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Iron‐Carbonyl‐Catalyzed Redox‐Neutral [4+2] Annulation of N−H Imines and Internal Alkynes by C−H Bond Activation 下载免费PDF全文
Teng Jia Chongyang Zhao Dr. Ruoyu He Prof. Dr. Hui Chen Prof. Dr. Congyang Wang 《Angewandte Chemie (International ed. in English)》2016,55(17):5268-5271
Stoichiometric C?H bond activation of arenes mediated by iron carbonyls was reported by Pauson as early as in 1965, yet the catalytic C?H transformations have not been developed. Herein, an iron‐catalyzed annulation of N?H imines and internal alkynes to furnish cis‐3,4‐dihydroisoquinolines is described, and represents the first iron‐carbonyl‐catalyzed C?H activation reaction of arenes. Remarkablely, this is also the first redox‐neutral [4+2] annulation of imines and alkynes proceeding by C?H activation. The reaction also features only cis stereoselectivity and excellent atom economy as neither base, nor external ligand, nor additive is required. Experimental and theoretical studies reveal an oxidative addition mechanism for C?H bond activation to afford a dinuclear ferracycle and a synergetic diiron‐promoted H‐transfer to the alkyne as the turnover‐determining step. 相似文献
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π‐Allyl (η3‐C3H5), a four‐electron donor, was used as a ligand model to replace η5‐C5Me4SiMe3 in DFT calculations on the tetranuclear yttrium polyhydrido complex (η5‐C5Me4SiMe3)4Y4H8 containing a Y4H8 tetrahedral core structure, which may separate the four π‐allyl groups and hence suppress the allyl ligand coupling during the computation. In terms of the calculated core geometry, isomerization energy barrier, charge population, and frontier orbital features of the complex, the η3‐C3H5 ligand model is comparable to η5‐C5H5. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007 相似文献
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Rhodium(III)‐Catalyzed [3+2]/[5+2] Annulation of 4‐Aryl 1,2,3‐Triazoles with Internal Alkynes through Dual C(sp2)H Functionalization 下载免费PDF全文
Yuan Yang Ming‐Bo Zhou Xuan‐Hui Ouyang Rui Pi Dr. Ren‐Jie Song Prof. Dr. Jin‐Heng Li 《Angewandte Chemie (International ed. in English)》2015,54(22):6595-6599
A rhodium(III)‐catalyzed [3+2]/[5+2] annulation of 4‐aryl 1‐tosyl‐1,2,3‐triazoles with internal alkynes is presented. This transformation provides straightforward access to indeno[1,7‐cd]azepine architectures through a sequence involving the formation of a rhodium(III) azavinyl carbene, dual C(sp2)? H functionalization, and [3+2]/[5+2] annulation. 相似文献
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Narayan S. Hosmane Chong Zheng 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(5):525-527
The title dimer, bis[1‐cyclopentadienyl‐2‐methyl‐1‐titana‐3‐trimethylsilyl‐2,3‐dicarba‐closo‐hexaborane(6)], [Ti(C5H5)(C6H16B4Si)]2, reveals that the centrosymmetric molecule consists of two bent‐sandwich titanacarboranes bridged by the B—H—Ti bonds. The average bond distances are Ti—B 2.445 (3), Ti—C(cage) 2.334 (2) and Ti—C(Cp) 2.376 (3) Å, and the corresponding bond angles are Cp—Ti—Cp 163.2 (1) and Cp—Ti—Cb (Cb = C2B3 face) 139.9 (1)°; the Ti—H separations are 2.10 (2) and 2.19 (2) Å. 相似文献
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Rhodium(III)‐Catalyzed [3+2] Annulation of 5‐Aryl‐2,3‐dihydro‐1H‐pyrroles with Internal Alkynes through C(sp2)H/Alkene Functionalization 下载免费PDF全文
Ming‐Bo Zhou Rui Pi Ming Hu Yuan Yang Ren‐Jie Song Dr. Yuanzhi Xia Prof. Dr. Jin‐Heng Li 《Angewandte Chemie (International ed. in English)》2014,53(42):11338-11341
This study describes a new rhodium(III)‐catalyzed [3+2] annulation of 5‐aryl‐2,3‐dihydro‐1H‐pyrroles with internal alkynes using a Cu(OAc)2 oxidant for building a spirocyclic ring system, which includes the functionalization of an aryl C(sp2)? H bond and addition/protonolysis of an alkene C?C bond. This method is applicable to a wide range of 5‐aryl‐2,3‐dihydro‐1H‐pyrroles and internal alkynes, and results in the assembly of the spiro[indene‐1,2′‐pyrrolidine] architectures in good yields with excellent regioselectivities. 相似文献
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Xin‐Qi Zhu Ze‐Shu Wang Bo‐Shang Hou Hao‐Wen Zhang Chao Deng Long‐Wu Ye 《Angewandte Chemie (International ed. in English)》2020,59(4):1666-1673
6π electrocyclization has attracted interest in organic synthesis because of its high stereospecificity and atom economy in the construction of versatile 5–7‐membered cycles. However, examples of asymmetric 6π electrocyclization are quite scarce, and have to rely on the use of chiral organocatalysts, and been limited to pentadienyl‐anion‐ and triene‐type 6π electrocyclizations. Described herein is a zinc‐catalyzed formal [4+3] annulation of isoxazoles with 3‐en‐1‐ynol ethers via 6π electrocyclization, leading to the site‐selective synthesis of functionalized 2H‐azepines and 4H‐azepines in good to excellent yields with broad substrate scope. Moreover, this strategy has also been used to produce chiral 2H‐azepines with high enantioselectivities (up to 97:3 e.r.). This protocol not only is the first asymmetric heptatrienyl‐cation‐type 6π electrocyclization, but also is the first asymmetric reaction of isoxazoles with alkynes and the first asymmetric catalysis based on ynol ethers. 相似文献
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Crystal Structures of the Carborane Dianions [1,4‐(PhCB10H10C)2C6H4]2− and [1,4‐(PhCB10H10C)2C6F4]2− and the Stabilizing Role of the para‐Phenylene Unit on 2 n+3 Skeletal Electron Clusters 下载免费PDF全文
Dr. Jan Kahlert Dr. Hans‐Georg Stammler Beate Neumann Dr. Rachel A. Harder Prof. Dr. Lothar Weber Dr. Mark A. Fox 《Angewandte Chemie (International ed. in English)》2014,53(14):3702-3705
While carboranes with 2 n+2 and 2 n+4 (n=number of skeletal atoms) skeletal electrons (SE) are widely known, little has been reported on carboranes with odd SE numbers. Electrochemical measurements on two‐cage assemblies, where two C‐phenyl‐ortho‐carboranyl groups are linked by a para‐phenylene or a para‐tetrafluorophenylene bridge, revealed two well separated and reversible two‐electron reduction waves indicating formation of stable dianions and tetraanions. The salts of the dianions were isolated by reduction with sodium metal and their unusual structures were determined by X‐ray crystallography. The diamagnetic dianions contain two 2 n+3 SE clusters where each cluster has a notably long carborane C–carborane C distance of ca 2.4 Å. The π conjugation within the phenylene bridge plays an important role in the stabilization of these carboranes with odd SE counts. 相似文献
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Brendan Twamley PhilipP. Power 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2000,112(19):3643-3646
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