Cyclization of 2- and 3-indolylthiobenzoic, phenylacetic and nicotinic acids and esters to novel indole-containing tetracyclic ring systems

Article abstract of DOI:10.1002/jhet.5570360312

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':5,6][1,3]thiazino[3,2- a]indole ring systems.