Download full text in PDF Opens in a new window. Article suggestions will be shown in a dialog on return to ScienceDirect. ... Please enable JavaScript to use all the features on this page. ... Tandem radical cyclisations of aminyl radicals generated from sulfenamide precursors have been used for the synthesis of pyrrolizidines and other polycyclic nitrogen heterocycles. The aminyl radicals are generated by reaction between sulfenamide precursors and Bu 3 SnH.