21. Despite mediocre yields, intermolecular cycloadditions of indole derivatives have been well documented. 22. Set the " 3, 4 "-bond of the indole horizontal. 23. Indole reacts with an enamide catalyzed by a chiral BINOL derived phosphoric acid:24. It is also rich in pharmacologically interesting indole alkaloids. 25. Typical simple aromatic compounds are benzene and indole . 26. Examples of non-basic nitrogen-containing aromatic rings are pyrrole and indole . 27. Thus melatonin contains an indole part, whereas agomelatine has a naphthalene bioisostere instead. 28. The Leimgruber-Batcho indole synthesis gives similar flexibility and regiospecificity to indole derivatives. 29. The Leimgruber-Batcho indole synthesis gives similar flexibility and regiospecificity to indole derivatives. 30. Indole itself was first obtained by Adolf von Baeyer in 1866 while decomposing Indigo.
