Divergent Synthesis of Heterocycles through Cascade Rearrangements of Dienyne-Amides and Dialkyl Bromomalonates

Abstract

Divergent synthesis provides efficient access to structurally diverse molecules from common precursors. Herein, we report a catalyst- and temperature-controlled cascade rearrangement of dienyne-amides with dialkyl bromomalonates, enabling selective access to three distinct N,O-heterocyclic scaffolds. Gold catalysis at room temperature promotes the cycloisomerization/cyclopropanation/1-aza-Cope rearrangement cascade to furnish furan-fused dihydroazepines, whereas heating triggers a formal [1,3]-rearrangement to afford spirocyclic heterocycles with high diastereoselectivity. Alternatively, silver catalysis redirects the reaction through oxotriene formation and vinyl cyclopropane rearrangement, providing a distinct class of spirocycles. This protocol features a broad substrate scope, high selectivity, and scalability, highlighting the utility of controlled skeletal rearrangements for divergent heterocycle synthesis.