Vinylcyclopropane annulation reactions with the use of radical intermediates have been in existence for over fifty years. Norman P. Neureiter, a chemist who worked for Humble Oil and Refining in Texas, first synthesized 2-chlorocyclopentadiene and 1,1-dichlorocyclopent-3-ene through a pyrolysis of 1,1-dichloro-2-vinylcyclopropane. A year later, in 1960, cyclopentene was made from vinylcyclopropane through thermal conversion by Vogel, Overberger, and Borchert (Hudlicky, et. Al). Throughout the time that this type of reaction has been used, the idea that there are radical intermediates that play a role in ring opening and ring formation is consistent. When paired with a catalyst such as a Lewis-Acid catalyst or an iron salt, a radical cation intermediate can help a vinylcyclopropane ring open and then form a five-membered ring with an alkene or a carbon-carbon double-bonded molecule of that nature (Dinnocenzo et. Al). Newer radical-intermediate reactions such as intramolecular metal - or thiyl radical - catalyzed cycloadditions of vinylcyclopropanes help combat the limitations of this reaction ("(-)-Pavidolide B"). Since vinylcyclopropane reactions require much experience and are run under extremely hot temperatures (200-600°C), it is very difficult to have a successful experiment under these conditions. The use of this newer type of radical-catalyzed reaction helps run the experiment in more stable conditions that require much less effort. One limitation, however, that cannot be fixed is that the vinylcyclopropane annulation reactions can only result in the formation of a five-membered ring, so no six-membered rings are able to be formed. This is also a utility of this reaction, as the ring opening and closing mechanism of the vinylcyclopropane reaction creates a stable five-carbon ring.