取代茚基二价稀土配合物催化己内酯开环聚合反应

研究了1-环戊烷基茚基二价镱配合物(1-C5H9C9H6)2Yb(THF)2作为单组分催化剂催化己内酯开环聚合反应, 考察了催化剂用量、聚合反应时间、聚合反应温度对己内酯聚合反应的影响. 结果表明, 配合物(1-C5H9C9H6)2Yb(THF)2对己内酯聚合有较高的催化活性; 温度升高, 聚合反应的转化率增加, 但产物的数均分子量及分子量分布无明显变化; 所得聚合物分子量分布较窄. 其它几种取代茚基稀土配合物也显示出较高的催化活性, 其活性有下列次序: (1-C2H5C9H6)2Sm(THF)2>(1-C5H9C9H6)2Sm(THF)>KSm(1-C5H9C9H6)3(THF)3>(1-PhCH2C9H6)2Sm(THF)2>(1-C5H9C9H6)2Yb(THF)2, 二价钐配合物较二价镱配合物具有较高的催化活性. 通过凝胶渗透色谱法测定了聚合产物的数均分子量及其分布.     

取代茚基二价稀土配合物催化甲基丙烯酸-N, N-二甲胺乙酯的聚合

研究了取代茚基二价稀土配合物（1-C5H9C9H6）2Yb（THF）2催化甲基丙烯酸-N,N-二甲胺乙酯的聚合。结果表明,配合物（1-C5H9C9H6）2Yb（THF）2作为单组分催化剂对甲基丙烯酸-N,N-二甲胺乙酯的聚合显示出较高的催化活性,反应温度、时间、催化剂用量及溶剂性质对聚合反应转化率和产物分子量有较大影响,在以甲苯为溶剂的催化体系中加入少量的极性溶剂THF,聚合活性有明显提高。其他几种取代茚基稀土配合物也显示出高的催化活性,其活性有下列次序：（1-C5H9C9H6）2Sm（THF）≈（1-C2H5C9H6）2Sm（THF）2〉（1-C5H9C9H6）2Yb（THF）2〉（1-PhCH2C9H6）2Sm（THF）2,二价钐配合物较二价镱的相应配合物具有较高的催化活性。聚合产物的分子量及分子量分布通过凝胶渗透色谱法表征,立构规整性由1H NMR谱表征,所得聚合物以间同立构为主。     

取代茚基二价稀土配合物催化甲基丙烯酸甲酯/甲基丙烯酸-N,N-二甲胺乙酯共聚反应的研究

研究了取代茚基二价稀土配合物（C5H9C9H6）2Yb（THF）2作为单组分催化剂，催化DMAEMA／MMA的共聚反应。结果表明，（C5H9C9H6）2Yb（THF）2对DMAEMA／MMA的共聚反应具有较高的催化活性，温度对共聚反应影响明显，单体配比对共聚反应的转化率影响不大，几种取代茚基二价稀土配合物都显示出较高的催化活性。其活性次序为：（C5H9C9H6）2Sm（THF）〉（C2H5C9H6）2Sm（THF）2〉（C5H9C986）2Yb（THF）2〉KSm（C5H9C9H6）3（THF）3〉（PhCH2C9H6）2Sm（THF）2。对聚合产物进行了热分析的表征，发现产物为两种单体的无轨共聚物。通过核磁共振技术确定了共聚物中两种单体所占的比例，并测定了（C5H9C9H6）2Yb（THF）2催化DMAEMA／MMA的共聚反应的竟聚率，其竟聚率为r1=0．98，r2=0．71。     

Schiff碱二价钐配合物[2-OC6H4CH＝N(2,6-iPr2C6H3)]2Sm(THF)2催化己内酯开环聚合

稀土配合物;Schiff碱二价钐配合物[2-OC6H4CH＝N(2;6-iPr2C6H3)]2Sm(THF)2催化己内酯开环聚合     

[(NaC9H6)Me2CC5H4]2Sm(Ⅱ)(THF)2的合成及其催化MMA聚合的研究

以茚基锂与6, 6-二甲基富瓦烯的环外双键加成反应合成了一个新型取代茂基锂 [(C9H7)Me2C]C5H4Li (1, 其中C5H4代表一取代环戊二烯基), (1)与无水三氯化钐按2∶1摩尔比反应后, 再用与稀土钐的摩尔比为3∶1的钠砂处理, 合成了二价钐的三核双金属配合物[(NaC9H6)Me2CC5H4]2Sm(Ⅱ)(THF)2 (2, 其中C9H6代表茚基). 该配合物经元素分析和红外光谱表征, 并发现 (2) 能高活性地催化甲基丙烯酸甲酯聚合, 得到等规含量较高的聚甲基丙烯酸甲酯.     

三(环戊基茚基)钐配合物(C5H9C9H6)3SmCl-Li+(THF)4的合成与晶体结构

稀土配合物能使极性和非极性单体聚合[1].虽然目前已测定了几乎所有的三(环戊二烯基)稀土配合物及部分三(取代环戊二烯基)稀土配合物的晶体结构, 但有关三(茚基)稀土配合物的报道较少. 第一个三(茚基)稀土配合物是无水三氯化稀土与3倍物质的量的茚基钠C9H7Na在四氢呋喃中反应而得, 但未报道其晶体结构 [2]. 后来用同样的反应却分离出以氯为桥的二聚体离子对配合物 [Na(THF)6] [Ln(η5-C9H7)3μ(Cl)Ln(η5-C9H7)3](Ln=Nd, Sm) [3]. 无水三氯化稀土与Mg(C9H7)2或C9H7K等物质的量反应则生成非溶剂化的(C9H7)3Sm[4], 而与茚基钠和环辛四烯钾(C8H8K)以1∶2∶1物质的量比反应时, 则得到(C9H7)3Ln(THF)(Ln=Nd, Gd) [5]. Bottomley [6]曾用(C9Me7)K(七甲基茚基钾)与LnCl3(物质的量比3∶1)反应制备(C9Me7)3Nd(THF)5和(C9Me7)3Er@(THF)3, 但未报道晶体结构. 因为取代茚的空间阻碍比茚的大, 三(取代茚基)稀土配合物较难合成. 迄今未见有关单晶结构报道. 本文首次报道三(环戊基茚基)钐配合物的合成及晶体结构.     

