Synthesis of 2-thiabicyclo[3.2.0]hept-3-enes by reaction of acetylene with sodium sulfide

The previously unknown2-thiabicyclo[2.3.0]hept-3-ene and exo- and endo-6-methyl-2-thiabicyclo[3.2.0]hept-3-enes were synthesized in one step from acetylene and sodium sulfide in aqueous dimethyl disulfoxide.