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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(30):8906-8910
We describe the synthetically useful enantioselective addition of Br−CX3 (X=Cl or Br) to terminal olefins to introduce a trihalomethyl group and generate optically active secondary bromides. Computational and experimental evidence supports an asymmetric atom‐transfer radical addition (ATRA) mechanism in which the stereodetermining step involves outer‐sphere bromine abstraction from a [(bisphosphine)RhIIBrCl] complex by a benzylic radical intermediate. This mechanism appears unprecedented in asymmetric catalysis. 相似文献
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Dino Berthold Arne G. A. Geissler Sabrina Giofr Bernhard Breit 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(29):10099-10102
The rhodium‐catalyzed asymmetric intramolecular hydroamination of sulfonyl amides with terminal allenes is reported. It provides selective access to 5‐ and 6‐membered N‐heterocycles, scaffolds found in a large range of different bioactive compounds. Moreover, gram scale reactions, as well as the application of suitable product transformations to natural products and key intermediates thereof are demonstrated. 相似文献
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Bowen Li Jianzhong Chen Zhenfeng Zhang Ilya D. Gridnev Wanbin Zhang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(22):7407-7412
An efficient nickel‐catalyzed asymmetric hydrogenation of N‐tBu ‐ sulfonyl imines was developed with excellent yields and enantioselectivities using (R,R)‐QuinoxP* as a chiral ligand. The use of a much lower catalyst loading (0.0095 mol %, S/C=10500) represents the highest catalytic activity for the Ni‐catalyzed asymmetric hydrogenations reported so far. Mechanistic studies suggest that a coordination equilibrium exists between the nickel salt and its complex, and that excess nickel salt promotes the formation of the active Ni‐complex, and therefore improved the efficiency of the hydrogenation. The catalytic cycle was also investigated by calculations to determine the origin of the enantioselectivity. An extensive network of numerous weak attractive interactions was found to exist between the catalyst and substrate in the transition state and may also contribute to the high catalytic activity. 相似文献
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Qingjing Yang Yanbo Wang Shihui Luo Jun Wang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(16):5397-5401
A highly efficient kinetic resolution and dynamic kinetic resolution of chromene is reported for the first time and they procced by a rhodium‐catalyzed asymmetric hydroarylation pathway. This new approach offers versatile access to various chiral 2,3‐diaryl‐chromanes containing vicinal stereogenic centers, as well as the recovered chiral flavenes, in high yields with excellent ee values (s factor up to 532). Particularly noteworthy is that this strategy can be further extended to the establishment of a dynamic version of the kinetic resolution of chromene acetals and allows complete access to chiral isoflavanes and α‐aryl hydrocoumarins. 相似文献
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Jinbin Zhu Linwei Huang Wei Dong Naikai Li Xingxin Yu Wei‐Ping Deng Wenjun Tang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(45):16265-16269
Highly enantioselective rhodium‐catalyzed addition of arylboroxines to N‐unprotected ketimines is realized for the first time by employing chiral BIBOP‐type ligands with a Rh loading as low as 1 mol %. A range of chiral α‐trifluoromethyl‐α,α‐diaryl α‐tertiary amines or 3‐amino‐3‐aryloxindoles were formed with excellent ee values and yields by employing either WingPhos or PFBO‐BIBOP as the ligand. The method has enabled an efficient enantioselective synthesis of cipargamin. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(16):4611-4615
Rhodium‐catalyzed C(sp2)−H functionalization reactions of 4‐aryl‐5‐pyrazolones followed by [3+2] annulation reactions with alkynes provide rapid access to highly enantioenriched five‐membered‐ring 4‐spiro‐5‐pyrazolones. The use of a chiral SCpRh catalyst enabled the synthesis of a large range of spiropyrazolones with all‐carbon quaternary stereogenic centers in up to 99 % yield and 98 % ee from readily available substrates. 相似文献
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Shu‐Sheng Zhang Tian‐Jiao Hu Meng‐Yao Li Yi‐Kang Song Xiao‐Di Yang Chen‐Guo Feng Guo‐Qiang Lin 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(11):3425-3429
The asymmetric rhodium‐catalyzed alkenylation of enones and imines with arylboronic acids has been developed. A highly controllable aryl to vinyl 1,4‐rhodium migration is the key step. Stereodefined vinyl moieties were installed in excellent enantioselectivies for most examined examples. DFT calculations reveal that the driving force of this rhodium migration is a kinetically favored process. 相似文献
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Andrew J. Bochat Veronika M. Shoba James M. Takacs 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(28):9534-9538
Regiocontrol in the rhodium‐catalyzed boration of vinyl arenes is typically dominated by the presence of the conjugated aryl substituent. However, small differences in TADDOL‐derived chiral monophosphite ligands can override this effect and direct rhodium‐catalyzed hydroboration of β‐aryl and β‐heteroaryl methylidenes by pinacolborane to selectively produce either chiral primary or tertiary borated products. The regiodivergent behavior is coupled with enantiodivergent addition of the borane. The nature of the TADDOL backbone substituents and that of the phosphite moiety function synergistically to direct the sense and extent of regioselectivity and enantioinduction. Twenty substrates are shown to undergo each reaction mode with regioselectivity values reaching greater than 20:1 and enantiomer ratios reaching up to 98:2. A variety of subsequent transformations illustrate the potential utility of each product. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(39):12089-12092
A rhodium‐Josiphos(L*) catalyzed enantioselective intramolecular hydroarylation reaction is described. The reductive cyclization of o ‐bromoaniline‐derived acrylamides provides convenient access to 3,3‐disubstituted oxindoles in good yields and with excellent enantioselectivity across a range of substrates. We propose that the key cyclization proceeds via a rhodium(III) intermediate. Overall, this method represents an unusual mode of reactivity for rhodium catalysis and is complementary to palladium(0)‐catalyzed α‐arylation methods. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(51):16570-16574
A chiral rhodium complex catalyzes the highly enantioselective coupling of arylboronic acids, 1,3‐enynes, and imines to give homoallylic sulfamates. The key step is the generation of allylrhodium(I) species by alkenyl‐to‐allyl 1,4‐rhodium(I) migration. 相似文献