A simple route to thiacrowns. Catalytic macrocyclization of thiirane by cationic manganese carbonyl complexes

Thiirane is transformed catalytically into the symmetric thiacrowns: 1,4,7,10-tetrathiacyclododecane, 12S4; 1,4,7,10,13-pentathiacyclopentadecane, 15S5; and 1,4,7,10,13,16-hexathiacyclooctadecane, 18S6, when treated with the manganese carbonyl monocations: [Mn(CO)4(L)(NCMe)]+, L=CO, PPh3, PMe2Ph and PEt3 at room temperature. 12S4 is the major thiacrown product. Considerable amounts of polymer are also formed. The phosphine-substituted catalysts are considerably more active and give better yields of the thiacrowns than the parent carbonyl, but they also give more polymer side product.