Baeyer-Villiger reaction chemoselectivity

By controlling reaction conditions and by proper choice of the peroxy acid, it is often possible to favor the Baeyer-Villiger reaction over epoxidation. An illustrative example of the usefulness of the Baeyer-Villiger reaction is the stereospecific, and regio- and chemoselective conversion of the unsaturated bicyclic ketone shown below to a cyclopentene containing three consecutive stereogenic centers. 

The high chemoselectivity for the Baeyer-Villiger process was utilized in the synthetic elaboration of another hetero-bicyclic substrate. The biooxidation only provides the expected unsaturated lactone in a desymmetrization reaction without compromising the olefin functionality. The biotransformation product was then converted to pivotal intermediates for C-nucleosides like showdomycin, tetrahydro-furan natural products like kumausyne, and goniofufurone analogs in subsequent chemical operations (Scheme 9.17) [161]. 

Cyclobutanones are susceptible to Baeyer-Villiger oxidation. The epoxide (186) cannot be prepared by reacting the ketoalkene (185 equation 67) with MCFBA. Moderate, chemoselective epoxidation has been observed in the reaction of (185 equation 68) with ( -trichloroethylperoxycaib(Miic acid (190) prepared in situ from the triazole (189) and H2O2. ... 

Baeyer-Villiger oxidation (p. 853) catalytic hydrogenation (p. 844) chemoselective reaction (p. 848) dissolving-metal reduction (p. 846) enantioselective reaction (p. 857) epoxidation (p. 855) functional group interconversion (p. glycol (p. 858)... 

Mukaiyama s conditions have also been used in other aerobic oxidation reactions of substrates including thiols (Table 5.2, entries 1—4, 10 and 11), alkanes (entries 8, 12 and 14) and alcohols (entries 9 and 13), as well as reactions involving lactone formation via a Baeyer-ViUiger oxidation (entries 5-7) and oxidative decarboxylation (entry 16) [15-17]. While nickel, iron and cobalt aU selectively oxidize thiols to sulfoxides, Co(II) is the most active (entries 1—4) [15 b]. Of particular synthetic interest, the chemoselective and diastereoselective aerobic oxidation of the complex sulfide, exomethylenecepham (entries 10 and 11), was observed with no overoxidation to the suUbne or oxidation of the olefin [16 a]. The diverse substrate scope in entries 1-9 suggest iron and nickel species tend to have similar reactivity with substrates, but cobalt behaves differently. For example, both iron and nickel displayed similar reactivity in Baeyer-Villiger oxidations, with cobalt being much less active (entries 5-7), yet the opposite trend was observed for sulfide oxidation (entries 1—4) [15]. Lastly, illustrating the broad potential scope of Mukaiyama-type oxidations, alcohol oxidation (entries 9 and 13) and oxidative decarbonylation (entry 15) reactions, which are oxidase systems, have also been reported [16b, 17b]. 

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