Reactions of Electron-Rich Heterocycles with Derivatives of Carboxylic Ortho Acids, II: Acid Catalysed Reactions of 3-Substituted Indoles with Ethyl Orthoformate

Article abstract of DOI:10.1002/ardp.19843170612

The indoles 1a and 1b react with the diethoxycarbenium ion 2b, generated in an acidic medium, to yield the di- and triindolylmethanes 3, 4, 5 and 7.Compound 5a is oxidized to the cyanine 6a.Tryptamine (8a) undergoes formylation with 2b.When the nucleophilicity of the amino group in 8a is reduced, formation of triindolylmethane is favored, as shown in the reaction of 8b with 2b.