共查询到20条相似文献,搜索用时 46 毫秒
1.
Rebecca M. Demming Stephan C. Hammer Bettina M. Nestl Sebastian Gergel Silvia Fademrecht Jürgen Pleiss Bernhard Hauer 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(1):179-183
The direct enantioselective addition of water to unactivated alkenes could simplify the synthesis of chiral alcohols and solve a long‐standing challenge in catalysis. Here we report that an engineered fatty acid hydratase can catalyze the asymmetric hydration of various terminal and internal alkenes. In the presence of a carboxylic acid decoy molecule for activation of the oleate hydratase from E. meningoseptica, asymmetric hydration of unactivated alkenes was achieved with up to 93 % conversion, excellent selectivity (>99 % ee, >95 % regioselectivity), and on a preparative scale. 相似文献
2.
Matúš Gajdoš Jendrik Wagner Felipe Ospina Antonia Köhler Dr. Martin K. M. Engqvist Prof. Dr. Stephan C. Hammer 《Angewandte Chemie (International ed. in English)》2023,62(7):e202215093
Enantioselective synthesis of chiral alcohols through asymmetric addition of water across an unactivated alkene is a highly sought-after transformation and a big challenge in catalysis. Herein we report the identification and directed evolution of a fatty acid hydratase from Marinitoga hydrogenitolerans for the highly enantioselective hydration of styrenes to yield chiral 1-arylethanols. While directed evolution for styrene hydration was performed in the presence of heptanoic acid to mimic fatty acid binding, the engineered enzyme displayed remarkable asymmetric styrene hydration activity in the absence of the small molecule activator. The evolved styrene hydratase provided access to chiral alcohols from simple alkenes and water with high enantioselectivity (>99 : 1 e.r.) and could be applied on a preparative scale. 相似文献
3.
Pengyuan Zhao Aolin Cheng Xinxu Wang Jiguo Ma Guoqing Zhao Yingkun Li Yi Zhang Baoguo Zhao 《中国化学》2020,38(6):565-569
By using a combination of a chiral N‐triflyl phosphoramide and TiCl4 as the catalyst, a new process for asymmetric intramolecular hydroalkoxylation of unactivated alkenes was developed, producing various chiral tetrahydrofuran derivatives in 51%—99% yields with 30%—71% ee's. 相似文献
4.
Wei Zhang Dr. Li-Li Liao Li Li Yi Liu Long-Fei Dai Dr. Guo-Quan Sun Chuan-Kun Ran Prof. Dr. Jian-Heng Ye Prof. Dr. Yu Lan Prof. Dr. Da-Gang Yu 《Angewandte Chemie (International ed. in English)》2023,62(23):e202301892
Carboxylation of easily available alkenes with CO2 is highly important to afford value-added carboxylic acids. Although dicarboxylation of activated alkenes, especially 1,3-dienes, has been widely investigated, the challenging dicarboxylation of unactivated 1,n-dienes (n>3) with CO2 remains unexplored. Herein, we report the first dicarboxylation of unactivated skipped dienes with CO2 via electrochemistry, affording valuable dicarboxylic acids. Control experiments and DFT calculations support the single electron transfer (SET) reduction of CO2 to its radical anion, which is followed by sluggish radical addition to unactivated alkenes, SET reduction of unstabilized alkyl radicals to carbanions and nucleophilic attack on CO2 to give desired products. This reaction features mild reaction conditions, broad substrate scope, facile derivations of products and promising application in polymer chemistry. 相似文献
5.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2018,130(39):13117-13121
We report an asymmetric synthesis of enantioenriched gem‐bis(boryl)alkanes in an enantioselective diborylation of 1,1‐disubstituted alkenes catalyzed by Co(acac)2/(R)‐DM‐segphos. A range of activated and unactivated alkenes underwent this asymmetric diborylation in the presence of cyclooctene as a hydrogen acceptor, affording the corresponding gem‐bis(boryl)alkanes with high enantioselectivity. The synthetic utility of these chiral organoboronate compounds was demonstrated through several stereospecific derivatizations and the synthesis of sesquiterpene and sesquiterpenoid natural products. 相似文献
6.
Haifeng Zheng Yan Wang Chaoran Xu Qian Xiong Lili Lin Xiaoming Feng 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(16):5381-5385
We report the combination of transition‐metal‐catalyzed diversified cycloisomerization of 1,6‐enynes with chiral Lewis acid promoted asymmetric Diels–Alder reaction to realize asymmetric cycloisomerization/Diels–Alder relay reactions of 1,6‐enynes with electron‐deficient alkenes. A broad spectrum of chiral [5,6]‐bicyclic products could be acquired in high yields (up to 99 %) with excellent diastereoselectivy (>19:1 dr) and enantioselectivity (up to 99 % ee). 相似文献
7.
