- A new method for mixed halogenation. N-chloroamine - phosphorus bromide system as a synthetic equivalent of the mixed halogen Cl+Br-
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A new method for the mixed halogenation of alkenes has been proposed based on the reaction of olefins with N-chloroamines in the presence of phosphorus bromide or oxybromide. The plausible reaction mechanism and the results of reactions with a number of model unsaturated compounds such as cyclohexene, 1-heptene, ethyl cinnamate, norbornene and those from the bicyclo[2.2.1]heptane series are discussed. In the reactions with reactive olefins this reagent acts as a synthetic equivalent of the unknown mixed halogen [Cl+Br-] with abnormal polarity of halogen atoms. The same reactions activated by PCl3 or POCl3 result in dichlorides in yields near to quantitative.
- Zyk, Nikolai V.,Beloglazkina, Elena K.,Tyurin, Vladimir S.,Zefirov, Nikolai S.
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- Continuous Flow Organocatalytic Chlorination of Alkenes
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A regioselective anti-dichlorination and allylic chlorination of isolated double bonds is described. Such chlorination reactions benefit from a combination of methyl phenyl sulfoxide and TMSCl. The method has been appropriately adjusted to fit the continuous flow technology requirements, aiming to a broader industrial implementation for the synthesis of pharmaceutically important compounds. Towards the same direction, a catalytic protocol has been developed, using sub-stoichiometric amount of sulfoxide and environmentally friendly H2O2 as the stoichiometric oxidant, with comparable efficacy.
- Iordanidis, Nicolaos S.,Zografos, Alexandros L.,Gallos, John K.,Koftis, Theocharis V.,Stathakis, Christos I.
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supporting information
p. 5058 - 5062
(2021/09/28)
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- Selective manganese-mediated transformations using the combination: KMnO4/Me3SiCl
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A novel manganese reagent, generated from KMnO4 and Me3SiCl, in the presence of a quaternary ammonium salt, is shown to smoothly dichlorinate alkenes, open epoxides and chemoselectively oxidise sulfides to sulfoxides.
- Marko, Istvan E.,Richardson, Paul R.,Bailey, Mark,Maguire, Anita R.,Coughlan, Niall
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p. 2339 - 2342
(2007/10/03)
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- Controlling the reactivity of permanganate anion. Novel, stereospecific, dichlorination of olefins
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Potassium permanganate reacts with oxalyl chloride to form a chlorine-containing manganese catalyst, of yet unknown structure, that stereospecifically trans-dichlorinates olefins.
- Marko,Richardson
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p. 1831 - 1834
(2007/10/02)
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- MECHANISMS OF FREE-RADICAL REACTIONS. XXIV. QUANTITATIVE DESCRIPTION OF THE POLAR EFFECTS OF SUBSTITUENTS ON THE KINETICS OF THE FREE-RADICAL CHLORINATION OF ALIPHATIC COMPOUNDS BY N-CHLOROPIPERIDINE
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The free-radical chlorination of 1-substituted alkanes with electron-withdrawing substituents by N-chloropiperidine in trifluoroacetic acid was studied by the method of competing reactions, and the relative rate constants were obtained for all positions of the substrates.The data on the position selectivity can be described satisfactorily by means of an electrostatic model of the polar effect of the substituent, calculated according to the Kirkwood-Westheimer equation.The obtained characteristics of the electrostatic effect can be successfully applied to calculation of the substrate selectivity and the intermolecular relative rate constants for all the positions, beginning with the third.The Taft equation is unsuitable for description of the effect of substituents on the reaction rate.
- Dneprovskii, A. S.,Mil'tsov, S. A.,Arbuzov, P. V.
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p. 1826 - 1835
(2007/10/02)
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- MECHANISMS OF FREE-RADICAL REACTIONS. XIX. SELECTIVITY OF THE FREE-RADICAL CHLORINATION OF 1-CHLOROALKANES BY N-CHLOROPIPERIDINE
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The free-radical chlorination of 1-chloroalkanes ClH2l+1Cl (l = 4-7) by N-chloropiperidine was studied by the method of competing reactions, and the relative constants for all the positions of the investigated substrates were determined.The chlorination is a highly electrophilic process, and the effect of the substituents is transmitted through at least six C-C bonds.The results can be described satisfactorily by means of an electrostatic model of the polar effect of the substituents according to the Kirkwood-Westheimer equation.At the same time an attempt to describe the obtained data by means of the Taft equation led to unsatisfactory results.
- Dneprovskii, A. S.,Mil'tsov, S. A.
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p. 265 - 269
(2007/10/02)
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- PARTICIPATION OF SULFONATE IONS IN THE ELECTROPHILIC ADDITION OF HALOGENS TO OLEFINS
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The reactions of ethylene, 1-heptene, cyclohexene, and styrene with chlorine and bromine in methylene chloride and chloroform in the presence of tetrabutylammonium p-toluenesulfonate and tetrabutylammonium methanesulfonate were investigated.In all cases the 2-halogenoalkyl esters of the sulfonic acids were obtained with comparable yields in addition to the 1,2-dihalides.The addition of chlorine and bromine to cyclohexene and also of bromine to 1-heptene in acetic acid in the presence of lithium p-nitrobenzenesulfonate leads to 2-halogenoalkyl esters of the sulfonicacids and acetic acid in addition to the 1,2-dihalides.These data indicate concurrent combination of the sulfonate anions at the concluding stage of AdE reactions.The mechanistic aspects and consequences of this effect are discussed.
- Zefirov, N. S.,Koz'min, A. S.,Dan'kov, Yu. V.,Zhdankin, V. V.,Kirin, V. N.
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p. 205 - 213
(2007/10/02)
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- Lithium Perchlorate as a Reagent for Synthesis of Covalently Bonded Organic Perchlorates via Electrophilic Additions of Halogens and Nitronium Tetrafluoroborate to Olefins
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The reaction of a series of olefins with chlorine and bromine in the presence of a large excess of lithium perchlorate in ether gave 1,2-halo perchlorates together with the corresponding 1,2-dihalides.Analogous reactions of NO2BF4 in methylene chloride or ethyl acetate with monoolefins gave 1,2-nitro perchlorates.Norbornadiene reacted with a NO2BF4/LiClO4 system to give two isomeric nitro perchlorates of nortricyclenic structure.Several synthetic and mechanistic aspects of this new reaction of electrophilic perchloration of olefins are discussed.
- Zefirov, N.S.,Koz'min, A.S.,Zhdankin, V.V.,Nikulin, A.V.,Zyk, N.V.
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p. 3679 - 3684
(2007/10/02)
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