Assembly of indole-2-carboxylic acid esters through a ligand-free copper-catalysed cascade process.

A straightforward synthesis of indole-2-carboxylic esters was developed through a ligand-free copper-catalysed condensation/coupling/deformylation cascade process from 2-halo aryl aldehydes or ketones with ethyl isocyanoacetate. The reactions proceeded well for most of the 2-iodo-, bromo-, and chloro-substrates under room temperature or mild conditions.