37581-48-9Relevant academic research and scientific papers
Acid- or base-promoted photostimulated homolytic tert-butylation of pyridines and thiophenes
Kim,Jeon,Han,Park,Jun
, p. 2035 - 2039 (2007/10/03)
Regioselective photostimulated homolytic tert-butylations for heteroaromatics such as pyridines or thiophenes are investigated with tert-butylmercury(II) chloride in the presence of toluene-p-sulfonic acid (PTSA) or 1,4-diaza-bicyclo[2.2.2]octane (DABCO)
A Novel, Simple and Cheap Source of Alkyl Radicals from Alcohols, Useful for Heterocyclic Substitution
Coppa, Fausta,Fontana, Francesca,Lazzarini, Edoardo,Minisci, Francesco,Pianese, Giuseppe,Zhao, Lihua
, p. 1295 - 1298 (2007/10/02)
Alkyl radicals were easily produced from secondary or tertiary alcohols in a cheap and simple way by silver-catalyzed decarboxylation of oxalic acid monoesters by S2O8(2-).They were utilized for the alkylation of heteroaromatic bases in a two-phase system, with high yields and selectivity.
Homolytic alkylation of heteroaromatic bases : The problem of monoalkylation
Fontana,Minisci,Barbosa, M. C. Nogueira,Vismara
, p. 2525 - 2538 (2007/10/02)
The silver-catalyzed decarboxylation of carboxylic acids by persulphate leads to alkyl radicals, which have been utilized for the selective alkylation of heteroaromatic bases. The method is particularly efficient in a water-chlorobenzene two-phase system for two reasons : it considerably increases the selectivity in monoalkylation when more positions of high nucleophilic reactivity (i.e. α and γ) are available in the heterocyclic ring (i.e. quinoline , 4-cyano- and 4-ethylpyridine, pyrazine , quinoxaline etc.) and it determines a much higher efficiency for the radical sources when the silver salt catalysis is deactivated by complexation of the salt with the heterocyclic compound . The high selectivity in monoalkylation has been obtained by the combination of polar effects and the increased lipophilicity of the alkylated product, which makes its extraction from the aqueous solution by the organic solvent easier.
Nucleophilic Character of the Alkyl Radicals. 19. Absolute Rate Constants in the Homolytic Alkylation of Protonated Heteroaromatic Bases by n-Butyl and tert-Butyl Radicals
Citterio, Attilio,Minisci, Francesco,Franchi, Valeria
, p. 4752 - 4757 (2007/10/02)
The rate constants for the homolytic alkylation of protonated heteroaromatic bases (quinoline, pyridine, and 4-cyano-, 4-acetyl-, 4-methyl-, and 4-methoxypyridine) by n-butyl and tert-butyl radicals were measured at 57 deg C by competition of the aromatic addition with the alkyl radical oxidation by Cu2+ salts (for which the rates are known).With the more activated substrates (quinoline and 4-cyano- and 4-acetylpyridine) the tert-butyl radical is significantly more reactive then the n-butyl radical, clearly showing that polar effects are more important than steric and enthalpic effects in determining the reaction rates.The reversibility of the alkylation by the tert-butyl radical is discussed.
