Cycloalkenes
Monocyclic cycloalkenes are cyclopropene, cyclobutene, cyclopentene, cyclohexene, cycloheptene, cyclooctene, and so on. Bicyclic alkenes include norbornene and norbornadiene.
Two more examples are shown below, on the left methylenecyclohexane and on the right 1-methylcyclohexene:
An exocyclic group is always shown outside the ring structure, take for instance the exocyclic double bond of the former molecule. Isotoluenes are a prominent class of compounds with exocyclic double bonds.
The placement of double bonds in many alicyclic compounds can be predicted with Bredt's rule.
Read more about this topic: Alicyclic Compound