Palladium-Catalyzed Tandem Reaction of Alkyne-Based Aryl Iodides and SalicylN-Tosylhydrazones to Construct the Spiro[benzofuran-3,2′-chromene] Skeleton

A convenient palladium-catalyzed tandem reaction of aryl iodides and salicyl N-tosylhydrazones has been achieved to afford a series of compounds containing the novel spiro[benzofuran-3,2′-chromene] scaffold in moderate to good yields. This efficient catalytic reaction, which tolerates various functional groups, combines alkyne-based 5-exo-dig cyclization, palladium(II) carbene migratory insertion and intramolecular cyclization, generating three new bonds in one reaction.