jhd5000 - 12-4-2008 at 15:03
Does anybody have an explanation for the observation that the Diels-Alder cycloaddition of cyclopentadiene and pentene favors the endo product? As
far as I can tell, there is no possibility for significant secondary orbital stabilization in the transition state. Therefore, I would expect the
exo-product, which is more sterically favored.