共查询到19条相似文献,搜索用时 125 毫秒
1.
反式-2,5-二芳基四氢呋喃合成的新方法 总被引:1,自引:1,他引:0
以(±)4,10-二氧杂三环[5,2,1,02,6]-癸-8-烯-3-醇为原料,经过芳基化、氧化、芳基化、环化、热分解和加氢反应,得到PAF新的拮抗物反式-2,5-二芳基四氢呋喃,并合成了化合物8. 相似文献
2.
3.
传统的烯烃二芳基化主要手段是,先通过过渡金属催化的芳基亲电试剂与烯烃发生交叉偶联,然后再与芳基亲核试剂发生反应[1].但是这种反应策略存在原子经济性低及反应步骤多的缺点.因此急需发展一种高效、高原子经济性的合成方法来实现烯烃的二芳基化.2015年,Bunel/Lei课题组[2]报道了FeCl3/2,3-二氯-5,6-二氰基对苯醌(DDQ)催化条件下苯乙烯的1,2-二芳基化;2017年,Bao课题组[3]报道了Fe(OTf)3/DDQ催化条件下苯乙烯的1,2-二芳基化。 相似文献
4.
三组分双官能化反应是一种高效、简便构建C―C键、C―X键的方式. 双键广泛存在于众多有机化合物中, 对双键的双官能化反应研究有巨大的应用潜力. 本工作以Ni(COD)2为催化剂, 以芳基溴化镁、芳基溴化物为芳基化试剂, 实现了3-芳基-2-丙烯醛亚胺中碳碳双键的双芳基化反应. 该反应建立了一个新的镍催化α,β-不饱和醛的α,β-双芳基化方法, 可以高度区域选择性地向底物分子中引入两个不同取代的芳环, 得到多种2,3,3-三芳基丙醛骨架的产物. 利用这一反应作为核心步骤实现了天然产物Quebecol的简便合成. 机理研究表明, 该反应可能经历了亲核加成、金属交换、还原消除的历程. 相似文献
5.
富电子、大位阻MOP型烷基膦配体2-二叔丁基膦-2’-异丙氧基-1,1’-联萘(L1)在钯催化的1,3-二羰基化合物的α-芳基化反应中显示了较好的催化活性. 在这类催化反应中, 碱的选择具有重要的影响: 以K3PO4为碱, Pd(OAc)2/L1催化体系在丙二酸二乙酯的α-芳基化中, 富电子溴代芳烃显示较好的活性; Pd(OAc)2/L1催化的乙酰乙酸乙酯α-芳基化时, 以 K2CO3为碱, 催化体系显示较好的活性, 这个催化体系可控制反应得到α-芳基乙酰乙酸乙酯, 而不是脱乙酰基的产物. 较为惰性的氯代芳烃在Pd(OAc)2/L1的催化下, 也能够跟1,3-二羰基化合物发生α-芳基化反应. 相似文献
6.
报道了一种高效的δ-三氟甲基-δ-芳基-取代对亚甲基苯醌的叠氮化芳基化反应. 以Na2CO3为催化剂, 叠氮三甲基硅烷与δ-三氟甲基-δ-芳基取代对亚甲基苯醌发生1,6-共轭加成反应, 以优异的分离产率(90%~96%)获得了结构多样的含有三氟甲基和叠氮取代的二芳基甲烷化合物.该反应具有良好的底物适用范围和官能团兼容性. 相似文献
7.
8.
9.
报道了一种合成3,3-二芳基氧化吲哚的新方法。以取代靛红为起始原料,THF为溶剂,在室温下用新制芳基格氏试剂与靛红的3-位羰基发生双芳基化反应,合成了12个未见文献报道的3,3-二芳基氧化吲哚(3a~3l),产率56%~78%,其结构经1H NMR, 13C NMR和HR-MS(ESI-TOF)表征。并分析了3a(CCDC: 1960434)和3b(CCDC: 1960436)的单晶结构。结果表明:3a属triclinic晶系,P-1空间群,晶胞参数a=8.736(2) , b=8.887(2) , c=13.862(3) , α=77.505(18)°, β=72.01(2)°, γ=64.68(2)°; 3b属monoclinic晶系,P21/c空间群,晶胞参数a=8.8877(10) , b=24.734(2) , c=8.5441(8) , α=90°, β=113.994(12)°, γ=90°。 相似文献
10.
11.
Takaya Matsumoto Roy A Periana Douglas J Taube Hajime Yoshida 《Journal of molecular catalysis. A, Chemical》2002,180(1-2):1-18
The novel, anti-Markovnikov, arylation of olefins with benzene to produce straight-chain alkylbenzenes with higher selectivity than branched alkylbenzenes is catalyzed by [Ir(μ-acac-O,O′,C3)(acac-O,O′)(acac-C3)]2 (acac=acetylacetonato), 1 [J. Am. Chem. Soc. 122 (2000) 7414]. The reaction of benzene with propylene gave n-propylbenzene and cumene in 61 and 39% selectivities, respectively. The reaction of benzene and styrene afforded 1,2-diphenylethane in 98% selectivity. Considering the anti-Markovnikov regioselectivity and lack of inhibition by water, we propose that the reaction does not proceed via a Friedel–Crafts, carbocation, mechanism. Complex 1, amongst the various transition metal complexes examined, is the most efficient for catalyzing the anti-Markovnikov olefin arylation. The crystal structure of complex 1 was solved and is consistent with a binuclear Ir(III) structure with three different types of coordinated acac ligands as reported by earlier solution IR and NMR analyses. [Ir(μ-acac-O,O′,C3)(acac-O,O′)Cl]2, 2, was prepared by the reaction of complex 1 with benzoyl chloride, and the crystal structure was also reported. 相似文献
12.
