providing the most convenient synthesis of thiirene 1-oxides. Disulfur dichloride also reacted with acetylenes to give 5 in good yields with the elimination of one sulfur atom. Although the alkalinehydrolysis of 5 provided 10 exclusively, acid hydrolysis gave a mixture of α-oxothioketone 9 and thiirene 1-oxide 10 in modest yields. All thiirene 1-oxides 10a–c isomerized to produce α-oxothioketones 9 in