Oxidative Coupling of Benzylamines with Indoles in Aqueous Medium to Realize Bis‐(Indolyl)Methanes Using a Water‐Soluble Cobalt Catalyst and Air as the Oxidant

• Published in: Chemistry, an Asian journal Vol. 14; no. 23; pp. 4154 - 4159
• Main Authors: Saini, Parul, Kumari, Pratishtha, Hazra, Susanta, Elias, Anil J.
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 02.12.2019
• Subjects: aerobic oxidation; Amines; Aqueous solutions; bis(indolyl)methane; Catalysts; Chemistry; cobalt catalyst; Cobalt compounds; Coupling; Indoles; oxidative coupling; Oxidizing agents; Reaction mechanisms; water soluble catalyst; water soluble catalyst; bis(indolyl)methane; oxidative coupling; aerobic oxidation; cobalt catalyst
• ISSN: 1861-4728; 1861-471X
• DOI: 10.1002/asia.201901313

Oxidative coupling of benzylamines with indoles to bis‐(indolyl)methanes (BIMs) was achieved using an inexpensive water‐soluble cobalt complex, Co(bpb). The catalyst was found to be quite effective when air was used as the oxidant and water as solvent under mild reaction conditions. Aromatic amines were successfully converted to the corresponding BIMs with yields up to 85 %. We have successfully carried out a 1 gram scale reaction, and few pharmaceutically relevant compounds were also synthesised by this method in good yields. Control experiments have also been carried out to understand the possible reaction mechanism. Oxidative coupling of benzylamines with indoles to bis‐(indolyl)methanes was achieved using an inexpensive water‐soluble cobalt complex, Co(bpb). This simple and green one‐pot synthesis produced good yields of bis‐(indolyl)methanes when air was used as the oxidant and water as the solvent under mild reaction conditions. Few pharmaceutically relevant compounds were also synthesised by this method in good yields.