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1.
Lei Dai Zi‐Hao Xia Yuan‐Yuan Gao Zhong‐Hua Gao Song Ye 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(50):18292-18298
The merging of photoredox catalysis and N‐heterocyclic carbene (NHC) catalysis for γ‐ and ?‐alkylation of enals with alkyl radicals was developed. The alkylation reaction of γ‐oxidized enals with alkyl halides worked well for the synthesis γ‐multisubstituted‐α,β‐unsaturated esters, including those with challenging vicinal all‐carbon quaternary centers. The synthesis of ?‐multisubstituted‐α,β‐γ,δ‐diunsaturated esters by an unprecedented NHC‐catalyzed ?‐functionalization was also established. 相似文献
2.
An efficient NaBArF4‐catalyzed oxidative cyclization of readily available 1,5‐ and 1,6‐diynes has been developed. Importantly, this transition metal‐free oxidative catalysis proceeds via a presumable Lewis acid‐catalyzed SN2’ pathway, which is distinct from the relevant oxidative rhodium and gold catalysis. This method leads to the facile and practical construction of a diverse range of synthetically useful γ‐ and δ‐lactams in mostly good to excellent yields with broad substrate scope. 相似文献
3.
Synthesis of Novel Fused Heterocycles Based on 6‐Amino‐4‐phenyl‐2‐thioxo‐1,2‐dihydropyridine‐3,5‐dicarbonitrile
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H. Abdel‐Ghany A. M. El‐Sayed A. A. Amer A. M. Ahmed 《Journal of heterocyclic chemistry》2016,53(6):2013-2019
Under phase transfer catalysis conditions, 6‐amino‐4‐phenyl‐2‐thioxo‐1,2‐dihydropyridine‐3,5‐dicarbonitrile ( 1 ) was allowed to react with halo compounds, acrylonitrile, chloroacetyl chloride, ethyl cyanoacetate, formamide, triethylorthoformate, or formic acid to give new derivatives of fused pyridines 2–22, respectively. Acetylation of compound 1 using acetic anhydride afforded product 23 , which in turn underwent intramolecular cyclization in pyridine to give the corresponding pyrido[2,3‐d]pyrimidine 24 . 相似文献
4.
In the presence of CuCl2, N‐(2′, 4′‐dienyl)‐2‐alkynamides can be converted to α‐alkylidene‐σ‐butyrolactams under the catalysis of palladium(II). In this reaction, CuCl2 is used to oxidize Pd(0) to regenerate Pd(II), or the carbon‐palladium bond is quenched by the oxidative cleavage reaction of CuCl2. 相似文献
5.
The Synthesis of New Organoselenium Heterocyclic Compounds: 2‐aryl‐4‐phenyl‐5,6,7,8‐tetrahydro‐4H‐selenochromenes
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Dmitriy Yurievich Direnko Yaroslav Borisovich Drevko Boris Ivanovich Drevko 《中国化学会会志》2015,62(12):1068-1071
We have explored the reactions of 2‐(3‐oxo‐1‐aryl‐3‐phenylpropyl)cyclohexanone ( 1–3 ) with hydrogen selenide in situ in conditions of acid catalysis, and synthesized new 2‐aryl‐4‐phenyl‐5,6,7,8‐tetrahydro‐4H‐selenochromenes ( 4–6 ). 相似文献
6.
《Journal of heterocyclic chemistry》2017,54(2):944-951
Reaction of 5,6‐dihydro‐4H‐pyrrolo[3,2,1‐ij ]quinoline‐1,2‐dione ( 3 ) with two equivalents of cyclic 1,3‐dicarbonyl compounds under acid catalysis generates spiro[4H‐pyran‐3,3′‐oxindoles] 7 . In contrast, though base catalysis also achieves double addition, the final products 8 result from subsequent ring opening of the five‐membered lactam via intramolecular attack by enolate; these products can be converted into the spiro[4H‐pyran‐3,3′‐oxindoles] by treatment with acid. 相似文献
7.
Redox‐Neutral α‐Allylation of Amines by Combining Palladium Catalysis and Visible‐Light Photoredox Catalysis
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Jun Xuan Ting‐Ting Zeng Zhu‐Jia Feng Qiao‐Hui Deng Prof. Dr. Jia‐Rong Chen Dr. Liang‐Qiu Lu Prof. Dr. Wen‐Jing Xiao Prof. Dr. Howard Alper 《Angewandte Chemie (International ed. in English)》2015,54(5):1625-1628
An unprecedented α‐allylation of amines was achieved by combining palladium catalysis and visible‐light photoredox catalysis. In this dual catalysis process, the catalytic generation of allyl radical from the corresponding π‐allylpalladium intermediate was achieved without additional metal reducing reagents (redox‐neutral). Various allylation products of amines were obtained in high yields through radical cross‐coupling under mild reaction conditions. Moreover, the transformation was applied to the formal synthesis of 8‐oxoprotoberberine derivatives which show potential anticancer properties. 相似文献
8.
