uncovered,which leads to the generation of 2-fluoro-1,3-dienes in moderate to good yields with excellent stereoselectivity under mild conditions.Preliminary mechanistic study suggests unique effects of fluorine substituents which allow the reactivity profile not observed with the congeners bearing heavier halides.展开更多
1 Results Polymerization of butadiene,isoprene and styrene and binary copolymerization of styrene with butadiene and isoprene were investigated using the catalyst Ti(η5-C5H5)(η2-MBMP)Cl (1) (MBMP=2,2′-methylenebis(...1 Results Polymerization of butadiene,isoprene and styrene and binary copolymerization of styrene with butadiene and isoprene were investigated using the catalyst Ti(η5-C5H5)(η2-MBMP)Cl (1) (MBMP=2,2′-methylenebis(6-tert-butyl-4-methylphenoxo) activated with methylaluminoxane (MAO).Syndiotactic polystyrene, cis-1,4- polybutadiene and cis-1,4-polyisoprene were obtained in good yields at 50 °C.Binary copolymerization of styrene with butadiene yielded block copolymers containing segments of cis-1,4-polybut...展开更多
The regio-and enantioselective functionalization of 1,3-dienes has become a powerful tool for the synthesis of allylic compounds,yet it remains a challenge for aliphatic dienes.Herein,we report a nickel-catalyzed asym...The regio-and enantioselective functionalization of 1,3-dienes has become a powerful tool for the synthesis of allylic compounds,yet it remains a challenge for aliphatic dienes.Herein,we report a nickel-catalyzed asymmetric hydroarylation reaction of aliphatic and aromatic dienes with indoles to afford chiral indole derivatives.展开更多
A series of metal complexes were designed and synthesized and a novel binuclear magnesium complex has been selected, namely [Mg-2(dien)Cl(OH2)(2)]Cl-2 . H2O (dien=diethylene-triamine), which can cleave the plasmid pBR...A series of metal complexes were designed and synthesized and a novel binuclear magnesium complex has been selected, namely [Mg-2(dien)Cl(OH2)(2)]Cl-2 . H2O (dien=diethylene-triamine), which can cleave the plasmid pBR322 DNA effectively in close to physiological condition without adding any external materials. Through biological and chemical methods, especially the comparative experiments, we find the interaction between the complex and DNA belongs to hydrolytic mechanism.展开更多
文摘New methods for dehydrogenation of steroidal 2,5(10)-dienes with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) or pyridinium hydrobromide perbromide(PHP,Py·HBr·Br_2) to aromatic A ring steroid in quantitative yield in short time are described.
基金The Project is supported by "Laboratory of Physics & Chemistry, Academia Sinica" and "National Natural Science Foundation of China"
文摘The reaction mechanisms of diene polymerization with homogeneous rare earth catalyst are studied by means of the spectra of ~1H-NMR, one-and two-dimensions ^(13)C-NMR. Based on the data of above NMR spectra, it is proposed that the polymerization reaction proceeds according to the following mechanism: η~4-diene (cis-trans-)and η~3-allyl (syn-anti-).
文摘With the increasing demand for homoallylic silanes and allylic silanes,the highly efficient and regioselective hydrosilylations of conjugated dienes are urgently needed.Herein,we developed a Ni-catalyzed regiodivergent hydrosilylation of aromatic conjugated dienes by adjusting the temperature and ligands.Under low temperature(-30℃),an eternal-ligand-free system(Ni/t-BuOk)can efficiently facilitate the 3,4-anti-Markovnikov hydrosilylation to provide homoallylic silanes via electrophilic activation process;under room temperature(25℃),a ligand-controlled system(Ni/t-BuOk/PPh3)can eventuate the 3,4-Markovnikov hydrosilylation to produce allylic silanes via Chalk-Harrod process.Both systems are compatible with various conjugated dienes and primary silanes in excellent yields andregioselectivities.
基金supported by the National Natural Science Foundation of China(22171224,21971204)the Innovation Capability Support Program of Shaanxi Province(2020TD-022)the Fund of Education Department of Shaanxi Provincial Government(22JP082)。
文摘Hydrocarbonylation of conjugated dienes is one of the most promising yet challenging methods for the synthesis of carbonyl compounds.Herein,we reported the development of an unprecedented palladium-catalyzed branched selective 3,4-hydroaminocarbonylation of 1,3-dienes with CO and amines hydrochloride to affordβ,γ-unsaturated amides.This reaction employs readily available starting materials(including anilines,amines,amino acids,peptides,aryl-1,3-dienes,alyl-1,3-dienes)and tolerates a wide range of functional groups,thus providing a facile and effective approach to access a diverse array ofα-substitutedβ,γ-unsaturated amides.Mechanistic investigations suggested that the hydropalladation of dienes is irreversible,and the insertion of CO into the allyl-Pd species is probably the rate-limiting step.
基金We are grateful for the financial support from the National Natural Science Foundation of China(21521002 and 21825108).
文摘Olefins are very easily accessible compounds which are both popular substrates in synthetic chemistry and good ligands in the organometallic complexes.This dual character makes olefins a rich source of chiral ligands and catalysts for asymmetric catalysis.Herein,we willbriefly summarize our studies on the development of chiral diene ligands for transition-metal catalyzed asymmetric reactions and chiral FLP catalysts for asymmetric metal-free hydrogenations and hydrosilylations.Several acyclic chiral diene ligands as well as P/olefin and S/olefin hybrid ligands were developed for Rh or Pd-catalyzed asymmetric reactions.With these ligands in hand,we further put forward a novel strategy for acquiring chiral FLP catalysts via the in situ hydroboration of chiral dienes with Piers'borane.These catalysts proved to be highly ffective for asymmetric metal-free hydrogenations and hydrosilylations of imines,ilyl enol ethers,ketones,and aromatic N-heterocycles.
