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Burkhard Krumm Thomas M. Klapötke Ingo Schwab 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3-4):957-960
Abstract We have been carrying out systematic studies on the preparation and properties of tellurium halide and pseudohalide compounds with a focus on tellurium azides. We were successful in the synthesis of various tellurium azides of both covalent and ionic nature. Several tellurium(IV) azides, tellurium(II) azides, and the first tellurium(VI) azides can be prepared in reasonable amounts. The first structural information of selenium azides is obtained for covalent and ionic derivatives, and spectroscopic data for the existence of selenium(iv) polyazides. 相似文献
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Varinder K. Aggarwal Alison Thompson Ray V.H. Jones Mike C.H. Standen 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):361-362
Abstract: This paper describes a new method for the preparation of aziridines from imines and diazocompounds which requires catalytic amounts of metal salts and sulfides and operates under neutral conditions. Using enantiomerically pure sulfides, high enantioselectivity has been achieved in the aziridination process. 相似文献
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新型手性膦-硼烷配合物的合成及其在不对称催化氢化反应中的应用 总被引:2,自引:0,他引:2
以苯乙烯为原料,通过Sharpless不对称二羟基化反应合成高对映体纯的苯基乙二醇,经酯化、亲核取代反应转化为手性膦-硼烷配合物.后者克服了有机膦配体易氧化的缺点,其制备过程简单,易于提纯,在空气中可长期保存.该手性膦-硼烷配合物在四氟硼酸-甲醚的存在下解络,生成的自由膦不经分离直接与[Rh(COD)Cl]2作用生成手性膦-铑原位催化剂.在α-乙酰氨基肉桂酸甲酯的不对称氢化反应中,转化率为100%,对映选择性88%e.e. 相似文献
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光学纯的环氧化物是合成许多药物和天然产物的重要中间体并构成不对称碳碳键的重要合成子 ,因此寻找不对称环氧化反应体系总是有机化学研究的重点和热点[1~ 3 ] .从 Sharpless[4 ] 到 Jacobsen[5] 的手性金属配合物催化体系 ,到杨丹 [6] 和施以安[7] 的手性有机酮催化体系 ,都取得了突破性的进展 ,并在天然产物、药物合成中得到了应用 [1,2 ,8] .但这些体系都有其局限性 ,每一类体系只能适用于某一类烯烃 ,因此开拓适用性更广的不对称环氧化催化剂 ,仍然是对有机化学工作者的挑战 .近年来 ,一种新的体系 ,即用手性亚胺盐或者手性亚胺盐氧… 相似文献
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The first investigation on catalytic asymmetric [2, 3]-sigmatrop-ic rearrangement of sulfur ylides generated from carbenoids andallenic phenyl sulfide was carried out. Up to 55% ee value wasobtained. 相似文献
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Anil K. Gupta Xiaopeng Yin Munmun Mukherjee Aman A. Desai Aliakbar Mohammadlou Kelsee Jurewicz William D. Wulff 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(11):3399-3405
A highly diastereo‐ and enantioselective method for the epoxidation of aldehydes with α‐diazoacetamides has been developed with two different borate ester catalysts of VANOL. Both catalytic systems are general for aromatic, aliphatic, and acetylenic aldehydes, giving high yields and inductions for nearly all cases. One borate ester catalyst has two molecules of VANOL and the other only one VANOL. Catalysts generated from BINOL and VAPOL are ineffective catalysts. An application is shown for access to the side‐chain of taxol. 相似文献
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A class of chiral ketone was synthesized for asymmetric epoxidation. High ee values have been obtained for a number of cis olefin and trans olefin. The epoxidation was stereospecific with no isomerizatiom observed in the epoxidation of acyclic system. Encourageingly high ee value has also been obtained for a number of terminal olefins. Mechanistic studies show that electronic interactions play an important role in the stereodifferentiation. O O O O O O NBoc O O t-BuO2CH2CN O O O … 相似文献
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The first investigation on catalytic asymmetric [2,3]-sigmatropic rearrangement of sulfur ylides generated from carbenoids and allenic phenyl sulfide was carried out. Up to 55% ee value was obtained. 相似文献
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合成了新型的手性铝/锌杂双金属复合物(R,S,S)-3,3'-二[(N-二苯基脯氨醇)甲基]-2,2'-二羟基-1,1'-联萘酚铝/锌复合物(ZABDP).在催化芳香酮与芳香醛的羟醛缩合(Aldol)反应中,该复合物中的铝作为路易斯酸活化醛,锌的烷氧化物作为Br?nsted碱,使苯乙酮形成活性锌的烯醇化物,2种金属的应用使得芳香醛与芳香酮的直接不对称Aldol反应顺利进行,反应的对映选择性最高达90%,产率最高达99%. 相似文献
