Cyclopropyl Thioethers, New Inputs for Palladium Catalyzed Ring Opening of Cyclopropanes

We present herein a new palladium-catalyzed ring opening of cyclopropane-substituted thioethers. The study involves an intramolecular trapping of an intermediate aryl palladium to afford thiochromene derivatives. In contrast to the analogous cyclopropylamines which led to efficient ring opening using triphenylphosphine as ligand for palladium, good yields for cyclopropyl thioethers required the use of bulkier electron-donating phosphines, such as tri-tert-butylphosphine.