The reaction of octafluoro-2, 3-epoxybutane 1 with 2-aminothiophenol gave three kinds of novel fluorocontaining N, S-heterocyclic compounds depending on the solvent nature: 2, 3- bis (trifluoromethyl)-3, 4-dihydro-2H-1, 4-benzothiazin-2-ol 2, 2-trifluoromethyl-2-[1-(2- aminophenylthio)-2, 2, 2-trifluoroethyl]-1, 3-benzothiazolidine 6 and 5a, 11a-bis (trifluoromethyl)-5a, 6, 11a, 12-tetrahydro-5, 11-dithia-6, 12-diazanaphthacene 5. Use of ...