ChemInform Abstract: Fluoride Ion Promoted Synthesis of Thiiranes

Thioxaphosphoranesulfenyl bromide 1 reacts with various aliphatic alkenes to give the corresponding adducts 3. These species can be reacted with tetrabutylammonium fluoride trihydrate (TBAF·3H2O) at room temperature to give the episulfides 4 in satisfactory yield. The great affinity of fluoride to phosphorus is claimed to be the driving force in the formation of the s-bromo thiolate ion 6 which gives ring closure.