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Rhodium(I)‐Catalyzed Cycloisomerization of Homopropargylallene‐Alkynes through C(sp3)−C(sp) Bond Activation 下载免费PDF全文
Yasuaki Kawaguchi Kenya Yabushita Prof. Dr. Chisato Mukai 《Angewandte Chemie (International ed. in English)》2018,57(17):4707-4711
Upon exposure to a catalytic amount of [RhCl(CO)2]2 in 1,4‐dioxane, homopropargylallene‐alkynes underwent a novel cycloisomerization accompanied by the migration of the alkyne moiety of the homopropargyl functional group to produce six/five/five tricyclic compounds in good yields. A plausible mechanism was proposed on the basis of an experiment with 13C‐labeled substrate. The resulting tricyclic derivatives were further converted into the corresponding bicyclo[3.3.0] skeletons with vicinal cis dihydroxy groups. 相似文献
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Dr. Shigeo Yasuda Yasuaki Kawaguchi Yuta Okamoto Prof. Dr. Chisato Mukai 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(34):12181-12188
A highly chemo‐ and regioselective partially intramolecular rhodium(I)‐catalyzed [2+2+2] cycloaddition of allenynes with alkynes is described. A range of diverse polysubstituted benzene derivatives could be synthesized in good to excellent yields, in which the allenynes served as synthetic equivalent to the diynes. A high regioselectivity could be observed when allenynes were treated with unsymmetrical alkynes. 相似文献
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Diels‐Alder reaction is one of the most important reactions in organic synthesis and has witnessed great achievements in total syntheses of complex natural products. In this review, we will focus on the [4 + 2] cycloaddition that utilizes 2‐pyrone as the diene component. Major advances of its applications in the total syntheses of natural products in the past fifty years will be discussed here. 相似文献
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A Cu‐catalyzed [4+1] annulation of N‐aryl‐1,2,3,4‐tetrahydroisoquinolines (N‐aryl THIQs) with α‐diazoketones has been established under oxidative conditions, leading to the construction of a series of indolo[2,1‐a]isoquinolines with generally good yields. The reaction enables dediazotized dicarbonylation of α‐diazoketones, creating direct C(sp3)/C(sp2)?H bond bifunctionalization to access tetracyclic aza‐heterocyclic skeletons. 相似文献
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《中国化学》2018,36(8):712-715
Herein, two efficient palladium‐catalyzed intermolecular oxidative coupling reactions of (Z)‐enamines with isocyanides via selective β‐C(sp2)‐H and/or C=C bond cleavage have been developed, leading to controllable chemodivergent and stereoselective construction of a wide range of (E)‐β‐carbamoylenamine derivatives containing strong intramolecular hydrogen bonds. Furthermore, possible reaction pathways for these transformations are proposed on the basis of preliminary mechanism studies. 相似文献
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Rhodium(III)‐Catalyzed Alkenylation Reactions of 8‐Methylquinolines with Alkynes by C(sp3)H Activation 下载免费PDF全文
Bingxian Liu Tao Zhou Prof. Dr. Bin Li Prof. Shansheng Xu Prof. Dr. Haibin Song Prof. Dr. Baiquan Wang 《Angewandte Chemie (International ed. in English)》2014,53(16):4191-4195
The alkenylation reactions of 8‐methylquinolines with alkynes, catalyzed by [{Cp*RhCl2}2], proceeds efficiently to give 8‐allylquinolines in good yields by C(sp3)? H bond activation. These reactions are highly regio‐ and stereoselective. A catalytically competent five‐membered rhodacycle has been structurally characterized, thus revealing a key intermediate in the catalytic cycle. 相似文献
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Rhodium(I)‐Catalyzed Sequential C(sp)C(sp3) and C(sp3)C(sp3) Bond Formation through Migratory Carbene Insertion 下载免费PDF全文
Ying Xia Sheng Feng Zhen Liu Dr. Yan Zhang Prof. Dr. Jianbo Wang 《Angewandte Chemie (International ed. in English)》2015,54(27):7891-7894
A RhI‐catalyzed three‐component reaction of tert‐propargyl alcohol, diazoester, and alkyl halide has been developed. This reaction can be considered as a carbene‐involving sequential alkyl and alkynyl coupling, in which C(sp)? C(sp3) and C(sp3)? C(sp3) bonds are built successively on the carbenic carbon atom. The RhI‐carbene migratory insertion of an alkynyl moiety and subsequent alkylation are proposed to account for the two separate C? C bond formations. This reaction provides an efficient and tunable method for the construction of all‐carbon quaternary center. 相似文献
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Rhodium(I)‐Catalyzed Decarbonylative Spirocyclization through CC Bond Cleavage of Benzocyclobutenones: An Efficient Approach to Functionalized Spirocycles 下载免费PDF全文
Dr. Tao Xu Nikolas A. Savage Prof. Dr. Guangbin Dong 《Angewandte Chemie (International ed. in English)》2014,53(7):1891-1895
