Deoligomerization: a new route to lactams from unsaturated amides via radical oligomerization.

[reaction: see text] Triethylborane-initiated atom transfer radical oligomerization of N-allyl or N-(3-butenyl)iodoacetamides followed by treatment with hydrochloric acid and subsequent neutralization with K(2)CO(3) led to the formation of the corresponding 5-hydroxyl-substituted delta-lactams or caprolactams, respectively. This oligomerization-deoligomerization sequence serves as an alternative to the corresponding intramolecular cyclization reactions.