Use of oxy-Cope rearrangement with alkyne systems:

Oxy-Cope rearrangements also work nicely with alkyne systems as shown below.  The reaction mechanism is identical to what was seen previously.  The major difference with an alkyne system is that an extra pi-bond is present.  The extra pi-bond, however, is perpendicular to the other 2 double bonds, and is not an active part of the reaction as a result.  As the mechanism below shows, an a,b-unsaturated carbonyl compound forms as the final product.

In summary, pericyclic reactions such as the Diels-Alder and Cope rearrangements are popular and powerful methods used by organic chemists to form new compounds by using aromatic transition states in the promotion of a reaction sequence.  The examples above reveal that these reactions are flexible and allow for a wide variety of molecules to be formed under diverse reaction conditions.

Other rearrangement reactions:

Although the Diels-Alder reaction and Cope rearrangement are very popular, they are not the only rearrangement reactions used by Organic chemists.  There are too many type of rearrangements to cover in this chapter, but we will discuss two more popular sequences.