The chemistry of indoles. CVII. A novel synthesis of 3,4,5,6-tetrahydro-7-hydroxy-1H-azepino[5,4,3-cd]indoles and a new finding on Pictet-Spengler reaction.

Serotonins were found to produce 3,4,5,6-tetrahydro-7-hydroxy-1H-azepino[5,4,3-cd]indoles by simple heating with amines under an oxygen atmosphere. Serotonins also reacted with various aldehydes to provide 3,4,5,6-tetrahydro-7-hydroxy-1H-azepino[5,4,3-cd]indoles rather than beta-carbolines under basic conditions. In these novel reactions, the presence of the 5-hydroxy group on the indole nucleus was suggested to be essential. Possible mechanisms are discussed.