惰性C(sp~3)—H键的直接三氟甲硫基化

<正>Angew.Chem.Int.Ed.2015,54,4070~4074三氟甲硫基具有强的吸电子性和亲脂性,将其引入到分子中能够明显地改变母体分子的理化性质进而影响到生物活性,因此含三氟甲硫基的分子在医药、农药及材料等领域受到极大的关注.近些年来发展了许多向分子中引入三氟甲硫基的方法,但大多需要对底物进行预官能团化,发展温和条件下直接高效地向分子中引入三氟甲硫基的方法一直是科学家们追求的目标.从实用和原子经济性的角度来看,C—H键活化三氟甲硫基化是最直接高效的方法.     

醇的直接脱羟三氟甲硫基化反应

<正>Angew.Chem.Int.Ed.2015,54,897~900三氟甲硫基(CF3S)是强吸电子和最强亲脂基团,因此含三氟甲硫基的化合物在药物和农药研制中有着广泛的应用.近二年来,发展向有机分子引入三氟甲硫基是继三氟甲基化反应后有机氟化学领域的热点研究课题之一,但目前的工作主要集中于芳基三氟甲硫醚化合物的合成.中国科学院上海有机化学研究所卿凤翎课题组发展了醇的直接脱羟三氟甲硫基化反应.三氟甲硫基负离子不稳定,它会分解生成硫氟光气A和氟负离子.卿凤翎等认为新生成的     

三氟甲硫基化反应的研究进展

由于三氟甲硫基具有强吸电子性和高亲脂性,含三氟甲硫基的化合物在医药和农药等领域具有重要的应用价值,因此发展向有机分子引入三氟甲硫基的方法已成为当前有机氟化学领域的热点研究课题之一。本文根据三氟甲硫基化试剂的性质总结了近5年在直接三氟甲硫基化反应研究领域取得的研究成果,包括新的三氟甲硫基化试剂以及新的合成方法在直接三氟甲硫基化反应中的应用。     

不对称三氟甲硫基化反应研究进展

三氟甲硫基吸电子能力强、脂溶性高,在药物分子内引入三氟甲硫基可以显著地提高化合物的细胞膜穿透性与代谢稳定性.而不同立体异构的药物分子会有不同的药理活性,因此不对称三氟甲硫基化反应在近几年内逐渐受到化学家们的重视.目前,这一领域还处于发展的初步阶段,本文将就目前为止已经发展的不对称三氟甲硫基化方法做简单的总结,包括使用亲电的三氟甲硫基试剂和使用含三氟甲硫基的合成砌块这两种不同的策略.最后对不对称三氟甲硫基化领域所存在的挑战进行简单的展望.     

基于二氟卡宾转化的芳基和烯基碘化物的三氟甲硫基化

二氟卡宾在有机氟化物的合成中发挥了重要作用.之前的发现,二氟卡宾能与硫单质反应产生硫代氟光气,这对二氟卡宾化学的新发现以及硫代氟光气的应用研究都具有重要价值.利用这一路径已经实现了端基炔烃和烷基卤化物的三氟甲硫基化.在此,继续深入研究这一路径在合成上的应用,并实现了芳基和烯基碘化物的三氟甲硫基化.三氟甲硫基化是有机氟化学的一个重要研究方向,常用方法一般需要使用含CF₃S基团的昂贵试剂.在该方法中, CF₃S基团是由二氟卡宾、硫单质和氟离子现场产生的,所用试剂都廉价易得.     

惰性C(sp~3)—H键的三氟甲硫基反应

<正>Angew.Chem.Int.Ed.2015,54,4065~4069三氟甲硫基官能团具有非常大的亲脂性和疏水性,将其引入到药物分子中,能大大增强药物的生物穿透性,因此含有该基团的有机分子在医药、农药等领域具有巨大的潜在应用价值.传统的惰性C(sp3)—H键的三氟甲硫基化方法相对较少,多是采用高毒气体CF3SCl作为三氟甲硫基化试剂,操作困难,反应选择差等缺点.最近,南开大学元素有机化学国家重点实验室汤平平课题组发展了采用稳定,易得的Ag SCF3作为三氟甲硫基化试剂,实现了惰性3     

直接二氟甲硫基化与一氟甲硫基化反应研究进展

含有二氟甲硫基基团(SCF2H)与含有一氟甲硫基基团(SCFH2)的有机化合物具有独特的物理和化学性质,在医药及农药等领域具有潜在的应用价值.这两类化合物的传统制备方法是巯基底物的二氟甲基化与一氟甲基化,但含巯基底物本身种类有限,极大地限制了该类化合物的应用与开发,因此开发新的直接二氟/一氟甲硫基化方法和开拓新型直接二氟/一氟甲硫基化试剂具有重要的意义.综述了直接二氟甲硫基化反应和一氟甲硫基化反应的最新研究进展,并对反应的相关机理进行了论述.     

三氟甲基芳基硫醚的合成

三氟甲基芳基硫醚由于具有高疏水性和亲脂性,在医药、农用化学品及材料科学中有着重要的应用。合成含三氟甲硫基的芳香化合物已成为有机氟化学领域的研究热点之一。本文从间接法和直接法两方面综述了向分子中引入三氟甲硫基的相关研究,包括新的三氟甲硫基化试剂以及新的合成方法在制备三氟甲基芳基硫醚中的应用,最后讨论了这些方法存在的问题,并为探索新型的、更加经济的三氟甲硫基化反应提供参考。     

分子内直接引入含氟基团以及~(18)F-标记方法研究进展

含氟基团拥有强吸电子性和高亲脂性,有机分子适当地引入含氟基团可以改善其原有的功能.因此,向分子内引入含氟基团的方法成为了当前的研究热点.由于三氟甲硫基拥有突出的性能,其引入方法成为主要研究热点之一,三氟甲硒基、三氟甲氧基以及三氟乙氧基的引入方法也受到了科研人员的关注.~(18)F拥有几乎理想的原子核性能,是临床成像使用最广泛的正电子发射断层显像(PET)放射性核素.因此,新型[~(18)F]放射性示踪剂的研发成为很多科研人员的研究方向.研发新型[~(18)F]放射性示踪剂的关键在于用~(18)F对生物分子进行标记.介绍了最近报道的向分子内直接引入CF_3X(X=S,Se,O,CH_2O)基团的新方法以及一些~(18)F-标记方法的研究成果.此外,总结了一些该领域值得关注的研究方向.     

直接三氟甲硫基化反应研究进展

三氟甲硫基由于具有较强的吸电子性和极高的亲脂性,使得含三氟甲硫基的化合物在医药、农药以及材料等领域发挥着重要的作用.从有机氟化学的发展历程来看,三氟甲硫基化反应是继三氟甲基化反应后的又一重要研究课题,受到化学家的广泛关注.重点论述了近5年来国内外学者在直接三氟甲硫基化反应的研究成果,并讨论了三氟甲硫基化反应所面临的一些挑战.     

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.     

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.