Efficient and General Synthesis of 2‐Substituted 2‐Methyl 2 H ‐Chromenes Under Lewis Acid‐Catalyzed Conditions

ABSTRACT An efficient and operationally straightforward approach has been developed for the synthesis of 2‐allyl‐2‐methyl‐2 H ‐chromenes under Lewis acid‐mediated conditions. The reaction proceeds via initial isomerization of the ( E )‐double bond in the enone substrate, followed by intramolecular cyclization and nucleophilic trapping. This cascade sequence offers several notable advantages, including mild reaction conditions, sequential isomerization with concurrent formation of both C–O and C–C bonds in a single step, the use of readily accessible reagents, broad substrate tolerance toward electron‐donating and halo substituents, and good to excellent isolated yields.