基金financially supported by the National Natural Science Foundation of China (Nos. 21634007 and 51773193)the Department of Science and Technology of Jilin Province(No. 20180101171JC)。
文摘Polymerization of 2-(4-halophenyl)-1,3-butadiene(2-XPB) and their copolymerization with isoprene using a yttrium catalyst have been examined. The β-diketiminato yttrium bis(alkyl) complex(1) activated by [Ph_3 C][B(C_(6) F_(5))_(4)] and Ali Bu3 shows high cis-1,4-selectivity(>98%) for the polymerization of 2-XPB(2-XPB = 2-FPB, 2-Cl PB and 2-Br PB) to afford halogenated plastic poly(dienes) with glass transition temperatures of30–55 ℃. Moreover, the copolymerization of 2-XPB with isoprene(IP) has also been achieved by this catalyst, and the insertion ratios of 2-XPB can be facilely tuned in a full range of 0%–100% simply by changing the 2-XPB-to-IP ratio. Quantitative hydrogenation of cis-1,4-poly(2-XPB) results in perfect alternating ethylene-halostyrene copolymers, and an alternating copolymer of 4-vinylbenzoic acid with ethylene is obtained by a consecutive reaction of ethylene-4-bromostyrene copolymer with ^(n)Bu Li, CO_(2) and HCl.
基金supported by the National Key R&D Program of China (2016YFA0202900, 2015CB856600)the National Natural Science Foundation of China (21825109, 21432011, 21572255, 21732006)+1 种基金Chinese Academy of Sciences (XDB20000000, QYZDB-SSWSLH016)Science and Technology Commission Shanghai Municipality (17JC1401200)
文摘Regiodivergent 1,2-hydroboration of 1,3-dienes with pinacolborane has been accomplished by well-defined cobalt complexes of different bidentate ligands. The iminopyridine-cobalt system is selective for Markovnikov 1,2-hydroboration to form allylboronates, while the FOXAP-cobalt(FOXAP=(S)-1-(diphenylphosphino)-2-[(S)-4-isopropyloxazolin-2-yl]ferrocene) catalyst effects the complementary anti-Markonikv 1,2-hydroboration to afford homoallyboronates with high regioselectivity.
基金Project supported by the National Natural Science Foundation of China.
文摘The deepening of the studies on essentials of rare earth coordination catalyst brings about more and more reports on model compounds as active centre of the catalyst. Among them the most significant researches are those with identification of the crystal structures of compounds.
基金Acknowledgement Financial support from National Natural Science Foundation of China （Nos. 21072100 21121002 21272119） is gratefully acknowledged.
文摘in this work, the phosphine-catalyzed annulation reactions between modified allylic derivatives and polar 1,1-dicyano-1,3-dienes have been studied. In the catalysis of PPh3 （20 mol%）, a [4 ＋ 1 ] annulation reaction is realized between a series of l,l-dicyano-2,4-diaryl-1,3-dienes and ethoxycarbonyl-activated allylic acetate, producing polysubstituted cyclopentenes in modest to excellent yields. It is also observed that the substituents of both 1,3-dienes and allylic derivatives have a significant influence on the annulation mode： under the catalysis of PPh3 or PBu3 （20 mol%）, regioselective [3 ＋ 2] annulation products are formed from differently substituted substratcs.
基金We gratefully acknowledge the financial support of the''Thousand Talents Planw Youth Program,the^Jiangsu Specially-Appointed Professor Planw,the National Natural Science Foundation of China(No.21871138)the Natural Science Foundation of Jiangsu Province(No.BK20170984).
文摘Herein,we present a strategy for the formation of 2-fluoro-1,3-diene derivatives via rhodium-catalyzed direct C(sp2)-C(sp2) cross-coupling of gem-difluoroalkenes and acrylamides.By merging Rh(Ⅲ)-catalyzed C(sp2)-H bond activation and nucleophilic addition/F-elimination of gem-difluoroalkene,an efficient defluorinative vinylation reaction is uncovered,which leads to the generation of 2-fluoro-1,3-dienes in moderate to good yields with excellent stereoselectivity under mild conditions.Preliminary mechanistic study suggests unique effects of fluorine substituents which allow the reactivity profile not observed with the congeners bearing heavier halides.
文摘1 Results Polymerization of butadiene,isoprene and styrene and binary copolymerization of styrene with butadiene and isoprene were investigated using the catalyst Ti(η5-C5H5)(η2-MBMP)Cl (1) (MBMP=2,2′-methylenebis(6-tert-butyl-4-methylphenoxo) activated with methylaluminoxane (MAO).Syndiotactic polystyrene, cis-1,4- polybutadiene and cis-1,4-polyisoprene were obtained in good yields at 50 °C.Binary copolymerization of styrene with butadiene yielded block copolymers containing segments of cis-1,4-polybut...
基金the National Natural Science Foundation of China(nos.21790330 and 91956000)and the“111”Project(no.B06005)of the Ministry of Education of China for financial support.
文摘The regio-and enantioselective functionalization of 1,3-dienes has become a powerful tool for the synthesis of allylic compounds,yet it remains a challenge for aliphatic dienes.Herein,we report a nickel-catalyzed asymmetric hydroarylation reaction of aliphatic and aromatic dienes with indoles to afford chiral indole derivatives.
文摘A series of metal complexes were designed and synthesized and a novel binuclear magnesium complex has been selected, namely [Mg-2(dien)Cl(OH2)(2)]Cl-2 . H2O (dien=diethylene-triamine), which can cleave the plasmid pBR322 DNA effectively in close to physiological condition without adding any external materials. Through biological and chemical methods, especially the comparative experiments, we find the interaction between the complex and DNA belongs to hydrolytic mechanism.
