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Inside Cover: Recyclable Ligands for the Non‐Enzymatic Dynamic Kinetic Resolution of Challenging α‐Amino Acids (Angew. Chem. Int. Ed. 44/2015) 下载免费PDF全文
Yong Nian Dr. Jiang Wang Dr. Shengbin Zhou Shuni Wang Dr. Hiroki Moriwaki Dr. Aki Kawashima Prof. Dr. Vadim A. Soloshonok Prof. Dr. Hong Liu 《Angewandte Chemie (International ed. in English)》2015,54(44):12826-12826
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Chemical Kinetic Resolution of Unprotected β‐Substituted β‐Amino Acids Using Recyclable Chiral Ligands 下载免费PDF全文
Shengbin Zhou Dr. Jiang Wang Xia Chen Dr. José Luis Aceña Prof. Dr. Vadim A. Soloshonok Prof. Dr. Hong Liu 《Angewandte Chemie (International ed. in English)》2014,53(30):7883-7886
The first chemical method for resolution of N,C‐unprotected β‐amino acids was developed through enantioselective formation and disassembly of nickel(II) complexes under operationally convenient conditions. The specially designed chiral ligands are inexpensive and can be quantitatively recycled along with isolation of the target β‐substituted‐β‐amino acids in good yields and excellent enantioselectivity. The method features a broad synthetic generality including β‐aryl, β‐heteroaryl, and β‐alkyl‐derived β‐amino acids. The procedure is easily scaled up, and was used for the synthetically and economically advanced preparation of the anti‐diabetic drug sitagliptin. 相似文献
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Ryosuke Takeda Akie Kawamura Aki Kawashima Dr. Tatsunori Sato Dr. Hiroki Moriwaki Dr. Kunisuke Izawa Prof. Dr. Kenichi Akaji Shuni Wang Prof. Dr. Hong Liu Dr. José Luis Aceña Prof. Dr. Vadim A. Soloshonok 《Angewandte Chemie (International ed. in English)》2014,53(45):12214-12217
Reported herein is the first purely chemical method for the dynamic kinetic resolution (DKR) of unprotected racemic α‐amino acids (α‐AAs), a method which can rival the economic efficiency of the enzymatic reactions. The DKR reaction principle can be readily applied for S/R interconversions of α‐AAs, the methodological versatility of which is unmatched by biocatalytic approaches. The presented process features a virtually complete stereochemical outcome, fully recyclable source of chirality, and operationally simple and convenient reaction conditions, thus allowing its ready scalability. A quite unique and novel mode of the thermodynamic control over the stereochemical outcome, including an exciting interplay between axial, helical, and central elements of chirality is proposed. 相似文献
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Enantioselective C−H Olefination of α‐Hydroxy and α‐Amino Phenylacetic Acids by Kinetic Resolution 下载免费PDF全文
Dr. Kai‐Jiong Xiao Ling Chu Prof. Dr. Jin‐Quan Yu 《Angewandte Chemie (International ed. in English)》2016,55(8):2856-2860
Significant progress has been made in the past decade regarding the development of enantioselective C?H activation reactions by desymmetrization. However, the requirement for the presence of two chemically identical prochiral C?H bonds represents an inherent limitation in scope. Reported is the first example of kinetic resolution by a palladium(II)‐catalyzed enantioselective C?H activation and C?C bond formation, thus significantly expanding the scope of enantioselective C?H activation reactions. 相似文献
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Shen Qu Samuel M. Smith Víctor Laina‐Martín Rifahath M. Neyyappadath Mark D. Greenhalgh Andrew D. Smith 《Angewandte Chemie (International ed. in English)》2020,59(38):16572-16578
A highly enantioselective isothiourea‐catalyzed acylative kinetic resolution (KR) of acyclic tertiary alcohols has been developed. Selectivity factors of up to 200 were achieved for the KR of tertiary alcohols bearing an adjacent ester substituent, with both reaction conversion and enantioselectivity found to be sensitive to the steric and electronic environment at the stereogenic tertiary carbinol centre. For more sterically congested alcohols, the use of a recently‐developed isoselenourea catalyst was optimal, with equivalent enantioselectivity but higher conversion achieved in comparison to the isothiourea HyperBTM. Diastereomeric acylation transition state models are proposed to rationalize the origins of enantiodiscrimination in this process. This KR procedure was also translated to a continuous‐flow process using a polymer‐supported variant of the catalyst. 相似文献
