Dithiaindenes: Synthesis of 6-thia-7H-benzo [b] thiophene (1,6-dithiaindene) and 1,3-dimethyl-5-thia-4H-benzo [c] thiopene (1,3-dimethyl-2,5-dithiaindene) and attempted synthesis of 5-thia-4H-benzo [b] thiophene (1,5-dithiaindene)

Synthesis of the heteroaromatic systems 6-thia-7H-benzo b] thiophene (3) and 1,3-dimethyl-5-thia-4H-benzo c] thiopbene (5) have been achieved by reduction and dehydration of 1,6-dithiaindan-4-one (4) and 1,3-dimethyl-2,5-dithiaindan-7-one (8) respectively. A similar attempt to synthesise 5-thia-4H-benzo b] thiophene (4) by dehydration of 7-hydroxy-1,5-dithiaindane (16) resulted in the formation of 7,7′-bis (1,5-dithiaindanyl) ether.