In the Baeyer-Villiger

The original library of 10 000 clones used in the Baeyer-Villiger reaction [89] was screened for performance as potential catalysts in the sulfoxidation [32]. This led to the discovery of at least 20 mutants having enantiomeric excess values in the range of 85-99%, some being (R) selective and others being (S) selective. Five mutants resulting in enantiomeric excess values of >95% were sequenced (Table 2.2) [32]. 

In the Baeyer-Villiger oxidation of [4.3.3]propellane-8,ll-dione 74 the propellane-bis-lactones formed, 75 and 76, are accompanied by a dispirolactone 77 22. Different product mixtures result when different (acidic or more basic) reaction conditions are employed but it has been shown experimentally for the head-to-tail propellane bis-lactone 75, vis-a-vis the isomeric dispiran 77, the latter appears to be the thermodynamically more stable product, resulting from the former under acidic conditions (p-TsOH/ C6H6, 7 days, r.t.). The structures were established by means of X-ray diffraction and H- and 13C-NMR spectroscopy. 

SCHEME 174. Yields and ee values obtained for different products in the Baeyer-Villiger oxidation employing chiral TADOOH hydroperoxide (60)... 

The migration order of groups in the Baeyer-Villiger oxidation is valid also for chlorofluoro-alkyl ketones, in which the isopropyl group specifically migrates to give the isopropyl ester of chlorofluoroacetic acid (Tabic 11).195... 

A new transition state (7) of the addition step in the Baeyer-Villiger reaction was found by B3LYP calculations. The role of proton acceptor is played by the carbonyl-oxygen atom, and the free energy barrier is lower than that previously estimated. This finding changes the mechanism for the acid catalysis.231... 

The hydrogenation of 63 occurred quantitatively and with high stereoselectivity (25 1 in favour of 62). The regioselectivity was similarly good in the Baeyer-Villiger rearrangement (12 1) in favour of 61 over the isomeric lactone. Attempts to convert the lactone directly to 60 X = z-Bu gave only low yields. 

Alternatively, acids can activate peroxides, for example, in the Baeyer-Villiger reaction (394) ... 

G. Strukul, Transition Metal Catalysis in the Baeyer-Villiger Oxidation of Ketones , Angew. Chem. Int. Ed. Engl. 1998, 37, 1198-1209. 

Similar migrations to electron-deficient oxygen also occur. In the Baeyer-Villiger rearrangement a ketone is reacted with a peracid. The product is an ester in which one of the alkyl groups of the ketone has migrated to oxygen ... 

The Baeyer-Villiger rearrangement often is called Baeyer-Villiger oxidation (see the last subsection of Section 14.3.2, Oxidative Cleavage of Ketones). In the Baeyer-Villiger rearrangement a carbonyl compound (ketones are almost always used) and an... 

G. Strukul, Transition Metal Catalysis in the Baeyer-Villiger Oxidation of Ketones, Angew. 

To finish this chapter, a Beckmann rearrangement that is not all that it seems, f-Butyl groups migrate well in the Baeyer-Villiger reaction and, indeed, Beckmann rearrangement of this compound appears to be quite normal too. 

In the Baeyer-Villiger reaction, a ketone is oxidized to an ester by persulfuric acid, H2S05. 

R, = disaccharide, Rj =trisaccharide Scheme 21.1 Site selectivity in the Baeyer-Villiger oxidation of premithramycin B by MtbOIV. 

The acylations of a-alkoxy hydroperoxides such as (79) furnish peroxy esters that are related to the intermediate produced in the Baeyer-Villiger reaction. " The peroxy ester undergoes the Criegee rearrangement to a dioxonium ion which in turn is converted into an ester. Thus, ozonolysis of (+)-( )-dihydrocarvone (78) affords a 1 1 mixture of diastereomers (79). Acetylation and rearrangement... 

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