-An oxetane ring can be constructed from 5 α-acyloxy-Δ4(20) -taxoids with osmylation as the first step in the usual manner. The innovation reported here is the use of an intramolecularly available acyl group for the...-An oxetane ring can be constructed from 5 α-acyloxy-Δ4(20) -taxoids with osmylation as the first step in the usual manner. The innovation reported here is the use of an intramolecularly available acyl group for the protection of 20-OH by an unexpected 5-to 20-migration under slightly basic conditions.展开更多
A rare earth Schiff base complex:lanthanum tris(N-phenylethyl-3,5-di-t-butylsalicylaldiminato)s [La(OPEBS)_3] was successfully applied as single component initiator for the ring-opening polymerization of 1,4-dioxan-2-...A rare earth Schiff base complex:lanthanum tris(N-phenylethyl-3,5-di-t-butylsalicylaldiminato)s [La(OPEBS)_3] was successfully applied as single component initiator for the ring-opening polymerization of 1,4-dioxan-2-one (PDO) in bulk.The influence of reaction conditions,such as polymerization temperature,the molar ratio of the monomer to initiator (M/I) on the monomer conversion and molecular weight of the polymer has been investigated.Poly(1,4-dioxan-2-one) with a viscosity-average molecular weight (My) o...展开更多
Various bond modes of the M-C（C5 ring） exist in metallocene compounds of group 14 heavier elements,mostly due to an intricate interaction between the lone electron pairs at the M center and the 6 p-electrons of the ...Various bond modes of the M-C（C5 ring） exist in metallocene compounds of group 14 heavier elements,mostly due to an intricate interaction between the lone electron pairs at the M center and the 6 p-electrons of the C5 ring.The tin（Ⅱ） metallocene complexes LSn R（L = HC[CMe（N-2,6-iPr2C6H3）]2,R = cyclopentadienyl,C5H5（1）; indenyl,C9H7（2）; fluorenyl,C（13）H9（3）） stabilized by the β-diketiminato ligand were prepared and utilized in the study on their solid and solution state structures.X-ray single-crystal diffraction data revealed an η~1-mode of the Sn-C（C5 ring） bond in each 1~3.However,the room temperature ~1H NMR spectral studies disclosed such a fluxional bonding mode in solution.The 119 Sn NMR studies suggested a quadruple coordination nature of the Sn center in 1 while the triple coordination manner was for the Sn atom in both 2 and 3.Then the variable-temperature（25~–75 ℃） ~1H NMR spectral studies for each 1~3 were performed,which detected the relaxation state structures of 1~3 at lower temperature.All of these results indicate a stereochemical activity of the lone electron pairs at the tin（Ⅱ） atom that definitely has an electronic interaction with the 6 p-electrons of the C5 ring.The observed Sn-C（C5 ring） bond modes appear influenced by either the metallocene size or the compound state existed.展开更多
Reaction products of 2,4,6-tris(4-phenyl-phenoxy)-1,3,5-triazine derived from 4-phenylphenol cyanate ester and phenyl glycidyl ether were analyzed. In addition to an isocyanurate compound and an oxazolidone compound w...Reaction products of 2,4,6-tris(4-phenyl-phenoxy)-1,3,5-triazine derived from 4-phenylphenol cyanate ester and phenyl glycidyl ether were analyzed. In addition to an isocyanurate compound and an oxazolidone compound which were well known as reaction products of cyanate esters and epoxy resins, compounds with hybrid ring structure of cyanurate/isocyanurate were determined. Gibbs free energies of the compound having hybrid ring structure of cyanurate/isocyanurate with two isocyanurate moiety were found to be lower than that of the compound with cyanurate ring structure through calculations. Calculation data supported the existence of hybrid ring structure of cy-anurate/isocyanurate. It was revealed that isomerization from cyanurate to isocyanurate occurs via hybrid ring structure of cyanurate/isocyanurate in the reaction of aryl cyanurate and epoxy.展开更多
目的探讨线粒体E3泛素蛋白连接酶MARCH5[membrane-associated ring finger(C3HC4)5]在肝癌转移中的调控作用。方法(1)采用生物信息学方法分析TCGA库中肝癌细胞中MARCH5表达是否发生了异常改变,并进一步分析MARCH5表达与肝癌患者预后相...目的探讨线粒体E3泛素蛋白连接酶MARCH5[membrane-associated ring finger(C3HC4)5]在肝癌转移中的调控作用。方法(1)采用生物信息学方法分析TCGA库中肝癌细胞中MARCH5表达是否发生了异常改变,并进一步分析MARCH5表达与肝癌患者预后相关性。(2)采用细胞生物学方法下调人肝癌细胞HLE中MARCH5表达后,利用划痕实验与Transwell侵袭实验分析对细胞迁移与侵袭能力的影响;下调人肝癌细胞HLE中MARCH5表达后,利用qRT-PCR实验分析对上皮间质转化标志分子(上皮标志Ecadherin与ZO-1;间质标志N-cadherin与Vimentin)表达的影响。结果(1)与正常肝组织相比,肝癌组织中MARCH5表达显著上调(P<0.001),尤其在转移性肝癌组织中(P<0.001);MARCH5高表达与患者不良预后显著相关(P=0.027)。(2)下调MARCH5表达可显著抑制人肝癌细胞HLE的迁移与侵袭能力;下调MARCH5表达后HLE细胞中上皮细胞标志分子E-cadherin与ZO-1表达显著上调,而间质细胞标志分子Ncadherin与Vimentin表达显著下调(P<0.05)。结论MARCH5表达上调可能通过诱导上皮间质转化促进肝癌细胞的迁移与侵袭。展开更多
文摘-An oxetane ring can be constructed from 5 α-acyloxy-Δ4(20) -taxoids with osmylation as the first step in the usual manner. The innovation reported here is the use of an intramolecularly available acyl group for the protection of 20-OH by an unexpected 5-to 20-migration under slightly basic conditions.
