Synthesis of quaternary stereogenic centres via stereoselective intermolecular Friedel-Crafts reactions.

Highly stereoselective Friedel-Crafts reactions have been performed using a chiral anthracene template to control the selectivity of the reaction. In the case of additions to fully substituted N-acyliminium ions, competitive elimination and condensation reactions were observed. Retro-Diels-Alder reaction of one of the reaction products led to a precursor that could be used for the construction of pyroglutamic acids bearing quaternary stereogenic centres.