Benzopentathiepins were synthesized by new reaction of 1,3-benzodithiole-2-thiones and 1,2-benzenedithiols with elemental sulfur/liquid ammonia at ambient temperature in high yields.

Many cyclic polysulfides, i.e., benzopentathiepins (3a–d), 6H-1,2,3,4,5-benzopentathiocin, 5H-1,2,3,4-benzotetrathiepin, 3H-1,2-benzodithiole, 1,5-dihydro-2,3,4-benzotrithiepin, 1,4-dihydro-2,3-benzodithiin, naphtho[1,8-cd]-1,2-dithiole, 1,2,3-trithiane, 1,2-dithiane, 2,3,4,5-tetrathiabicyclo[4.4.0]decane, and 2,3,4,5,6-pentathiabicyclo[5.4.0]undecane, were synthesized in high yields by new reactions of their corresponding dithiols and related compounds, 1,3-benzodithiole-2-thiones (5) and 1,3-dithiolane-2-thione, with elemental sulfur in liquid ammonia at ambient temperature. In the synthesis of 3a–d from 1,2-benzenedithiol or 5, considerable increase in the product yield was observed upon adding 1,3-dinitrobenzene to the solvent used in work-up.

Die Benzothione (I) werden mit Schwefel in flüssiem Ammoniak unter Zusatz von 1,3‐Dinitrobenzol (II) zu den Pentathiepinen (III) umgesetzt.