- Copper-Catalyzed Annulation of Oxime Acetates with α-Amino Acid Ester Derivatives: Synthesis of 3-Sulfonamido/Imino 4-Pyrrolin-2-ones
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A copper-catalyzed annulation of oxime acetates and α-amino acid ester derivatives for the easy preparation of 4-pyrrolin-2-ones bearing a 3-amino group has been developed. This process features the oxidation of amines with oxime esters as the internal oxidant to produce the active 1,3-dinucleophilic and 1,2-dielectrophilic species concurrently. The subsequent nucleophilic cyclization realizes the efficient construction of 4-pyrrolin-2-one derivatives.
- Miao, Chun-Bao,Zheng, An-Qi,Zhou, Li-Jin,Lyu, Xinyu,Yang, Hai-Tao
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supporting information
p. 3381 - 3385
(2020/04/21)
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- CuCl2-catalyzed N[sbnd]O bond cleavage of oxime esters: Approach to imidazoheterocycles and furo[3,2-c]chromenyl fused imidazoles
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An articulate approach to a diverse set of imidazoheterocycles in good to high yields via a copper-catalyzed aza-annulation of several oxime esters with a group of 2-amino-azaarenes was developed. The above cyclization reaction probably proceeds via a single electron transfer process which embodies a new technique for creating two new C[sbnd]N bonds for imidazole ring synthesis. Gratifyingly, the implementation of this chemistry could be further stretched to the synthesis of a novel class of fused imidazoles bearing a furo[3,2-c]chromene moiety via a sequential C[sbnd]N bond formation, followed by C(sp2)-H functionalization/5-endo-dig-oxacyclization (C[sbnd]C and C[sbnd]O bonds) of in situ produced fused imidazoles with cyclic enynones in the presence of copper(II) as a π-electrophilic Lewis acid catalyst.
- Gudimella, Santosh K.,Kaur, Amanpreet,Kumar, Ram,Samanta, Sampak
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- Copper(0)/PPh3-Mediated Bisheteroannulations of o-Nitroalkynes with Methylketoximes Accessing Pyrazo-Fused Pseudoindoxyls
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A copper(0)/PPh3-mediated cascade bisheteroannulation reaction of o-nitroalkynes with methylketoximes has been developed that provides viable access to a diverse range of pyrazo-fused pseudoindoxyl compounds. Synthetically useful functional groups including sensitive C-I bonds are compatible with this system. Mechanistic studies suggest a reaction cascade involving sequential PPh3-mediated deoxygenative cycloisomerization and copper-catalyzed [3 + 2] pyrazo-annulation.
- Meng, Huanxin,Xu, Zhenhua,Qu, Zhonghua,Huang, Huawen,Deng, Guo-Jun
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p. 6117 - 6121
(2020/08/12)
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- Dual Roles of tert-Butyl Nitrite in the Transition Metal- and External Oxidant-Free Trifluoromethyloximation of Alkenes
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By employing tert-butyl nitrite as both nitrogen source and oxidant, the trifluoromethyloximation of alkenes proceeds smoothly in a free-radical process. The developed difunctionalization reaction enables practical and efficient synthesis of a wide range of α-CF3 ketoximes in moderate yields with excellent regioselectivity. This method features the use of readily available and stable alkenes as substrates and inexpensive CF3SO2Na as a CF3 reagent, no involvement of transition metals or external oxidant, and room-temperature conditions. Moreover, a scale-up of the reaction, further transformation of the products into various valuable CF3-containing compounds, and removal of the trifluoromethyl group are readily achieved.
- Wu, Ya,Zhang, Yanli,Yang, Zhen,Jiao, Jingchao,Zheng, Xiaoke,Feng, Weisheng,Zhang, Mengsha,Cheng, Hao,Tang, Lin
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p. 3960 - 3966
(2019/08/21)
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- Rhodium(III)-Catalyzed Annulation of Acetophenone O-Acetyl Oximes with Allenoates through Arene C-H Activation: An Access to Isoquinolines
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Rhodium(III)-catalyzed annulation of acetophenone O-acetyl oximes with allenoates was achieved, affording isoquinolines in good to excellent yields with high regioselectivities under redox-neutral conditions. Allenoates acted as the C2 synthons in the annulation reaction. The present synthetic methodology features good functional group tolerance and avoids metal salts as the external oxidants. The proposed mechanism suggests that the reaction proceeds through arene C-H activation, allene insertion, and C-N coupling.
