Ligand-Free and Solvent-Free Synthesis of 1,3-Disubstituted Naphthalenes through Stille Coupling

A variety of 1,3-disubstituted naphthalenes have been prepared by palladium-catalyzed annulation of (o-ethynylphenyl)acetyl chloride with design of a new synthetic strategy by Stille coupling using functionalized organostannanes. The method affords excellent yields of the substituted naphthalenes and accommodates a wide variety of functional groups under mild conditions. Mechanistic studies show intramolecular cyclization as a major step following C-C bond coupling.