Chemistry of 6H-pyrido[4,3-b]carbazoles. Part 9. An efficient route to 3-[1-(3-ethylpyridyl)]indoles and the synthesis of some new ellipticines

Abstract

A new and efficient route to 3-[1-(3-ethylpyridyl)]indoles has been developed which requires the Fischer indolisation of 3-(3-pyridyl)butanal with arylhydrazines. The ethylpyridylindoles can be converted into 6H-pyrido[4,3-b]carbazoles by a known procedure, leading to the first syntheses of 7-chloro-, 7-fluoro-, 7-methyl-, 8-methoxy-, and 8-hydroxy-ellipticines. The last-named compound is identical with a minor metabolite of ellipticine in Aspergillus alliaceus.