利用Paal-Knorr反应在无催化剂和溶剂条件下合成吡咯衍生物

Paal-Knorr合成法是一个常见的吡咯合成方法。本文报道了无需使用任何催化剂和溶剂,在室温条件下多种胺(包括脂肪胺、芳香胺)和2,5-己二酮发生Paal-Knorr缩合反应,且合成的吡咯衍生物产率较高。这种合成方法具有反应条件温和、实验操作步骤简单以及产物容易分离等优点,具有一定的实用价值。     

甲酸催化的室温无溶剂条件下利用Paal-Knorr反应合成吡咯衍生物的方法

以甲酸为催化剂, 无需使用任何溶剂, 在室温条件下, 多种伯胺(包括脂肪胺、芳香胺)与2,5-己二酮发生Paal-Knorr缩合反应, 生成相应的吡咯衍生物. 该方法反应条件温和、操作简便、反应时间比较短、产物易于分离、收率高、环境友好.     

新型吡咯类衍生物的合成

2,5-己二酮和胺(氨基硫脲、硫脲、苯胺、氨基酸)经过Paal-Knorr反应合成6个2,5-二甲基-N-取代吡咯衍生物;分别以新合成的N-吡咯甘氨酸、N-苯基吡咯化合物为原料,进行酯化反应和Mannich,Friedel-Craft反应,合成3个N-(2,5-二甲基吡咯)甘氨酸酯类化合物和2个N-苯基-2,5-二甲基吡咯衍生物.所有化合物都通过IR,1HNMR,13CNMR,HRMS波谱方法对其结构进行了确证.     

木质素磺酸铁催化合成N-取代吡咯

以造纸废料木质素磺酸钠为原料制备了木质素磺酸铁。以木质素磺酸铁为催化剂,催化2,5-己二酮与伯胺发生Paal-Knorr反应,生成了高产率的N-取代吡咯。该反应是典型的亲核反应,伯胺亲核性越强,反应速率越快,N-取代吡咯产率越高。反应中木质素磺酸铁电离出的Fe~(3+)是Lewis酸,起催化作用。木质素磺酸铁是一种生物质基固体催化剂,价廉易得、环境友好、操作简便、易于和产物分离、可回收循环使用。     

生物质木质素磺酸催化合成N-取代吡咯

木质素磺酸是非均相、环境友好的生物质催化剂。本文以造纸废料木质素磺酸钠为原料,通过离子交换的方法制备了木质素磺酸。通过红外、元素分析、滴定等方法表征了木质素磺酸的结构。以木质素磺酸为催化剂,2,5-己二酮与伯胺发生Paal-Knorr反应以较优的产率合成了N-取代吡咯。伯胺的亲核能力越强,反应越容易进行,是典型的亲核反应。     

二碘化镁催化Paal-Knorr反应合成手性吡咯衍生物的方法

报道了二碘化镁催化的2,5-己二酮与多种手性氨基酸酯的Paal-Knorr缩合反应,制备单吡咯和双吡咯手性衍生物,该方法反应条件温和、操作简便、收率高、立体选择性好且环境友好.     

有机小分子不对称催化Michael加成的研究进展

有机小分子催化成为现在最热门的研究领域之一.不对称Michael加成反应是合成具有一个或多个手性中心合成砌块和药物中间体的重要方法.介绍了近3年来有机小分子伯胺衍生物、吡咯烷衍生物、(硫)脲、手性方酰胺和磷酸等在不对称催化Michael加成中的应用研究进展.对各种小分子结构和催化活性的关系、催化剂诱导活化机理以及各种催化体系在药物和关键中间体合成中的应用也进行详细的评述.     

可回收(S)-脯氨醇衍生物在催化查尔酮类化合物不对称环氧化反应中的催化性能研究

将以L-脯氨酸为原料合成的光学活性脯氨醇衍生物((S)-2-吡咯烷基-α,α-二(α-萘基)甲醇1),作为有机小分子催化剂,在催化8种α,β-不饱和酮的不对称环氧化反应中表现出较好的立体选择性(58.0~84.6?)和催化活性(58.0~89.7%).反应结束后,通过简单的酸碱调整,可使催化剂回收和重复使用.循环使用5次,催化剂的回收率均在93~97%之间,催化剂的催化活性和立体选择性无明显改变.     

溴化二甲基溴化硫催化下合成N-取代吡咯类化合物

室温、无溶剂条件下,以溴化二甲基溴化硫(BDMS)为催化剂,以2,5-己二酮和伯胺类化合物为原料,能高收率的实现一系列N-取代吡咯衍生物的合成.所有化合物结构通过1H NMR,13C NMR和元素分析确定.     

2,5-二噻吩基吡咯衍生物的合成与应用研究进展

2,5-二噻吩基吡咯衍生物具有良好的环境稳定性和电化学性质,在光电子领域有广泛的应用前景.综述了2,5-二噻吩基吡咯衍生物中噻吩环和吡咯环上不同位置取代衍生物的合成方法,并对2,5-二噻吩基吡咯衍生物在电致变色器件、光电子器件、传感器等方面的应用进行了概述.     

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.