Access to Eight-Membered Ring Lactams from Five-Membered Ring 1,4-Diketones and Primary Amines

Unsaturated eight-membered ring lactams are obtained by expansion of the five-membered ring of a 1,4-diketone with primary amines. Azabicyclo[3.3.0]octanes are the proposed reaction intermediates; there has been a single azabicyclo[3.3.0]octane isolated. Reaction of the 1,4-diketone with phenylhydrazine yields a new cyclopenta[c]pyridazine.