Two-step transformation of ketones to carboxylic acids through a ring-opening reaction of epoxynitriles with a squarate anion

Abstract Herein, we describe a new method to convert epoxynitriles, which can be synthesized from ketones via the Darzens condensations, into carboxylic acids using a squaric acid and 1,8-diazabicyclo[4.3.0]undec-7-ene. The epoxide ring is opened via nucleophilic attack by the squarate anion, prepared in situ, at the sterically less hindered site of the epoxide moiety, and the resulting intermediate is transformed into an acyl cyanide, which is subjected to basic hydrolysis to afford the corresponding carboxylic acids.