Chloroperoxidase oxidation

Figure 17.14 Proposed mechanism for the vanadium chloroperoxidase oxidation of chloride by hydrogen peroxide. (From Ligtenbarg et al., 2003. Copyright 2003, with permission from Elsevier.)...

Chloroperoxidase Oxidation of primary alcohols to aldehydes in acetate or citrate buffer/hexane or ethyl acetate [66]... 

The enantioselective epoxidation of a series of co-bromo-2-methylalkenes catalyzed by chloroperoxidase (oxidant t-BuOOH) is correlated somewhat with the molecular dissynunetry. ... 

Styrene was successfully oxidized to the S-product both by xylene monooxygenase from P. putida mt-2 [113] and styrene monooxygenase from Pseudomonas sp.VLB120 [114] (Scheme 9.13), with the latter enzyme displaying a particularly large substrate tolerance with excellent stereoselectivity (>99% ee). In this context it is interesting to note that both xylene monooxygenase as well as chloroperoxidase are very selective for mono-epoxidation in case of presence of multiple alkene functionalities [115]. 

Ayala, M. Robledo, N. R. Lopez-Munguia, A., and Vazquez-Duhalt, R., Substrate specificity and ionization potential in chloroperoxidase-catalyzed oxidation of diesel fuel. Environmental Science Technology, 2000. 34(13) pp. 2804-2809. 

Taurog et al. [216] showed that contrary to previous suggestions, both iodination and coupling are catalyzed by the oxoferryl porphyrin Tr-cation radical of TPO Compound I and not the oxoferryl protein radical. HRP catalyzed the oxidation of bisulfite to sulfate with the intermediate formation of sulfur trioxide radical anion S03 [217] HPO, MPO, LPO, chloroperoxidase, NADH peroxidase, and methemoglobin oxidized cyanide to cyanyl radical [218],... 

Oxidation and Halo-hydroxylation of Monoterpenes with Chloroperoxidase from Leptoxyphium fumago... 

Kaup, B.A., Piantini, U., Wust, M. and Schrader, J., Monoterpenes as novel substrates for oxidation and halo-hydroxylation with chloroperoxidase from Caldariomyces fumago. Appl. Microbiol. Biotechnol., 2007, 73, 1087-1096. 

Chloroperoxidase-cataiyzed Oxidation of Phenyl MethylsuMde in Ionic Liquids... 

The heme enzyme chloroperoxidase (CPO), produced by the marine fungus Caldariomycesfumago, is a versatile enzyme which exhibits a broad spectrum of chemical reactivities and it is recognized as a most promising biocatalyst for synthetic applications. Recently, pure (R)-phenyl methylsulfoxide (ee > 99 %) was prepared by chemo- and stereo-selective oxidation of phenyl methylsulfide with CPO in citrate buffer-ionic liquid mixtures. ... 

Chiappe C., Neri, L. and Pieraccini, D., Application of hydrophilic ionic liquids as co-solvents in chloroperoxidase catalyzed oxidations. Tetrahedron Lett., 2006, 47, 5089. 

In the oxidation of aryl methyl sulfides catalyzed by chloroperoxidase from Caldariomyces fumago with racemic 1-phenylethyl hydroperoxide instead of H2O2 as oxygen donor, it was found that (k)-sulfoxides, the (S)-hydroperoxides and the corresponding (k)-alcohol are produced in moderate to good enantiomeric excesses by double stereodifferentiation of the substrate and oxidant (Eq. 2, Table 3) [68]. 

Furthermore, the preparation of the antibiotic Pyrrolnitrine by oxidation of the amino-functionalized precursor with the chloroperoxidase from Pseudomonas pyrrocinia was reported (Eq. 13) [155]. The mechanism of this peroxidase-catalyzed N-oxidation has not been elucidated. 

Oxidation of benzyl alcohol catalysed by chloroperoxidase exhibits a very high prochiral selectivity involving only the cleavage of the pro-S C-H bond. The reaction mechanism involved the transfer of a hydrogen atom to the ferryl oxygen of the iron-oxo complex. An a-hydroxy-carbon radical and the iron-hydroxy complex P-Fe -OH form. They may lead to the hydrated benzaldehyde or stepwise with the formation of the intermediate a-hydroxy cation. 

The reaction of other minor or type D catalases such as methemoglo-bin and metmyoglobin is not treated in detail here, because they are minor activities, significantly lower than even that of chloroperoxidase. The orientation of residues on the distal side of the heme is not optimized for the catalatic reaction to the extent that there is even a sixth ligand of the heme, a histidine, that would preclude a close association of the heme with hydrogen peroxide without a significant side-chain movement. It is only after an extended treatment with H2O2 and oxidation of the Fe that a low level of catalatic activity becomes evident. 

Oxidizing enzymes have also been used as key catalysts in mulH-step reacHons for the production of antibacterial and anHviral agents. Horseradish peroxidase and chloroperoxidase have been used in the producHon of the macrocycHc glyco-... 

As already reported in Section II.A.2, the enzymes chloroperoxidase (CPO) and Copri-nus peroxidase (CiP) catalyze the enantioselective oxidation of aryl alkyl sulfides. If a racemic mixture of a chiral secondary hydroperoxide is used as oxidant, kinetic resolution takes place and enantiomerically enriched hydroperoxides and the corresponding alcohols can be obtained together with the enantiomerically enriched sulfoxides. An overview of the results obtained in this reaction published by Wong and coworkers, Hoft and... 

The enzyme-catalyzed stereoselective oxidations of 1,2-dithiane and l,4-dihydro-2,3-benzodithiin were also investigated <2002CC1452>. Using naphthalene dioxygenase and chloroperoxidase, enantiomerically enriched sulfoxides (1,2-dithiane 1-oxides) were obtained l,4-dihydro-2,3-benzodithiin yielded a product of 32—47% ee with an excess of the (6)-configuration while 1,2-dithiane yielded almost enantiopure (96% ee) (R)-configured 1-oxide. Finally, 1,4-dihydro-2,3-benzodithiin 2-oxide was also prepared by perborate oxidation <1988JOC2608>. 

During the past year, chloroperoxidase (CPO) was found to catalyze the smooth asymmetric epoxidation of functionalized cii-alkenes, such as the unsaturated ester 32. The reaction appears to be limited to 2-alkenes (i.e., methyl group on one side of the alkene), although some branching on the longer alkyl chain is tolerated. Allylic alcohols are oxidized to the corresponding unsaturated aldehydes but without epoxide formation <99TL1641>. 

The haem peroxidases are a superfamily of enzymes which oxidise a broad range of structurally diverse substrates by using hydroperoxides as oxidants. For example, chloroperoxidase catalyses the regioselective and stereoselective haloge-nation of glycals, the enantioselective epoxidation of distributed alkenes and the stereoselective sulfoxidation of prochiral thioethers by racemic arylethyl hydroperoxides [62]. The latter reaction ends in (i )-sulfoxides, (S)-hydroperoxides and the corresponding (R)-alcohol, all In optically active forms. 

---