基金supported by the National Natural Science Foundation of China (Key program,Nos.G20434020 and G20774078).
文摘A rare earth Schiff base complex:lanthanum tris(N-phenylethyl-3,5-di-t-butylsalicylaldiminato)s [La(OPEBS)_3] was successfully applied as single component initiator for the ring-opening polymerization of 1,4-dioxan-2-one (PDO) in bulk.The influence of reaction conditions,such as polymerization temperature,the molar ratio of the monomer to initiator (M/I) on the monomer conversion and molecular weight of the polymer has been investigated.Poly(1,4-dioxan-2-one) with a viscosity-average molecular weight (My) o...
基金supported by the National Natural Science Foundation of China(21473142 and 21673191)the National Innovative Research Team of China(IRT_14R31 and J1310024)
文摘Various bond modes of the M-C（C5 ring） exist in metallocene compounds of group 14 heavier elements,mostly due to an intricate interaction between the lone electron pairs at the M center and the 6 p-electrons of the C5 ring.The tin（Ⅱ） metallocene complexes LSn R（L = HC[CMe（N-2,6-iPr2C6H3）]2,R = cyclopentadienyl,C5H5（1）; indenyl,C9H7（2）; fluorenyl,C（13）H9（3）） stabilized by the β-diketiminato ligand were prepared and utilized in the study on their solid and solution state structures.X-ray single-crystal diffraction data revealed an η~1-mode of the Sn-C（C5 ring） bond in each 1~3.However,the room temperature ~1H NMR spectral studies disclosed such a fluxional bonding mode in solution.The 119 Sn NMR studies suggested a quadruple coordination nature of the Sn center in 1 while the triple coordination manner was for the Sn atom in both 2 and 3.Then the variable-temperature（25~–75 ℃） ~1H NMR spectral studies for each 1~3 were performed,which detected the relaxation state structures of 1~3 at lower temperature.All of these results indicate a stereochemical activity of the lone electron pairs at the tin（Ⅱ） atom that definitely has an electronic interaction with the 6 p-electrons of the C5 ring.The observed Sn-C（C5 ring） bond modes appear influenced by either the metallocene size or the compound state existed.
文摘Reaction products of 2,4,6-tris(4-phenyl-phenoxy)-1,3,5-triazine derived from 4-phenylphenol cyanate ester and phenyl glycidyl ether were analyzed. In addition to an isocyanurate compound and an oxazolidone compound which were well known as reaction products of cyanate esters and epoxy resins, compounds with hybrid ring structure of cyanurate/isocyanurate were determined. Gibbs free energies of the compound having hybrid ring structure of cyanurate/isocyanurate with two isocyanurate moiety were found to be lower than that of the compound with cyanurate ring structure through calculations. Calculation data supported the existence of hybrid ring structure of cy-anurate/isocyanurate. It was revealed that isomerization from cyanurate to isocyanurate occurs via hybrid ring structure of cyanurate/isocyanurate in the reaction of aryl cyanurate and epoxy.
文摘目的探讨线粒体E3泛素蛋白连接酶MARCH5[membrane-associated ring finger(C3HC4)5]在肝癌转移中的调控作用。方法(1)采用生物信息学方法分析TCGA库中肝癌细胞中MARCH5表达是否发生了异常改变,并进一步分析MARCH5表达与肝癌患者预后相关性。(2)采用细胞生物学方法下调人肝癌细胞HLE中MARCH5表达后,利用划痕实验与Transwell侵袭实验分析对细胞迁移与侵袭能力的影响;下调人肝癌细胞HLE中MARCH5表达后,利用qRT-PCR实验分析对上皮间质转化标志分子(上皮标志Ecadherin与ZO-1;间质标志N-cadherin与Vimentin)表达的影响。结果(1)与正常肝组织相比,肝癌组织中MARCH5表达显著上调(P<0.001),尤其在转移性肝癌组织中(P<0.001);MARCH5高表达与患者不良预后显著相关(P=0.027)。(2)下调MARCH5表达可显著抑制人肝癌细胞HLE的迁移与侵袭能力;下调MARCH5表达后HLE细胞中上皮细胞标志分子E-cadherin与ZO-1表达显著上调,而间质细胞标志分子Ncadherin与Vimentin表达显著下调(P<0.05)。结论MARCH5表达上调可能通过诱导上皮间质转化促进肝癌细胞的迁移与侵袭。
