Process for the preparation of indoles

US5179211A · kind A · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

• Heinz U. Blank · Odenthal, DE
• Friedrich-Wilhelm Ullrich · Bensberg, DE
• Karlheinrich Meisel · Odenthal, DE
• Willi Streicher · Krefeld, DE
• Nikolaus Schulz · Cologne, DE
• Dieter Irmscher · Bensberg, DE
• Gunther Klag · Leverkusen, DE

Key dates

• Filing date: Nov 13, 1991
• Grant date: Jan 12, 1993
• Expiry date: Nov 13, 2011

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07D209/86
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

Indoles of the formula ##STR1## can be prepared by reaction of a phenylhydrazine of the formula ##STR2## which is unsubstituted in at least one ortho-position, with a ketone of the formula ##STR3## in an aqueous medium in the presence of an acid compound, less than 5 equivalents, based on 1 mol of phenylhydrazine, of an acid compound having a pK value of 1.3-4.5 being employed.