《化学:亚洲杂志》2017,12(18):2399-2403
An intramolecular exo ‐hydroarylation of 2‐aryloxy‐1,4‐disilylbut‐1‐en‐3‐ynes via ortho ‐C−H bond activation under palladium(0) and acid catalysis was found to give 2,3‐bis(silylmethylidene)‐2,3‐dihydrobenzofurans. The two silyl groups present probably promoted the reaction and played a key role in stabilizing the diene moiety in the product. The products readily led to functionalized condensed cycles by a Diels–Alder reaction. 相似文献
9.
Palladium‐Titanium Relay Catalysis Enables Switch from Alkoxide‐π‐Allyl to Dienolate Reactivity for Spiro‐Heterocycle Synthesis
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Dr. Li‐Cheng Yang Zher Yin Tan Dr. Zi‐Qiang Rong Ruoyang Liu Ya‐Nong Wang Prof. Yu Zhao 《Angewandte Chemie (International ed. in English)》2018,57(26):7860-7864
Reported herein is the divergent syntheses of [5,5] and [6,5] spiro‐heterocycles under Lewis‐acid‐assisted palladium catalysis. In particular, an unprecedented switch from alkoxide‐π‐allyl to dienolate reactivity was achieved by the use of palladium‐titanium relay catalysis, and represents umpolung reactivity of vinylethylene carbonates. This method uses a simple procedure and commercially available catalysts, and delivers both classes of spiro‐heterocycles, bearing three contiguous stereocenters, in high yield and uniformly excellent diastereoselectivity. 相似文献
10.
11.
Copper‐Catalyzed Aerobic Oxidations of 3‐N‐Hydoxyaminoprop‐1‐ynes to Form 3‐Substituted 3‐Amino‐2‐en‐1‐ones: Oxidative Mannich Reactions with a Skeletal Rearrangement
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Rahul Kisan Kawade Chang‐Chin Tseng Prof. Dr. Rai‐Shung Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(43):13927-13931
Cu‐catalyzed aerobic oxidations of readily available 3‐N‐hydroxyaminopro‐1‐ynes with water, alcohols, or thiols to form diverse 3‐substituted 3‐amino‐2‐en‐1‐ones are described. The utility of this catalysis is manifested by a wide scope of applicable N‐hydroxyl propargylamines and nucleophiles, thus enabling the design of one‐pot cascade or two‐step sequential reactions. Besides synthetic significances, such oxidative Mannich reactions are mechanistically interesting because structurally reorganized products were obtained. Our mechanistic studies reveal that the aerobic oxidations involve initial formation of nitrone intermediates, followed by the attack of nucleophiles. Herein, water and MeOH implement the conversion of nitrone intermediates to reaction products in two distinct pathways. 相似文献
12.
Melissa A. Ashley Chiaki Yamauchi John C. K. Chu Shinya Otsuka Hideki Yorimitsu Tomislav Rovis 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(12):4042-4046
The synthetic utility of tertiary amines to oxidatively generate α‐amino radicals is well established, however, primary amines remain challenging because of competitive side reactions. This report describes the site‐selective α‐functionalization of primary amine derivatives through the generation of α‐amino radical intermediates. Employing visible‐light photoredox catalysis, primary sulfonamides are coupled with electron‐deficient alkenes to efficiently and mildly construct C?C bonds. Interestingly, a divergence between intermolecular hydrogen‐atom transfer (HAT) catalysis and intramolecular [1,5] HAT was observed through precise manipulation of the protecting group. This dichotomy was leveraged to achieve excellent α/δ site‐selectivity. 相似文献
13.
Xuan Ding Chun‐Lin Dong Zhi Guan Yan‐Hong He 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(1):124-130
The combination of photoredox and enzymatic catalysis for the direct asymmetric one‐pot synthesis of 2,2‐disubstituted indol‐3‐ones from 2‐arylindoles through concurrent oxidization and alkylation reactions is described. 2‐Arylindoles can be photocatalytically oxidized to 2‐arylindol‐3‐one with subsequent enantioselective alkylation with ketones catalyzed by wheat germ lipase (WGL). The chiral quaternary carbon center at C2 of the indoles was directly constructed. This mode of concurrent photobiocatalysis provides a mild and powerful strategy for one‐pot enantioselective synthesis of complex compounds. The experiments proved that other lipases containing structurally analogous catalytic triad in the active site also can catalyze the reaction in the same way. This reaction is the first example of combining the non‐natural catalytic activity of hydrolases with visible‐light catalysis for enantioselective organic synthesis and it does not require any cofactors. 相似文献
14.
