- Encapsulated reagents for nitrosation
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(Matrix presented) A novel class of stable, mild, and size-shape-selective nitrosating agents for secondary amides is introduced. These are based on reversible entrapment and release of reactive nitrosonium species by calix[4]arenes. The NO+ encapsulation controls the reaction selectivity.
- Zyryanov, Grigory V.,Rudkevich, Dmitry M.
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p. 1253 - 1256
(2007/10/03)
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- High Yield Acyl Anion Trapping Reactions: Direct Nucleophilic Acylation of Isocyanates and Isothiocyanates.
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The reactions of t-BuLi, sec-BuLi and n-BuLi with CO in the presence of isothiocyanates and isocyanates gives, after hydrolytic work-up, α-oxothioamides, RC(O)C(S)NHR', and α-oxoamides, RC(O)C(O)NHR', respectively, in good yield.Competition from the direct reaction of RLi with the substrate is encountered only in the case of reactions of the n-BuLi/CO system with isocyanates.
- Seyferth, Dietmar,Hui, Richard C.
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p. 5251 - 5254
(2007/10/02)
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- Direct Oxidation of Alkanoic Acids and their Amides to γ-Lactones by Peroxydisulphate-containing Systems
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The reaction of one-electron oxidation of alkanoic acids (I) and their amides (VI) on treatment with Na2S2O8-containing systems has been studied.As a result of the direct one-pot reaction acids (I) and amides (VI) are converted into γ and δ-lactones, the reaction being regioselective and leading mainly to γ-lactones in up to 35percent yield.The regioselectivity of the oxidative lactonisation depends greatly on the nature of alkyl substituents.The results obtained are presented in terms of a mechanism suggesting the generation of acyloxyl and amidyl radicals from (I) and (VI), respectively, followed by a rearrangement via a 1,5- or 1,6-H shift into the corresponding 3- and 4-carboxy- or -carboxamido-alkyl ra The latter undergo oxidative cyclisation to produce γ and δ lactones.The system Na2S2O8-NaCl-NaOH converts carboxamides (VI) into amines with loss of one carbon atom as a result of a Hoffmann type rearrangement.
- Nikishin, Gennady I.,Svitanko, Igor V.,Troyansky, Emmanuil I.
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p. 595 - 602
(2007/10/02)
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