Rose bengal photocatalyzed Knoevenagel condensation of aldehydes and ketones in aqueous medium

Abstract

Knoevenagel condensation is widely used in organic synthetic chemistry and several reaction conditions have been demonstrated. These reactions in neutral medium are challenging. In this report, we present a sustainable and greener method for Knoevenagel condensation reaction between carbonyl compounds (both aldehydes and ketones) and active methylene compounds using rose bengal as a photosensitizer in an aqueous medium. This protocol works smoothly for aromatic aldehydes and ketones containing both electron-donating and electron-withdrawing substituents.