Palladium/copper-cocatalyzed three-component tandem cyclization of o-alkenyl arylisocyanides and sulfur ylides with alcohols: direct synthesis of spiro 3,3′-cyclopropyl oxindoles

A novel palladium/copper-cocatalyzed three-component tandem cyclization of o-alkenyl arylisocyanides and sulfur ylides with alcohols has been developed for the first time. The reaction provides a simple and efficient method for the direct synthesis of spiro 3,3 '-cyclopropyl oxindoles from easily available acyclic starting materials in a single step. Further applications, including the synthesis of spiro 3,3 '-cyclopropyl oxindoles bearing a hydroxyl group and dihydro-1H-cyclopropa[c]quinolines, demonstrated the tremendous potential of the three-component tandem cyclization.