A stereocontrolled access to ring-fused piperidines through a formal [2+2+2] process.

[reaction: see text] A formal [2+2+2] process has been devised that allows the stereocontrolled formation of ring-fused piperidines from allylsilanes possessing an oxime moiety. The cascade involves an intermolecular radical addition of an alpha-iodoacetate onto an allylsilane double bond, which is followed by a 5-exo-trig cyclization onto an oxime and is completed by the formation of the amide bond by nucleophilic attack of the amine onto the ester function.