- Visible-Light-Driven Oxidative Mono- and Dibromination of Benzylic sp 3 C-H Bonds with Potassium Bromide/Oxone at Room Temperature
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Benzylic sp 3 C-H bonds have been successfully brominated with potassium bromide by using Oxone as an oxidant in water/dichloromethane under visible light at room temperature. Toluene, ethylbenzene and other alkylbenzenes bearing an electron-withdrawing group, such as Br, Cl, COMe, CO 2 Et, CO 2 H, CN or NO 2, provide the corresponding benzylic monobromides in good to excellent yields in this reaction. Dibromides can also be produced in the presence of excess potassium bromide in a prolonged reaction time. Control of the illuminance of visible light (~500 lux) is crucial to achieving both high yield and high selectivity in these brominations. Mono- and difluorides can be conveniently prepared through nucleophilic substitutions of the benzylic bromides with potassium fluoride.
- Zhao, Mengdi,Li, Meiqi,Lu, Wenjun
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supporting information
p. 4933 - 4939
(2018/12/14)
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- SPIROINDANE OPIATE ANALOGS
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The present invention provides biologically active compounds of the formulas (I) and (II): (* CHEMICAL STRUCTURE *) (I) (* CHEMICAL STRUCTURE *) (II) wherein R3 is H or a hydroxyl protecting group, R2 is OH, H or a protected hydroxyl group, R1 is alkyl, c
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- Photothermal Side-Chain Bromination of Methyl-, Dimethyl-, and Trimethylbenzenes with N-Bromosuccinimide
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Tri- and dibromination of methyl-, dimethyl-, and trimethylbenzenes with N-bromosuccinimide were accomplished by photothermal reaction with a tungsten lamp in carbon tetrachloride or benzene. (Dibromomethyl)arenes and (tribromomethyl) derivatives were produced depending upon a solvent used and a substituent on the benzene ring.In the bromination of methylbenzenes without a substituent on the ortho-position, (tribromomethyl)benzenes were formed.On the other hand, ortho-substituted methylbenzenes gave (dibromomethyl)benzenes. α,β-Dibromo-1,2-diarylstilbenes were formed via the debrominative carbon-carbon coupling reaction of ...
- Mataka, Shuntaro,Liu, Guo-Bin,Sawada, Tsuyoshi,Kurisu, Masayoshi,Tashiro, Masashi
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p. 1113 - 1119
(2007/10/02)
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- Dihalomethylation of Nitroarenes via Vicarious Nucleophilic Substitution of Hydrogen with Trihalomethyl Carbanions
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Trichloro- and tribromomethyl carbanions generated by deprotonation of haloforms with potassium tert-butoxide in a THF-DMF mixture at ca. -70 deg C react with a variety of carbocyclic and heterocyclic nitroarenes according to the vicarious nucleophilic substitution scheme.The reaction provides an efficient and convenient way for the direct introduction of dihalomethyl substituents ortho and para to the nitro group, which in turn can be hydrolyzed to produce nitroaryl aldehydes.
- Makosza, M.,Owczarczyk, Z.
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p. 5094 - 5100
(2007/10/02)
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- Benzylic Bromination-Acetoxylation of Toluenes by Bromide Ion Catalyzed Thermal Decomposition of Peroxydisulfate in Acetic Acid in the Presence of Acetate Ions
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Side-chain bromination and acetoxylation of alkylaromatics by halide ion induced decomposition of potassium peroxydisulfate in acetic acid have been studied by product analysis techniques.Catalytic amounts of lithium bromide in the presence of sodium acetate were found effective in promoting benzylic bromination, followed by conversion to the corresponding benzyl acetates by reaction with acetate.The reaction is interpreted to take place by the redox and free-radical chain mechanism involving bromine atoms (ρ = -1.38 vs. ? + for substituted toluenes).In competiti ve experiments, benzyl and 4-nitrobenzyl acetates were found lees reactive than the corresponding toluenes in acetic acid with the couple S2O82-/Br- but more reactive in carbon tetrachloride with N-bromosuccinimide.
- Citterio, Attilio,Santi, Roberto,Pagani, Anselmo
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p. 4925 - 4927
(2007/10/02)
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