BaeyerVilliger

Baeyer–Villiger oxidation is a chemical reaction that converts ketones into esters (or cyclic ketones into lactones) through oxidation with peracids. It was discovered by Adolf von Baeyer and Victor Villiger in 1899. The reaction is widely used in organic synthesis to introduce an oxygen atom adjacent to the carbonyl and to rearrange the carbon skeleton.

Mechanism: The process proceeds via formation of a Criegee intermediate, a tetrahedral peroxide derived from the ketone and a peracid. Migration of a substituent from the carbonyl-bearing carbon to the adjacent oxygen occurs, accompanied by departure of a carboxylate leaving group. The migrating group determines the regioselectivity, yielding esters from acyclic ketones and lactones from cyclic ketones.

Reagents and conditions: Common reagents include peracids such as mCPBA or peracetic acid, used in various solvents and temperatures. The reaction is compatible with many functional groups but can be sensitive to harsh conditions or highly reactive substrates. The migration aptitude influences the product when both sides could migrate.

Scope, limitations, and variants: It efficiently converts many aryl, alkyl, and cyclic ketones to the corresponding esters and lactones. Aldehydes are generally not substrates for standard Baeyer–Villiger oxidations. Enantioselective versions exist using enzymes, notably Baeyer–Villiger monooxygenases, enabling asymmetric oxidations to chiral lactones and esters.

Applications: The BV oxidation is a staple method in natural product synthesis and in the preparation of polymer precursors such as lactones used in polyesters. In modern chemistry, enzymatic BV oxidation provides sustainable routes to enantioenriched products and expands the method's utility.