Graphene Oxide as a Carbocatalyst for a Diels-Alder Reaction in an Aqueous Medium

The Diels-Alder (DA) reaction, a [4+2] cycloaddition reaction, is highly important in synthetic organic chemistry and is frequently used in the synthesis of natural products containing six-membered rings. Herein, we report an efficient protocol for the DA reaction between 9-hydroxymethylanthracene and N-substituted maleimides using two-dimensional graphene oxide (GO) as a heterogeneous carbocatalyst in an aqueous medium at room temperature. High yields, a wide substrate scope, low temperature, excellent functional group tolerance, atom economy, and water as a green solvent are noteworthy features of this protocol. The heterogeneous GO catalyst can be easily recovered and used multiple times without any significant loss in catalytic activity.