共查询到20条相似文献,搜索用时 15 毫秒
1.
Benedikt S. Schreib Marlene Fadel Erick M. Carreira 《Angewandte Chemie (International ed. in English)》2020,59(20):7818-7822
Palladium‐catalyzed regio‐ and diastereoselective C?H functionalization with bromoalkynes and electronically unbiased olefins is reported. The picolinamide directing group enables the formation of putative 5 and 6‐exo‐metallacycles as intermediates to afford monoalkynylated products in up to 91 % yield in a stereospecific fashion. The systematic study reveals that substrates with a wide range of substituents on the olefin and bromoalkyne coupling partners are tolerated. Chemoselective transformations were demonstrated for the obtained amides, olefins, and alkynes. 相似文献
2.
Yan Lin Wei‐Yang Ma Zheng Xu Zhan‐Jiang Zheng Jian Cao Ke‐Fang Yang Yu‐Ming Cui Li‐Wen Xu 《化学:亚洲杂志》2019,14(12):2082-2085
A palladium‐catalyzed chelation‐assisted enantioselective C?H olefination of symmetrically diaryl‐substituted tetraorganosilicon derivatives was developed, enabling the generation of nitrogen‐containing silicon‐stereogenic tetraorganosilicon compounds with modest to good yields and good to excellent enantioselectivities (up to 95.5:4.5 e.r.). The Thorpe–Ingold effect exerted by the substituents on silicon was observed to have a profound influence on formation of olefinated products which were further converted into other relevant chiral organosilanes without the loss of enantiomeric purity, thus demonstrating the synthetic utility of the developed enantioselective olefination. 相似文献
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1,4‐Iron Migration for Expedient Allene Annulations through Iron‐Catalyzed C−H/N−H/C−O/C−H Functionalizations 下载免费PDF全文
Jiayu Mo Thomas Müller Dr. João C. A. Oliveira Prof. Dr. Lutz Ackermann 《Angewandte Chemie (International ed. in English)》2018,57(26):7719-7723
C?H activation bears great potential for enabling sustainable molecular syntheses in a step‐ and atom‐economical manner, with major advances having been realized with precious 4d and 5d transition metals. In contrast, we employed earth abundant, nontoxic iron catalysts for versatile allene annulations through a unique C?H/N?H/C?O/C?H functionalization sequence. The powerful iron catalysis occurred under external‐oxidant‐free conditions even at room temperature, while detailed mechanistic studies revealed an unprecedented 1,4‐iron migration regime for facile C?H activations. 相似文献
5.
Ailan Lu Xiaoming Ji Bo Zhou Zhuo Wu Prof. Dr. Yanghui Zhang 《Angewandte Chemie (International ed. in English)》2018,57(12):3233-3237
A highly efficient palladium‐catalyzed disilylation reaction of aryl halides through C?H activation has been developed for the first time. The reaction has broad substrate scope. A variety of aryl halides can be disilylated by three types of C?H activation, including C(sp2)?H, C(sp3)?H, and remote C?H activation. In particular, the reactions are also unusually efficient. The yields are essentially quantitative in many cases, even in the presence of less than 1 mol % catalyst and 1 equivalent of the silylating reagent under relatively mild conditions. The disilylated biphenyls can be converted into disiloxane‐bridged biphenyls. 相似文献
6.
Guangying Tan Shuang He Xiaolei Huang Xingrong Liao Yangyang Cheng Prof. Dr. Jingsong You 《Angewandte Chemie (International ed. in English)》2016,55(35):10414-10418
The first example of cobalt‐catalyzed oxidative C?H/C?H cross‐coupling between two heteroarenes is reported, which exhibits a broad substrate scope and a high tolerance level for sensitive functional groups. When the amount of Co(OAc)2?4 H2O is reduced from 6.0 to 0.5 mol %, an excellent yield is still obtained at an elevated temperature with a prolonged reaction time. The method can be extended to the reaction between an arene and a heteroarene. It is worth noting that the Ag2CO3 oxidant is renewable. Preliminary mechanistic studies by radical trapping experiments, hydrogen/deuterium exchange experiments, kinetic isotope effect, electron paramagnetic resonance (EPR), and high resolution mass spectrometry (HRMS) suggest that a single electron transfer (SET) pathway is operative, which is distinctly different from the dual C?H bond activation pathway that the well‐described oxidative C?H/C?H cross‐coupling reactions between two heteroarenes typically undergo. 相似文献
7.
Ming Gong Prof. Dr. Jing‐Mei Huang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(40):14293-14296
A mild method for the direct C?H/N?H coupling between γ‐lactams and anilines through electrochemical oxidation has been developed. The protocol proceeded smoothly without metal catalysts at room temperature to afford γ‐substituted γ‐lactams in good yields. It has been revealed that the quasi‐divided cell which provided high current density on the anode was crucial for this reaction. 相似文献
8.
