Three-component Pd/Cu-catalyzed cascade reactions of cyclic iodoniums, alkynes, and boronic acids: an approach to methylidenefluorenes.

Linear diaryliodonium salts are widely used as arylating reagents for C-C and C-X bond formation. Meanwhile, synthetic applications of cyclic iodoniums are relatively rare although they offer the opportunity to set up reaction cascades. We demonstrate an atom and step economical three-component reaction involving cyclic diphenyleneiodoniums, alkynes, and boronic acids, resulting in the construction of methylidenefluorenes in a single operation. Our route enables facile access to both symmetrical and unsymmetrical methylidenefluorene derivatives, compounds that have attracted interest due to their optical properties.