Dr. Rakesh K. Saunthwal Dr. Maria Schwarz Dr. Rajendra K. Mallick William Terry-Wright Prof. Jonathan Clayden 《Angewandte Chemie (International ed. in English)》2023,62(14):e202216758
A practical, transition metal-free method allows the enantioselective synthesis of α,α-diarylmethylamines by asymmetric α-arylation of benzylamines. Enantioselective lithiation of N′-aryl-N-benzyl-N-isopropyl ureas using a chiral lithium amide base generates a benzyllithium that undergoes an unactivated stereospecific intramolecular nucleophilic aromatic substitution to generate an α,α-diarylmethylamine in the form of its urea derivative, in up to >99 % ee. Treatment with acid induces an “azatropic shift” with retention of configuration, the product of which may be hydrolysed to the target amine. 相似文献
8.
Fan Xu Lin Zhu Dr. Shaobin Zhu Prof. Dr. Xiaomei Yan Dr. Hai‐Chao Xu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(40):12740-12744
An electrochemical approach to the intramolecular aminooxygenation of unactivated alkenes has been developed. This process is based on the addition of nitrogen‐centered radicals, generated through electrochemical oxidation, to alkenes followed by trapping of the cyclized radical intermediate with 2,2,6,6‐tetramethylpiperidine‐N‐oxyl radical (TEMPO). Difunctionalization of a variety of alkenes with easily available carbamates/amides and TEMPO affords aminooxygenation products in high yields and with excellent trans selectivity for cyclic systems (d.r. up to>20:1). The approach provides a much‐needed complementary route to existing cis‐selective methods. 相似文献
9.
Qing-Yun Fang Jie Han Mingzhe Qin Weipeng Li Prof. Dr. Chengjian Zhu Prof. Dr. Jin Xie 《Angewandte Chemie (International ed. in English)》2023,62(34):e202305121
Activated alkyl halides have been extensively explored to generate alkyl radicals with Ru- and Ir- photocatalysts for 1,2-difunctionalization of alkenes, but unactivated alkyl bromides remain challenging substrates due to their strong reduction potential. Here we report a three-component 1,2-difunctionalization reaction of alkenes, unactivated alkyl bromides and nucleophiles (e.g., amines and indoles) using a trinuclear gold catalyst [Au3(tppm)2](OTf)3. It can achieve the 1,2-aminoalkylation and 1,2-alkylarylation readily. This protocol has a broad reaction scope and excellent functional group compatibility (>100 examples with up to 96 % yield). It also affords a robust formal [2+2+1] cyclization strategy for the concise construction of pyrrolidine skeletons under mild reaction conditions. Mechanistic studies support an inner-sphere single electron transfer pathway for the successful cleavage of inert C−Br bonds. 相似文献
10.
Enantioselective CH Bond Functionalization Triggered by Radical Trifluoromethylation of Unactivated Alkene 下载免费PDF全文
Peng Yu Jin‐Shun Lin Lei Li Sheng‐Cai Zheng Ya‐Ping Xiong Li‐Jiao Zhao Prof. Dr. Bin Tan Prof. Dr. Xin‐Yuan Liu 《Angewandte Chemie (International ed. in English)》2014,53(44):11890-11894
An asymmetric unactivated alkene/C? H bond difunctionalization reaction for the concomitant construction of C? CF3 and C? O bonds was realized by using a Cu/Brønsted acid cooperative catalytic system, thus providing facile access to valuable chiral CF3‐containing N,O‐aminals with excellent regio‐, chemo‐, and enantioselectivity. Mechanistic studies revealed that this reaction may proceed by an unprecedented 1,5‐hydride shift involving activation of unactivated alkenes and a radical trifluoromethylation to initiate subsequent enantioselective functionalization of C? H bonds. Control experiments also suggested that chiral Brønsted acid plays multiple roles and not only controls the stereoselectivity but also increases the reaction rate through activation of Togni’s reagent. 相似文献
11.
