Alkylation of remote non-activated δ-carbon atoms: Addition of δ-carbon radicals, generated by 1,5-hydrogen transfer in alkoxy radical intermediates, to activated olefins

Abstract

A free radical introduction of a functionalized alkyl chain onto remote non-activated δ-carbon atoms (Michael type alkylation) has been achieved. Photolysis of suitable alkyl nitrites involves generation of δ-alkyl radicals and in the presence of radicophilic olefins, intermolecular addition takes place and affords δ-alkylated products in 36–80% yields. δ-Alkylation is also achieved in the reaction of alkyl benzenesulfenates with tributyltin hydride (TBTH), in the presence of activated olefins and introduction of a functionalized alkyl chain involves alkoxy and δ-carbon radicals. Products with functionalized alkyl chains were obtained in 36–86% yields. δ-Alkylation of alkyl benzenesulfenates also occurs in the reaction with hexabutylditin in the presence of activated olefins.