超声辐射下二(2''''-氯喹啉)-乙二醇的合成

()呐醇是有机合成中的重要中间体[1],广泛应用于农药、医药等精细化工品的合成;作为能够构建碳碳键的一个重要反应,羰基化合物还原偶联为()呐醇的反应一直是有机合成领域中的一个重要研究课题;同时又形成了两个手性中心,光学活性的邻二醇可作为手性配体广泛应用于手性拆分与不对称合成,特别是在生物活性的天然化合物[2]的合成.1973年,Mukaiyama[3]首次将低价钛运用于醛酮的还原偶联反应,此后随着还原体系的改进和扩充,利用低价钛配合物合成()呐醇的研究也在逐步深入,近年来已有诸多文献报道[4,5].     

过渡金属催化1,3-二羰基化合物不对称烯丙基烷基化反应的研究进展

1,3-二羰基化合物的不对称烯丙基烷基化反应是构筑手性中心的重要方法.综述了过渡金属催化1,3-二羰基化合物不对称烯丙基烷基化反应的进展.按照烯丙基化试剂的不同,主要讨论了以烯丙基酯类、烯丙醇、烯丙基卤化物、烯烃、联烯作为烯丙基化试剂或其他烯丙基化方法合成手性α-烯丙基取代的1,3-二羰基化合物.     

手性芳基邻二醇的不对称合成

具有特定功能基团的手性芳基邻二醇是许多具有特殊功能的药物、农药和信息素的重要中间体,近年来手性芳基邻二醇类化合物的合成与应用研究引起了人们的广泛关注。本文从生物催化不对称合成和化学催化不对称合成两方面综述了近年来手性芳基邻二醇的合成进展,概述了前手性底物上取代基的电子效应和空间效应、手性催化剂的种类和反应体系等因素对合成手性芳基邻二醇产率及光学活性的影响,并对手性芳基邻二醇不对称合成的发展趋势进行了展望。     

烯丙基溴化钐与羰基化合物反应合成高烯丙基醇

高烯丙基醇是有机合成中的一类非常重要的中间体,以烯丙基金属试剂与羰基化合物加成反应为其主要合成方法,常用的金属烯丙基化合物有烯丙基锂(镁、锌、硼、铟、硅、锡、钛)等.由于烯丙基的Grignard试剂制备过程中常伴随着大量的烯丙基偶联反应,所以用烯丙基的Grignard试剂来合.     

纳米铝粉促进羰基化合物水相烯丙基化反应

氮气保护条件下,纳米铝在0.1 N NH₄Cl溶液中,能有效地促进羰基化合物与烯丙基溴进行Barbier-Grignard型烯丙基化反应,得到相应高烯丙醇。芳香族醛或酮的烯丙基化产率较高,而脂肪族羰基化合物反应产率低,反应产率受羰基空间位阻影响大,在同样条件下,邻羟基羰基化合物烯丙基化产物主要是赤式-邻二醇。     

1,8-双(邻羧基苯甲酰)萘酸酐的合成

研究了1,8-双(邻甲酸酐苯甲酰基)萘的合成方法.从7,8-苊二酮出发,与邻溴甲苯的格氏试剂生成7,8-(邻甲基基)苊二醇,用重铬酸钾把羟基氧化成酮.并形成与羰基相邻的羧基.这一反应使在苯环上与羰基相邻的羧基处于有利位置,以使两个羧基脱水成酸酐.     

手性受阻路易斯酸碱对(FLPs)催化邻羰基化合物的高对映选择性硅氢化反应

正J.Am.Chem.Soc.2016,138,810~813光学活性α-羟基酮广泛存在于很多具有重要生物活性的分子中,邻羰基酮化合物的不对称还原反应是获得这类化合物最有效的方法之一.目前所报道的例子主要是利用生物催化剂实现邻羰基酮化合物的直接还原,而利用分子催化剂,如过渡金属催化剂的报道还非常少,并且对映选择性不高.中国科学院化学所杜海峰课题组利用手性双炔     

α-羰基二硫缩烯酮类化合物在杂环合成中的应用进展

α-羰基二硫缩烯酮是一类重要的有机合成中间体,其官能团的多样性决定了反应的多样性.基于α-羰基二硫缩烯酮的主要反应有与亲核体的共轭加成、与金属有机试剂的选择性加成、环合、还原、缩合等反应以及作为代硫醇试剂的应用等.本文介绍了此类化合物的结构特征及合成方法,并着重按所合成杂环化合物的类型,分别对其在含氮、含氧、含硫及含多...     

过渡金属催化烯丙醇异构化反应的研究进展

羰基化合物是一类重要的有机合成中间体,其在医药、农药、香料和化妆品领域具有重要应用.近年来,利用烯丙醇异构化反应快速合成一系列羰基化合物和构建新化合物的方法受到化学家的广泛关注.由于过渡金属催化的烯丙醇异构化反应具有良好的原子经济性,在合成方面具有独特的优势,烯丙醇异构化反应成为金属有机化学研究的热点之一.综述了近年来过渡金属催化的烯丙醇异构化反应的研究进展和应用.     

不对称环氧化反应

环氧基存在于大量的天然化合物中,是一些多羟基天然化合物的羟基的来源。在有机合成中,环氧化合物是制备二醇、卤代醇、羰基化合物的重要中间体。不对称环氧化反应是制备有生物活性的天然化合物的重要手段,近年来,国外在这方面已取得重大进展,在用于昆虫信息素的合成方面,已取得实用性的研究成果。     

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.     

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%).     

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.     

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.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.