Cyclopentathiadiazines, Cyclohepta‐ and Cyclopentadithiazoles: New Materials and a Rich Heterocyclic Chemistry of Cyclic Enaminonitriles

3‐Amino‐1 H ‐indene‐2‐carbonitrile and 2‐amino‐3 H ‐indene‐1‐carbonitrile reacted with SCl 2 , i Bu 3 N and NCS to give benzocyclopenta[1,2,6]thiadiazines, and whilst 2‐aminocyclopent‐1‐enecarbonitrile gave, under the same conditions, a cyclopenta[1,2,6]thiadiazine, its reaction with mixtures of S 2 Cl 2 , SCl 2 and i Bu 3 N under different conditions gave, selectively, an isothiazolo[3,4‐ d ]cyclopenta[1,2,3]dithiazole and new cyclopenta[1,2,3]dithiazole derivatives. Similarly, 2‐aminocyclohept‐1‐enecarbonitrile reacted with SCl 2 , i Bu 3 N and NCS to give a formally antiaromatic cyclohepta[1,2,3]dithiazole. Some of the compounds obtained showed characteristics useful as new materials, for example, as liquid crystals and near‐infrared dyes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)