Practical and Green Protocol for the Synthesis of Substituted 4<i>H</i>‐Chromenes Using Room Temperature Ionic Liquid Choline Chloride–Urea

Abstract

An efficient and convenient synthesis of substituted 4 H ‐chromenes is described using room temperature ionic liquid (RTIL) choline chloride–urea in one pot under solvent free conditions. Three‐component Knoevenagel condensation of an aromatic aldehyde, with an active methylene compound, and a cyclohexane dione is reported. This new approach has advantage of excellent yields (82–96%), clean reaction, and short reaction time (15–30 min) at room temperature.