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Kirill Nikitin Kamalraj V. Rajendran Helge Müller‐Bunz Declan G. Gilheany 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(7):1937-1940
Synthetic routes that provide facile access to either enantiomeric form of a target compound are particularly valuable. The crystallization‐free dual resolution of phosphine oxides that gives highly enantioenriched materials (up to 94 % ee) in excellent yields is reported. Both enantiomeric oxides have been prepared from a single intermediate, (RP)‐alkoxyphosphonium chloride, which is formed in the course of a selective dynamic kinetic resolution using a single enantiomer of menthol as the chiral auxiliary. The origin of the dual stereoselectivity lies in bifurcation of the reaction pathway of this intermediate, which works as a stereochemical railroad switch. Under controlled conditions, Arbuzov‐type collapse of this intermediate proceeds through C O bond fission with retention of the configuration at the phosphorus center. Conversely, alkaline hydrolysis of the P O bond leads to the opposite SP enantiomer. 相似文献
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Kuan Hu Hao Geng Qingzhou Zhang Qisong Liu Mingsheng Xie Chengjie Sun Wenjun Li Huacan Lin Fan Jiang Tao Wang Yun‐Dong Wu Zigang Li 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2016,128(28):8145-8149
The addition of a precisely positioned chiral center in the tether of a constrained peptide is reported, yielding two separable peptide diastereomers with significantly different helicity, as supported by circular dichroism (CD) and NMR spectroscopy. Single crystal X‐ray diffraction analysis suggests that the absolute configuration of the in‐tether chiral center in helical form is R, which is in agreement with theoretical simulations. The relationship between the secondary structure of the short peptides and their biochemical/biophysical properties remains elusive, largely because of the lack of proper controls. The present strategy provides the only method for investigating the influence of solely conformational differences upon the biochemical/biophysical properties of peptides. The significant differences in permeability and target binding affinity between the peptide diastereomers demonstrate the importance of helical conformation. 相似文献
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Yu‐Peng Zhou Matthias Driess 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(12):3753-3766
A significant number of isolable silylenes are currently known. They have quickly developed from laboratory curiosities to useful ligands in metal‐mediated homogeneous catalysis. This includes their utilization in various catalytic transformations, such as C?C cross‐coupling, cyclotrimerization, hydroformylation, borylation, deuteration, hydrosilylation, amination, hydrogenation, and transfer semi‐hydrogenation reactions. Recent studies suggest that the silylene ligands surpass the steering properties of their phosphine and N‐heterocyclic carbene (NHC) analogues and provide excellent chemo‐, regio‐, and stereoselectivites. Mechanistic studies suggest that their promoted performance of metal‐mediated catalytic transformations results from a strong σ‐donor character along with cooperative effects of their SiII centers. This Minireview covers the most recent advances in the field. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(1):122-127
The first enantioselective construction of a new class of axially chiral naphthyl‐indole skeletons has been established by organocatalytic asymmetric coupling reactions of 2‐naphthols with 2‐indolylmethanols (up to 99 % yield, 97:3 e.r.). This approach not only affords a new type of axially chiral heterobiaryl backbone, but also provides a new catalytic enantioselective strategy for constructing axially chiral biaryl scaffolds by making use of the C3‐electrophilicity of 2‐indolylmethanols. 相似文献
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Fei Jiang Ke‐Wei Chen Ping Wu Yu‐Chen Zhang Yinchun Jiao Feng Shi 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(42):15248-15254
A new strategy for enantioselective synthesis of axially chiral naphthyl‐indoles has been established through catalytic asymmetric addition reactions of racemic naphthyl‐indoles with bulky electrophiles. Under chiral phosphoric acid catalysis, azodicarboxylates and o‐hydroxybenzyl alcohols served as bulky but reactive electrophiles that were attacked by C2‐unsubstituted naphthyl‐indoles, which underwent a dynamic kinetic resolution to afford two series of axially chiral naphthyl‐indoles in good yields (up to 98 %) and high enantioselectivities (up to 98:2 er). 相似文献
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Jorge S. Valera Rafael Gmez Luis Snchez 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(2):520-524
The helical stereomutation in the kinetically controlled coassembly of the reported carbonyl‐bridged triarylamines (CBTs) is described. The copolymerization of chiral CBTs (S)‐1 or (R)‐1 with achiral 2 in sergeants‐and‐soldiers (SaS) experiments results in a tunable helicity conditioned by the percentage of the chiral sergeant and by the cooling rate. The dissimilar inherent chirality of the extended monomeric (M) and intramolecularly H‐bonded metastable (M*) species, as well as the different stability of the kinetic trap of the chiral CBTs (S)‐1 / (R)‐1 and the achiral CBT 2 , condition the chirality transfer and afford J‐aggregates of inverse handedness. 相似文献
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