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Asymmetric Dearomatization of β‐Naphthols through an Amination Reaction Catalyzed by a Chiral Phosphoric Acid 下载免费PDF全文
Shou‐Guo Wang Dr. Qin Yin Dr. Chun‐Xiang Zhuo Prof. Dr. Shu‐Li You 《Angewandte Chemie (International ed. in English)》2015,54(2):647-650
A highly efficient catalytic asymmetric dearomatization of naphthols by means of an electrophilic amination reaction catalyzed by chiral phosphoric acid is presented. This protocol provides a facile access to functionalized β‐naphthalenone compounds with a chiral quaternary carbon center in excellent yields and enantioselectivity (up to 99 % yield, up to 96 % ee). 相似文献
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Theoretical Studies on the Asymmetric Baeyer–Villiger Oxidation Reaction of 4‐Phenylcyclohexanone with m‐Chloroperoxobenzoic Acid Catalyzed by Chiral Scandium(III)–N,N′‐Dioxide Complexes 下载免费PDF全文
Dr. Na Yang Dr. Zhishan Su Prof. Dr. Xiaoming Feng Prof. Dr. Changwei Hu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(19):7264-7277
The mechanism and enantioselectivity of the asymmetric Baeyer–Villiger oxidation reaction between 4‐phenylcyclohexanone and m‐chloroperoxobenzoic acid ( m ‐CPBA ) catalyzed by ScIII–N,N′‐dioxide complexes were investigated theoretically. The calculations indicated that the first step, corresponding to the addition of m ‐CPBA to the carbonyl group of 4‐phenylcyclohexanone, is the rate‐determining step (RDS) for all the pathways studied. The activation barrier of the RDS for the uncatalyzed reaction was predicted to be 189.8 kJ mol?1. The combination of an ScIII–N,N′‐dioxide complex and the m ‐CBA molecule can construct a bifunctional catalyst in which the Lewis acidic ScIII center activates the carbonyl group of 4‐phenylcyclohexanone while m ‐CBA transfers a proton, which lowers the activation barrier of the addition step (RDS) to 86.7 kJ mol?1. The repulsion between the m‐chlorophenyl group of m ‐CPBA and the 2,4,6‐iPr3C6H2 group of the N,N′‐dioxide ligand, as well as the steric hindrance between the phenyl group of 4‐phenylcyclohexanone and the amino acid skeleton of the N,N′‐dioxide ligand, play important roles in the control of the enantioselectivity. 相似文献
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Giorgio Strukul 《Angewandte Chemie (International ed. in English)》1998,37(9):1198-1209
Environmentally friendly oxidizing agents such as hydrogen peroxide or dioxygen can be used today in catalytic versions of the almost one century old Baeyer–Villiger oxidation with transition metal complexes as catalysts. On the right is a sketch of a possible mechanism for this reaction with a platinum catalyst in homogeneous solution. 相似文献
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Xu Tian Dr. Nora Hofmann Prof. Dr. Paolo Melchiorre 《Angewandte Chemie (International ed. in English)》2014,53(11):2997-3000
An unprecedented way to extend the synthetic utility of the Diels–Alder reaction to include a vinylogous reactivity space is described. A commercially available chiral phosphoric acid catalyst effectively activates cyclic 2,4‐dienones towards a vinylogous [4+2] cycloaddition with 2‐vinylindoles, which leads to stereochemically dense tetrahydrocarbazoles. The reaction proceeds with a high level of remote stereocontrol and exclusive chemoselectivity for the more distant double bond of the dienone. 相似文献
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Baeyer–Villiger oxidation of cyclohexanone by molecular oxygen with Fe–Sn–O mixed oxides as catalysts 下载免费PDF全文
Fe–Sn–O mixed oxides were synthesized and used as catalysts for Baeyer–Villiger oxidation of cyclohexanone, which showed both high catalytic activity and selectivity. X‐ray powder diffraction and scanning electron microscopy suggested that the Fe–Sn–O catalysts had a tetragonal structure with a grain size of 29.3 nm. An ε‐caprolactone yield as high as 98.8% was obtained in a small‐scale experiment (5 mmol of cyclohexanone). In a scale‐up test (20 mmol of cyclohexanone), the cyclohexanone conversion and ε‐caprolactone yield were 96.7 and 96.5%, respectively. In addition, the catalysts can be reused five times without any major decline in catalytic activity. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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An organocatalyst formed from a binaphthyl‐substituted diamine and trifluoromethanesulfonic acid exhibited unprecedented levels of exo selectivity in the Diels–Alder reaction of α,β‐unsaturated aldehydes with cyclopentadiene. A novel axially chiral diamine was also designed as an organocatalyst for an asymmetric variant of this reaction, in which the desired cycloadducts were formed with high diastereo‐ and enantioselectivities. The highest diastereoselectivity observed was greater than 20:1 in favor of the exo cycloadduct in the asymmetric Diels–Alder reaction of crotonaldehyde with cyclopentadiene. 相似文献
