A Few Experimental Observations for the Baeyer-Villiger Oxidation

Furthermore, stereogenic R groups migrate with retention of configuration. 

Another common and useful rearrangement is the Favorskii rearrangement, which involves a carbanion intermediate. An example is shown in Eq. 11.60. It involves the base-induced conversion of an a-halo carbonyl to a carboxylate. If the starting material is a cyclic ketone, a ring contraction results, and this is one of the most useful applications of the Favorskii rearrangement. 

In some cases an alternative mechanism is involved in what has been called a pseudo-Favorskii rearrangement (Eq. 11.61). The reaction involves nucleophilic addition to the carbonyl, followed by breakdown of the tetrahedral intermediate with concomitant migration 

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