Gerald Dyker 《Angewandte Chemie (International ed. in English)》1999,38(12):1698-1712
C−C coupling by transition metal catalyzed C−H activation has developed into a diverse area of research. The applicable catalysts are manifold, and the variety of products obtained range from basic chemicals to pharmaceuticals and building blocks for carbon networks. One reaction, in which several C−C bonds are formed under C−H activation of a methyl group, is the conversion of ortho-iodoanisole according to Equation (1). 相似文献
9.
《化学:亚洲杂志》2017,12(1):130-144
An efficient palladium(II)‐catalyzed intermolecular direct ortho ‐alkenylation and acetoxylation of phenols has been developed. The reaction proceeded via a seven‐membered cyclopalladated intermediate and showed complete regio‐ and diastereoselectivity. The approach also provided an efficient route for the synthesis of coumarins and benzofurans. 相似文献
10.
Palladium‐Catalyzed Enantioselective C−H Olefination of Diaryl Sulfoxides through Parallel Kinetic Resolution and Desymmetrization 下载免费PDF全文
Yu‐Chao Zhu Dr. Yan Li Bo‐Chao Zhang Feng‐Xu Zhang Yi‐Nuo Yang Prof. Dr. Xi‐Sheng Wang 《Angewandte Chemie (International ed. in English)》2018,57(18):5129-5133
The first example of PdII‐catalyzed enantioselective C?H olefination with non‐chiral or racemic sulfoxides as directing groups was developed. A variety of chiral diaryl sulfoxides were synthesized with high enantioselectivity (up to 99 %) through both desymmetrization and parallel kinetic resolution (PKR). This is the first report of PdII‐catalyzed enantioselective C(sp2)?H functionalization through PKR, and it represents a novel strategy to construct sulfur chiral centers. 相似文献
11.
Synthesis of Strained γ‐Lactams by Palladium(0)‐Catalyzed C(sp3)−H Alkenylation and Application to Alkaloid Synthesis 下载免费PDF全文
Dr. Philipp M. Holstein David Dailler Julien Vantourout Janah Shaya Dr. Anthony Millet Prof. Dr. Olivier Baudoin 《Angewandte Chemie (International ed. in English)》2016,55(8):2805-2809
A variety of strained α‐alkylidene‐γ‐lactams were synthesized by palladium(0)‐catalyzed intramolecular C(sp3)?H alkenylation from easily accessible acyclic and monocyclic bromoalkene precursors. These lactams are valuable intermediates for accessing various classes of mono‐ and bicylic alkaloids containing a pyrrolidine ring, as illustrated with the synthesis of an advanced model of the marine natural product plakoridine A and of the indolizidine alkaloid δ‐coniceine. 相似文献
12.
Hayate Saito Keita Yamamoto Yosuke Sumiya Ling‐Jun Liu Keisuke Nogi Satoshi Maeda Hideki Yorimitsu 《化学:亚洲杂志》2020,15(16):2442-2446
C?H iodination of aromatic compounds has been accomplished with the aid of sulfinyl directing groups under palladium catalysis. The reaction proceeds selectively at the peri‐position of polycyclic aryl sulfoxides or at the ortho‐position of phenyl sulfoxides. The iodination products can be further converted via iterative catalytic cross‐coupling at the expense of the C?I and C?S bonds. Computational studies suggest that peri‐C?H palladation would proceed via a non‐directed pathway, wherein neither of the sulfur nor oxygen atom of the sulfinyl group coordinates to the palladium before and at the transition state. 相似文献
13.
Mild and Efficient Palladium‐Catalyzed Direct Trifluoroethylation of Aromatic Systems by C−H Activation 下载免费PDF全文
Balázs L. Tóth Dr. Szabolcs Kovács Gergő Sályi Dr. Zoltán Novák 《Angewandte Chemie (International ed. in English)》2016,55(6):1988-1992
The introduction of trifluoroalkyl groups into aromatic molecules is an important transformation in the field of organic and medicinal chemistry. However, the direct installation of fluoroalkyl groups onto aromatic molecules still represents a challenging and highly demanding synthetic task. Herein, a simple trifluoroethylation process that relies on the palladium‐catalyzed C?H activation of aromatic compounds is described. With the utilization of a highly active trifluoroethyl(mesityl)iodonium salt, the developed catalytic method enables the first highly efficient and selective trifluoroethylation of aromatic compounds. The robust catalytic procedure provides the desired products in up to 95 % yield at 25 °C in 1.5 to 3 hours and tolerates a broad range of functional groups. The utilization of hypervalent reagents opens new synthetic possibilities for direct alkylations and fluoroalkylations in the field of transition‐metal‐catalyzed C?H activation. 相似文献
14.
