Cyclooctene

Cyclooctene is a cycloalkene with an eight-membered ring. It is notable because it is the smallest cycloalkene that can exist as either the cis- or trans-isomer with the cis-isomer more common. Its most stable cis stereoisomer can adopt various conformations, the most stable one being shaped like a ribbon; its most stable trans-conformer is shaped like the 8-carbon equivalent chair conformation of cyclohexane.