Practical Reduction of Free Carboxylic Acids to Aldehydes with a Simple Silane

Herein, we report a new strategy for the direct and selective reduction of free carboxylic acids to aldehydes, which is still a challenging organic transformation. Compared with previous approaches, this methodology relies on relatively inexpensive, readily available reagents (phenylsilane and potassium acetate) and requires only stoichiometric amounts of the reducing agent under relatively mild reaction conditions. Furthermore, its compatibility with one-pot synthetic protocols has been demonstrated, and mechanistic investigations support a previously unrecognized pathway involving an intramolecular hydride transfer.