Reductive cyclizations (tributylin hydride, AIBN) of several α-(penthylthio) glycine derivatives with a 30alkenyl substituent at nitrogen are reported. These reactions proceed via 2-aza-5- alken-1-yl radicals as intermediates which bear electron-withdrawing carbonyl substituents at the radical center and at nitrogen. Such radicals can be considered as relatively stable captodative radicals, but are reactive enough for olefin cyclization. The main products ...