- Wang, Quannan,Lou, Jiang,Huang, Zilong,Yu, Zhengkun
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p. 2083 - 2092
(2019/02/19)
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- Direct access to bis-S-heterocycles via copper-catalyzed three component tandem cyclization using S8 as a sulfur source
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A novel strategy for constructing sulfur containing bis-S-heterocyclic compounds from oxime esters/vinyl azide, phenylacetylene/aldehydes and elemental sulfur (S8) has been developed. These transformations show good functional group tolerance. Various bis-S-heterocyclic products were efficiently synthesized from easily prepared or widely commercially available starting materials. In this protocol, S8 successfully served as a two-sulfur atom donor for thiophene and thiazole rings, respectively.
- Zhou, Peiqi,Huang, Yubing,Wu, Wanqing,Yu, Wentao,Li, Jianxiao,Zhu, Zhongzhi,Jiang, Huanfeng
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p. 3424 - 3432
(2019/04/01)
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- Catalyst free synthesis of mono- and disubstituted pyrimidines from O-acyl oximes
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Transition-metal or iodine catalyzed transformations of O-acyl oximes to various N-heterocycles are well established. Herein, we report a catalyst free, oxime carboxylate based, three-component condensation method to access mono- and disubstituted pyrimidines. A broad range of substituted pyrimidines were prepared in moderate to excellent yields. Control experiments reveal that in situ generated formamidine is the key intermediate.
- Upare, Atul,Sathyanarayana, Pochampalli,Kore, Ranjith,Sharma, Komal,Bathula, Surendar Reddy
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supporting information
p. 2430 - 2433
(2018/05/23)
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- Copper-catalyzed synthesis of thiazol-2-yl ethers from oxime acetates and xanthates under redox-neutral conditions
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A novel copper-catalyzed annulation of oxime acetates and xanthates for the synthesis of thiazol-2-yl ethers with remarkable regioselectivity has been developed. Various oxime acetates, whether derived from aryl ketones or alkyl ketones, or natural product cores are suitable for this conversion. Unique dihydrothiazoles were also obtained when both reaction sites were methine. Mechanistic studies indicated that imino copper(iii) intermediates were involved. In addition, this protocol proceeded under redox-neutral conditions and did not require additives or ligands.
- Zhu, Zhongzhi,Tang, Xiaodong,Cen, Jinghe,Li, Jianxiao,Wu, Wanqing,Jiang, Huanfeng
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p. 3767 - 3770
(2018/04/17)
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- Elemental tellurium mediated synthesis of 2-(trifluoromethyl)oxazoles using trifluoroacetic anhydride as reagent
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An elemental tellurium mediated synthesis of 2-(trifluoromethyl)oxazoles from the reaction of acetophenone oxime acetates with trifluoroacetic anhydride has been developed. This new tandem cyclization proceeds in good to excellent yields via a SET reduction followed by a 5-endo-trig pathway. Some of the title compounds showed fungicidal and insecticidal activities.
- Luo, Beibei,Weng, Zhiqiang
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p. 10750 - 10753
(2018/09/29)
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- Synthesis of enaminones via copper-catalyzed decarboxylative coupling reaction under redox-neutral conditions
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A novel copper-catalyzed C(sp3)-H oxidative functionalization of aromatic oxime acetates with α-oxocarboxylic acids was reported. This process involved N-O/C-C bond cleavages and C-C bond formations to furnish substituted enaminones under redox-neutral conditions. The oxime acetates served as both reactants and internal oxidants. Furthermore, this transformation also features good functional group tolerance and needs no ligands or additional bases.
- Zhu, Zhongzhi,Tang, Xiaodong,Li, Jianxiao,Li, Xianwei,Wu, Wanqing,Deng, Guohua,Jiang, Huanfeng
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p. 3228 - 3231
(2017/03/20)
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- Iron-Catalyzed Synthesis of 2H-Imidazoles from Oxime Acetates and Vinyl Azides under Redox-Neutral Conditions
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A novel and versatile method for the synthesis of 2H-imidazoles via iron-catalyzed [3 + 2] annulation from readily available oxime acetates with vinyl azides has been developed. This denitrogenative process involved N-O/N-N bond cleavages and two C-N bond formations to furnish 2,4-substituted 2H-imidazoles. This protocol was performed under mild reaction conditions and needed no additives or ligands. Furthermore, this is a green reaction involving oxime acetate as internal oxidant, acetic acid, and nitrogen as byproducts.
