Selective homolytic alkylation of protonated quinoxaline has been achieved by using an alkyl derivative with N-chlorodialkylamine as radical source. The method shows great synthetic potential and can also be used for other heteroaromatic bases. A free-radical chain process involving amine radical cations is suggested to explain the clean reaction. Positional selectivity is strongly affected by the medium acidity, and a correlation between the π-electron density of mono- and di-protonated quinoxaline and the substitution orientation is found, in agreement with the nucleophilic character of the alkyl radicals.
Nucleophilic character of alkyl radicals. Part 15. Selective homolytic alkylation of quinoxaline by N-chloro-amines; influence of medium acidity
Caronna, T.;Citterio, A.;Minisci, F.
1977-01-01
Abstract
Selective homolytic alkylation of protonated quinoxaline has been achieved by using an alkyl derivative with N-chlorodialkylamine as radical source. The method shows great synthetic potential and can also be used for other heteroaromatic bases. A free-radical chain process involving amine radical cations is suggested to explain the clean reaction. Positional selectivity is strongly affected by the medium acidity, and a correlation between the π-electron density of mono- and di-protonated quinoxaline and the substitution orientation is found, in agreement with the nucleophilic character of the alkyl radicals.File in questo prodotto:
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