High Facial Diastereoselectivity in Intra- and Intermolecular Reactions of Chiral Benzylic Cations

Chiral carbenium ions can be attacked by arene nucleophiles with high facial diastereoselectivity (dr ≥ 94/6). Benzylic cations, such as 2, were generated under acidic conditions and reacted with arenes in intra- and intermolecular Friedel−Crafts alkylation reaction. The depicted reaction 1 → 3 represents one example for the unprecedented, highly diastereoselective intermolecular Friedel−Crafts alkylation reactions which were observed in this study.