Overview:

Baeyer-Villiger oxidations are a really handy way to make esters from ketones. The general form of this reaction is as follows:

Under basic conditions, a peroxide can be deprotonated. This nucleophilic species can then attack a carbonyl group to form a tetrahedral intermediate. Once the tetrahedral intermediate collapses, instead of kicking the peroxide back off, the more highly substituted alkyl substituent makes a sigmatropic shift to the oxygen, kicking off the alcoxide as the leaving group, forming the ester.

Example of a Baeyer-Villiger oxidation:

Here the common MCPBA (m-chloroperoxybenzoic acid) is used as the peroxide. It is one of the most common peroxides because it is cheap and crystalline, and can be used in stoichiometric quantities.