The rhodium‐catalyzed formation of all‐carbon spirocenters involves a decarbonylative coupling of trisubstituted cyclic olefins and benzocyclobutenones through C? C activation. The metal–ligand combination [{Rh(CO)2Cl}2]/P(C6F5)3 catalyzed this transformation most efficiently. A range of diverse spirocycles were synthesized in good to excellent yields and many sensitive functional groups were tolerated. A mechanistic study supports a hydrogen‐transfer process that occurs through a β‐H elimination/decarbonylation pathway. 相似文献
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Yasuaki Kawaguchi Dr. Shigeo Yasuda Akira Kaneko Yuki Oura Prof. Dr. Chisato Mukai 《Angewandte Chemie (International ed. in English)》2014,53(29):7608-7612
The efficient RhI‐catalyzed cycloisomerization of benzylallene‐alkynes produced the tricyclo[9.4.0.03,8]pentadecapentaene skeleton through a C? H bond activation in good yields. A plausible reaction mechanism proceeds via oxidative addition of the acetylenic C? H bond to RhI, an ene‐type cyclization to the vinylidenecarbene–RhI intermediate, and an electrophilic aromatic substitution with the vinylidenecarbene species. It was proposed based on deuteration and competition experiments. 相似文献
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Benjamin W. Gung Prof. Dr. Derek T. Craft Lauren N. Bailey Kristin Kirschbaum Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(2):639-644
Macrocyclic propargyl acetates containing a furan ring were prepared by using a CrCl2‐promoted reaction. In the presence of either a AuI or AuIII catalyst, a tandem 3,3‐rearrangement/transannular [4+3] cycloaddition reaction occurred to give propargyl acetates that are regio‐ and diastereospecific. The regiochemistry of the product is controlled by the position of the acetoxy group in the starting material and the stereochemistry of the reaction depends on the ring size. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(30):8793-8797
Previously reported was that cis‐ene‐vinylcyclopropanes (cis‐ene‐VCPs) underwent Rh‐catalyzed [5+2] reaction to give 5,7‐fused bicyclic products, where vinylcyclopropane (VCP) acts as five‐carbon synthon. Unfortunately, this reaction had very limited scope. Replacing the 2π component of cis‐ene‐VCPs to allene moiety, the corresponding cis‐allene‐VCPs did not undergo the expected normal [5+2] cycloaddition to give 5,7‐fused bicyclic products. Instead, the challenging bicyclo[4.3.1]decane skeleton was obtained via an unprecedented bridged [5+2] cycloaddition. DFT calculations were applied to understand why this bridged [5+2] reaction is favored over the anticipated but not realized normal [5+2] reaction. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(35):10675-10680
The silver‐catalyzed oxidative C(sp3)−H/P−H cross‐coupling of 1,3‐dicarbonyl compounds with H‐phosphonates, followed by a chemo‐ and regioselective C(sp3)−C(CO) bond‐cleavage step, provided heavily functionalized β‐ketophosphonates. This novel method based on a readily available reaction system exhibits wide scope, high functional‐group tolerance, and exclusive selectivity. 相似文献
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Sheng Feng Prof. Fanyang Mo Dr. Ying Xia Zhenxing Liu Zhen Liu Prof. Yan Zhang Prof. Jianbo Wang 《Angewandte Chemie (International ed. in English)》2016,55(49):15401-15405
The rhodium(I)‐catalyzed C?C bond activation reaction of siloxyvinylcyclopropanes with diazoesters demonstrates a novel mode of C?C bond cleavage of siloxyvinvylcyclopanes. The alkene products were obtained as single E‐configured isomers in good yields. A σ,η3‐allyl rhodium complex, which has been previously proposed as the key intermediate in rhodium(I)‐catalyzed cycloaddition of vinylcyclopropanes, has been isolated and characterized by X‐ray crystallography. 相似文献
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Sehoon Park 《中国化学》2019,37(10):1057-1071
Transition metal‐catalyzed hydrosilylation is one of the most widely utilized reduction methods as an alternative to hydrogenation in academia and industry. One feature distinct from hydrogenation would be able to install sp3 C—Si bond(s) onto substrates skeleton via hydrosilylation of alkenes. Recently, B(C6F5)3 with hydrosilanes has been demonstrated to be an efficient, metal‐free catalyst system for the consecutive transformation of heteroatom‐containing substrates accompanied by the formation of sp3 C—Si bond(s), which has not been realized thus far under the transition metal‐catalyzed hydrosilylative conditions. In this review, I outline the B(C6F5)3‐mediated consecutive hydrosilylations of heteroarenes containing quinolines, pyridines, and furans, and of conjugated nitriles/imines to provide a new family of compounds having sp3 C—Si bond(s) with high chemo‐, regio‐ and/or stereoselectivities. The silylative cascade conversion of unactivated N‐aryl piperidines to sila‐N‐heterocycles catalyzed by B(C6F5)3 involving consecutive dehydrogenation, hydrosilylation, and intramolecular C(sp2)—H silylation, is presented in another section. Chemical selectivity and mechanism of the boron catalysis focused on the sp3 C—Si bond formation are highlighted. 相似文献