Synthesis of substituted piperidines, decahydroquinolines and octahydroindolizines by radical rearrangement reactions of 2-alkylideneaziridines

Rearrangement of a variety of 3-(2-methyleneaziridin-1-yl)propyl radicals, generated using Bu3SnH/AIBN by homolytic cleavage of phenylselenide substituted 2-methyleneaziridines, produces 3-methylenepiperidines in yields ranging from 58 to 68%. By combining this radical rearrangement with an additional 5-exo-trig cyclisation, this method provides an octahydroindolizine with moderate levels of diastereocontrol (d.r.=4:1). This rearrangement works with related 2-isopropylideneaziridines, but cannot be successfully extended to 4-(2-methyleneaziridin-1-yl)butyl radicals.