Mn-mediated sequential three-component domino Knoevenagel/cyclization/Michael addition/oxidative cyclization reaction towards annulated imidazo[1,2-a]pyridines

• Main Authors: Olga A. Storozhenko, Alexey A. Festa, Delphine R. Bella Ndoutoume, Alexander V. Aksenov, Alexey V. Varlamov, Leonid G. Voskressensky
• Format: Article
• Language: English
• Published: Beilstein-Institut 2018-12-01
• Series: Beilstein Journal of Organic Chemistry
• Subjects: 2-aminochromene; domino reaction; imidazo[1,2-a]pyridine; 2-iminochromene; Michael addition; multicomponent reaction; oxidation; pyridine amination
• Online Access: https://doi.org/10.3762/bjoc.14.287

The sequential three-component reaction between o-hydroxybenzaldehydes, N-(cyanomethyl)pyridinium salts and a nucleophile towards substituted chromenoimidazopyridines under oxidative conditions has been developed. The employment of Mn(OAc)3·2H2O or KMnO4 as stoichiometric oxidants allowed the use of a wide range of nucleophiles, such as nitromethane, (aza)indoles, pyrroles, phenols, pyrazole, indazole and diethyl malonate. The formation of the target compounds presumably proceeds through a domino Knoevenagel/cyclization/Michael addition/oxidative cyclization reaction sequence.