Cascade Intramolecular Prins/Friedel–Crafts Cyclization for the Synthesis of 4-Aryl-tetralin-2-ols and 5-Aryl-tetrahydro-5H-benzo[7]annulen-7-ols

Abstract

Treatment of 2-(2-vinylphenyl)acetaldehydes or 3-(2-vinylphenyl)propanals with BF3×Et2O results in intramolecular Prins reaction affording intermediary benzyl carbenium ions, which are then trapped by a variety of electron-rich aromatics via Friedel–Crafts alkylation. This cascade Prins/Friedel–Crafts cyclization protocol paves an expedient path to medicinally useful 4-aryl-tetralin-2-ol and 5-aryl-tetrahydro-5H-benzo[7]annulen-7-ol derivatives.