Green access to flavonols by one-pot serial aldol-condensation/Algar-Flynn- Oyamada reaction catalyzed by new bio-based catalyst of alkaline-amylopectin

Abstract

Abstract Herein, alkaline-amylopectin (AAp) was prepared under chemo-mechanically dry conditions, characterized by base capacity, FT-IR, FESEM, TEM, and TGA analyses, and held as a new bio-organic base catalyst in the one-pot synthesis of flavonols. With a base capacity of 7.3 mmolHO-/g, AAp catalyzed initial aldol condensation and co-operated with the aqueous hydrogen peroxide in the further Algar-Flynn-Oyamada reaction to give high yield of flavonol anti-oxidants. So, either the first aldol-condensation or the latter oxidative cyclization/hydroxylation of the in situ formed 2´-hydroxy-chalcons proceeded successfully in a pot and flavonol products formed with no aurone side product. The structure of the supra-molecular base catalyst AAp was found to be well preserved after five times reusing. This protocol rewards the simple available reactants, no aurone side product, short reaction time, high yield, and catalyst reusability.