[Nemesisof99]

Are reverse Diels Alder reactions possible. If so, what are the reagents used to bring about the reverse reaction?

[stewie griffin]

Retro-Diels-Alder reactions are indeed possible. Usually the "reagent" of choice is heat... other than that I haven't seen anything else. There usually needs to be some sort of driving force however, such as formation of simple stable molecules like N₂ or acetone. In other words, you wouldn't propose to make a diene and an alkene from a retro-Diels-Alder.

[movies]

We do it all the time when we crack the dimer of cyclopentadiene!

In principle anything that promotes the forward Diels–Alder reaction should also promote the retro-D–A.