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Leo A. Joyce Prof. James W. Canary Prof. Eric V. Anslyn 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(26):8064-8069
The association between an achiral copper(II)‐containing host 1 and chiral carboxylates has been expanded beyond previous studies to new chiral carboxylate guests, both α‐amino acids and β‐homoamino acids. The observed exciton‐coupled circular dichroism (ECCD) signals for the enantiomers of each carboxylate were equal and opposite, and these signals differed in size and shape between the individual amino acids. Linear discriminant analysis (LDA) was applied as a statistical analysis technique to differentiate the amino acids, both enantioselectively and chemoselectively, giving the absolute configuration and identity of the amino acid. The identity of each of the α‐amino acids and β‐homoamino acids were determined independently by LDA, and then the two were considered together. Each of these analyses showed good differentiation of the amino acid guests with the use of only one host molecule. 相似文献
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Kinetic Resolution of 1,1′‐Biaryl‐2,2′‐Diols and Amino Alcohols through NHC‐Catalyzed Atroposelective Acylation 下载免费PDF全文
Dr. Shenci Lu Si Bei Poh Prof. Yu Zhao 《Angewandte Chemie (International ed. in English)》2014,53(41):11041-11045
We present here a highly efficient NHC‐catalyzed kinetic resolution of a wide range of 1,1′‐biaryl‐2,2′‐diols and amino alcohols to provide them in uniformly ≥99 % ee. This represents the first highly enantioselective catalytic acylation of axially chiral alcohols. The aldehyde backbone that is incorporated into the chiral acyl azolium intermediate was found to have a significant effect on the enantioselectivity of the process. 相似文献
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Nickel‐Catalyzed Asymmetric Transfer Hydrogenation of Olefins for the Synthesis of α‐ and β‐Amino Acids 下载免费PDF全文
Peng Yang Haiyan Xu Jianrong Zhou 《Angewandte Chemie (International ed. in English)》2014,53(45):12210-12213
The field of asymmetric (transfer) hydrogenation of prochiral olefins has been dominated by noble metal catalysts based on rhodium, ruthenium, and iridium. Herein we report that a simple nickel catalyst is highly active in the transfer hydrogenation using formic acid. Chiral α‐ and β‐amino acid derivatives were obtained in good to excellent enantioselectivity. The key toward success was the use of the strongly donating and sterically demanding bisphosphine Binapine. 相似文献
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Dipl.‐Chem. Patrick Bongen Prof. Dr. Jörg Pietruszka Dr. Robert Christian Simon 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(35):11063-11070
An efficient asymmetric synthesis of (S)‐2,3‐dihydrobenzo[b]furan‐3‐carboxylic acid ( 8 a ) and (S)‐5‐chloro‐2,3‐dihydrobenzo[b]furan‐3‐carboxylic acid ( 8 b ) was established. Key to the success was the highly stereoselective enzymatic kinetic resolution of the corresponding methyl or ethyl esters that was further developed into a dynamic process. As a reliable and fast tool for analysing the enantiomeric excess, HPLC coupled with a CD detector was utilized. The route was completed by a Friedel–Crafts acylation of ethyl (S)‐5‐chloro‐2,3‐dihydrobenzo[b]furan‐3‐carboxylate ( 7 c ) followed by saponification leading to (S)‐5‐chloro‐2,3‐dihydrobenzo[b]furan‐3‐carboxylic acid ( 2 ), an analgesic agent. 相似文献
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Stereoarrayed CF3‐Substituted 1,3‐Diols by Dynamic Kinetic Resolution: Ruthenium(II)‐Catalyzed Asymmetric Transfer Hydrogenation 下载免费PDF全文
Andrej Emanuel Cotman Dr. Dominique Cahard Dr. Barbara Mohar 《Angewandte Chemie (International ed. in English)》2016,55(17):5294-5298
CF3‐substituted 1,3‐diols were stereoselectively prepared in excellent enantiopurity and high yield from CF3‐substituted diketones by using an ansa‐ruthenium(II)‐catalyzed asymmetric transfer hydrogenation in formic acid/triethylamine. The intermediate mono‐reduced alcohol was also obtained in very high enantiopurity by applying milder reaction conditions. In particular, CF3C(O)‐substituted benzofused cyclic ketones underwent either a single or a double dynamic kinetic resolution during their reduction. 相似文献