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Interrupted Baeyer–Villiger Rearrangement: Building A Stereoelectronic Trap for the Criegee Intermediate 下载免费PDF全文
Dr. Vera A. Vil' Gabriel dos Passos Gomes Oleg V. Bityukov Prof. Konstantin A. Lyssenko Prof. Gennady I. Nikishin Prof. Igor V. Alabugin Prof. Alexander O. Terent'ev 《Angewandte Chemie (International ed. in English)》2018,57(13):3372-3376
The instability of hydroxy peroxyesters, the elusive Criegee intermediates of the Baeyer–Villiger rearrangement, can be alleviated by selective deactivation of the stereoelectronic effects that promote the 1,2‐alkyl shift. Stable cyclic Criegee intermediates constrained within a five‐membered ring can be prepared by mild reduction of the respective hydroperoxy peroxyesters (β‐hydroperoxy‐β‐peroxylactones) which were formed in high yields in reaction of β‐ketoesters with BF3?Et2O/H2O2. 相似文献
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Dr. Bertrand Schweitzer‐Chaput Dr. Theo Kurtén Dr. Martin Klussmann 《Angewandte Chemie (International ed. in English)》2015,54(40):11848-11851
The acid‐mediated reaction of ketones with hydroperoxides generates radicals, a process with reaction conditions similar to those of the Baeyer–Villiger oxidation but with an outcome resembling the formation of hydroxyl radicals via ozonolysis in the atmosphere. The Baeyer–Villiger oxidation forms esters from ketones, with the preferred use of peracids. In contrast, alkyl hydroperoxides and hydrogen peroxide react with ketones by condensation to form alkenyl peroxides, which rapidly undergo homolytic O? O bond cleavage to form radicals. Both reactions are believed to proceed via Criegee adducts, but the electronic nature of the peroxide residue determines the subsequent reaction pathways. DFT calculations and experimental results support the idea that, unlike previously assumed, the Baeyer–Villiger reaction is not intrinsically difficult with alkyl hydroperoxides and hydrogen peroxide but rather that the alternative radical formation is increasingly favored. 相似文献
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Phosphoric Acid Catalyzed Asymmetric 1,6‐Conjugate Addition of Thioacetic Acid to para‐Quinone Methides 下载免费PDF全文
Nan Dong Zhi‐Pei Zhang Dr. Xiao‐Song Xue Prof. Xin Li Prof. Jin‐Pei Cheng 《Angewandte Chemie (International ed. in English)》2016,55(4):1460-1464
An asymmetric 1,6‐conjugate addition of thioacetic acid with para‐quinone methides has been developed by using chiral phosphoric acid catalysis in the presence of water. A series of sulfur‐containing compounds were thus obtained in high yields with good to excellent enantioselectivities. Theoretical studies indicated that the water‐bridged proton transfer is a potentially favorable reaction pathway. An unprecedented O?H???π interaction between water and the aromatic nucleus of chiral phosphoric acid was discovered to contribute significantly to the stereocontrol in the catalysis. 相似文献
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Chiral Phosphoric Acid Catalyzed Asymmetric Ugi Reaction by Dynamic Kinetic Resolution of the Primary Multicomponent Adduct 下载免费PDF全文
Yun Zhang Dr. Yu‐Fei Ao Prof. Dr. Zhi‐Tang Huang Prof. Dr. De‐Xian Wang Prof. Dr. Mei‐Xiang Wang Prof. Dr. Jieping Zhu 《Angewandte Chemie (International ed. in English)》2016,55(17):5282-5285
