Treatment of 2, 4, 6-trisubstituted 5, 6-dihydro-1, 3, 5-dithiazines with NCS or NBS afforded highly reactive thial S-sulfides, which underwent dimerization to give the corresponding 1, 2, 4, 5-tetrathianes. The products were also selectively converted into naturally-occurring cyclic polysulfides, 1, 2, 4-trithiolanes and 1, 2, 3, 5, 6-pentathiepanes, by treatment with Ph 3 P, KCN, or Na 2 S 4.
