Baeyer-Villiger mono-oxygenase

Table 2.4. Microbial Baeyer- Villiger mono-oxygenases in lactone formation...

Baeyer-Villiger mono-oxygenase with sufficiently broad substrate range to be able to biotransform other substrates, including bicyclo(3.2.0.)hept-2-en-6-one (1)... 

The mono-oxygenases which catalyse a series of oxidations such as hydroxylation, epoxidation, heteroatom oxidation and Baeyer-Villiger oxidation (Figure 2.24), depend on NADH or NADPH and cofactors usually Fe or Cu. A particularly important reaction is the direct incorporation of molecular oxygen into non-activated carbon centres, such as in synthesis of important steroidal drags by microbial 11 dr-hydroxylation of... 

Figure 2.24 Reactions catalysed by mono-oxygenases, hydroxylation of carbon centres, aromatic hydroxylation, epoxidation of alkenes, heteroatom oxidation and Baeyer-Villiger oxidation of a ketone.

Mono-oxygenase Hydroxylation, Baeyer-Villiger, epoxidation Chemocatalysis fails Multi-component sensitive NADPH-enzymes... 

The mono-oxygenase from Acinetobacter sp NCIB 9871 can be cloned and expressed in the same baker s yeast that we met at the start of this chapter. This yeast carries out Baeyer-Villiger reactions and supplies its own NADPH from other enzymes in the yeast. A conventional kinetic resolution of cyclopentanones 113 gives single enantiomers of lactone and starting material.35... 

Figure 4.9. Mono-oxygenase-catalysed Baeyer-Villiger reactions.

Walsh, C. T., Chen, Y. C. (1988). Enzyme Baeyer-Villiger Oxidations by IHavin Dependant Mono-oxygenases. Angew. Chem. Int. Ed., 27, 333. 

Mono oxygenases have been used in Baeyer-Villiger oxidations to obtain optically active lactones (Fig. 10.18). A cyclohexanone monooxygenase from Acmetobacter calcoaceticus has been widely used. In the oxidation of2-oxabicyclo [3.2.0] -heptan-7-oneby A. calcoaceticus (Fig. 10.18(a), n = 0, m = 2), the S,S-substrate led to the normal lactone, whereas the R,R-substrate gave the abnormal lactone, with ee s of 90 and >98%, respectively. Other substrates proceeded with a similar stereochemical outcome. 

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