Reaction of isonitriles with 3‐(arylamino)isobenzofuran‐1(3H)‐ones in the presence of a catalytic amount of an octahydro (R)‐binol‐derived chiral phosphoric acid afforded 3‐oxo‐2‐arylisoindoline‐1‐carboxamides in high yields with good to high enantioselectivities. An enantioselective Ugi four‐center three‐component reaction of 2‐formylbenzoic acids, anilines, and isonitriles was subsequently developed for the synthesis of the same heterocycle. Mechanistic studies indicate that the enantioselectivity results from the dynamic kinetic resolution of the primary Ugi adduct, rather than from the C?C bond‐forming process. The resulting heterocycle products are of significant medicinal importance. 相似文献
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Asymmetric Diels–Alder Reaction of α‐Substituted and β,β‐Disubstituted α,β‐Enals via Diarylprolinol Silyl Ether for the Construction of All‐Carbon Quaternary Stereocenters 下载免费PDF全文
Prof. Dr. Yujiro Hayashi Dr. Bojan P. Bondzic Tatsuya Yamazaki Yogesh Gupta Shin Ogasawara Prof. Dr. Tohru Taniguchi Prof. Dr. Kenji Monde 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(44):15874-15880
The asymmetric Diels–Alder reaction of α‐substituted acrolein proceeds in the presence of the trifluoroacetic acid salt of trifluoromethyl‐substituted diarylprolinol silyl ether to afford the exo‐isomer with both excellent diastereoselectivity and high enantioselectivity. In the Diels–Alder reaction of a β,β‐disubstituted α,β‐unsaturated aldehyde, good exo‐selectivity and excellent enantioselectivity was obtained when the perchloric acid salt of the bulky triisopropyl silyl ether of trifluoromethyl substituted diarylprolinol was employed as an organocatalyst in the presence of water. In both cases, all‐carbon quaternary stereocenters are constructed enantioselectively. 相似文献
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Thomas Varlet Coralie Gelis Pascal Retailleau Guillaume Bernadat Luc Neuville Graldine Masson 《Angewandte Chemie (International ed. in English)》2020,59(22):8491-8496
An efficient enantioselective construction of tetrahydronaphthalene‐1,4‐diones as well as dihydronaphthalene‐1,4‐diols by a chiral phosphoric acid catalyzed quinone Diels–Alder reaction with dienecarbamates is reported. The nature of the protecting group on the diene is key to the success of achieving high enantioselectivity. The divergent “redox” selectivity is controlled by using an adequate amount of quinones. Reversible redox switching without erosion of enantioselectivity was possible from individual redox isomers. 相似文献
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γ′‐Selective Functionalization of Cyclic Enones: Construction of a Chiral Quaternary Carbon Center by [4+2] Cycloaddition/Retro‐Mannich Reaction with 3‐Substituted Maleimides 下载免费PDF全文
Chuncheng Zou Chuikun Zeng Prof. Dr. Zhen Liu Min Lu Xiaohua Sun Prof. Dr. Jinxing Ye 《Angewandte Chemie (International ed. in English)》2016,55(46):14257-14261
The first example of organocatalyzed γ′‐selective functionalization of cyclic enones with 3‐substituted maleimides results in the stereoselective construction quaternary carbon center is presented. The reactions provided γ′‐functionalized cyclic enones and β‐functionalized cyclopentenones in good to excellent yields with excellent diastereo‐ and enantioselectivities. DFT calculations indicated that the reaction might proceed as a [4+2] cycloaddition/retro‐Mannich reaction which could explain the unexpected product with a chiral quaternary carbon center and the excellent stereoselectivity. 相似文献
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Unprecedented 1,14‐seco‐Crotofolanes from Croton insularis: Oxidative Cleavage of Crotofolin C by a Putative Homo‐Baeyer–Villiger Rearrangement 下载免费PDF全文
Dr. Lidiya A. Maslovskaya Dr. Andrei I. Savchenko Carly J. Pierce Dr. Victoria A. Gordon Dr. Paul W. Reddell Prof. Peter G. Parsons Prof. Craig M. Williams 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(44):14226-14230
EBC‐162 isolated from Croton insularis, obtained from the northern rainforest of Australia, was structurally affirmed as crotofolin C ( 4 ). Novel oxidative degradation products, EBC‐233 and EBC‐300, which are the first crotofolane endoperoxides, were also isolated. Both endoperoxides were found to be stable intermediates, which are proposed to undergo an unprecedented homo‐Baeyer–Villiger biosynthetic rearrangement to give a new class of 1,14‐seco‐crotofolane diterpenes. Prolonged storage of all isolates assisted in authenticating their natural product status. Anticancer activities of reported compounds are presented. 相似文献