Synthesis of thiiranes by rhodium-catalyzed sulfur addition reaction to reactive alkenes

A rhodium complex derived from RhH(PPh3)4, dppe, and 4-ethynyltoluene catalyzes the addition reaction of sulfur to norbornenes giving the corresponding thiiranes under acetone reflux conditions. The rhodium complex effectively transfers a sulfur atom to the double bond from sulfur, and exo-adducts are obtained. The reaction is also applicable to (E)-cyclooctene and cyclic allenes. The ring-opening reaction of the thiiranes with lithium aluminium hydride gives the corresponding thiols.