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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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Biocatalytic Dynamic Kinetic Resolution for the Synthesis of Atropisomeric Biaryl N‐Oxide Lewis Base Catalysts 下载免费PDF全文
Dr. Samantha Staniland Dr. Ralph W. Adams Dr. Joseph J. W. McDouall Dr. Irene Maffucci Dr. Alessandro Contini Dr. Damian M. Grainger Prof. Nicholas J. Turner Prof. Jonathan Clayden 《Angewandte Chemie (International ed. in English)》2016,55(36):10755-10759
Atropisomeric biaryl pyridine and isoquinoline N‐oxides were synthesized enantioselectively by dynamic kinetic resolution (DKR) of rapidly racemizing precursors exhibiting free bond rotation. The DKR was achieved by ketoreductase (KRED) catalyzed reduction of an aldehyde to form a configurationally stable atropisomeric alcohol, with the substantial increase in rotational barrier arising from the loss of a bonding interaction between the N‐oxide and the aldehyde. Use of different KREDs allowed either the M or P enantiomer to be synthesized in excellent enantiopurity. The enantioenriched biaryl N‐oxide compounds catalyze the asymmetric allylation of benzaldehyde derivatives with allyltrichlorosilane. 相似文献
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Gaoyuan Ma Prof. Dr. Mukund P. Sibi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(33):11644-11657
Biaryl compounds with axial chirality are very common in synthetic chemistry, especially in catalysis. Axially chiral biaryls are important due to their biological activities and extensive applications in asymmetric catalysis. Thus the development of efficient enantioselective methods for their synthesis has attracted considerable attention. This Minireview discusses the progress made in catalytic kinetic resolution of biaryl compounds and chronicles significant advances made recently in catalytic kinetic resolution of biaryl scaffolds. 相似文献
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《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(1):330-343
New efficient chiral auxiliaries for dynamic kinetic resolution (DKR) of bromides into amines are proposed, based on a theoretical rationalisation of known literature results. One example was synthesized and tested, affording diastereoselectivities up to 100 %. Several results of DKR reactions are known, based on oxazolidinone or imidazolidinone units as chiral auxiliaries. Nevertheless, their behaviour was not fully understood until a recent paper that we published. We now used our proposed mechanism to rationalize the behaviour of other similar chiral auxiliaries and to propose small structure changes in imidazolidinone rings which could largely improve their performance. We could show that the good performance of these molecules as chiral auxiliaries for DKR reactions where bromine is the leaving group and a primary or secondary amine is the nucleophile is due, in a first step, to the formation of a hydrogen bond between the amine and the ring carbonyl oxygen and, in a second step, to the strong electrostatic interaction between the leaving bromide and the carbonyl oxygen in the C‐3 substituent. Considering the behaviour of this substituent which rotates to minimize the electrostatic repulsion with the bromide when reaching the transition state, we proposed the introduction of a second substituent in the C‐4 position of the imidazolidinone ring, which prevents such rotation, thus increasing the energy difference between the transition states of the two distereoisomers. With such an auxiliary we were able to increase the best de known in literature (88 %), when benzylamine is used as nucleophile, to 99, or even 100 %, when iodide replaces the bromide in the substrate. 相似文献
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光学活性仲醇是非常重要的合成多种具有药物和生物活性化合物的原料和关键中间体,它们可通过外消旋仲醇的氧化动力学拆分获得。本文按氧化剂和手性催化剂的类别分类综述了近年来通过氧化动力学拆分获得光学活性仲醇方法的进展,并对一些方法的机理进行了描述。对以(-)-金雀花碱-钯(Ⅱ)、金雀花碱类似物-钯(Ⅱ)、N-杂环卡宾(NHC)-钯(Ⅱ)、手性双官能团-铱配合物以及手性(ON)-钌(salen)配合物催化的分子氧为氧化剂的仲醇的氧化动力学拆分进行了充分讨论。此外,还讨论了手性salen-锰(Ⅲ)催化二乙酰基碘苯以及通过不对称氢转移的方法对仲醇的氧化动力拆分。可以发现,(-)-金雀花碱-钯(Ⅱ)-分子氧体系在目前所有仲醇氧化动力学拆分体系中表现最佳。用于仲醇氧化动力学拆分的高效体系仍有待进一步开发。 相似文献
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K. Michał Pietrusiewicz Anna M. Maj Wanda Wieczorek 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1)
Abstract Secondary phosphine oxides constitute an important class of organophosphorus compounds and are higly useful as versatile phosphinoylating agents and as ligands [1,2] They are however not readily available in the optically active form.[3–5] We wish to demonstrate that P-chiral secondary teri-butylphenylphosphine oxide (I) can be promptly resolved into enantiomers by means of its diastereoisomeric complexes with L-O,O-dibenzoyltanaric acid (L-DBTA) Dissolution of equimolar amounts of racemic I and L-DBTA in the 4 I benzene acetone mixture yields crystalline II complex containing exclusively the R-enantiomer of the starting phosphine oxide The complexed S-enantiomer is obtained from the mother liquor by crystallization from benzene The enantiomers of I are freed from their L-DBTA complexes by simple washing with aqueous NaOH Both enantiomers of 1 of very high optical purity are thus obtained from a single batch These enantiomers have subsequently been tested for their configurational stability in selected synthetic applications. 相似文献