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Cong‐Shuai Wang Tian‐Zhen Li Si‐Jia Liu Yu‐Chen Zhang Shuang Deng Yinchun Jiao Feng Shi 《中国化学》2020,38(6):543-552
A new class of axially chiral aryl‐alkene‐indole frameworks have been designed, and the first catalytic asymmetric construction of such scaffolds has been established by the strategy of organocatalytic (Z/E)‐selective and enantioselective (4+3) cyclization of 3‐alkynyl‐2‐indolylmethanols with 2‐naphthols or phenols (all >95 : 5 E/Z, up to 98% yield, 97% ee). This reaction also represents the first catalytic asymmetric construction of axially chiral alkene‐heteroaryl scaffolds, which will add a new member to the atropisomeric family. This approach has not only confronted the great challenges in constructing axially chiral alkene‐heteroaryl scaffolds but also provided a powerful strategy for the enantioselective construction of axially chiral aryl‐alkene‐indole frameworks. 相似文献
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LIYan-yun CHENJian-shan YANGChuan-bo DONGZhen-rong LIBao-zhu ZHANGHui GAOJing-xing TAKAOIkariya 《高等学校化学研究》2004,20(2):180-184
The efficient chiral Ru3(CO)12 systems were prepared in situ from Ru3(CO)12 and various chiral diiminoor diamino-diphosphine tetradentate ligands. The systems have been used for the asymmetric transfer hydrogenation of propiophenone in 2-propanol, leading to 1-phenyl-1-propanol in a 98% yield and 96% e.e. The IR study suggests that the carbonyl hydride anion [HRu3(CO)11]^- most probably exists as a principal species under the reaction conditions. The high chiral efficiency may be due to the synergetic effect produced by the neighboring ruthenium atoms and a special chiral micro-environment involving the polydentate ligand and the Ru3 framework. 相似文献
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Kuiling Ding Akihiro Ishii Koichi Mikami 《Angewandte Chemie (International ed. in English)》1999,38(4):497-501
The most effective catalyst system for the enantioselective alkylation of an aldehyde on the basis of “asymmetric activation” can be found by super high throughput screening of chiral ligands (L*) and activators (A*) for the diethylzinc complex. The product, an optically active alcohol, could be obtained with 99% ee and in up to 100% yield (see reaction scheme). R=benzylidene. 相似文献
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以天然L-脯氨酸为原料, 经酯化、氨基保护、格氏反应和催化氢解等4步反应合成了光学活性的β-氨基醇. 将其作为催化剂用于二烷基锌和醛的不对称加成反应, 分别考察了催化剂结构、用量、溶剂、反应温度等因素. 结果表明, 当催化剂质量分数为5%, 甲苯作溶剂, 在-10 ℃下, 以(S)-N- 苄基-2-吡咯烷-α,α-二(α-萘基)甲醇(3)作催化剂时, 所得仲醇的对映体过量(e.e.)最高为82%, 产率高达到100%. 相似文献
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Yasser S. Sokeirik Dr. Akiko Hoshina Masaaki Omote Dr. Kazuyuki Sato Dr. Atsushi Tarui Itsumaro Kumadaki Prof. Akira Ando Prof. 《化学:亚洲杂志》2008,3(10):1850-1856
The asymmetric addition of Me2Zn to aldehydes is very slow and mostly gives low ee values. Previously, we reported the synthesis of a fluorous chiral ligand, (4R,5S,α′R)‐2,2‐dimethyl‐α,α,α′‐tris(perfluorooctyl)‐2,3‐dioxolane‐4,5‐dimethanol ( 1 a ), derived from tartarate as a chiral pool. Ligand 1 a showed high activity toward the addition of Me2Zn to aldehydes with high enantiomeric excess. However, the very high content of fluorine makes 1 a difficult to dissolve in common solvents; hence, much solvent is required, which limits its use. This report describes the modification of 1 a by replacing either the perfluorooctyl groups with shorter perfluoroalkyl ones or the acetone ketal part with cyclohexanone ketal. The perfluorobutyl analogue 1 c is much more soluble than 1 a and shows comparable asymmetric induction toward the addition of Me2Zn to aldehydes. Furthermore, 1 c has a much lower molecular weight than 1 a . This means that 1 c is used in smaller amounts (weight) than 1 a . The cyclohexanone ketal analogue 1 d is more soluble than 1 a and more easily synthesized owing to its high solubility and ease of crystallization. Ligand 1 d showed much higher asymmetric induction toward cyclohexanecarbaldehyde, a branched aldehyde, than 1 a . Thus, 1 a was modified into ligands with higher performance. 相似文献