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Yusuke Iwama Dr. Kentaro Okano Dr. Kenji Sugimoto Prof. Dr. Hidetoshi Tokuyama 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(28):9325-9334
A racemic synthesis of mersicarpine ( 1 ) was achieved by the Mizoroki–Heck reaction and a DIBALH‐mediated reductive ring‐expansion reaction. Based on a first‐generation synthesis, a second‐generation enantiocontrolled total synthesis of (?)‐mersicarpine ( 1 ) was achieved by an 8‐pot/11‐step sequence in 21 % overall yield from commercially available 2‐ethylcyclohexanone. Subjection of a ketoester, which was prepared by an asymmetric Michael addition (according to the protocol by d’Angelo and Desmaële), and phenylhydrazine to modified Fischer indole conditions provided a six‐membered tricyclic indole. Benzylic oxidation and subsequent oxime formation provided a ketoxime, which was treated with diisobutylaluminum hydride (DIBALH) to construct the characteristic azepinoindole skeleton in good yield. In the DIBALH‐mediated reductive ring‐expansion reaction, gradually increasing the reaction temperature and in situ‐protection of the nitrogen in an oxygen‐sensitive azepinoindole with a benzyloxycarbonyl (Cbz) group were crucial for the high‐yielding process. With these methodologies, the short‐step and efficient synthesis of (?)‐mersicarpine was accomplished. Several synthetic efforts are also described. 相似文献
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The synthesis of a series of 3,5‐disubstituted isoxazole‐4‐carboxylic esters containing N‐substituted 1,2,3‐triazoles ( V ) starting from various benzaldehydes ( I ) is reported. Benzaldehydes undergo oximation with hydroxylamine hydrosulfate. Later, chlorination followed by condensation with methylacetoacetate and the hydrolysis of the resulting ester afforded respective carboxylic acid ( II ), which on chlorination with PCl5 gave the corresponding acid chlorides ( III ). The coraboxylic acid chlorides ( III ) on propargylation gave propargylic esters ( IV ) and these on click reaction gave the title compounds ( V ). 相似文献
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Azidoperfluoroalkanes: Synthesis and Application in Copper(I)‐Catalyzed Azide–Alkyne Cycloaddition 下载免费PDF全文
《Angewandte Chemie (International ed. in English)》2017,56(1):346-349
We report an efficient and scalable synthesis of azidotrifluoromethane (CF3N3) and longer perfluorocarbon‐chain analogues (RFN3; RF=C2F5, n C3F7, n C8F17), which enables the direct insertion of CF3 and perfluoroalkyl groups into triazole ring systems. The azidoperfluoroalkanes show good reactivity with terminal alkynes in copper(I)‐catalyzed azide–alkyne cycloaddition (CuAAC), giving access to rare and stable N ‐perfluoroalkyl triazoles. Azidoperfluoroalkanes are thermally stable and the efficiency of their preparation should be attractive for discovery programs. 相似文献
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Kostiantyn O. Marichev Kan Wang Kuiyong Dong Nicole Greco Lyne A. Massey Yongming Deng Hadi Arman Michael P. Doyle 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(45):16334-16338
The all‐cis stereoisomers of tetrasubstituted azetidine‐2‐carboxylic acids and derivatives that possess three chiral centers have been prepared in high yield and stereocontrol from silyl‐protected Z‐γ‐substituted enoldiazoacetates and imido‐sulfur ylides by asymmetric [3+1]‐cycloaddition using chiral sabox copper(I) catalysis followed by Pd/C catalytic hydrogenation. Hydrogenation of the chiral p‐methoxybenzyl azetine‐2‐carboxylates occurs with both hydrogen addition to the C=C bond and hydrogenolysis of the ester. 相似文献
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As a new class of potential catalysts for 1,3‐dipolar cycloaddition reactions, fourteen L‐amino acid Schiff base Cu(II) and Ti(IV) complexes were synthesized, characterized, and evaluated for their catalytic activities in the reaction between C,N‐diphenylnitrone and electron‐rich ethyl vinyl ether under both homogeneous and in situ conditions. The methods for preparation and utilization of the catalysts were elucidated in detail, and the results of the catalytic reactions were described and discussed as well. Excellent reaction results were found in the presence of some catalysts (20 mol%) with > 90% endo‐isoazolidines produced, compared with predominantly exo‐isoazolidine produced without a catalyst. In addition, the reaction rate is found to be enhanced remarkably by a Cu(II) complex Schiff base catalyst at room temperature. 相似文献
