Practical and Green Protocol for the Synthesis of Substituted 4<i>H</i>-Chromenes Using Room Temperature Ionic Liquid Choline Chloride-Urea
作者:C. N. Revanna、T. R. Swaroop、G. M. Raghavendra、D. G. Bhadregowda、K. Mantelingu、K. S. Rangappa
DOI:10.1002/jhet.880
日期:2012.7
An efficient and convenient synthesis of substituted 4H‐chromenes is described usingroomtemperatureionicliquid (RTIL) cholinechloride–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