Synthesis of the Tetracyclic Core (ABCE Rings) of Daphenylline

摘要

A concise synthesis of the tetracyclic core (ABCE rings) of daphenylline has been accomplished involving anbenzobicyclo[3.3.1] lactam as the key intermediate. This bridged bicyclic intermediate was efficiently constructed via a Brønstednacid promoted intramolecular Friedel−Crafts type Michael addition of a δ-benzyl α,β-unsaturated δ-lactam.