Furans bearing alkynyl substituents are highly useful in organic
synthesis. However, the methodologies to access these important furan
derivatives are rather limited. We herein report an efficient synthesis
of alkynylated furan derivatives based on Pd-catalyzed oxidative
cross-coupling reaction between allenyl ketones and terminal alkynes.
This novel synthesis of alkynylated furans with wide substrate scope is
operationally simple and tolerates various functional groups.
Mechanistically, the formation of the palladium carbene through
cycloisomerization and the subsequent alkynyl migratory insertion are
proposed as the key steps in the transformation. The reaction reported
in this manuscript further demonstrates the generality of the
carbene-based cross coupling.