钯催化剂催化交叉偶联反应形成P-C键和复杂含磷化合物的研究进展

综述了利用金属钯催化交叉偶联反应形成P-C键以合成各种复杂的含磷化合物特别是手性膦配体的研究进展;介绍了参加偶联反应的不同价态的P化合物亲核试剂,以及卤代烯烃、卤代芳烃、三氟甲磺酸烯基脂、三氟甲磺酸芳基脂、乙烯基硼酸脂等亲电试剂;探讨了相应的偶联反应的反应条件、反应机理及其在材料、医药、农药等领域的应用.     

无水二氯化镍催化下醋酸烯丙酯与亚磷酸二酯的反应

利用Pd(O)催化下R~2R~3P(O)H(R~2,R~3=烷基、芳基、烷氧基)与芳基溴,烯基溴以及丁二烯反应合成芳基、烯基和烯丙基膦酸酯近年来有较多报道,但后者产率仅为10%。Fiaud曾报道了二苯基膦锂和醋酸烯丙酯的反应,但烯丙基膦化合物产率低于15%。我们曾发现醋酸烯丙酯在O,N-二(三甲硅基)乙酰胺(BSA)存在下,用Ni(cod)_3为催化剂与亚磷酸二酯反应,高产率地得到了烯丙基膦酸酯,而Pd(PPh_3)_4不能催化这个反应。我们认为反应的关键是亚磷酸二酯首先与BSA反应生成O,O-二烷基-O-三甲硅基亚磷酸酯     

无过渡金属参与的三芳基膦化合物合成新方法研究

三芳基膦化合物在医药合成、过渡金属催化等方面扮演十分重要的角色.报道了碱促进的芳基卤代物与烷基取代的二芳基膦的C(sp~2)—P键偶联新方法合成三芳基膦.该方法具有无过渡金属催化剂参与、反应底物来源广泛、后处理简洁等优点.     

钯催化Stille交叉偶联反应研究新进展

综述了钯催化Stille交叉偶联反应的最新研究进展, 主要包括三个方面: (1)有机锡化合物与有机亲电试剂如卤代芳香烃、卤代烷烃、酰氯等的反应; (2)Stille反应的机理; (3) Stille反应在有机合成中的应用.     

手性膦过渡金属配合物催化不对称交叉偶联反应的研究

自1973年Consiglio和Botteghi首次报道用(一)-DIOP的NiCl_2配合物催化芳基或乙烯基卤代物与仲烷基卤化镁交叉偶联生成光学活性的偶联产物以来,化学家们对不对称交叉偶联反应进行了深入研究。Hayashi等用手性二茂铁膦和手性β-氨基烷基膦的NiCl_2和PdCl_2配合物催化1-苯基乙基氯化     

钯等过渡金属催化的卤代芳烃和胺的偶联反应

综述了钯等过渡金属催化的卤代芳烃或芳基碘酸酯和胺的偶联反应以及催化这 一新反应的催化剂的发展和应用。用于该反应的配体由P（o-tolyl)3发展到BINAP 及二烷基芳基膦，基底物由溴代芳烃扩展到经济易得的氯化芳烃及碘酸酯和各种胺。     

钯催化下芳基磺酸酯和芳基硅烷的Hiyama交叉偶联反应

钯催化下有机硅试剂和有机亲电试剂的Hiyama偶联反应是形成碳-碳键的重要方法之一．相较于有机锌、锡试剂和格氏试剂,有机硅试剂易于操作,对空气和水也较稳定,且毒性很低．另一方面,芳基磺酸酯作为交叉偶联反应中的亲电试剂正在受到很大关注．作为酚的衍生物,此类化合物廉价易得,性质稳定且易于操作．     

Pd(Ⅱ)催化的芳基次膦酸衍生物C-H键活化芳基化反应及衍生化反应

通过对钯催化的不同次膦酸衍生物芳基偶联反应的深入探索,发现在Pd(OAc)2作催化剂,Ag2CO3作氧化剂,对苯醌(BQ)作添加剂的反应条件下,可以高效地实现芳基次膦酰胺邻位C—H键的直接芳基化。机理研究表明,芳基次膦酰胺邻位C—H键活化芳基偶联反应经历了Pd(0)到Pd(Ⅱ)的催化循环。在对偶联产物衍生化的研究过程中,发现芳基次膦酰胺化合物可以高效地转化为芳基次膦酸酯和芳基膦化氢,收率分别为98%和82%。因此,本文报道的实验结果可以为多芳基膦化合物的合成提供一个新的方法。     

镍催化构筑C(sp3)—C(sp3)键反应研究进展

过渡金属催化的偶联反应是构筑C-C键的高效方法,在有机合成中得到了广泛的应用.然而,相对于Heck反应、Negishi偶联与Suzuki偶联等构筑C（sp²）-C（sp²）键的反应,过渡金属催化的构筑C（sp³）-C（sp³）键的偶联反应较难进行,发展较晚.近年来,烷基-烷基C-C键偶联反应受到广泛的重视,一些高效催化剂被开发出来,其中镍催化剂展示出独特的催化活性和选择性.本文将综述镍催化烷基-烷基C-C键偶联反应最新研究进展,主要包括烷基亲电试剂与金属有机试剂交叉偶联反应、导向基参与的C（sp³）-H键活化的偶联反应、镍-光反应催化剂协同催化偶联反应、烷基亲电试剂与亲电试剂的还原偶联反应和镍催化烯烃加成反应等.     

Pd催化P-C偶联合成膦配体的进展

本文综述了Pd催化的P-C偶联反应在多种膦化物合成中的应用,以及近年来利用Pd催化的P-C偶联和C-C偶联相结合在合成复杂的手性膦化物和对有机膦功能化研究中的成就。     

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.