A rearrangement reaction, sometimes known as the Dakin reaction, commonly used in organic synthesis in which a ketone reacts with a peroxy acid to form an ester. For example,
R-CO-R → R-CO-O-R
The reaction is equivalent to the insertion of an oxygen atom next to the ketone's carbonyl (>C=O) group. Meta-chloroperbenzoic acid (m-CPBA; ClC6H4.CO.O.OH) and trifluoroperethanoic acid (CF3.CO.O.OH) are typical peroxy acids employed in the reaction. It was discovered by Adolf von Baeyer and the German chemist V. Villiger in 1899.