Facile Reduction of Carboxylic Acids by Zinc Borohydride

摘要

It is well-known that basic borohydrides do not reduce carboxylic acids directly and invariably need addition of other reagents such as AlCla, I_2, etc. to effect this transformation. However, zinc borohydride, which is considered to be a mild reagent, readily reduces both aliphatic and aromatic acids to the corresponding alcohols in refluxing THF. The reaction requires only stoichiometric quantities of hydride for this conversion.