- Convenient one-pot synthesis of 2,5-disubstituted oxazoles via a catalytic oxidative dehydrogenation of F3CSO3H·SiO 2-DDQ/CuCl2/LiCl
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A facile one-pot synthesis of 2,5-disubstituted oxazoles was developed via cyclization of aldoximes and phenylacetylene then dehydrogenation oxidation. 2,3-dichloro-5,6-dicyano-1,4-benzoquinone was studied for the selective oxidation of oxazolines using Cu2+/Li+ as catalyst and O2 as indirect oxidant. The reaction results showed that this catalyst system can effectively catalyze the oxidation of oxazolines to the corresponding oxazoles. Thus, a variety of polysubstituted oxazoles was easily synthesized in high yields by catalytic oxidation of 2,3-dichloro-5,6-dicyano-1, 4-benzoquinone/CuCl2/LiCl/O2.
- Yuan, Shizhen,Li, Zhen,Xu, Ling
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Read Online
- Divergent Conversion of N-Acyl-isoxazol-5(2 H)-ones to Oxazoles and 1,3-Oxazin-6-ones Using Photoredox Catalysis
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The fragmentation of N-acyl-isoxazol-5-ones using visible light photoredox catalysis has been disclosed. The catalyst-controlled divergent mechanisms, namely the oxidative and reductive quenching catalytic cycle, are utilized. Various oxazoles and 1,3-oxazin-6-ones are selectively obtained from the same isoxazol-5-one skeleton under mild conditions.
- Mei, Mingjing,Anand, Devireddy,Zhou, Lei
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supporting information
p. 3548 - 3553
(2019/05/24)
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- One-pot conversion of amino acids into 2,5-disubstituted oxazoles: No metals needed
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2,5-Disubstituted oxazoles with a variety of alkyl and aryl groups are efficiently formed from N-acylamino acids, by a one-pot radical decarboxylation- oxidation-enolization and iodine-promoted cyclization process. Remarkably, the reaction takes place under mild conditions, and no metal catalysis is needed. The process can be useful for the direct modification of small peptides.
- Romero-Estudillo, Ivan,Batchu, Venkateswara Rao,Boto, Alicia
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supporting information
p. 3742 - 3748
(2015/01/16)
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- Practical oxazole synthesis mediated by iodine from α-bromoketones and benzylamine derivatives
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The reagent system of I2/K2CO3 could efficiently promote the oxazole synthesis from α-bromoketones and benzylamine derivatives in DMF. This method was not only suitable for 2,5-diaryl oxazole synthesis but also for 2,4,5-trisubstituted oxazole and 5-alkyl/alkenyl oxazole synthesis. Furthermore, this method was successfully applied to a one-step synthesis of a natural product halfordinol in 62% yield.
- Gao, Wen-Chao,Wang, Ruo-Lin,Zhang, Chi
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p. 7123 - 7128
(2013/10/22)
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- Metal-free dual sp3 C-H functionalization: I2- promoted domino oxidative cyclization to construct 2,5-disubstituted oxazoles
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An I2-promoted sp3 C-H functionalization has been developed for the synthesis of 2,5-disubstituted oxazoles from easily available methyl ketones and benzylamines without any metal and peroxide catalyst. This domino oxidative cyclization process involves the cleavage of C-H bond and the formation of C-N, C-O bonds.
- Gao, Qing-He,Fei, Zhuan,Zhu, Yan-Ping,Lian, Mi,Jia, Feng-Cheng,Liu, Mei-Cai,She, Neng-Fang,Wu, An-Xin
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- Room temperature copper(II)-catalyzed oxidative cyclization of enamides to 2,5-disubstituted oxazoles via vinylic C-H functionalization
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A copper(II)-catalyzed oxidative cyclization of enamides to oxazoles via vinylic C-H bond functionalization at room temperature is described. Various 2,5-disubstituted oxazoles bearing aryl, vinyl, alkyl, and heteroaryl substituents could be synthesized in moderate to high yields. This reaction protocol is complementary to our previously reported iodine-mediated cyclization of enamides to afford 2,4,5-trisubstituted oxazoles.
- Cheung, Chi Wai,Buchwald, Stephen L.
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p. 7526 - 7537
(2012/10/30)
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- Synthesis of 2,5-disubstituted oxazoles and oxazolines catalyzed by ruthenium(II) porphyrin and simple copper salts
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A novel and moderate synthesis of 2,5-disubstituted oxazoles and oxazolines involving ruthenium(II) porphyrin-copper chloride catalyzed cyclization was developed. These reactions using readily available benzene carboxylic acids and phenylethenes or phenylacetylenes are performed under mild conditions. The reactions proceed in series, giving rise to the formation of an intermolecular C-N bond and an intramolecular C-O bond, which yield oxazole or oxazoline derivatives simultaneously.
- Zhong, Chuan Long,Tang, Bo Yang,Yin, Ping,Chen, Yue,He, Ling
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experimental part
p. 4271 - 4277
(2012/06/18)
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- Simple and efficient preparation of 2,5-disubstituted oxazoles via a metal-free-catalyzed cascade cyclization
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A practical and simple synthesis of 2,5-disubstituted oxazoles was developed via an iodine-catalyzed tandem oxidative cyclization. A wide range of common commercial aromatic aldehydes can be used as reaction substrates, which displayed excellent functional group compatibility in this reaction.
- Wan, Changfeng,Gao, Linfeng,Wang, Qiang,Zhang, Jintang,Wang, Zhiyong
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supporting information; experimental part
p. 3902 - 3905
(2010/11/04)
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- A New Versatile Synthesis of Oxazoles by Intramolecular Aza-Wittig Reaction
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A new synthesis of oxazoles by an intramolecular aza-Wittig reaction is described.Readily available α-azido ketones 2 were converted to (Z)-β-(acyloxy)vinyl azides 3 by selective enol acylation.These vinyl azides 3 reacted with triethyl phosphite to afford the corresponding oxazole derivatives 5 via the Staudinger reaction, followed by an intramolecular aza-Wittig reaction.In particular, this oxazole synthesis was useful for oxazoles having acid-labile substituents.
- Takeuchi, Hisato,Yanagida, Shun-ichi,Ozaki, Tooru,Hagiwara, Satoshi,Eguchi, Shoji
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p. 431 - 434
(2007/10/02)
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