Peng Yu Jin‐Shun Lin Lei Li Sheng‐Cai Zheng Ya‐Ping Xiong Li‐Jiao Zhao Bin Tan Xin‐Yuan Liu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(44):12084-12088
An asymmetric unactivated alkene/C H bond difunctionalization reaction for the concomitant construction of C CF3 and C O bonds was realized by using a Cu/Brønsted acid cooperative catalytic system, thus providing facile access to valuable chiral CF3‐containing N,O‐aminals with excellent regio‐, chemo‐, and enantioselectivity. Mechanistic studies revealed that this reaction may proceed by an unprecedented 1,5‐hydride shift involving activation of unactivated alkenes and a radical trifluoromethylation to initiate subsequent enantioselective functionalization of C H bonds. Control experiments also suggested that chiral Brønsted acid plays multiple roles and not only controls the stereoselectivity but also increases the reaction rate through activation of Togni’s reagent. 相似文献
12.
Herein we report a nickel-catalyzed asymmetric reductive aryl-allylation of aryl iodide-tethered unactivated alkenes, wherein both acyclic allyl carbonates and cyclic vinyl ethylene carbonates can serve as the coupling partners. Furthermore, the direct use of allylic alcohols as the electrophilic allyl source in this reaction is also viable in the presence of BOC anhydride. Remarkably, this reaction proceeds with high linear/branched-, E/Z- and enantio-selectivity, allowing the synthesis of various chiral indanes and dihydrobenzofurans (50 examples) containing a homoallyl-substituted quaternary stereocenter with high optical purity (90–98% ee). In this reductive reaction, the use of pregenerated organometallics can be circumvented, giving this process good functionality tolerance and high step-economy.A nickel-catalyzed reductive asymmetric aryl-allylation of tethered unactivated alkenes has been developed, providing diverse benzene-annulated cyclic compounds bearing a quaternary stereocenter with high regio-, E/Z- and enantio-selectivity. 相似文献
13.
Chuanqi Hou Dr. Pinhong Chen Prof. Dr. Guosheng Liu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(7):2757-2761
The first asymmetric PdII-catalyzed aminofluorination of unactivated alkenes using chiral quinoline-oxazolines (Quox) as ligands has been developed. This reaction provides easy access to a wide array of enantiomerically enriched β-fluoropiperidines in good yields and with excellent enantioselectivity. Notably, Et4NF⋅3 HF as a readily accessible nucleophilic fluoride source was found to play an essential role in the enantioselective control, and CsOCF3 also acts a key additive to improve the excellent ee value of products. 相似文献
14.
Chuanqi Hou Pinhong Chen Guosheng Liu 《Angewandte Chemie (International ed. in English)》2020,59(7):2735-2739
The first asymmetric PdII‐catalyzed aminofluorination of unactivated alkenes using chiral quinoline‐oxazolines (Quox) as ligands has been developed. This reaction provides easy access to a wide array of enantiomerically enriched β‐fluoropiperidines in good yields and with excellent enantioselectivity. Notably, Et4NF?3 HF as a readily accessible nucleophilic fluoride source was found to play an essential role in the enantioselective control, and CsOCF3 also acts a key additive to improve the excellent ee value of products. 相似文献
15.
Lu Wang Minxu Shi Xiaoping Chen Nicholas Su Weili Luo Xiaheng Zhang 《Angewandte Chemie (International ed. in English)》2023,62(52):e202314312
Nitrogen-centered radicals (NCRs) have been widely recognized as versatile synthetic intermediates for the construction of nitrogen containing molecules of high value. As such, there has been a long-standing interest in the field of organic synthesis to develop novel nitrogen-based radicals and explore their inherent reactivity. In this study, we present the generation of aromatic N-heterocyclic radicals and their application in a novel and diverse functionalization of unactivated alkenes. Bench-stable aromatic N-heterocyclic pyridinium salts were employed as crucial NCR precursors, which enabled the efficient conversion of various unactivated alkenes into medicinally relevant alkylated N-heterocyclic amines. This approach offers an unexplored retrosynthetic disconnection for the synthesis of related molecules that commonly possess therapeutic value. Furthermore, this platform can be extended to the synthesis of densely functionalized heterocyclic amines by utilizing disulfides and diethyl bromomalonate as radical quenchers. Mechanistic investigations indicate an energy transfer (EnT) pathway involving the formation of a transient aromatic N-heterocyclic radical, radical addition to unactivated alkenes, and subsequent generation of the amination product through either hydrogen atom transfer (HAT) or radical addition processes. 相似文献
16.
