Cascade intramolecular Prins/Friedel–Crafts cyclization for the synthesis of 4-aryltetralin-2-ols and 5-aryltetrahydro-5<i>H</i>-benzo[7]annulen-7-ols

The treatment of 2-(2-vinylphenyl)acetaldehydes or 3-(2-vinylphenyl)propanals with BF 3 ·Et 2 O results in an intramolecular Prins reaction affording intermediary benzyl carbenium ions, which are then trapped by a variety electron-rich aromatics via Friedel–Crafts alkylation. This cascade Prins/Friedel–Crafts cyclization protocol paves expedient path to medicinally useful 4-aryltetralin-2-ol and 5-aryltetrahydro-5 H -benzo[7]annulen-7-ol derivatives.