A simple and efficient method for the conversion of oxiranes to thiiranes using ammonium thiocyanate (NH 4 SCN) under solvent- and catalyst-free conditions is described. These conditions enable clean and fast conversion of oxiranes to the corresponding thiirane. ... A simple and efficient method for the conversion of oxiranes to thiiranes using ammonium thiocyanate (NH 4 SCN) under solvent- and catalyst-free conditions is described. These conditions enable clean ...