An efficient synthesis of 1,2-dithiolanes and 1,2,4-trithiolanes by the reaction of phosphorus ylides with elemental sulfur

Reaction of diaryl methylenetriphenylphosphoranes wi th elemental sulfur followed by the addition of maleic anhydride afforded 1,2-dithiolanes in good yields. When the reaction was carried out in the presence of adamantane-2-thione, two types of 1,2,4-trithiolane were formed. Thiation of thiobenzophenones with elemental sulfur also afforded the corresponding 1,2-dithiolanes.