ArylationofN-VinylsuccinimideandPreparationof2-Arylethylamines*//PANYi,ZHANGZhuang-yu,WANGLian-sheng,JIANGXin,HUHong-wen(Depa... 相似文献
13.
On treatment with Pd(PPh3)4 allyl vinyl ether (1) undergoes a Pd(0) catalysed 1,3 oxygen to carbon allyl shift to afford -allyl ketone (2). In the presence of both Pd(PPh3)4 and base the allyl vinyl ether undergoes a Pd(0) catalysed tandem 1,3 allyl shift and intramolecular Heck arylation to give the spiro indane (3). Mechanistic investigations suggest that the 1,3-allyl shift proceeds via a π-allyl palladium intermediate. 相似文献
14.
Zhenyu Yao Xing Lin Remi Chauvin Lianhui Wang Emmanuel Gras Xiuling Cui 《中国化学快报》2021,31(12):3250-3254
As balanced electron-rich P,C-chelating ligands, phosphine-phosphonium-ylides are considered for their ability to in situ promote palladium-catalysed direct C(sp2)-H arylation. Using methyl phosphonium salts of 2,2'-bis(diphenylphosphino)-1,1'-binaphtyl ("methyl-BINAPIUM") as ylide precursors under optimized reaction conditions, arylation of benzoxazole was found to proceed in moderate to high yield to give functional 2-aryl benzoxazoles. A strong anion effect of the non-salt free ylide was evidenced (TfO- > I- > PF6- ≈ salt-free). This first example of phosphonium ylides as ligands in catalytic C-H activation extends the prospect of their general implementation in homogeneous transition metal catalysis. 相似文献
15.
Reported herein is the first example of heterogeneous palladium catalyzed C(sp3)-H bonds arylation by a transient-ligand-directed strategy.Using supported palladium(metallic state) na nopariticles as catalyst,a wide range of aryl iodides undergo the coupling with various o-methylbenzaldehyde derivatives to assemble a library of highly selective and functionalized o-benzylbenzaldehydes.The stability of the catalyst was easily recovered four runs without significant loss of activity.The XPS analysis of the catalyst before and after reaction indicated that the reaction might be carried out by a catalytic cycle starting with Pd~0. 相似文献
16.
An orthopalladated complex of commercially available tris(2,4-di-tert-butylphenyl)phosphite proves to be an extremely active catalyst in the Heck arylation of alkenes, with turnover numbers of up to 5,750,000 (mol product.mol Pd−1) and turnover frequencies of up to nearly 300,000 (mol product.mol Pd−1.h−1). 相似文献
17.
On the basis of a series of control experiments and nuclear magnetic resonance analyses, it is discovered that Boc-protected amino acid ligand coordinated to Pd center is partly replaced by N,N-dimethylformamide, and H2O can inhibit coordination of N,N-dimethylformamide to Pd center. The novel action mechanism perfectly explains H2O promotion for stereoselectivity in Pd(II)-catalyzed C-H arylation of diarylphosphinamides with arylboronic acids. 相似文献
18.
The use of ligands to control regioselectivity in transition-metal-catalyzed C-H activation/functionalization is a highly desirable but challenging task. Recently, Itami et al. reported an important finding relating to Pd-catalyzed ligand-controlled α/β-selective C-H arylation of thiophenes. Specifically, the use of the 2,2'-bipyridyl ligand resulted in α-arylation, whereas the use of the bulky fluorinated phosphine ligand P[OCH(CF(3))(2)](3) resulted in β-arylation. Understanding of this surprising ligand-controlled α/β-selectivity could provide important insights into the development of more efficient catalyst systems for selective C-H arylation, and so we carried out a detailed computational study on the problem with use of density functional theory methods. Three mechanistic possibilities--S(E)Ar and migration, metalation/deprotonation, and Heck-type arylation mechanisms--were examined. The results showed that the S(E)Ar and migration mechanism might not be plausible, because the key Wheland intermediates could not be obtained. On the other hand, our study indicated that the metalation/deprotonation and Heck-type arylation mechanisms were both involved in Itami's reactions. In the metalation/deprotonation pathway the α-selective product (C5-product) was preferred, whereas in the Heck-type arylation mechanism the β-selective product (C4-product) was favored. The ligands played crucial roles in tuning the relative barriers of the two different pathways. In the 2,2'-bipyridyl-assisted system, the metalation/deprotonation pathway was energetically advantageous, leading to α-selectivity. In the P[OCH(CF(3))(2)](3)-assisted system, on the other hand, the Heck-type arylation mechanism was kinetically favored, leading to β-selectivity. An interesting finding was that P[OCH(CF(3))(2)](3) could produce a C-H···O hydrogen bond in the catalyst system, which was crucial for stabilization of the Heck-type transition state. In comparison, this C-H···O hydrogen bond was absent with the other phosphine ligands [i.e., P(OMe)(3), PPh(3), PCy(3)] and these phosphine ligands therefore favored the metalation/deprotonation pathway leading to α-selectivity. Furthermore, in this study we have provided theoretical evidence showing that the Heck-type arylation reaction could proceed through an anti-β-hydride elimination process. 相似文献
19.
[reaction: see text] The Pd-catalyzed one-pot rearrangement/arylation of 2-allyloxypyridine is described. The catalyst/base combination of Pd[P(t-Bu)(3)](2)/Ag(2)CO(3) was found to be optimal for this one-pot rearrangement/arylation. The initial rearrangement of 2-allyloxypyridine was found to be catalyzed by both Pd(0) and Pd(II) complexes with different mechanisms. 相似文献