Oxidation selective enzymatic

A Potthast, T Rosenau, C-L Chen, JS Gratzl. Selective enzymatic oxidation of aromatic methyl groups to aldehydes. J Org Chem 60 4320-4321,1995. 

Figure 16.4-1. Selected enzymatic oxidations of aldehydes. A oxidation of complex natural products such as retinal B oxidation of aliphatic and a,P-unsaturated aldehydes C oxidation of (hetero)arylic aldehydes D oxidative cleavage of the aldehyde-carbon atom yielding terminal alkenes.

For example, the method potentially opens an access to compounds with a doubly chiral isopropyl unit (Scheme 14). In the pro-5-selective enzymatic hydroxylation of isobutyric acid (88) to (S)-/3-hydroxyisobutyric acid (89) the stereochemistry of the hydroxylation at C-3 is not known. It could be studied by preparing 88 in a doubly chiral form via stereocontrolled ami-SN2 reaction of dimethyl cuprate with the tosy-late 90 to give 91 which is then degraded by Lemieux- and then Baeyer-Villiger oxidation to 88. 

Figure 16. Highly stylized representation of the essential features of selective enzymatic oxidations...

Bes T, Gomez-Moreno C, Guisan JM et al. (1995) Selective enzymatic oxidations stabiUzation by multipoint covalent attachment of ferredoxin NAD-reductase an interesting cofactor recycling enzyme. J Mol Catal 98 161-169... 

The separation has proved to be difficult, although methods based on supported liquid membranes with chiral selectors [165] and selective enzymatic oxidation to pyruvic acid have been reported [166]. Either the enantiomer selectivity is too low or the loss of raie of the lactate isomers is limiting. To overcome this, our group... 

Hummel, W., Kuzxi, M., and Geueke, B. (2003) An efficient and selective enzymatic oxidation system for the synthesis of enantiomerically pure D-tert-leucine. Org. Lett., 5, 3649-3650. 

Finally, if only the -CH2OH end of the aldose is oxidized without affecting the -CHO group, the product is a monocarboxylic acid called a uronic acid. The reaction must be done enzymatically no satisfactory chemical reagent is known that can accomplish this selective oxidation in the laboratory. 

Enantiomers, preferential crystallization of 59 Endo selectivity 798 Ene reactions 808, 809 Enones, synthesis of 732 Enthalpies of formation 102, 103 Enynes, synthesis of 956 Enzymatic kinetic resolution 829 Epimerization 399 Episulphides, oxidation of 237 Episulphones 650, 775 Episulphoxides, photolysis of 742 a,/J-Epoxysulphones reactions of 811, 812 rearrangement of 685 synthesis of 612 / ,y-Epoxysulphones 781 y,<5-Epoxysulphones 627, 628 Epoxysulphoxides reactions of 613 rearrangement of 744 synthesis of 327, 612 Erythronolides 831... 

Enzymatic Oxidations Clean, Highly Selective and Catalytic 314... 

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