Extensions of the Nazarov cyclization are generally also subsumed under the same name . For example , an α @-@ β , γ @-@ δ unsaturated ketone can undergo a similar cationic conrotatory cyclization that is typically referred to as an iso @-@ Nazarov cyclization reaction . Other such extensions have been given similar names , including homo @-@ Nazarov cyclizations and vinylogous Nazarov cyclizations .