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Jin‐Wei Yuan Ling‐Bo Qu Xiao‐Lan Chen Zhi‐Bo Qu Xiang‐Qian Liu Dian‐Dian Ke 《中国化学会会志》2011,58(1):24-30
An efficient synthesis of novel mono and bis‐1,2,3‐triazoles 3′‐azido‐2′‐deoxythymidine (AZT) derivatives via copper(I)‐catalyzed 1,3‐dipolar cycloaddition reaction is described. Starting from AZT and terminal alkyne derivatives, mono and bis‐1,2,3‐triazole AZT derivatives are regioselectively obtained in good yields under mild conditions using CuSO4·5H2O and sodium ascorbate as a catalyst system, and t‐BuOH/H2O (1:1, v/v) as a co‐solvent. The structures of these compounds were elucidated by IR, HR MS and NMR. 相似文献
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A Cyclization–Rearrangement Cascade for the Synthesis of Structurally Complex Chiral Gold(I)–Aminocarbene Complexes 下载免费PDF全文
Dr. Filip Kolundžić Dr. Annamalai Murali Dr. Patricia Pérez‐Galán Dipl.‐Chem. Jonathan O. Bauer Prof. Dr. Carsten Strohmann Dr. Kamal Kumar Prof. Dr. Herbert Waldmann 《Angewandte Chemie (International ed. in English)》2014,53(31):8122-8126
A facile synthesis of chiral cyclic alkyl aminocarbene–gold(I) complexes from gold‐free 1,7‐enyne substrates was developed. The novel cyclization–rearrangement reaction sequence is triggered by the addition of (Me2S)AuCl to different 1,7‐enynes and leads to structurally unique carbene–gold(I) complexes in high yields. These novel complexes are catalytically active and inhibit the proliferation of different human cancer cell lines. 相似文献
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Thomas Cruchter Dr. Klaus Harms Prof. Dr. Eric Meggers 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(49):16682-16689
The reactivity of an exemplary ruthenium(II)–azido complex towards non‐activated, electron‐deficient, and towards strain‐activated alkynes at room temperature and low millimolar azide and alkyne concentrations has been investigated. Non‐activated terminal and internal alkynes failed to react under such conditions, even under copper(I) catalysis conditions. In contrast, as expected, rapid cycloaddition was observed with electron‐deficient dimethyl acetylenedicarboxylate (DMAD) as the dipolarophile. Since DMAD and related propargylic esters are excellent Michael acceptors and thus unsuitable for biological applications, we investigated the reactivity of the azido complex towards cycloaddition with derivatives of cyclooctyne (OCT), bicyclo[6.1.0]non‐4‐yne (BCN), and azadibenzocyclooctyne (ADIBO). While no reaction could be observed in the case of the less strained cyclooctyne OCT, the highly strained cyclooctynes BCN and ADIBO readily reacted with the azido complex, providing the corresponding stable triazolato complexes, which were amenable to purification by conventional silica gel column chromatography. An X‐ray crystal structure of an ADIBO cycloadduct was obtained and verified that the formed 1,2,3‐triazolato ligand coordinates the metal center through the central N2 atom. Importantly, the determined second‐order rate constant for the ADIBO cycloaddition with the azido complex (k2=6.9 × 10?2 M ?1 s?1) is comparable to the rate determined for the ADIBO cycloaddition with organic benzyl azide (k2=4.0 × 10?1 M ?1 s?1). Our results demonstrate that it is possible to transfer the concept of strain‐promoted azide–alkyne cycloaddition (SPAAC) from purely organic azides to metal‐coordinated azido ligands. The favorable reaction kinetics for the ADIBO‐azido‐ligand cycloaddition and the well‐proven bioorthogonality of strain‐activated alkynes should pave the way for applications in living biological systems. 相似文献
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Synthesis of Spirocyclic and Tricyclic Isoxazoline via 1,3‐Dipolar Cycloaddition Reactions 下载免费PDF全文
