Answer:
1-(cyclopent-1-en-1-yl)ethanone is the product.
Step-by-step explanation:
Intramolecular aldol condesation of hexanedial will produce a 5-membered cyclic enone.
At first, deprotonation takes place from carbon atom adjacent to any one of the two aldehyde groups.
Then the resulting carbanion gives intramolecular nucleophilic addition reaction at the carbonyl center of another aldehyde group.
Then protonation of resulting alkoxide ion takes place.
Lastly, dehydration takes place to produce cyclic enone.
Reaction mechanism and structure of product has been shown below.