Directed Asymmetric Nickel-Catalyzed Reductive 1,2-Diarylation of Electronically Unactivated Alkenes
Dr. Zhan Dong Qiongyao Tang Changyu Xu Li Chen Haiting Ji Sitian Zhou Dr. Liangliang Song Prof. Dr. Liang-An Chen 《Angewandte Chemie (International ed. in English)》2023,62(13):e202218286
Transition-metal catalyzed intermolecular 1,2-diarylation of electronically unactivated alkenes has emerged as an extensive research topic in organic synthesis. However, most examples are mainly limited to terminal alkenes. Furthermore, transition-metal catalyzed asymmetric 1,2-diarylation of unactivated alkenes still remains unsolved and is a formidable challenge. Herein, we describe a highly efficient directed nickel-catalyzed reductive 1,2-diarylation of unactivated internal alkenes with high diastereoselectivities. More importantly, our further effort towards enantioselective 1,2-diarylation of the unactivated terminal and challenging internal alkenes is achieved, furnishing various polyarylalkanes featuring benzylic stereocenters in high yields and with good to high enantioselectivities and high diastereoselectivities. Interestingly, the generation of cationic Ni-catalyst by adding alkali metal fluoride is the key to increased efficiency of this enantioselective reaction. 相似文献
17.
Xiuxiu Li Cai You Jiaxin Yang Shuailong Li Dequan Zhang Hui Lv Xumu Zhang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(32):11044-11047
A general and efficient rhodium‐catalyzed asymmetric cyanide‐free hydrocyanation of alkenes has been developed. Based on the asymmetric hydroformylation/condensation/aza‐Cope elimination sequences, a broad scope of substrates including mono‐substituted, 1,2‐, and 1,1‐disubstituted alkenes (involving natural product R‐ and S‐limonene) were employed, and a series of valuable chiral nitriles are prepared with high yields (up to 95 %) and enantioselectivities (up to 98 % ee). Notably, the critical factor to achieve high enantioseletivies is the addition of catalytic amount of benzoic acid. This novel methodology provides an efficient and concise synthetic route to the intermediate of vildagliptin and anagliptin. 相似文献
18.
Javier Mazuela Alexander Paptchikhine Oscar Pàmies Pher G. Andersson Montserrat Diéguez 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(15):4567-4576
A library of readily available phosphite–oxazole/thiazole ligands ( L1 a – g – L7 a – g ) was applied in the Ir‐catalyzed asymmetric hydrogenation of several largely unfunctionalized E‐ and Z‐trisubstituted and 1,1‐disubstituted terminal alkenes. The ability of the catalysts to transfer chiral information to the product could be tuned by choosing suitable ligand components (bridge length, the substituents in the heterocyclic ring and the alkyl backbone chain, the configuration of the ligand backbone, and the substituents/configurations in the biaryl phosphite moiety), so that enantioselectivities could be maximized for each substrate as required. Enantioselectivities were therefore excellent (enantiomeric excess (ee) values up to >99 %) for a wide range of E‐ and Z‐trisubstituted and 1,1‐disubstituted terminal alkenes. The biaryl phosphite moiety was a very advantageous ligand component in terms of substrate versatility. 相似文献
19.
Asymmetric [3+2] Photocycloadditions of Cyclopropanes with Alkenes or Alkynes through Visible‐Light Excitation of Catalyst‐Bound Substrates 下载免费PDF全文
Xiaoqiang Huang Jiahui Lin Tianqi Shen Dr. Klaus Harms Dr. Marianna Marchini Prof. Dr. Paola Ceroni Prof. Dr. Eric Meggers 《Angewandte Chemie (International ed. in English)》2018,57(19):5454-5458
The herein reported visible‐light‐activated catalytic asymmetric [3+2] photocycloadditions between cyclopropanes and alkenes or alkynes provide access to chiral cyclopentanes and cyclopentenes, respectively, in 63–99 % yields and with excellent enantioselectivities of up to >99 % ee. The reactions are catalyzed by a single bis‐cyclometalated chiral‐at‐metal rhodium complex (2–8 mol %) which after coordination to the cyclopropane generates the visible‐light‐absorbing complex, lowers the reduction potential of the cyclopropane, and provides the asymmetric induction and overall stereocontrol. Enabled by a mild single‐electron‐transfer reduction of directly photoexcited catalyst/substrate complexes, the presented transformations expand the scope of catalytic asymmetric photocycloadditions to simple mono‐acceptor‐substituted cyclopropanes affording previously inaccessible chiral cyclopentane and cyclopentene derivatives. 相似文献
20.
Yongtao Xie Peng‐Wei Sun Yuxin Li Siwei Wang Mengchun Ye Zhengming Li 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(21):7171-7175
An iron‐catalyzed hydrofluorination of unactivated alkenes has been developed. The use of a multidentate ligand and the fluorination reagent N‐fluorobenzenesulfonimide (NFSI) proved to be critical for this reaction, which afforded various fluorinated compounds in up to 94 % yield. 相似文献