- Visible Light-Induced [3+2] Cyclization Reactions of Hydrazones with Hypervalent Iodine Diazo Reagents for the Synthesis of 1-Amino-1,2,3-Triazoles
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In this study, visible-light-induced [3+2] cyclization reactions of hydrazones with hypervalent iodine diazo reagents as diazomethyl radical precursors are reported. Mild reaction conditions, a broad substrate scope, and excellent functional group compatibility were observed. Furthermore, the synthetic utility was demonstrated by gram-scale synthesis and elaboration to several value-added products. This protocol broadens the scope of diazo chemistry, and is applicable to the late-stage functionalization of natural products. (Figure presented.).
- Dong, Jun-Ying,Wang, He,Mao, Shukuan,Wang, Xin,Zhou, Ming-Dong,Li, Lei
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supporting information
p. 2133 - 2139
(2021/03/03)
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- Dioxygen-Triggered Oxo-Sulfonylation of Hydrazones
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A simple and highly efficient method for the oxo-sulfonylation of aldehyde-derived hydrazones has been developed using sulfinic acid as a source of sulfonyl group and oxygen as a green oxidant under metal-free conditions at room temperature. The present C
- Ghosh, Asim Kumar,Mondal, Susmita,Hajra, Alakananda
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supporting information
p. 2771 - 2775
(2020/03/30)
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- Visible-light-enabled C(sp2)-H difluoroalkylation of aldehyde-derived hydrazones under metal-free conditions
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A Eosin Y-catalyzed C(sp2)-H difluoromethylation of aldehyde-derived hydrazones between difluoroalkyl bromides and aldehyde-derived hydrazones is reported. This reaction has a wide range of substrates and occurs under metal-free condition. A me
- Liu, Wen-Qiang,Chen, Wei-Hao,Li, Xiao-Xuan,Tang, Wei-Ke,Tao, Ting-Ting,Feng, Yi-Si
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p. 570 - 581
(2019/08/01)
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- Transition-Metal-Free Trifluoromethylation of Aldehyde Derivatives with Sodium Trifluoromethanesulfinate
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A metal-free and cost-effective synthetic protocol for the trifluoromethylation of N,N-disubstituted hydrazones with Langlois's reagent (CF3SO2Na) to afford the corresponding functionalized trifluoromethyl ketone hydrazones has been established. It is proposed that a radical/SET mechanism proceeding via a trifluoroalkyl radical may be involved in the reaction. Applications of the methodology in industry will be found and the development of new methods for trifluoromethylation with Langlois's reagent will be continued in our laboratory.
- Tan, Zheng,Zhang, Shiwei,Zhang, Yan,Li, Yunpeng,Ni, Minjie,Feng, Bainian
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p. 9384 - 9399
(2017/09/23)
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- Continuous Flow α-Arylation of N,N-Dialkylhydrazones under Visible-Light Photoredox Catalysis
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The first direct α-arylation of aldehyde-derived N,N-dialkylhydrazones with electron deficient aryl and heteroaryl cyanides under visible-light photoredox catalysis has been developed. Structurally complex α,α′-diaryl-N,N-cycloalkylhydrazones were obtaine
- Vega, Juan A.,Alonso, José Manuel,Méndez, Gabriela,Ciordia, Myriam,Delgado, Francisca,Trabanco, Andrés A.
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supporting information
p. 938 - 941
(2017/02/26)
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- Gold-Catalyzed Highly Selective Photoredox C(sp2)-H Difluoroalkylation and Perfluoroalkylation of Hydrazones
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The first gold-catalyzed photoredox C(sp2)-H difluoroalkylation and perfluoroalkylation of hydrazones with readily available RF-Br reagents is reported. The resulting gem-difluoromethylated and perfluoroalkylated hydrazones are highl
- Xie, Jin,Zhang, Tuo,Chen, Fei,Mehrkens, Nina,Rominger, Frank,Rudolph, Matthias,Hashmi, A. Stephen K.
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supporting information
p. 2934 - 2938
(2016/02/27)
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- Synthesis of bicyclic N-methylpyrazoline and pyrazole derivatives from α,β-unsaturated ketones and N,N-dimethylhydrazine: An illustration of reductive cyclization
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The reaction of N,N-dimethylhydrazine with α,β-unsaturated keto precursors such as 2-benzylidenecyclohexanone, 2,6-bis(benzylidene) cyclohexanone, and 3,5-bis(benzylidene)-1-methyl-4-piperidone hydrochloride provided bicyclic N-methylpyrazoles instead of hydrazones or any Michael addition products. The crystal structure of a representative pyrazole is reported. The proposed mechanism for the formation of the bicyclic N-methylpyrazole 1 is outlined.
- Panda,Das,Quail,Dimmock
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p. 219 - 223
(2014/02/14)
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- Synthesis of o -(dimethylamino)aryl ketones, acridones, acridinium salts, and 1 H -indazoles by the reaction of hydrazones and arynes
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A novel, efficient route to biologically and pharmaceutically important o-(dimethylamino)aryl ketones, acridones, acridinium salts, and 1H-indazoles has been developed starting from readily available hydrazones of aldehydes and o-(trimethylsilyl)aryl triflates. The reaction proceeds through arynes under mild conditions, tolerates a wide range of functional groups, and provides the final products in good to excellent yields.
- Dubrovskiy, Anton V.,Larock, Richard C.
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p. 11232 - 11256
(2013/02/23)
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- Reaction of the lithio-derivative of methoxyallene with hydrazones. Part 1: Synthesis and transformation of α-allenyl hydrazines
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The lithio-derivative of methoxyallene reacts with aldehyde hydrazones leading to expected α-allenyl hydrazines when ether is the solvent of the reaction. The yields are good as well as the diastereoselectivity observed in the case of SAMP-hydrazones. These hydrazines are cleanly transformed to N-dialkylamino-3-methoxy-3-pyrrolines when they are reacted with n-BuLi in THF. These compounds are sometimes accompanied by the isomeric 4-methyl azetidines. The N-dialkylamino-3-methoxy-3-pyrrolines are transformed to 3-methoxy-3-pyrrolines by hydrogenolysis of the nitrogen-nitrogen bond, to 3-alkoxy-pyrroles by treatment with a peracid and to 3-amino-pyrroles by acidic migration of the dialkylamino group. In the case of SAMP-hydrazines, the obtained 3-methoxy-3-pyrrolines have a high enantiomeric purity. Lastly, attempts to prepare α-hydrazino-esters (and subsequently α-amino-esters) by ozonolysis of the allenyl moiety failed due to the formation of a methyl glyoxylate.
- Breuil-Desvergnes, Valérie,Goré, Jacques
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p. 1939 - 1950
(2007/10/03)
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- Aza-enamines, VIII. - Electrophilic Substitution reactions at the Azomethine C-Atom of Aldehyde Dialkylhydrazones: Vilsmeier Formylation and Consecutive Reactions
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The reaction of hydrazones 1 with the Vilsmeier reagent yields 3-phenyl-1,4,5-triaza-1,3-pentadienium salts according to their aza-enamine character.Hydrolysis of 2 gives 1-phenylglyoxal 1-dialkylhydrazones 3, which rearrange in acidic media to 1-phenylglyoxal 2-dialkylhydrazones 4.Compound 3h forms the dihydropyrroloimidazole 5 in boiling ethanol.Pyrrolotriazinium salt 6 is obtained by the reaction of 1b with the isolated Vilsmeier reagent from dimethylformamide/oxalyl chloride.
- Brehme, Rainer
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p. 2039 - 2046
(2007/10/02)
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