二价钐配合物和异氰酸苯酯的反应[(CH3C5H4)2(THF)Sm]2[μ-η4-(PhN)OCCO(NPh)]*2THF的合成、晶体结构及其催化性能

报道了二价配合物(CH3C5H4)2Sm(THF)和SmI2(THF)x与异氰酸苯酯的反应. (CH3C5H4)2Sm(THF)和异氰酸苯酯反应生成配合物[(CH3C5H4)2(THF)Sm]2[μ-η4-(PhN)OCCO(NPh)]*2THF(1), 而SmI2(THF)x则被异氰酸苯酯氧化为[SmI2(THF)5][SmI4(THF)2]. (CH3C5H4)2Sm(THF)和配合物1都能催化异氰酸苯酯的齐聚反应.(CH3C5H4)2Sm(THF)和异氰酸苯酯作用生成配合物1的反应可以认为是 (CH3C5H4)2Sm(THF)催化异氰酸苯酯齐聚的引发反应, 而配合物1是该齐聚反应的活性中间体. X射线衍射分析表明, 配合物1是一个由草酰胺双负离子桥联的双金属化合物.     

二氧化硅负载[C5Me5]2SmMe(THF)引发甲基丙烯酸甲酯聚合

近年来 ,有许多文献报道茂金属催化剂的负载化及其在烯烃聚合中的应用 ,这对发展新型茂金属催化剂和开发新型高分子材料有重要意义 [1,2 ] .我们 [3]曾报道壳聚糖负载稀土催化剂用于甲基丙烯酸甲酯的配位聚合有优良性能 .以五甲基环戊二烯为配体的有机稀土配合物 ,如 [Sm H( C5Me5) ]2 ,[C5Me5]Ln Me( THF) ( Ln=Sm,Yb)等在甲苯中单组分引发甲基丙烯酸甲酯聚合及内酯开环聚合具有许多优异性能[4 ,5] ,但是经负载化的该类催化剂的聚合性能尚未见报道 .本文报道将 [C5Me5]2 Sm Me·( THF)负载于二氧化硅 ,引发甲基丙烯酸甲酯聚合的结…     

三（环戊基茚基）钐配合物（C5H9C9H6）3SmCl^—Li^＋（THF）4的合成与晶体结构

稀土配合物能使极性和非极性单体聚合[1] .虽然目前已测定了几乎所有的三 (环戊二烯基 )稀土配合物及部分三 (取代环戊二烯基 )稀土配合物的晶体结构 ,但有关三 (茚基 )稀土配合物的报道较少 .第一个三 (茚基 )稀土配合物是无水三氯化稀土与 3倍物质的量的茚基钠 C9H7Na在四氢呋喃中反应而得 ,但未报道其晶体结构[2 ] .后来用同样的反应却分离出以氯为桥的二聚体离子对配合物[Na( THF) 6][Ln( η5- C9H7) 3μ( Cl) Ln( η5- C9H7) 3]( Ln=Nd,Sm) [3] .无水三氯化稀土与 Mg( C9H7) 2 或C9H7K等物质的量反应则生成非溶剂化的 ( C9H7…     

二(β-二亚胺基)二价稀土配合物催化醛/酮与亚磷酸二乙酯的氢磷化反应

研究了一系列二(β-二亚胺基)二价稀土配合物[Eu(L~(2,6-ipr2))_2·CH_3C_6H_5,L~(2,6-ipr2)=[N(2,6-~(i)Pr_2C_6H_3)C(Me)]_2CH~-(1);Eu(L~(2,6-Me2))_2(THF),L~(2,6-Me2)=[N(2,6-Me_2C_6H_3)C(Me)]_2CH~-(2);Eu(L~(2,4,6-Me3))_2(THF),L~(2,4,6-Me3)=[N(2,4,6-Me_3C_6H_2)-C(Me)]_2CH~-(3);Eu(L~(2,6-ipr2)Ph)2,L~(2,6-ipr2)Ph=[(2,6-iPr_2C_6H3_)NC(Me)CHC(Me)N(C_6H_5)]–(4);Sm(L~(2,6-ipr2))_2·CH_3C_6H_5(5);Yb(L~(2,6-ipr2)Ph)2(6);Yb(L~(2-Me))2(THF),L~(2-Me)=[N(2-Me C6H4)C(Me)]2CH–(7)]对醛/酮与亚磷酸二乙酯的氢磷化反应的催化行为.发现所有配合物都可以在温和条件下,高效地催化芳醛以及杂环芳醛与亚磷酸二乙酯的氢磷化反应,在催化剂用量为0.08 mol%,25℃,无溶剂条件下反应5 min,α-羟基膦酸酯的收率可以达到90%~99%.催化活性有赖于β-二亚胺基的结构,其活性顺序为L~(2,6-Me2)L~(2,4,6-Me3)L~(2,6-ipr2)≈L~(2,6-ipr2)Ph.该催化体系具有优秀的醛底物适应能力.这类二价稀土配合物也可以有效地催化未活化的酮与亚磷酸二乙酯的反应,并显示良好的底物适应能力.     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.