Cyclopropanes

Cyclopropanes are a family of organic compounds containing the cyclopropyl group. The parent is cyclopropane (C3H6).

Synthesis and reactions
Most cyclopropanes are not prepared from the parent cyclopropane, which is somewhat inert. Cyclopropyl groups are often prepared by cyclization of 1,3-difunctional alkanes. An example of the former, cyclopropyl cyanide is prepared by the reaction of 4-chlorobutyronitrile with a strong base. Phenylcyclopropane is produced analogously from the 1,3-dibromide.

A second major route to cyclopropanes entails addition of methylene (or its substituted derivatives) to an alkene, a process called cyclopropanation.

Substituted cyclopropanes undergo the reactions associated with the cyclopropyl ring or the substituents. Vinylcyclopropanes are a special case as they undergo vinylcyclopropane rearrangement.

Applications and occurrence
Cyclopropane derivatives are numerous. Many biomolecules and pharmaceutical drugs feature the cyclopropane ring. Famous example is aminocyclopropane carboxylic acid, which is the precursor to ethylene, a plant hormone.

The pyrethroids are the basis of many insecticides. Several cyclopropane fatty acids are known.


 * [[file:1-aminocyclopropanecarboxylic acid 200.svg|thumb|left|122 px|[[1-Aminocyclopropane-1-carboxylic acid]] plays an important role in the biosynthesis of the plant hormone ethylene. ]]