Microbial Baeyer-Villiger reactions

Another example of a highly regio- and enantiospccific microbial Baeyer-Villiger reaction is the transformation of racemic bicyclic ketone 17 by Acinetobacter TD 63433. This leads to chiral lactones 18 and 19 which are of particular interest as synthons for prostaglandin synthesis. Interestingly, each enantiomer of the racemic substrate reacts with a different regioselectivity for the oxygen atom insertion, and the enantioselectivity of the reaction is excellent. 

To avoid rapid further degradation of esters and lactones in microbial Baeyer-Villiger reactions catalyzed by hydrolytic enzymes and to maximize product accumulation in the culture medium, three approaches are possible ... 

The molecular reasons of enantiodivergent Baeyer-Villiger reactions [1229, 1230] can either be the docking of the substrate in a single enzyme in two opposite modes or due to the presence of different monooxygenases present in the microbial cells [1231]. 

Mihovilovic and coworkers have utilized a microbial Baeyer-Villiger oxidation to desymmetrize readily available 8-oxabicyclo[3.2.1]octene 218. Their key reaction used E. coli in a whole-cell oxidation to give multi-gram quantities of 219 in high optical purity (Scheme 59) [67], To demonstrate its utility they transformed 219 into 220, 221, and 222 thus intercepting intermediates that had previously been converted into the namral products (+)-trani-kumausyne, goniofufurone, and (+)-showdomycin. 

Bacteriological sulfur, 23 577-578 Bacteriophages, 3 135 12 474 in fermentation, 11 46 Bacteriorhodopsin, 20 826, 840 photochromic material, 6 603 Bacteriosins, 12 76. See also Bacteriocins Bacteriostatic water, 18 714 Bacterium lactis, 11 7 Baculovirus expression system, 5 346 Baddeleyite, 21 489 26 623-624 colorants for ceramics, 7 346t Badische Anilin und Soda Fabrik (BASF) terpenoid manufacture process, 24 481 Baeyer-Villiger oxidation reactions, 14 592 chiral recognition by enzymes, 3 675 microbial, 16 401 Baffled shellside flow, 13 262 Baffles, in stirred tank geometries,... 

Alphand, V., Archelas, A. andFurstoss, R., Microbial transformations 16. One-step synthesis of a pivotal prostaglandin chiral synthon via a highly enantioselective microbiological Baeyer-Villiger-type reaction. Tetrahedron Lett., 1989, 30, 3663. 

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... 

The microbial reaction sequence to testololactone (24) involves an intermediate ester 23 from the first Baeyer-Villiger oxidation that ordinarily undergoes hydrolysis by the esterases present in the fermentation environment. However, the tendency of the ester to undergo hydrolysis and further conversion can be blocked by the use of the potent esterase inhibitor diisopropylfluorophosphate. Most of the reported work417-421 with steroids is concerned with the oxidation of 22 to acetate 23. 

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