An opened route to 1,3-dimethylenecyclobutanes via sequential ruthenium-catalyzed [2+2] cycloaddition of allenyl boronate and palladium Suzuki coupling

The first direct access to rigid 1,3-dimethylenecyclobutane derivatives through an original head-to-head [2+2] cyclodimerization of allenyl boronate, which is catalyzed by a ruthenium/palladium catalyst, is reported. The studies aim to develop the functionalization of dimer through the rich boron chemistry and search the access to new polymeric materials bearing rigid cyclobutane units.