Rice husk ash supported FeCl2·2H2O: A mild and highly efficient heterogeneous catalyst for the synthesis of polysubstituted quinolines by Friedländer heteroannulation

Rice husk ash was used as a new, green, and cheap adsorbent for FeCl3. Characterization of the obtained reagent showed that rice husk ash supported FeCl2·2H2O was formed. This reagent is efficient at catalyzing the synthesis of multisubstituted quinolines by the Friedländer heteroannulation of o-aminoaryl ketones with ketones or β-diketones under mild reaction conditions. This methodology allows for the synthesis of a broad range of substituted quinolines in high yields and with excellent regioselectivity in the absence of a solvent.

Graphical AbstractA new, green, and efficient catalyst FeCl2·2H2O-rice husk ash was prepared and used in the synthesis of polysubstituted quinoline derivatives by Friedländer heteroannulation.Figure optionsDownload full-size imageDownload as PowerPoint slide