A comprehensive solvent-free approach for the esterification and amidation of carboxylic acids mediated by carbodiimides

In this work we report an unprecedented solvent-free approach for the condensation of carboxylic acids with alcohols and amines mediated by carbodiimides, the most widely adopted coupling agents. The solventless procedure enabled fast and high-yielding reactions at either room temperature or under conventional heating despite the use of a catalytic loading of DMAP as the additive (1–5 mol%), far below the amounts typically reported in literature; moreover, it was found broadly applicable in the synthesis of various ester/amide linkages even from non-trivial carbohydrate and amino acid precursors. In view of its versatility and multiple environmental, experimental and economic advantages, this new approach is expected to beneficially impact several scientific areas where esters and amides hold prominent roles.