室温离子液体中GuBr-脯氨酸催化的硫醇、硫酚与卤代芳烃的偶联反应

室温离子液体中,用脯氨酸为配体,CuBr催化作用下有效地实现了硫醇、硫酚与溴代芳烃的偶联反应.该反应时间较短,反应条件温和,收率高,CuBr-脯氨酸离子液体可以循环使用三次.     

脯氨酸离子液体催化Knoevenagel缩合反应(英文)

改进了1-丁基-3-甲基咪唑L-脯氨酸([bmim][Pro])功能化离子液体的合成路线,并将该离子液体用于催化含活泼亚甲基化合物与醛或酮的Knoevenagel缩合反应.在水介质中,室温下,该离子液体可快速催化上述Knoevenagel缩合反应,并选择性生成α,β-不饱和羰基化合物且分离收率可达到88%～97%.该脯氨酸离子液体循环重复使用6次后,催化活性没有明显的下降.此外,初步探讨了其催化过程机理.     

负载脯氨酸及其衍生物催化的不对称C-C键形成反应研究进展

近年来脯氨酸及其衍生物催化的不对称有机反应受到了广泛关注,将其负载于载体上使用也引起了人们的极大兴趣.负载方式大致分为3种:共价键负载,离子对结合或物理吸附等作用负载,以及在离子液体中的两相催化剂.本文对近年来出现的负载脯氨酸及其衍生物催化的不对称反应(Aldol反应、Michael加成反应)研究进展进行了综述.     

新型脯氨酸类手性离子液体的合成

2-氨甲基吡啶分别与N-Boc-L-氨酸、N-Boc-L-羟脯氨酸及N-Boc-L-乙酰氧基脯氨酸反应合成了三个新的手性酰胺化合物(2a～2c);2a ～2c依次经季铵化、离子交换、脱Boc保护基制得新型脯氨酸类手性离子液体,其结构经UV-Vis,1H NMR和IR表征.     

L-脯氨酸对离子液体介质中的不对称Michael反应催化性能研究

研究了L-脯氨酸对离子液体介质中醛(酮)与β-硝基烯烃的不对称Michael加成反应的催化性能, 利用X射线单晶衍射对Michael产物结构进行了表征. 结果表明, 反应在遵循胺催化机理的同时, 烯胺是从Re面对β-硝基烯烃进行加成, 产物的优势结构为(1R,2S)的syn型. 脯氨酸在离子液体1-正己基-3-甲基咪唑氯盐中显示良好的催化性能, 室温反应3～5 h, 得到89%以上收率的Michael产物, 其ee值最高70%. 脯氨酸与离子液体形成的催化体系具有良好的重复使用性能, 可至少稳定地重复使用6次.     

SBA-15 固载离子液体功能化脯氨酸的制备及其催化 Knoevenagel 缩合反应

 以 L-脯氨酸为原料合成了离子液体功能化脯氨酸前驱体 (IL-Pro), 并将其固载到 SBA-15 介孔分子筛上, 制得 IL-Pro/SBA-15 催化剂. 用红外光谱、热重、N2 吸附-脱附、X 射线衍射和透射电镜等手段表征了 IL-Pro/SBA-15 催化剂, 并考察了该催化剂在 Knoevenagel 缩合反应中的催化性能. 结果表明, 固载离子液体功能化脯氨酸没有破坏 SBA-15 的有序介孔结构, 但孔体积、孔径和比面表积有所下降; IL-Pro/SBA-15 的失重峰在 250~360 oC (峰值为 310 oC). 在以苯甲醛和丙二腈为底物的 Knoevenagel 反应中, IL-Pro/SBA-15 催化剂表现出较高的活性, 缩合产物收率高达 94%; 经简单分离后催化剂可重复使用 7 次以上而活性基本保持不变.     

功能化离子液体支载脯氨酸催化的不对称Henry缩合反应

以L-脯氨酸支载在功能化离子液体四氟硼酸1-(2-羟乙基)-3-甲基咪唑鎓盐上的离子液体([Promim]CF3CO2)为催化剂兼溶剂,可在温和条件下顺利地催化硝基乙烷、硝基甲烷和各种醛的Henry缩合反应,目标产物的产率达79％～95％,非对映选择性可达3∶1,对映选择性可达85%ee。 反应操作和后处理简单方便。 [Promim]CF3CO2离子液体通过简单的处理即可实现循环利用,以邻-硝基苯甲醛和硝基乙烷为反应底物的模板反应,这种离子液体可以较稳定地循环使用6次,催化活性不降。     

离子对负载L-脯氨酸阴离子催化下的不对称Aldol反应

在水相中,通过阴阳离子结合使L-脯氨酸阴离子负载在基于Merrifield树脂的季铵根阳离子上,制备出功能性高分子离子液体.将该体系作为一种高效、可回收的催化剂用于催化醛与酮的不对称Aldol反应.结果表明:该催化体系在微量水中有很好的催化活性和立体选择性,相应的Aldol反应产物获得了6∶94的dr值以及高达98%的ee值,且该催化体系有较好的重复使用性能.     

吗啉基功能化酸性离子液体催化苯酚-叔丁醇选择性烷基化反应

研究了吗啉基磺酸功能化离子液体催化苯酚与叔丁醇的烷基化反应.考察不同的功能化离子液体、反应时间、反应温度、苯酚与叔丁醇的摩尔比以及离子液体的用量等反应条件对烷基化反应的影响,并考察了离子液体的循环使用.研究结果表明离子液体用量为20%苯酚时,在最佳优化条件下苯酚的转化率和选择性分别为92.4%和64.1%;离子液体重复使用三次,其催化活性不变.     

含离子液体［bmim］Cl的反应介质中马肝醇脱氢酶的催化特性

 研究了马肝醇脱氢酶(HLADH)在含离子液体1-丁基-3-甲基咪唑氯酸盐(［bmim］Cl)的反应介质中的催化特性. 以乙醇为底物时,该酶在［bmim］Cl含量≤0.15 g/ml的体系中的活力高于在不含离子液体的体系中的活力; 离子液体浓度过高(＞0.15 g/ml)对酶活性有明显的抑制作用. 反应温度和pH对含离子液体的反应介质中酶活力的影响规律与不含离子液体时的规律相似. 与不含离子液体的反应介质相比, HLADH在含0.05 g/ml ［bmim］Cl的体系中催化乙醇氧化的活化能下降,酶反应的Vmax和Km均升高. 反应体系中低浓度(≤0.1 g/ml)的离子液体能提高酶的热稳定性,但高浓度(＞0.1 g/ml)的离子液体可降低酶的热稳定性. 紫外二阶导数光谱显示,在含不同浓度离子液体的反应介质中酶分子构象的变化有较大的差异.     

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.     

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.     

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.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

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.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

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.