Migratory aptitude, in the Baeyer-Villiger

In general, the ability of a group to migrate in the Baeyer-Villiger reaction (the migratory aptitude ) appears to increase in the series ... 

One example is the Baeyer-Villiger reaction. The migratory aptitude of groups in the Baeyer-Villiger reaction depends on their ability to bear a positive charge . Hudrlik... 

An experimental and theoretical study of the Baeyer-Villiger (BV) oxidation of ketones has examined its uncatalysed and acid-catalysed forms, and fluoro- and chloro-substituted substrates.344 In assessing migratory aptitudes, fluoroalkyl groups are only slightly less favourable than alkyl (by 0.3/0.5 kcal mol-1, calculated/observed), whereas migration of a chlorinated substituent is significantly more difficult (ca 2.6 kcal mol-1). 

The second reason the Baeyer-Villiger reaction is significant is that it cleaves a carbon-carbon bond. You have seen only u very small number of reaetions capable of this (e.g., o/.onolysis Chapter 12). The power of this method to be a synthetic tool lies both in its high. selectivity when the carbonyl compound i.s not symmetrical tsee di.sciis.sion of migratory aptitudes) and in the. subsequent chemistry available iVom the ester or acid, which will be covered shortly. 

Problem 9.2. When cyclohexyl methyl ketone is treated with trifluoroperethanoic acid (trilluoroperacetic add, CF3CO3H), the Baeyer-Villiger reaction occurs to yield a product, the and C spectra of which are shown. Given these results and the anticipated migratory aptitude expressed in the series shown above, decide which of the two possible products, cyclohexyl ethanoate (cyclohexyl acetate) or methyl cyclohexanecarboxylate, is obtained. 

The regioselectivity of the Baeyer-Villiger oxidation of a-chlorocyclobutanones has been reported to be affected by substituents in position y to the carbonyl group such that stereoelectronic effects outweigh the relative migratory aptitudes of the groups... 

An investigation into the migratory aptitudes of C-2 versus C-4 in Beckmann, Schmidt, and Baeyer-Villiger reactions employed 13C n.m.r. spectroscopy and demonstrated that all reactions proceeded with migration of both C-2 and C-4... 

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