- Tris(pentafluorophenyl)borane-Catalyzed Oxygen Insertion Reaction of α-Diazoesters (α-Diazoamides) with Dimethyl Sulfoxide
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A tris(pentafluorophenyl)borane-catalyzed oxidation reaction of α-diazoesters (α-diazo amides) with dimethyl sulfoxide has been developed. The reaction proceeds under metal free conditions to afford a series α-ketoesters and α-ketoamides. The synthetic utility of this protocol is demonstrated through synthetic transformations and scaled-up synthesis. (Figure presented.).
- Gao, Wen-Xia,Liu, Miao-Chang,Wu, Hua-Yue,Wu, Xiao-Yang,Zhou, Yun-Bing
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supporting information
(2022/01/19)
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- Diversity in Heterocycle Synthesis Using α-Iminocarboxylic Acids: Decarboxylation Dichotomy
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Despite the structural similarity with imines, α-iminocarboxylic acids have seldom been used in heterocycles synthesis. The reactions of ortho-substituted anilines and arylglyoxylic acids in DMSO at 40 °C gave various benzo-fused five- to six-membered N-heterocycles in good to excellent yields. The reaction proceeds via intramolecular Michael addition of α-iminocarboxylic acids, generated in situ, with an ortho-substituted nucleophile, yielding an isolable unprecedented tetrahedral carboxylic acids, which upon decarboxylation without any aid of additional reagents forms the N-heterocycles. DMSO is crucial in this reaction, perhaps because of improved solubility and the ease of decarboxylation of these tetrahedral carboxylic acids. However, a copper-catalyzed reaction of ortho-substituted anilines and 2-bromoarylglyoxylic acids gave a dibenzo-fused seven-membered N-heterocycle under a basic reaction condition. Unlike intramolecular cyclization with α-iminocarboxylic acids in the first case, α-iminocarboxylic acid undergoes a competitive decarboxylation under the copper-catalyzed conditions, which upon subsequent heteroarylation form the heterocycles. Taken together, the study described herein represents two different modes of decarboxylation observed with α-iminocarboxylic acids, leading to the synthesis of divergent heterocycles and pharmaceuticals, which remained unexplored previously.
- Hunjan, Mandeep Kaur,Laha, Joydev K.
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- Hypervalent Iodine(III)-Promoted Radical Oxidative C-H Annulation of Arylamines with α-Keto Acids
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A novel catalyst-free radical oxidative C-H annulation reaction of arylamines with α-keto acids toward benzoxazin-2-ones synthesis under mild conditions was developed. This hypervalent iodine(III)-promoted process eliminated the use of a metal catalyst or additive with high levels of functional group tolerance. Hypervalent iodine(III) was both an oxidant and a radical initiator for this reaction. The synthetic utility of this method was confirmed by the synthesis of the natural product cephalandole A.
- Long, Lipeng,Wang, Jieyan,Gu, Liuqing,Yang, Shiguang,Qiao, Liang,Luo, Guotian,Chen, Zhengwang
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p. 12084 - 12092
(2021/08/24)
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- α-Keto Acids as Triggers and Partners for the Synthesis of Quinazolinones, Quinoxalinones, Benzooxazinones, and Benzothiazoles in Water
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A general and efficient method for the synthesis of quinazolinones, quinoxalinones, benzooxazinones, and benzothiazoles from the reactions of α-keto acids with 2-aminobenzamides, benzene-1,2-diamines, 2-aminophenols, and 2-aminobenzenethiols, respectively, is described. The reactions were conducted under catalyst-free conditions, using water as the sole solvent with no additive required, and successfully applied to the synthesis of sildenafil. More importantly, these reactions can be conducted on a mass scale, and the products can be easily purified through filtration and washing with ethanol (or crystallized).
- Huang, Jian,Chen, Wei,Liang, Jiazhi,Yang, Qin,Fan, Yan,Chen, Mu-Wang,Peng, Yiyuan
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p. 14866 - 14882
(2021/10/25)
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- Preparation method of 3-aryl-2H-benzo [beta] [1, 4] benzoxazine-2-ketone compound
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The invention discloses a preparation method of a 3-aryl-2H-benzo [beta] [1, 4] benzoxazine-2-ketone compound, which comprises the following steps: carrying out magnetic stirring on a reaction substrate 2-aminophenol compound and a ketonic acid compound i
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Paragraph 0028-0036
(2020/05/14)
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- Mn(OAc)3*2H2O promoted addition of arylboronic acids to quinoxalin-2-ones
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A simple method has been developed for the synthesis of 3-aryl quinoxalin-2-one derivatives through an oxidative cross-coupling of arylboronic acids with quinoxalin-2-ones using a readily available oxidant Mn(III) acetate dihydrate. This method provides 3-aryl quinoxalin-2-one scaffolds with a broad substrate scope.
- Ramesh, Boora,Reddy, C. Ravikumar,Kumar, G. Ravi,Reddy, B.V. Subba
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supporting information
p. 628 - 631
(2018/01/17)
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- Niobium-promoted reaction of α-phenylglyoxylic acid with ortho-functionalized anilines: Synthesis of 2-arylbenzothiazoles and 3-aryl-2H-benzo[b][1,4]benzoxazin-2-ones
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A new and general method to prepare 2-arylbenzothiazoles and 3-aryl-2H-benzo[b][1,4]benzoxazin-2-ones by the reaction of α-arylglyoxylic acid with o-aminothiophenol and o-aminophenol respectively is described. The use of ammonium niobium oxalate (ANO) as the catalyst and PEG-400 as the solvent were crucial to afford the title compounds in good yields and selectivity. The reaction time can be reduced from hours to few minutes when ultrasound is used as an alternative energy source.