Chetan C. Chintawar Amit K. Yadav Nitin T. Patil 《Angewandte Chemie (International ed. in English)》2020,59(29):11808-11813
Herein, we disclose the gold‐catalyzed 1,2‐diarylation of alkenes through the interplay of ligand‐enabled AuI/AuIII catalysis with the idiosyncratic π‐activation mode of gold complexes. Unlike the classical migratory‐insertion‐based approach to 1,2‐diarylation, the present approach not only circumvents the formation of direct Ar?Ar′ coupling and Heck‐type side products but more intriguingly demonstrates reactivity and selectivity complementary to those of previously known metal catalysis (Pd, Ni, or Cu). Detailed investigations to underpin the mechanistic scenario revealed oxidative addition of aryl iodides to an AuI complex to be the rate‐limiting step owing to the non‐innocent nature of the aryl alkene. 相似文献
15.
Starting from 1‐[(tert‐butoxy)carbonyl]piperidine‐4‐carboxylic acid and 2‐bromoaniline, the spiro[indole‐3,4′‐piperidin]‐2‐one system was obtained in three high‐yielding steps: anilide formation, N(1)‐protection, and intramolecular cyclization under Pd catalysis as the key reaction. The preparation of the corresponding 2‐bromoanilide was studied. In extension, the same sequence was developed with 4‐methyl‐ and 4‐nitro‐2‐bromoaniline. In the key step, the NO2 group led to a rather diminished yield. The transformation of the protected spiro[indole‐3,4′‐piperidin]‐2‐one to the corresponding unprotected dihydroindoles is discussed. 相似文献
16.
《Journal of heterocyclic chemistry》2017,54(3):2029-2037
The transamination of 6‐chloro‐2‐(3‐chlorophenyl)‐1H‐benz[de ]isoquinoline‐1,3‐(2H )‐dione with primary alkylamines under pseudo‐first‐order conditions is shown to be unimolecular in both reagents as well as unimolecular in methanol (in methanol solution). The reaction is subject to both general acid and general base catalysis. A termolecular, solvated transition state model and a putative model for the early steps of laser tissue welding with aminonaphthalimide dyes are proposed. 相似文献
17.
Wenzhong Huang Lingli Nang Xiangguang Li Lin Yuan Yinhai Ma Deqiang Liang 《中国化学》2015,33(10):1167-1172
Under the catalysis of only 3 mol% of Br2 at room temperature, indoles reacted rapidly with isatins to form biologically important 3,3‐bis(indole‐3‐yl)indoline‐2‐(1H)‐ones with high efficiency and wide substrate scope. Moreover, we demonstrated that p‐toluenesulfonic acid (TsOH) could serve as a surrogate to catalyze this transformation. 相似文献
18.
《Journal of heterocyclic chemistry》2017,54(6):3008-3014
Partitioning of neutron‐poisoning lanthanides from minor actinides in used nuclear fuel using liquid–liquid separation techniques with moderately soft Lewis basic heterocyclic scaffolds is an area of intense research focus. Nitrogen heterocycles have demonstrated potential for the selective separation of Am3+ from Eu3+ in separations processes. Improved synthetic strategies are required to access more diversified complexant scaffolds for further study. The present work describes an efficient synthetic strategy for the preparation of functionalized [2,2′]‐bipyridinyl scaffolds using Pd catalysis to prepare the requisite starting material and telescoped condensation to afford direct access to hemi‐1,2,4‐triazinyl‐[2,2′]‐bipyridines with aliphatic character and potentially greater solubility in less polar diluents. Synthetic method development, optimization, and substrate scope are reported herein. 相似文献
19.
David Rombach Hans‐Achim Wagenknecht 《Angewandte Chemie (International ed. in English)》2020,59(1):300-303
SF6 was applied as pentafluorosulfanylation reagent to prepare ethers with a vicinal SF5 substituent through a one‐step method involving photoredox catalysis. This method shows a broad substrate scope with respect to applicable alcohols for the conversion of α‐methyl and α‐phenyl styrenes. The products bear a new structural motif with two functional groups installed in one step. The alkoxy group allows elimination and azidation as further transformations into valuable pentafluorosulfanylated compounds. These results confirm that non‐toxic SF6 is a useful SF5 transfer reagent if properly activated by photoredox catalysis, and toxic reagents are completely avoided. In combination with light as an energy source, a high level of sustainability is achieved. Through this method, the proposed potential of the SF5 substituent in medicinal chemistry, agrochemistry, and materials chemistry may be exploited in the future. 相似文献
20.
α‐Aminoxy‐Acid‐Auxiliary‐Enabled Intermolecular Radical γ‐C(sp3)−H Functionalization of Ketones
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Dr. Heng Jiang Prof. Dr. Armido Studer 《Angewandte Chemie (International ed. in English)》2018,57(6):1692-1696
A method for site‐specific intermolecular γ‐C(sp3)?H functionalization of ketones has been developed using an α‐aminoxy acid auxiliary applying photoredox catalysis. Regioselective activation of an inert C?H bond is achieved by 1,5‐hydrogen atom abstraction by an oxidatively generated iminyl radical. Tertiary and secondary C‐radicals thus formed at the γ‐position of the imine functionality undergo radical conjugate addition to various Michael acceptors to provide, after reduction and imine hydrolysis, the corresponding γ‐functionalized ketones. 相似文献