is an alicyclic compound with a double bond. Monocyclic
cycloalkenes are
cyclopropene,
cyclobutene,
cyclopentene,
cyclohexene,
cycloheptene,
cyclooctene, and so on. Bicyclic alkenes include
norbornene and
norbornadiene. Two more examples are shown below,
methylenecyclohexane on the left and
1-methylcyclohexene on the right: 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. ==References==