Jayanta Ghorai Angula Chandra Shekar Reddy Prof. Dr. Pazhamalai Anbarasan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(45):16042-16046
An efficient cobalt(III)‐catalyzed intramolecular cross‐dehydrogenative C?H/N?H coupling of ortho‐alkenylanilines has been developed utilizing O2 as a terminal oxidant. The developed reaction tolerates various reactive functional groups and allows the synthesis of diverse indole derivatives in good to excellent yields. The method was successfully extended to the synthesis of benzofurans through the intramolecular cross‐dehydrogenative C?H/O?H coupling of ortho‐alkenylphenols. 相似文献
15.
Axially Chiral Dibenzazepinones by a Palladium(0)‐Catalyzed Atropo‐enantioselective C−H Arylation 下载免费PDF全文
Dr. Christopher G. Newton Elena Braconi Jennifer Kuziola Dr. Matthew D. Wodrich Prof. Dr. Nicolai Cramer 《Angewandte Chemie (International ed. in English)》2018,57(34):11040-11044
Atropo‐enantioselective C?H functionalization reactions are largely limited to the dynamic kinetic resolution of biaryl substrates through the introduction of steric bulk proximal to the axis of chirality. Reported herein is a highly atropo‐enantioselective palladium(0)‐catalyzed methodology that forges the axis of chirality during the C?H functionalization process, enabling the synthesis of axially chiral dibenzazepinones. Computational investigations support experimentally determined racemization barriers, while also indicating C?H functionalization proceeds by an enantio‐determining CMD to yield configurationally stable eight‐membered palladacycles. 相似文献
16.
A rhodium(III)‐catalyzed redox‐neutral coupling of α‐trifluoromethylacrylic acid with bezamides proceeds smoothly accompanied by amide‐directed C?H bond cleavage to produce β‐[2‐(aminocarbonyl)phenyl]‐α‐trifluoromethylpropanoic acid derivatives. One of the products can be transformed to a trifluoromethyl substituted heterocyclic compound. In addition, the redox‐neutral coupling of α‐trifluoromethylacrylic acid with related aromatic substrates possessing a nitrogen‐containing directing group can also be conducted under similar conditions. 相似文献
17.
Phenol and its derivatives are extremely useful compounds in organic synthesis, medicinal chemistry and material sciences. The synthesis of phenols involving selective construction of the C?O bond at a C?H bond of arenes using transition‐metal catalysis represents the most appealing strategy. Indeed, active research is currently going on for the synthesis of valuable phenolic compounds using a transition‐metal‐catalyzed C?H functionalization strategy. This short review summarizes recent advances on palladium‐catalyzed C?O bond forming reactions that enable direct access to phenolic compounds. These catalytic reactions proceed either via C?H esterification with trifluoroacetic acid/trifluoroacetic anhydride followed by in situ hydrolysis of the ester or via direct C?H hydroxylation. A brief analysis of substrate scope and limitation, reaction mechanism as well as synthetic utility of these reactions has been included. 相似文献
18.
Thioketone‐Directed Palladium(II)‐Catalyzed C−H Arylation of Ferrocenes with Aryl Boronic Acids 下载免费PDF全文
Zhong‐Jian Cai Chen‐Xu Liu Dr. Qing Gu Prof. Dr. Shu‐Li You 《Angewandte Chemie (International ed. in English)》2018,57(5):1296-1299
A palladium(II)‐catalyzed thioketone‐chelation‐assisted direct C?H arylation of ferrocenes is described. With thioketone as an efficient directing group, various monoaryl‐ and diaryl‐substituted thiocarbonylferrocenes were obtained by palladium‐catalyzed direct C?H functionalization in high yields under mild and base‐free reaction conditions. Furthermore, the arylated thiocarbonylferrocene could undergo diverse transformations. 相似文献
19.
Shibo Xu Kazutaka Takamatsu Prof. Dr. Koji Hirano Prof. Dr. Masahiro Miura 《Angewandte Chemie (International ed. in English)》2018,57(36):11797-11801
A Ni(OAc)2‐catalyzed C?H coupling of 8‐aminoquinoline‐derived benzamides with epoxides has been developed. The reaction proceeds with concomitant removal of the 8‐aminoquinoline auxiliary to form the corresponding 3,4‐dihydroisocoumarins directly. Additionally, the nickel catalysis is stereospecific, and the cis‐ and trans‐epoxides are converted into the corresponding cis‐ and trans‐dihydroisocoumarins with retention of configuration, which is complementary to previously reported palladium catalysis. Moreover, while still preliminary, the C ?H functionalization is also achieved in the presence of modified NiCl2 catalysts. 相似文献
20.
Copper‐Catalyzed Direct Sulfoximination of Heteroaromatic N‐Oxides by Dual C−H/N−H Dehydrogenative Cross‐Coupling 下载免费PDF全文
A dual C?H/N?H dehydrogenative coupling of quinoline‐type N‐oxides with sulfoximines that leads to N‐(hetero)arylsulfoximines in high yields has been realized by using a catalytic amount of CuBr in air. The method does not require any additional ligand, base, reactivity modifier or oxidant and provides a practical route towards a series of sulfoximidoyl‐functionalized quinolines and derivatives. 相似文献