- Penteado, Filipe,Vieira, Marcelo M.,Perin, Gelson,Alves, Diego,Jacob, Raquel G.,Santi, Claudio,Lenard?o, Eder J.
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supporting information
p. 6675 - 6680
(2017/10/19)
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- Unexpected TFA-catalyzed tandem reaction of benzo[d]oxazoles with 2-oxo-2-arylacetic acids: Synthesis of 3-aryl-2H-benzo[b][1,4]oxazin-2-ones and cephalandole A
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A convenient and efficient method for the TFA-catalyzed synthesis of 3-aryl-2H-benzo[b][1,4]oxazin-2-ones via a tandem reaction of benzo[d]oxazoles with 2-oxo-2-arylacetic acids was reported for the first time. The efficiency of this transformation was demonstrated by compatibility with a wide range of functional groups. The synthetic utility of this method was confirmed by the synthesis of the natural product cephalandole A. Moreover, a plausible mechanism for the formation of 3-aryl-2H-benzo[b][1,4]oxazin-2-ones involving ring-opening and cyclization steps is proposed. The present synthetic route to 3-aryl-2H-benzo[b][1,4]oxazin-2-ones could be readily scaled up to gram quantity without difficulty.
- Yan, Shaoxi,Ye, Leping,Liu, Miaochang,Chen, Jiuxi,Ding, Jinchang,Gao, Wenxia,Huang, Xiaobo,Wu, Huayue
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p. 16705 - 16709
(2014/05/06)
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- Oxone-mediated oxidative carbon-heteroatom bond cleavage: Synthesis of benzoxazinones from benzoxazoles with α-oxocarboxylic acids
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A metal-free oxidative cleavage of benzoxazoles using Oxone as an oxidant has been developed. The in situ formed o-aminophenol has been proved to react successfully with α-oxocarboxylic acids affording the benzoxazinones in moderate to good yields. The Royal Society of Chemistry.
- Wang, Hua,Yang, Hua,Li, Yiping,Duan, Xin-Hua
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p. 8720 - 8722
(2014/03/21)
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- [Ir(P-OP)]-catalyzed asymmetric hydrogenation of diversely substituted C=N-containing heterocycles
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Iridium(I) complexes of enantiomerically pure phosphine-phosphite ligands ([Ir(Cl)(cod)(P - OP)]) efficiently catalyze the enantioselective hydrogenation of diverse C=N-containing heterocyclic compounds (benzoxazines, benzoxazinones, benzothiazinones, and quinoxalinones; 25 examples, up to 99% ee). A substrate-to-catalyst ratio as high as 2000:1 was reached.
- Nunez-Rico, Jose Luis,Vidal-Ferran, Anton
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supporting information
p. 2066 - 2069
(2013/06/04)
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- An efficient synthetic protocol for quinoxalinones, Benzoxazinones, and benzothiazinones from 2-oxo-2-aryl-acetyl bromide precursors
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α-Bromoketones undergo selenium dioxide oxidation to yield reactive 2-oxo-2-arylacetyl bromides that are trapped by aryl-1,2-diamines, 1,2-aminophenol or 1,2-aminothiophenol to give quinoxalinones, benzoxazinones, and benzothiazinones, respectively, in go
- Nagaraj, Muthupandi,Sathiyamoorthy, Sithuraj,Boominathan, Muthusamy,Muthusubramanian, Shanmugam,Bhuvanesh, Nattamai
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p. 1146 - 1151
(2013/10/21)
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- The first general, highly enantioselective lewis base organocatalyzed hydrosilylation of benzoxazinones and quinoxalinones
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The first general, highly enantioselective hydrosilylation of benzoxazinones and quinoxalinones has been developed. The chiral Lewis base organocatalysis that are readily accessible from (1S,2R)-ephedrine and (1R,2S)-ephedrine promoted the title reaction to afford various chiral dihydrobenzoxazinones and dihydroquinoxalinones with good yields as well as good enantioselectivities.
- Xue, Zhou-Yang,Jiang, Yan,Peng, Xiao-Zhi,Yuan, Wei-Cheng,Zhang, Xiao-Mei
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supporting information; experimental part
p. 2132 - 2136
(2010/11/04)
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- New synthesis of naphtho- and benzoxazoles: Decomposition of naphtho- and benzoxazinones with KOH
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A method that allows the synthesis of 4 different heterocyclic systems of fused aryl oxazoles, i.e., naphtho[1.2-d]. naphtho[2. 1-d]. naphtho[2.3-d]. and benzo[d]oxazoles in reasonable yield is described. This method consists of the decomposition of naphtho-and benzoxazinones with KOH.
- Saitz,Rodriguez,Marquez,Canete,Jullian,Zanocco
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p. 135 - 140
(2007/10/03)
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- Photochemical Reactions of 3-Phenyl-2H-1,4-benzoxazin-2-one and of Related Compounds in the Singlet and Triplet State
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Illumination of 3-phenyl-2H-1,4-benzoxazin-2-one (6) leads to the formation of 2-phenylbenzoxazole (2) and CO.From the excited singlet state of 6 other transients are formed than from its triplet state.In protic solvents in addition to 2, the Schiff base N-benzylidene-2-aminophenol (7) is formed under ring opening from the triplet state of 6.In kinetic experiments some transients emerging during the photolysis of 6 were observed and characterized.We show qualitatively that the sulfur-containing analogue to 6, phenylbenzothiazinone, reacts similar to 6 and that the corresponding phenylquinoxalinones have different properties.
- Tauer, Erich,Grellmann, Karl-Heinz
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p. 215 - 228
(2007/10/02)
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