5009-36-9Relevant academic research and scientific papers
Decarboxylative Bromination of Sterically Hindered Carboxylic Acids with Hypervalent Iodine(III) Reagents
Kanazawa, Junichiro,Koyamada, Kenta,Miyamoto, Kazunori,Uchiyama, Masanobu,Watanabe, Ayumi
supporting information, p. 1328 - 1334 (2020/08/14)
Sterically hindered three-dimensional (3D) alkyl halides are promising precursors for various reactions; however, they are difficult to synthesize via conventional reactions. We present an efficient and practical method for decarboxylative bromination of sterically hindered 3D aliphatic carboxylic acids using commercially available (diacetoxyiodo)benzene and potassium bromide, one of the most stable and cheapest bromine sources in nature. The present method features a metal-free/Br2-free system, mild reaction conditions, one-pot operation under air at room temperature, wide functional group compatibility, and gram-scale synthetic capability. This highly efficient reaction cleanly converts a broad range of carboxylic acids, the most inexpensive and readily available sources of highly strained/naturally occurring/drug-related scaffolds, into the corresponding alkyl bromides in good to high yields.
Catalytic Access to Alkyl Bromides, Chlorides and Iodides via Visible Light-Promoted Decarboxylative Halogenation
Candish, Lisa,Standley, Eric A.,Gómez-Suárez, Adrián,Mukherjee, Satobhisha,Glorius, Frank
supporting information, p. 9971 - 9974 (2016/07/19)
Herein is reported the catalytic, visible light-promoted, decarboxylative halogenation (bromination, chlorination, and iodination) of aliphatic carboxylic acids. This operationally-simple reaction tolerates a range of functional groups, proceeds at room temperature, and is redox neutral. By employing an iridium photocatalyst in concert with a halogen atom source, the use of stoichiometric metals such as silver, mercury, thallium, and lead can be circumvented. This reaction grants access to valuable synthetic building blocks from the large pool of cheap, readily available carboxylic acids.
Reductive Chlorination and Bromination of Ketones via Trityl Hydrazones
Reyes, Julius R.,Rawal, Viresh H.
, p. 3077 - 3080 (2016/03/12)
A method is presented for the direct transformation of a ketone to the corresponding reduced alkyl chloride or bromide. The process involves the reaction of a ketone trityl hydrazone with tBuOCl to give a diazene which readily collapses to the α-chlorocar
Simple, chemoselective hydrogenation with thermodynamic stereocontrol
Iwasaki, Kotaro,Wan, Kanny K.,Oppedisano, Alberto,Crossley, Steven W. M.,Shenvi, Ryan A.
supporting information, p. 1300 - 1303 (2014/02/14)
Few methods permit the hydrogenation of alkenes to a thermodynamically favored configuration when steric effects dictate the alternative trajectory of hydrogen delivery. Dissolving metal reduction achieves this control, but with extremely low functional group tolerance. Here we demonstrate a catalytic hydrogenation of alkenes that affords the thermodynamic alkane products with remarkably broad functional group compatibility and rapid reaction rates at standard temperature and pressure.
Diastereofacial selectivity in reactions of substituted cyclohexyl radicals. An experimental and theoretical study
Damm,Giese,Hartung,Hasskerl,Houk,Hüter,Zipse
, p. 4067 - 4079 (2007/10/02)
The diastereofacial selectivity in reactions of a series of alkyl-substituted cyclohexyl radicals has been investigated. In additions of cyclohexyl radicals to alkenes, it has been found that only substituents bound at the olefinic center being attacked by the radical influence the equatorial-axial selectivity. Substituents bound to the radical center or axial substituents β to the radical center lead to increased axial attack. Equatorial β-substituents or axial γ-substituents increase the amount of equatorial attack. The same trends are observed for halogen and hydrogen abstraction reactions; the amount of axial reaction product is usually somewhat higher than in the addition reactions. The stereoselectivities can be explained with steric and torsional effects very similar to those suggested for nucleophilic addition reactions to cyclohexanones. A MM2 force field has been parameterized to gain further insight into the stereochemistry of the reaction.
MECHANISMS OF FREE-RADICAL REACTIONS. XVII. STEREOSELECTIVITY OF THE FREE-RADICAL ABSTRACTION OF A HALOGEN ATOM FROM 4-tert-BUTYLCYCLOHEXYL HALIDES AND 2-NORBORNYL HALIDES
Dneprovskii, A. S.,Pertsikov, B. Z.
, p. 222 - 227 (2007/10/02)
The free-radical reduction of cis- and trans-4-tert-butylcyclohexyl halides and also of exo- and endo-2-chloronorbornanes by the trialkyl hydrides of group IVB elements was studied by the method of competing reactions.For the derivatives of cyclohexane the reactivity of the axial C-Hlg bond is 2-4 times higher than the reactivity of the equatorial bond.In the case of halogenonorbornanes the abstraction of the exo-halogen atom takes place at a higher rate.The stereoselectivity of the reaction increases in the transition from the bromides to the chlorides.The nature of the changes in the stereoselectivity with variation in the structure of the reagents and in the nature of the halogen atom agrees well with theories about the torsional interactions arising in the transition state.
Stereoelectronic Effects in Hydrogen-atom Transfer Reactions of Substituted Cyclohexyl Radicals
Beckwith, Athelstan L. J.,Easton, Christopher J.
, p. 661 - 668 (2007/10/02)
Thermolysis of the peroxyoxalates (1)-(7) and the diacyl peroxides (8)-(11) in cyclohexane at 100 deg C gives cycloalkenes and cycloalkanes by hydrogen-atom transfer reactions of the initially formed conformationally biased 4-t-butyl-, 4-t-butyl-cis,cis-2,6-dimethyl-, 4-t-butyl-cis,trans-2,6-dimethyl-, 4-t-butyl-cis-2-methyl-, 4-t-butyl-trans-2-methyl-, and 5-t-butyl-cis-2-methylcyclohexyl radicals (12)-(17).The composition of the product mixtures indicates that transfer of axial β-hydrogen atoms occurs more rapidly than does transfer of equatorial β-hydrogen atoms.These results support the hypothesis that homolytic fission of a C-H bond is favoured when it lies chlose to the plane of an adjacent semi-occupied orbital.
New Stereoselective Routes from Alcohols to Secondary Alkyl Bromides with Retention of Configuration
Sevrin, Mireille,Krief, Alain
, p. 656 - 657 (2007/10/02)
Secondary alcohols can be converted into the corresponding bromides with high stereoselective retention of configuration; this two-step process proceeds by a double inversion involving the intermediate selenides.
