Synthesis of dihydropyrroles by the intramolecular addition of alkylideneaminyl radicals generated from O-2,4-dinitrophenyloximes of γ,δ-unsaturated ketones
Alkylideneaminyl radicals are generated from O-2,4-dinitrophenyloximes of γ,δ-unsaturated ketones by treatment with NaH and 3,4-methylenedioxyphenol. The resulting radical species successively add to the olefinic moiety intramolecularly to afford dihydropyrroles in the presence of a radical trapping agent. This method is applied for the stereoselective synthesis of xenovenine, a bicyclic 3,5-dialkylpyrrolizidine