Reagent for the Chemoselective Reduction of Carboxylic Acids to Aldehydes

We report the development of a multifunctional reagent for the direct conversion of carboxylic acids to aldehydes under mild conditions and with exquisite chemoselectivity. These reactions proceed in aqueous solvent at room temperature in 20 min, can be done open to air, require no metal catalysts, and employ near-stoichiometric amounts of both reducing agent and a mild base. No over-reduction, epimerization, or reduction of other reducible functional groups is observed. With this reagent, a broad scope of complex, drug-like aryl and alkyl carboxylic acids can be reduced directly to aldehydes.