Abstract A series of 2-and 3-indolylthio benzoic, phenylacetic and nicotinic acids or esters were cyclized under dehydrative conditions affording several tetracyclic indole-containing ketones, several of which constitute the first reported examples of novel ring systems, such as the [1] benzothiepino [2, 3-b] and [3, 2-b] indole and the pyrido [3′ 2′: 5, 6] and [3′ 4′: 5, 6] thiopyrano [2, 3-b] and [3, 2-b] indole as well as the [3′ 2′: 5, 6] and [3′ 4′: 5 ...