1,3‐Dipolar cycloadditions of the bicyclic monoterpenes (S)‐(?)‐camphene ( 1 ), (R)‐(+)‐a‐pinene ( 2 ), and (S)‐(?)‐b‐pinene ( 3 ) with aryl and heteroaryl nitrile oxides afforded new spirocyclic and tricyclic isoxazoline derivatives 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 whose biological activities were evaluated in bioassay studies. 相似文献
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Summary. 1,3-Dipolar cycloadditions of chiral nitrones to Baylis-Hillman adducts (-hydroxy--methylene esters) proceed with complete regioselectivity in good yields to afford the corresponding diastereomeric 3,5,5-trisubstituted isoxazolidines. Attack of the dipole from the less sterically hindered side of the dipolarophiles affords C-3/C-5 cis isoxazolidines as the predominant isomers. The strong preference for the C-3/C-5 cis isoxazolidines provided more sterically demanding O-tert-butyldimethylsilylsubstituted nitrone 2. Addition of Lewis acids accelerates the reaction and increases the portion of C-3/C-5 trans isoxazolidines. Microwave irradiation accelerates the reaction, but it produces only a small effect on the diastereoisomeric product ratio. 相似文献
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A new versatile and efficient regio-, diastereo-, and enantioselective synthesis of vicinal diols s-trans- 4 , s-trans- 5 , and s-cis- 4 is described. Symmetrical ketones are converted into their SAMP-or RAMP-hydrazones which are then silylated with (isopropyloxy)dimethylsilyl chloride, followed by ozonolysis to afford the α-silyl ketones (R)- 2 of high enantiomeric purity (ee 90– ≥ 98%). On the other hand, methyl ketones, after conversion into the corresponding (?)–(S)-1-amino-2-(methoxymethyl) pyrrolidine (SAMP) hydrazones, are silylated and then alkylated with RI to afford unsymmetrical α-silyl ketones (S)- 3 of high enantiomeric purity (ee 90- ≥ 98%). The reduction of the above obtained α-silyl ketones with L -Selectride, followed by oxidative cleavage of the C? Si bond gives rise to s-trans-4, s-trans- 5 , and s-cis- 4 with high diastereoselectivity (de 95- ≥ 98%) and without racemization (ee ≥ 90– ≥ 98%). 相似文献
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Yang Fu Yan Liu Xiaoping Fu Li Zou Hua Li Ming Li Prof. Dr. Xingguo Chen Jingui Qin 《中国化学》2010,28(11):2226-2232
The click‐ligands based on 1,2,3‐triazole and pyridine unit has been synthesized via Cu(I)‐catalyzed alkyne‐azide cycloaddition from corresponding organic azides and terminal alkynes. The ligand structure was characterized by NMR, IR and elemental analysis as well as single crystal diffractions. The single crystal structure of the complexes from two different ligands coordinating to Cu(II) and Co(II) ions indicated that the N(2) atom in 1,2,3‐triazole unit can act as an efficient donor to metals through the rational molecular design. 相似文献
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《Journal of heterocyclic chemistry》2018,55(9):2069-2074
The syntheses of an important class of enantiopure five‐membered glyconjucates containing furan unit are described. The regioselective synthesis of a series of sugar‐fused pyrazole heterocycles was achieved by the Huisgen cyclization of aryl diazomethanes with propargyl O‐glycoside derivatives in good yields. The cycloaddition regioselectivity was confirmed by NMR. 相似文献
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《Journal of heterocyclic chemistry》2018,55(1):199-208
An efficient protocol for the synthesis of substituted 1,2,3‐triazol‐9H‐purines via copper (I)‐catalyzed click chemistry of 2,6‐dichloropurine with aromatic azide has been reported. A wide range of 1,4‐disubstituted triazoles ( N‐9 substituted purines) was accessible in good‐to‐excellent yields with remarkable functional group tolerance. The base‐catalyst ratio was tuned to achieve optimum reaction condition (>95% conversion and purity in most cases). Furthermore, the structure of 4i has been unambiguously assigned by X‐ray crystallographic study to yield structural information on the 1,3‐dipoles entering the reaction. 相似文献