An efficient and straightforward L-proline catalyzed one-pot synthesis of a series of biologically relevant gem-(β-dicarbonyl)arylmethanes has been developed via a three-component reaction between indoles, aldehydes and C–H activated acids by grinding them together under solvent-free conditions at room temperature. Mild reaction conditions, high atom-economy, good yields, and eco-friendliness are some of the salient features of the present protocol.