共查询到20条相似文献,搜索用时 15 毫秒
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Ying‐Ni Cheng Dr. Hsyueh‐Liang Wu Dr. Ping‐Yu Wu Ying‐Ying Shen Prof. Dr. Biing‐Jiun Uang 《化学:亚洲杂志》2012,7(12):2921-2924
An effective catalytic system that imparts high enantioselectivity has been disclosed for the synthesis of optically active alcohols, which may undergo further chemical transformations. The enantioselective alkylation of aldehydes with dialkylzincs to afford the corresponding optically active alcohols with excellent enantioselectvities has been achieved in the presence of 0.1–0.5 mol % of the camphor‐derived chiral ligand (?)‐2‐exo‐morpholinoisobornane‐10‐thiol (MITH) ( 1 ) at room temperature or at 0 °C. 相似文献
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Ami Uenishi Yuya Nakagawa Hironobu Osumi Prof. Dr. Toshiro Harada 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(15):4896-4905
A highly efficient and practical method for the catalytic enantioselective arylation and heteroarylation of aldehydes with organotitanium reagents, prepared in situ by the reaction of aryl‐ and heteroaryllithium reagents with ClTi(OiPr)3, is described. Titanium complexes derived from DPP‐H8‐BINOL ( 3 d ; DPP=3,5‐diphenylphenyl) and DTBP‐H8‐BINOL ( 3 e ; DTBP=3,5‐di‐tert‐butylphenyl) exhibit excellent catalytic activity in terms of enantioselectivity and turnover efficiency for the transformation, providing diaryl‐, aryl heteroaryl‐, and diheteroarylmethanol derivatives in high enantioselectivity at low catalyst loading (0.2–2 mol %). The reaction begins with a variety of aryl and heteroaryl bromides through their conversion into organolithium intermediates by Br/Li exchange with nBuLi, thus providing straightforward access to a range of enantioenriched alcohols from commercially available starting materials. Various 2‐thienylmethanols can be synthesized enantioselectively by using commercially available 2‐thienyllithium in THF. The reaction can be carried out on a 10 mmol scale at 0.5 mol % catalyst loading, demonstrating its preparative utility. 相似文献
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Enantioselective Rhodium‐Catalyzed Dearomative Arylation or Alkenylation of Quinolinium Salts 下载免费PDF全文
Yan Wang Yunlong Liu Dongdong Zhang Prof. Hao Wei Prof. Min Shi Prof. Feijun Wang 《Angewandte Chemie (International ed. in English)》2016,55(11):3776-3780
A highly enantioselective rhodium(I)‐catalyzed dearomative arylation or alkenylation of easily available N‐alkylquinolinium salts is reported, thus providing an effective and practical approach to the synthesis of dihydroquinolines in up to 99 % ee. This reaction tolerates a wide range of functional groups with respect to both the organic boronic acids and the quinoline starting materials. Moreover, the synthetic utility of this protocol is demonstrated in the formal asymmetric synthesis of bioactive tetrahydroquinoline and the total syntheses of (?)‐angustureine and (+)‐cuspareine. 相似文献
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Hak‐Suk Sim Xinhui Feng Jaesook Yun Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(8):1939-1943
Josi or Mandy? Asymmetric conjugate addition of diboron to acyclic enones catalyzed by copper affords chiral organoboronates that possess a boronate group at the β stereocenter with excellent chemical yields and enantioselectivities (see scheme). This method accommodates the structural variation of acyclic enones and provides access to highly functionalized chiral organoboronates in one step.
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Enantioselective Synthesis of Allylboronates and Allylic Alcohols by Copper‐Catalyzed 1,6‐Boration 下载免费PDF全文
Dr. Yunfei Luo Iain D. Roy Amaël G. E. Madec Prof. Hon Wai Lam 《Angewandte Chemie (International ed. in English)》2014,53(16):4186-4190
Chiral secondary allylboronates are obtained in high enantioselectivities and 1,6:1,4 ratios by the copper‐catalyzed 1,6‐boration of electron‐deficient dienes with bis(pinacolato)diboron (B2(pin)2). The reactions proceed efficiently using catalyst loadings as low as 0.0049 mol %. The allylboronates may be oxidized to the allylic alcohols, and can be used in stereoselective aldehyde allylborations. This process was applied to a concise synthesis of atorvastatin, in which the key 1,6‐boration was performed using only a 0.02 mol % catalyst loading. 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
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Rhodium/Chiral Diene‐Catalyzed Asymmetric 1,4‐Addition of Arylboronic Acids to Chromones: A Highly Enantioselective Pathway for Accessing Chiral Flavanones 下载免费PDF全文
Qijie He Dr. Chau Ming So Prof. Dr. Zhaoxiang Bian Prof. Dr. Tamio Hayashi Prof. Dr. Jun Wang 《化学:亚洲杂志》2015,10(3):540-543
Chromone has been noted to be one of the most challenging substrates in the asymmetric 1,4‐addition of α,β‐unsaturated carbonyl compounds. By employing the rhodium complex associated with a chiral diene ligand, (R,R)‐Ph‐bod*, the 1,4‐addition of a variety of arylboronic acids was realized to give high yields of the corresponding flavanones with excellent enantioselectivities (≥97 % ee, 99 % ee for most substrates). Ring‐opening side products, which would lead to erosion of product enantioselectivity, were not observed under the stated reaction conditions. 相似文献
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《Angewandte Chemie (International ed. in English)》2017,56(32):9487-9491
A chiral‐amine‐catalyzed enantioselective and diastereodivergent method for aldehyde addition to electron‐deficient olefins is presented. Hydrogen bonding was used as a control element to achieve unusual anti selectivity, which was further elucidated through mechanistic and computational studies. 相似文献
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Copper‐Catalyzed Tandem Hydrocupration and Diastereo‐ and Enantioselective Borylalkyl Addition to Aldehydes 下载免费PDF全文
Won Jun Jang Prof. Jaesook Yun 《Angewandte Chemie (International ed. in English)》2018,57(37):12116-12120
We report the copper‐catalyzed stereoselective addition of in situ generated chiral boron‐α‐alkyl intermediates to various aldehydes including α,β‐unsaturated aldehydes under mild conditions. This tandem and multicomponent method facilitated the synthesis of enantiomerically enriched 1,2‐hydroxyboronates bearing contiguous stereocenters in good yield with high diastereo‐ and enantioselectivity up to a ratio greater than 98:2. In particular, α,β‐unsaturated aldehydes were successfully used as electrophiles in Cu?H catalysis through 1,2‐addition without significant reduction. The resulting 1,2‐hydroxyboronates were used in various transformations. 相似文献
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Dr. Sandip Murarka Zhi‐Jun Jia Dr. Christian Merten Dr. Constantin‐G. Daniliuc Dr. Andrey P. Antonchick Prof. Dr. Herbert Waldmann 《Angewandte Chemie (International ed. in English)》2015,54(26):7653-7656
We report a rhodium(II)‐catalyzed highly enantioselective 1,3‐dipolar cycloaddition reaction between the carbonyl moiety of tropone and carbonyl ylides to afford troponoids in good to high yields with excellent enantioselectivity. We demonstrate that α‐diazoketone‐derived carbonyl ylides, in contrast to carbonyl ylides derived from diazodiketoesters, undergo [6+3] cycloaddition reactions with tropone to yield the corresponding bridged heterocycles with excellent stereoselectivity. 相似文献