Single-Flask Multicomponent Synthesis of Highly Substituted α‑Pyrones via a Sequential Enolate Arylation and Alkenylation Strategy

Trisubstituted
α-pyrones are obtained by a Pd-catalyzed three-component,
single-flask operation via an α-arylation, subsequent α-alkenylation,
alkene isomerization, and dienolate lactonization. A variety of coupling
components under mild conditions afforded isolated yields of up to
93% of the pyrones with complete control of regioselectivity. Metal
dependence was noted for three of the steps of the pathway. Utility
of the pyrone products was demonstrated by further transformations
providing convenient access to polyaromatic compounds, exhibiting
broad molecular diversity.