无配体铜催化芳溴和Ｋ４［Ｆｅ（ＣＮ）６］的氰化

铜催化芳溴氰化反应通常在惰性气体保护下进行,而且配体和碱的使用也是必要的．本文发现无配体的Ｃｕ（ＯＡｃ）２·Ｈ２Ｏ能够有效地催化芳溴的氰化;并且反应无需使用碱,无需惰性气体保护;为芳腈的合成提供一种经济有效的方法．此方法可应用到多种芳溴的腈化,在１６种芳溴底物反应的例子中,得到了５６％９４％的产率．     

CsOH/DMSO促进下卤代芳烃与酚的反应:一种合成二芳基醚的简便方法

在氢氧化铯/二甲基亚砜(CsOH/DMSO)碱体系促进下,卤代芳烃与酚可在加热条件下直接反应,生成二芳基醚.该反应无需使用过渡金属催化剂和配体,亦无需惰性气体保护,是一种简洁的绿色合成方法.基于一系列实验结果,我们提出了经由苯炔进行的反应机理.     

铜催化2-（2,2-二溴乙烯基）苯酚化合物与苯酚衍生物的串联醚化反应

首次报道铜催化2-（2,2-二溴乙烯基）苯酚类化合物与苯酚衍生物的串联醚化反应. 以2-（2,2-二溴乙烯基）苯酚衍生物与苯酚类化合物为起始原料,醋酸铜为催化剂、碳酸铯作为碱,在N,N-二甲基甲酰胺中通过一锅法合成了24个未见文献报道的2-芳氧基苯并呋喃类化合物. 此合成方法具有原料易得、操作简便、分离纯化简单和无需昂贵配体等优点.     

乙二醇中钯催化无配体的室温Suzuki反应

报道了一种在室温下醋酸钯催化乙二醇中无外加配体的Suzuki反应体系.以K3PO4·7H2O为碱,在该体系中可高效进行芳基溴代物和芳基硼酸的Suzuki交叉偶联反应,具有反应条件温和、无需惰性气体保护等特点.在n(ArBr)=0.5mmol,n(ArB(OH)2)=0.75mmol,x(Pd(OAc)2)=0.5mol%,n(K3PO4·7H2O)=1.0mmol,v(乙二醇)=2ml的优化条件下,4-溴苯甲醚和苯硼酸反应20min,分离收率即达95%.     

三芳胺合成的研究进展

三芳胺化合物的合成方法主要有3种:(1)非金属催化的胺化反应;(2)铜催化的Ullnann反应,包括使用过量铜粉为催化剂的传统的Ullmann反应、使用相转移催化剂的Ullmann反应以及使用配体的post-Ullmann反应;(3)钯催化的Buchwald-Hartwig反应.该类反应活性的关键是配体的选择,根据配体结构的不同可分为双膦螯合型配体、单膦配体和非膦配体.对该类化合物的这几种合成方法的研究进展进行了总结.     

3-戊烯腈在零价镍催化体系中的平衡反应

在探索3-戊烯腈氢氰化合成己二腈反应的机理过程中,发现3-戊烯腈在零价镍体系中可能同时存在多个平衡反应,在不外加氰化氢条件下,3-戊烯腈可以生成甲基戊二腈和己二腈.采用零价镍、膦配体和无水ZnCl2组成的催化体系研究了该反应过程,考察了反应温度和配体的影响,并采用原位红外对反应进行监测,提出了可能的反应机理.     

醋酸钯催化甲苯中无配体的 Suzuki 反应

 报道了一种甲苯中醋酸钯催化无配体的 Suzuki 反应体系. 以 K₃PO₄·7H₂O 为碱, 在该体系中可高效进行芳基溴代物和芳基硼酸的 Suzuki 反应, 且具有反应条件温和、无需惰性气体保护等特点. 在 n(ArBr) = 0.5 mmol, n(ArB(OH)₂) = 0.75 mmol, x(Pd(OAc)₂) = 1 mol%, n(K₃PO₄·7H₂O) = 1.0 mmol, v(甲苯) = 2 ml 的优化条件下, 4-溴硝基苯和苯硼酸在 75 °C 反应 5 min, 分离收率即达 99%, TOF 高达 1 188 h?1.     

室温铜催化芳基硼酸与氨水偶联合成一级芳胺

一级芳胺广泛用于天然产物、药物、高分子和材料的合成中, 传统合成一级芳胺是在高温、高压和封闭容器中采用钯催化卤代芳烃与氨气反应来制备, 也可以在钯催化下使用氨的替代物, 如Li[N(SiMe3)2], Zn[N(SiMe3)2]与卤代芳烃反应来合成. 显然, 这些方法有以下缺点: (a)由于采用钯催化剂和复杂的配体, 成本较高、毒性较大; (b)当使用氨气作为氨基源时, 高温、高压和封闭容器是必不可少的; (c)当使用氨的替代物作为氨基源时, 由于这些氨的替代物不易制备、成本也就较高. 清华大学化学系付华课题组建立了一种合成一级芳胺的新方法, 即在室温和常压下, 使用Cu2O作催化剂, 芳基硼酸与氨水在甲醇溶液中反应合成了一级芳胺. 反应容器不需要封闭, 不需要惰性气体保护, 也不需要在反应体系中加入任何配体或添加剂. 这种方法能够容忍各种官能团的存在, 如芳基硼酸的碳-卤键、羟基、醛基、酯基、羧基、氨基等. 这种方法反应条件温和、高效、实用, 能够广泛应用于一级芳胺的合成中.     

低温Suzuki反应合成联苯及三联苯化合物

发展了一个低温下无配体钯催化溴代芳烃与芳基硼酸的Suzuki反应体系。该体系以醋酸钯为催化剂,无水碳酸钾为碱,乙醇水溶液为溶剂,无需加入任何配体,在0oC下即可高效催化溴代芳烃与芳基硼酸的Suzuki反应;反应的底物容忍性好,产品分离收率最高达97%。以溴代芳基N-甲基亚氨基二乙酸硼酸酯为砌块分子,通过调控反应温度,实现了砌块分子选择性Suzuki反应,从而一锅合成了不对称三联苯化合物,产品收率最高为81%。     

水相铜/十二烷基取代酰肼-吡啶-N-氧化物催化咪唑的N-芳基化

设计合成了5种新型烷基取代酰肼-吡啶-N-氧化物,并将其作为水相铜催化含氮杂环与芳香碘代物偶联反应的配体.实验结果表明,十二烷基取代酰肼-吡啶-N-氧化物的催化效果最佳.对影响反应的其它条件,如铜源、碱、反应时间和温度等条件进行了优化,建立了最佳反应条件:CuO(10%,摩尔分数),NaOH(1 mmol),TBAB(5%,摩尔分数),L5(20%,摩尔分数),于120℃反应12 h,无需惰性气体保护.在此条件下,芳香碘代物与咪唑偶联反应的产率为60%~92%.该方法的特点是以水作为反应溶剂,长链烷基取代酰肼-吡啶-N-氧化物同时起到了铜催化剂配体和相转移催化剂的作用.     

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%.     

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.     

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.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

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.