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(S)‐Selective Kinetic Resolution and Chemoenzymatic Dynamic Kinetic Resolution of Secondary Alcohols
《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(1):225-232
(S)‐Selective kinetic resolution was achieved through the use of a commercially available protease, which was activated with a combination of two different surfactants. The kinetic resolution (KR) process was optimized with respect to activation of the protease and to the acyl donor. The KR proved to be compatible with a range of functionalized sec‐alcohols, giving good to high enantiomeric ratio values (up to >200). The enzymatic resolution was combined with a ruthenium‐catalyzed racemization to give an (S)‐selective dynamic kinetic resolution (DKR) of sec‐alcohols. The DKR process works under very mild reaction conditions to give the corresponding esters in high yields and with excellent enantioselectivities. 相似文献
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An efficient lipase-catalyzedenantioselective hydrolysis of butyryloxyalkanephosphonates in water-equillbrated diisopropyl ether was developed. The relationship between the substrates‘ structure and the reactivity, as well as the enantioselectivlty of this enzymatic transformation was studied. The catalytic preference of crude Candida rugosa lipase toward such molecules was assigned according to modified Mosher‘s method and Xray crystallographic analysis. Optically pure 2-hydroxy-2-arylethanephosphonates, 3-hydroxy-3-phenylpropanephosphonate, and 3, 3, 3-trifluoro-2-hydroxypropanephosphonates were conveniently prepared in this manner. 相似文献
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Zhiwei Chen Yusuke Aota Hillary M. H. Nguyen Vy M. Dong 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(14):4753-4757
We report a dynamic kinetic resolution (DKR) of chiral 4‐pentenals by olefin hydroacylation. A primary amine racemizes the aldehyde substrate via enamine formation and hydrolysis. Then, a cationic rhodium catalyst promotes hydroacylation to generate α,γ‐disubstituted cyclopentanones with high enantio‐ and diastereoselectivities. 相似文献
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几种外消旋环氧化合物的水解动力学拆分 总被引:1,自引:0,他引:1
2 羟基 3 叔丁基 5 甲基苯甲醛 (5 )与 (S ,S) 1 ,2 二苯基乙二胺 ((S,S) 1 1 )缩合 ,得手性Salen 1 2 ,再与Co(OAc) 2 ·4H2 O反应得钴络合物 1 3 ,后者经氧化制得Salen型手性催化剂 (S ,S) 2。几种外消旋环氧化合物用 (S ,S) 2催化水解进行动力学拆分 ,同时得到光学活性环氧化合物和二醇 ,对映体过量最高达 61 6%。根据分子力学对催化剂构象优化的结果讨论了催化剂结构对其催化效率和选择性的影响 相似文献
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Shutao Sun Yingang Ma Ziqiang Liu Lei Liu 《Angewandte Chemie (International ed. in English)》2021,60(1):176-180
A manganese‐catalyzed oxidative kinetic resolution of cyclic benzylic ethers through asymmetric C(sp3)?H oxidation is reported. The practical approach is applicable to a wide range of 1,3‐dihydroisobenzofurans bearing diverse functional groups and substituent patterns at the α position with extremely efficient enantiodiscrimination. The generality of the strategy was further demonstrated by efficient oxidative kinetic resolution of another type of five‐membered cyclic benzylic ether, 2,3‐dihydrobenzofurans, and six‐membered 6H‐benzo[c]chromenes. Direct late‐stage oxidative kinetic resolution of bioactive molecules that are otherwise difficult to access was further explored. 相似文献
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An asymmetric cyanation of acylsilanes involving the in‐situ formation of chiral acylsilane cyanohydrins followed by their kinetic resolution via organocatalytic cycloetherification is described. The highly enantio‐ and diastereoselective cycloetherification was crucial for achieving a high efficiency in the kinetic resolution. Consequently, acylsilane cyanohydrins containing a tetrasubstituted chiral carbon atom bearing silyl, cyano, and hydroxy groups were obtained in an enantioenriched form. This protocol therefore offers an efficient catalytic approach to optically active acylsilane cyanohydrins, which exhibit potential as chiral building blocks for the synthesis of pharmaceutically relevant chiral organosilanes. 相似文献
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Dr. Jingyun Ren Dr. Xu Ban Dr. Xin Zhang Dr. Siu Min Tan Dr. Richmond Lee Prof. Dr. Choon-Hong Tan 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(23):9140-9143
We have developed a method to afford enantiomerically enriched tertiary azides and bromides through pentanidium-catalyzed kinetic resolution (KR) of racemic tertiary bromides under base-free conditions. We found that the absence of water is crucial to attain a high selectivity factor (s). On the other hand, new experimental observations and DFT modeling led us to propose that enantioconvergent azidation of tertiary bromides proceeded through dynamic kinetic resolution (DKR). The investigations particularly identified the crucial roles of base and water in the enantioconvergent process, thus supporting the proposal that the tertiary bromide isomerizes in the presence of base and water through a SN2X pathway. 相似文献