Regioselective and diastereoselective synthesis of highly substituted cyclopentanes

Highly substituted cyclopentane rings are present in a wide range of targets, and the efficient synthesis of such compounds constitutes a continuing challenge to organic synthesis. We present two complementary approaches to the regio- and diastereoselective synthesis of highly substituted cyclopentane structures. In both cases, a non-symmetrically disposed norbornene is employed as a common intermediate. One strategy relies on the Lewis acid-catalyzed ring opening of an anhydride, while the other employs production of a bicyclic lactone followed by its selective functionalization.