Reaction of phosphonium ylides with excess sulfur afforded the corresp
onding thiosulfines, which were trapped with maleic anhydride to give
the corresponding cycloadducts (1,2-dithiolanes) in good yields. Inter
mediary thiosulfines were also formed by sulfurization of thiobenzophe
nones with elemental sulfur to give the 1,2-dithiolanes in moderate yi
elds.