Organic chemistry help ASAP

[kika09]

Can you predict whether the endo or exo isomer is favored as the product for the Diels-Alder reaction of cyclopentadiene and maleic anhydride.

[kingchemist]

I would have predicted the exo product merely on energy terms but what do I know.

However, have a look at the link below - I think it includes your reaction

http://www.meta-synthesis.com/webbook/49_pericyclic/pericyclic.html

[kyle1990]

I would have predicted the exo product merely on energy terms but what do I know

Endo products result from Diels-Alder reactions. You can think about it like this: A Diels-Alder reaction occurs between a diene and a dienophile (diene-lover). So the diene and dienophile are naturally attracted to each other, and prefer to be on top of each other so that there is a greater degree of orbital overlap. Here's a picture I swiped out of Organic Chemistry 7th ED by John McMurry. Notice the diene and dieneophile are directly on top of each other