- Zhu, Zhongzhi,Tang, Xiaodong,Li, Jianxiao,Li, Xianwei,Wu, Wanqing,Deng, Guohua,Jiang, Huanfeng
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p. 1370 - 1373
(2017/03/23)
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- Synthesis of symmetrical pyridines by iron-catalyzed cyclization of ketoxime acetates and aldehydes
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A novel and facile iron-catalyzed cyclization of ketoxime acetates and aldehydes for the green synthesis of substituted pyridines has been developed. In the presence of a FeCl3 catalyst, this reaction exhibited a good functional group tolerance to produce 2,4,6-triarylsubstituted symmetrical pyridines in high yields in the absence of any additive. A gram-scale reaction sequence was performed to demonstrate the scaled-up applicability of this synthetic method.
- Yi, Yukun,Zhao, Mi-Na,Ren, Zhi-Hui,Wang, Yao-Yu,Guan, Zheng-Hui
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supporting information
p. 1023 - 1027
(2017/08/18)
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- Iron-Catalyzed Cyclization of Ketoxime Carboxylates and Tertiary Anilines for the Synthesis of Pyridines
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A novel and efficient iron-catalyzed cyclization of ketoxime carboxylates and N,N-dialkylanilines for the modular synthesis of diverse pyridines was developed. The reaction was initiated by Fe-catalyzed N-O bond cleavage of ketoxime carboxylates in the presence of tertiary anilines. The methylene carbon on N,N-dialkylanilines functioned as a source of one-carbon synthon in the reaction. The reaction used readily available starting materials, tolerated various functional groups, and afforded 2,4-disubstituted and 2,4,6-trisubstituted pyridines in good to high yields under mild conditions.
- Zhao, Mi-Na,Ren, Zhi-Hui,Yu, Le,Wang, Yao-Yu,Guan, Zheng-Hui
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supporting information
p. 1194 - 1197
(2016/03/15)
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- An efficient synthesis of polysubstituted pyrroles via copper-catalyzed coupling of oxime acetates with dialkyl acetylenedicarboxylates under aerobic conditions
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A Cu-catalyzed [3+2]-type condensation reaction of oxime acetates and dialkyl acetylenedicarboxylates that provides highly substituted pyrroles under aerobic conditions is described. The newly formed pyrroles are easily employed for further transformations to prepare pyrrolo[2,1-a]isoquinoline skeletons. The Royal Society of Chemistry 2013.
- Tang, Xiaodong,Huang, Liangbin,Qi, Chaorong,Wu, Wanqing,Jiang, Huanfeng
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supporting information
p. 9597 - 9599
(2013/10/08)
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- Copper-Catalyzed coupling of oxime acetates with aldehydes: A new strategy for synthesis of pyridines
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Copper-catalyzed coupling of oxime acetates with aldehydes offers a new strategy for the synthesis of highly substituted pyridines. This novel method tolerates a wide range of functionality and allows for rapid elaboration of the oxime acetates into a variety of substituted pyridines.
- Ren, Zhi-Hui,Zhang, Zhi-Yuan,Yang, Bing-Qin,Wang, Yao-Yu,Guan, Zheng-Hui
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supporting information; experimental part
p. 5394 - 5397
(2011/12/02)
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- Efficient microwave-assisted synthesis of oximes from acetohydroxamic acid and carbonyl compounds using BF3·OEt2 as the catalyst
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An efficient synthesis of oximes by reaction of carbonyls with acetohydroxamic acid using BF3·OEt2 as a catalyst is described.
- Sridhar, Madabhushi,Narsaiah, Chinthala,Raveendra, Jillella,Kondal Reddy, Godala,Kishore Kumar Reddy, Mallu,China Ramanaiah, Beeram
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scheme or table
p. 4701 - 4704
(2011/09/20)
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