Pd-Catalyzed Formal [3+3] Annulation of Benzylic gem-Diacetates: Synthesis of Various (Hetero)Arene-Fused Benzo[ f]chromenes

Abstract

Unlike that of benzyl acetates, the chemistry of benzyl gem-diacetates is rarely explored under metal catalysis. Here, we describe the first palladium-catalyzed cascade annulative allylic alkylation of benzylic gem-diacetates to access complex analogues of (hetero)arene-fused benzo[f]chromenes, which find relevance in medicinal chemistry and materials science. This synthetic feat has been achieved through the formal [3+3] heterocyclization of easily accessible (hetero)aryl gem-diacetates and readily available 2-naphthols under neutral conditions. Detailed mechanistic studies and synthetic elaborations have also been performed.